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[Articles Home]  [Add Article]  

Homebrew Tak-tenna

from Bill Brown, KA6KBC on January 12, 2009
View comments about this article!

HomeBrewed - 40 Meter TAK-tenna

Project Overview:

So I've been reading about this Small Space antenna that is being sold as the TAK-Tenna. Really neat idea - Has a 30 inch boom and Spiral Coils on the ends. See a picture at http://www.taktenna.com/

Looks easy to build -- Right?
So I Built my version out of wood - Mine is very ugly as compared to the store bought one (See Picture).

Materials and Tools Parts:

1.) 3 - Wooden sections - 1 1/2 in X 1/2 in X 8 ft - Cost 92 Cents each - Home Depot

2.) 1 - 100' Spool of Steel Guide/fence Wire - Cost - $7 - Home Depot - The purchased version uses some type of "Special" patented wire, but this seemed fine. I tried Copper, but it was not stiff enough to make the Spiral Coils. Again from quick test it did not seem critical - From what I read larger gauge wire is better for improved band width.

3.) 1 - 25 foot RG8 coax with PL259 - Radio Shack - Close Out - $5

4.) 2 - Packages - Nuts/Bolts - $2 - Home Depot

5.) 2 - Alligator Clips - Free from my junk Box.

6.) Few Feet of Electrical Tape - Free from my junk Box.

Total Material Cost: $16.76

The commercial version uses PVC and tie wraps, which would have been much easier.

Tools:

a.) Saw - I just used a simple hand saw.

b.) Drill with wood bits - I just used a simple hand electric drill.

c.) Flat Screw Driver and Rubber Mallet.

d.) Wire Cutters.

e.) Gloves and Eye Protection.

Fab Time:

For my version was about 4 hours - Drilling Lots of Holes and feeding the wire in to make the Spiral Coils was most of the work.

Testing:

However -- Test wise it isn't bad I got it tuned up on 40 meters at about 8 feet off the ground and it has an SWR 1:2 to 1:5 from 7.30 to 7.175 MHZ (Without a Transmatch). Also does ok on 15 meter - Tune up wise. Bad news the performance is not Great - Signal pick up is several S units below my Dipole, but it does work. From what I have read the Antenna has problems in that most of the performance is based on feedline radiation (See the links below):

http://lists.conting.com/archives//html/Towertalk/2008-04/msg00339.html
http://groups.google.ie/group/rec.radio.amateur.antenna/browse_thread/thread/167fb7a34305cf3e

Summary of Results:

I'm still testing and it was an interesting experiment. The Antenna fits into a small space 25 inch X 30 inch. Hey it works. If you have no space it might be worth $20 and a few hours of your time or If you aren't a Homebrewer Buy one. If you make your own one point - I needed more wire than the 468/7.2 MHZ = 65 Feet Total or 32.5 Feet per side - I had to add wire after the fact. So I would make it about 33.5 per side.

Measurements:

One more added item - Someone had a question about my dimensions: Boom = 30 inches meaning Cross Pieces are about 30 inches a part. Cross Pieces = 25 Inches Across or 12.5 Inches from center Hole Spacing from Center, but this did not seem critical, but I used: 12 in 11 in 10 in 9 in 8 in 7 in 6 in 5 in 4 in 3 in Total Turns = 10

Tuning:

a.) Put the antenna in the expected operating position (Mine was about 8 feet in the air).

b.) Connect the Coax via the Alligator Clips about 2 inches from the end of the smallest inner Spiral Coils.

c.) Measure SWR in the Center of the 40 Meter Band (SSB or CW) you intend to use most. If the SWR is too high move to Step d.

d.) Move the Alligator Clips/Coax out evenly about 2 inches on each Spiral Coil.

e.) Repeat Step c.

I was able to achieve acceptable SWR after about 3 cycles of adjustment without a Transmatch.

Construction Steps:

a.) Measure/Cut - (1) - 30 inch boom section.

b.) Measure/Cut (4) - Cross members - 25 inches sections.

c.) Measure/Notch @ about 12.5 Inches - I just cut with a hand saw then tapped out with a Flat Screw Driver and Rubber Mallet.

d.) Drill holes in Cross members as noted above - Starting 3 inches from center then working out in 1 inch steps out to 12 inches. If you are careful you can save sometime by drilling two parts at a time.

e.) Here is the Hard part - Put the Notched Cross members together then start feeding the wire to create the Spiral Coils. I started from the biggest to the smallest. I would recommend Gloves and Eye Protection.

f.) Once the Spiral Coils are completed bolt them to the Boom.

g.) I then used the last section of wood for mast and bolted the Boom to this part.

Credit Where Credit is Due:

Very important work on this orignial Design was done first by:

Bill Petlowany, K6NO

http://www.wr6wr.com/newSite/articles/features/olderfeatures/antennaswithtwist.html

Then Refined by:

Steve -- WA2TAK

http://www.tak-tenna.com/

Also some very interesting Recent work from WBillJohnson - Looking at Boom Lengths and Coils Spacing:

http://wbilljohnson.com/zmvantenna/zmvantenna.htm#intro

73 Bill -- KA6KBC

Member Comments:
This article has expired. No more comments may be added.
 
Homebrew Tak-tenna  
by W9PMZ on January 12, 2009 Mail this to a friend!
"Bad news the performance is not Great "

If you made the cross arms out of ceramic then the elements could double as barbecue grill tops...

Interesting article!

73,

Carl - W9PMZ
 
Homebrew Tak-tenna  
by K9ZF on January 12, 2009 Mail this to a friend!
A VERY short loaded dipole....


73
Dan
--
Amateur Radio Emergency Service, Clark County Indiana.
K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla> List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Mailing list!

 
RE: Homebrew Tak-tenna  
by KG4YMC on January 12, 2009 Mail this to a friend!
I noticed that these antennas look like an old nikon film developing reels . Wonder if they got the inspiration from them ? could you load up a 120 film reel ? same results? kg4ymc
 
Homebrew Tak-tenna  
by K1CJS on January 12, 2009 Mail this to a friend!
Considering that the "Taktenna" kit used to cost about $70 and the price doubled in the past year, the article is useful to those who wanted to experiment with the design. Isn't it odd how about $20 or $30 of parts and a little prefabrication can add up to a 300 or 400 percent profit? Only in America!
 
RE: Homebrew Tak-tenna  
by PULLRAFT on January 12, 2009 Mail this to a friend!
I wish the article would detail the new law of physics, where when measured, the VSWR shows the reflected power many times greater than the forward power applied to the load.

The world's "energy problems" have been solved. It is a true miracle.
 
RE: Homebrew Tak-tenna  
by K0BG on January 12, 2009 Mail this to a friend!
How many people know that it was designed by PT Barnum?

Alan, KBG
www.k0bg.com
 
RE: Homebrew Tak-tenna  
by N4LQ on January 12, 2009 Mail this to a friend!
A VERY loaded short dipole!
Steel wire???? Very high currents here. Use heavy guage copper or tubing. Wood insulatation? Very high voltage here. Use better insulation. Also use a 1:1 current balun at the feed point. This thing is like one big coil. Follow all precautions used in coil design. It won't cost much more.
 
RE: Homebrew Tak-tenna  
by WG8Z on January 12, 2009 Mail this to a friend!
Amazing the effort some will put forth to build a lousy performing antenna. Whats next? Gold plated PL-259's and Oxygen free coax.
Zed
 
RE: Homebrew Tak-tenna  
by N2RRA on January 12, 2009 Mail this to a friend!
Great article Bill!

You provided theory and technical information that makes this a perfect example of what we should expect from future editors.

Now! To the Tac-Tenna

I purchased this antenna before the Tac-Tenna was even heard of and performed testing and operating of my own. At that time it was 2007 and band conditions were extremely poor. A friend has recently purchased one himself and allowed me to build it for him and test once more to give it a second chance. Here are the results I've experienced!

Construction the first time took me about an hour and a half and found working with the wire Elements made it necessary for gloves to be used. The new Tac-Tennas now use a different stock of wire that is softer and easier to assemble. Time to build on the second one was 30mins. On both versions I was able to aquire about a 1.5 swr on 40 meters. The rig of choice used was an Icom 7000 and LDG AT 100 pro auto tuner. I'm able to tune on every band from 80m-10m no problem running up to a 75 ft of RG-8X coax.

Performance results!

In 2007 I found the Tac-Tenna in my view a horrible antenna. I made A/B switch comparison checks to a G5RV type antenna. Not even an actual resonant 40 meter dipole. Both were at the same height! All bands were suffering from no sun spots which made for poor band conditions. For these times you need to pull out every bit of gain with least compromises possible. This antenna is a compromise but if there are no other options well you do what you can.

The most recent test for 2008!

I started testing about 3 months ago and found better results. Of course the bands are doing better than the first test results I encountered. Forty meters seems to work quite well but still yet does not beat my dipole. Now I'm a bit impressed that I can hold long QSO's.

There are times receive can be down on the Tac from my dipole about 3-5 S-units and most times the G5RV is stronger on TX by about 2 S-units. If you can't put up a dipole this Tac-Tenna should work as well as a traped 40 meter dipole. All you need is a little RF to reach the Ionosphere and your in the game.

Results will vary on other bands! Don't expect a whole lot and hope that the DX, or state side contact is running a great receiver and yagi, because that's what it will take to help you and your Tac- Tenna out.

This is a very cool concept and project to build and will be worth while building to work HF. Get your tools out and get building. It'll be fun!

73!


 
RE: Homebrew Tak-tenna  
by KT8K on January 12, 2009 Mail this to a friend!
Has anyone compared its performance to a light bulb on a post? It might beat that ... I'm pretty sure, however, that a practically invisible, full size dipole made of 20 gauge magnet wire would beat it by at least a couple of S-units, and would probably still beat it when lying on the ground.
Maybe the high price of the Tak-Tenna is to cover the advertising ...
73 de kt8k - Tim
 
RE: Homebrew Tak-tenna  
by KT8K on January 12, 2009 Mail this to a friend!
Has anyone tried making several of these, mounting them on a boom, and tuning them so they make a multi-element beam? Has anyone tried modeling that?
73 de kt8k - Tim
 
Homebrew Tak-tenna  
by KB8NDM on January 12, 2009 Mail this to a friend!
I notice that the ARRL site has a commercial Tak-Tenna featured prominently: http://www.wedothat-radio.org/
 
Homebrew Tak-tenna  
by W0ZD on January 12, 2009 Mail this to a friend!
I perfer the light bulb antenna.
 
RE: Homebrew Tak-tenna  
by N3OX on January 12, 2009 Mail this to a friend!
N2RRA says: "If you can't put up a dipole this Tac-Tenna should work as well as a traped 40 meter dipole"

No, it won't. Not even close, unless that trapped dipole is also 30 inches long... or maybe 60 inches and poorly constructed.

Trapped and loaded dipoles can actually do about equally as well efficiency-wise as full size ones as long as they're not too much shorter than maybe 66% size. Largely you trade off bandwidth for performance in a good one. Between 66% and 50% performance drops of a noticeable but not too severe amount. Well below half size you have to work pretty hard to keep efficiency above abysmal and when you get down to a little tiny thing like this antenna, it's probably only going to be a fraction of a percent efficient... a few to 10% max if it excites the feedline sufficiently.

I think it's worth mentioning there's no such thing as a 30 inch antenna that can even touch a 30 to 60 foot long antenna, or even a well constructed **10-15 foot long antenna** on 40m and there likely never will be.

The only thing that could come even remotely close is a superconducting magnetic loop, and it would probably have a bandwidth too narrow to pass a SSB signal. You'd have to use CW and you'd have to keep filling it with liquid nitrogen ;-)

I do recognize that some people want to get on the lower bands in extremely limited space, but I have yet to see one of these installed where you couldn't fit a 10 or 15 foot long conventionally end loaded (coil and capacitance hat) dipole.


KA6KBC says:

"Bad news the performance is not Great - Signal pick up is several S units below my Dipole, but it does work."

That's the cool thing about ham radio. Everything works.

I can work European stations on 80m with 2.5W power output to a 1/4 wave vertical. I've worked maybe 5 countries on 160m with 5W output, and an effective radiated power of probably 1.25W. NU4B, another participant in these forums, has 86 countries on 80m with 5W to a Windom.

So it's no surprise to me that a TakTenna style antenna on 40m can make lots of contacts.

But if we quadrupled the length of the antenna and used good high Q copper loading coils out near conventional capacitance hats, it could probably be 10dB better and still fit the bill for people who need a very compact 40m antenna.

For those people who have enough coax to be radiating from the coax, a simple slim vertical on a fiberglass pole would be much less obtrusive and work much better.

Oh well. Bill, thanks for writing it up so that others can try it for themselves.

-Dan
















 
RE: Homebrew Tak-tenna  
by WA8MEA on January 12, 2009 Mail this to a friend!
Isn't it odd how about $20 or $30 of parts and a little prefabrication can add up to a 300 or 400 percent profit? Only in America!
-------------------------------------------------------
Although these people a somewhat of a competitor, I cannot stand by and let statements like this go creeping by.

It's obvious some people have NO idea what it takes to run a ham business. (Or ANY business for that matter.) This person obviously thinks that $20 to 40 worth of parts is the only expense a ham business endures.

What about taxes in NUMEROUS forms? Advertising? Shipping supplies? Copy costs? Rent? Utilities? (Which are often much higher for a business....) Bank merchant services and associated fees? Insurance? Catalog printing and distribution? Website design and maintenance? Need I go on??????

Then there are those who try to reduce the ham business's sales by either copying the product (Like MFJ....) or putting out homebrew articles of popular products so the ham business gets even LESS revenue.

Yep, ham businesses are getting filthy rich. (Sarcasm dripping....)

73, Bill - WA8MEA
 
RE: Homebrew Tak-tenna  
by K6CRC on January 12, 2009 Mail this to a friend!
A ham sez "Isn't it odd how about $20 or $30 of parts and a little prefabrication can add up to a 300 or 400 percent profit? Only in America!"

Hopefully, this is a joke. The cost of running a business that makes anything means a profit margin barely in double digits. That PC you bought at Fry's gave the manufacture 7-9% margin on the sale, if they were lucky.

The lack of knowledge of how a business runs is staggering.
 
RE: Homebrew Tak-tenna  
by WA7NCL on January 12, 2009 Mail this to a friend!
Next time you see an antenna like this. Check out the drawings and pictures of Heinrich Hertz original antenna system. Nothing new here folks ... more along now.
 
RE: Homebrew Tak-tenna  
by W7ETA on January 12, 2009 Mail this to a friend!
Thanks for the pix and the "article".

Looks like a FUN experiment.

Best from Tucson
Bob
 
RE: Homebrew Tak-tenna  
by N2RRA on January 12, 2009 Mail this to a friend!
W3OX,

Your absolutely right!

If you would read my first review of this antenna I was the only one to give it a 1 out of 5. I thought I was the only one with sense on that review.

Thanks for knocking it down when I thought I'd tried to keep it sensitive on this review.

73 all!
 
RE: Homebrew Tak-tenna  
by WB2LCW on January 12, 2009 Mail this to a friend!
Original article about an antenna like this one is in 73 Magazine issue #113 February 1970, Titled
" 18 Inch Dipole for 15 meters" by K9LGH!
 
RE: Homebrew Tak-tenna  
by WB2LCW on January 12, 2009 Mail this to a friend!
I was thinking about trying to build one. But I am thinking about a six foot boom! The longer straight portion is the better I think! I have a tiny back yard
myself!

73 Mike
 
RE: Homebrew Tak-tenna  
by K1CJS on January 12, 2009 Mail this to a friend!
Well gee, excuse me! I made that 'profit' statement somewhat in jest and also in admiration. If I remember, when this antenna came out, Bill was putting the kits together in his garage in his spare time. If you wanted one, most of the time you had to go on a waiting list.

The cost of the parts was about $25, the packing and shipping materials took about $15 more, and there were still more costs--warehousing, instruction printing, etc. Maybe Bill made $10 per antenna, if that. He wasn't getting rich, but he was making a little money--if he wasn't he wouldn't offer the kit at all.

Obviously, he has had to expand his operation because of the amount of orders he was getting and has to charge more to cover his expenses. Today with the state of the economy, that is to be expected. Nobody said he was becoming a millionaire from this venture.

For cripe sake, lighten up!
 
Homebrew Tak-tenna  
by W8KQE on January 12, 2009 Mail this to a friend!
Many of us living on smaller 'postage stamp' sized lots realistically have room only for a 20 meter dipole or smaller (if you are to keep the antenna in the backyard only). And we don't have much room for verticals with long radials. The 'Tak-tenna' design is very compact, but I am wondering if there are any 40m wire antenna designs around the size of a 20m dipole that would perform better than the 'Tak-tenna' on 40m?
 
RE: Homebrew Tak-tenna  
by KC0JGJ on January 12, 2009 Mail this to a friend!
I echo Bill - WA8MEA input.
This is a well done article.
Snarkizims aside.
Their are a lot of people who could and would benefit from this info.

That is what this hobby is all about. Experiment and tell others of our results. Adapt to our environment. Make due with what we have to work with. This makes for interesting innovations and discovery's.

To berate MFG's for the cost of a product... GEEE Wizzz!!

By the time you calculate the time, skill, resources, and energy you put into a project like this the cost benefit is not as much as you would think. If this was a Communist country then you could a valid point. But we are based on free enterprise. If you can produce a product that costs significantly less than other products on the market then by all means do so. Put up or shut up as they say...

73
kc0jgj




 
RE: Homebrew Tak-tenna  
by N3OX on January 12, 2009 Mail this to a friend!
"was thinking about trying to build one. But I am thinking about a six foot boom! The longer straight portion is the better I think! I have a tiny back yard
myself! "

Absolutely. The longer the straight portion the better. Six feet is much better than 30 inches and 12 feet is much better than six feet.

I very much doubt your backyard is so small you couldn't swing an antenna 12 feet long. But if it is, it is (though you may be better off with a vertical).

But there are other improvements you can make. Use fairly heavy conductors. Use 1" aluminum tubing for the horizontal sections and instead of steel (presumably galvanized) spiral hats use conventional spoked hats and good form factor copper loading inductors.

Or if you feel strongly about trying the spiral hats, at least use copper. Copper clad steel wire would be a good combination of conductivity and strength/stiffness that was missing in the author's experience. You can wind a beautiful looking spiral hat out of #12 copper clad steel, I'm sure.

I do have to say that there's at least one major advantage to the TakTenna /Petlowany design for homebrewers. The "wind some wire on a thing until it resonates" is a very popular form of homebrew antenna building, and for good reason. It's easy to do.

This antenna is in that class of antennas, but at least has the resonators out at the very ends of the antenna, so you end up with the horizontal portion at constant current.

So for a given length of horizontal radiator, and a given type of conductor, the TakTenna/Petlowany type design will outperform the "wind some wire on a broomstick until it resonates" type of continuous helical antenna.

End loading is a good thing, and this design does have that going for it. However, 30 inches is ridiculously short, and even apartment dwellers could do better than that.

If you can do 12 feet, do it. If you can do 20 feet, do it! There's nothing at all magical about 30 inches, and there is *definately* nothing magical about having an "electrical quarter wavelength" of wire on either side of the antenna. That is essentially a *pure coincidence* that works out just right in this form factor.

If you build these things for small backyard use:

1) Don't get tied up in thinking you need 32 or 33 or 34 feet of wire on either side. You might need more, you might need less.

2) Make the center section as long as you can. That's the part that radiates. Take it out to the actual limits of your physical space. Seems like the antenna in the picture could have been 10 or 12 feet at least.

3) Use decent gauge copper clad steel wire to build the antenna. Resistive losses are a killer, and copper has several times less RF resistance than galvanized steel.

73
Dan

 
RE: Homebrew Tak-tenna  
by N3OX on January 12, 2009 Mail this to a friend!
" The 'Tak-tenna' design is very compact, but I am wondering if there are any 40m wire antenna designs around the size of a 20m dipole that would perform better than the 'Tak-tenna' on 40m?
"

I'm thinking that there really, really needs to be one and I might design one for public consumption.

I can go around eHam saying "use conventional spoked capacitance hats and lumped element inductors of good form factor" all I want, and it's going to increase the number of builders who do so maybe 1%. But if I put a complete design with pictures on my website, I bet more people would do it.

Most people don't want to design a homebrew antenna, they want a weekend construction project, and that's a fair desire, so maybe I'll hit the Home Depot some weekend in the near future and see what I can come up with.

73
Dan
 
Homebrew Tak-tenna  
by KB2DHG on January 12, 2009 Mail this to a friend!
Nice try and I commend your willingness to experament. OM I tried a lot of antenna projects and I always come back to the famed G5RV dipole.
TO ALL you hams and readers out there, listen up. If you can't put up a tower and beam antennas, if you can't have a verticle with LOTs of ground radials... I reccomend a G5RV HOME BUILT!
simple and effective. use 450 ohm ladder line at 31 feet... use bear copper clad wire 12 or 14 guage cut at 51 feet each. DO NOT use any balun and connect the ladder line to the shortest possable run of coax. get the antenna up as high as you can, 35 feet being a good place and enjoy! 20 meters workes best and I can tune every band except 160 meters... My home brew G5RV is yealding me very good results, the Condo's HOA don't see it and I am working the world!
 
Homebrew Tak-tenna  
by KL7AJ on January 12, 2009 Mail this to a friend!
For its dimensions, it's probably about as good a configuration as any. I wonder if anyone has ever measured the current distribution on the horizontal element.
 
Homebrew Tak-tenna  
by KE4ZHN on January 12, 2009 Mail this to a friend!
Seems like an awful lot of effort to build what amounts to a leaky dummy load.
 
RE: Homebrew Tak-tenna  
by LOVEHANDLES on January 12, 2009 Mail this to a friend!
I wonder if this antenna would work for shooting skip on the CB bands?
 
RE: Homebrew Tak-tenna  
by WI7B on January 12, 2009 Mail this to a friend!

Cool article. Most especially your inventiveness based on your inquistiveness.

If indeed it acts as a short-form dipole on 40m, did you attempt to use a balun besides directly connecting a coax with alligator clips?

73,

---* Ken
 
RE: Homebrew Tak-tenna  
by AB7E on January 12, 2009 Mail this to a friend!

The Tak-tenna gets rave reviews from people who never bothered to compare it to anything else, which as one poster here mentioned, illustrates a neat thing about ham radio ... under the right conditions almost anything will work. I've experimented with a lot of different wire antennas, and one of the very worst of the bunch was a long rectangular loop close to the ground fed for vertical polarization. It was generally pathetic for both DX and USA, probably due to large ground losses, but I still managed a QSO with Reunion Island from Arizona on it one evening using just 5 watts from my end.

None of that means we should knowingly and willingly put up an inferior radiator. It's not surprising that the author experienced a several S-unit disadvantage from his home-brew Tak-tenna compared to his dipole at the same height. Antennex (www.antennex.com) recently ran a couple of articles exploring the theoretical and measured peformance of the commercial Tak-tenna and found it to be roughly 20 db worse than a dipole if you discount the feedline radiation. With feedline radiation the performance disadvantage is less, but it is still typically several db worse than any decent wire antenna (dipole or vertical). I guess I can understand someone using the Tak-tenna if all they can put up is a balcony antenna, but in almost all other cases I just can't fathom how there wouldn't be a much better performing (and much cheaper) alternative.

So far 78 people here on eHam have given the Tak-tenna an average rating of 4.8, but I haven't found a single one of them who performed an A-B comparison to justify their high rating. Pretty sad. Kudos to KA6KBC for doing the comparison.

By the way, I don't see the ZR-series vertical antennas on the Force 12 website any more. It's a similar concept to the Tak-tenna but scaled for decent efficiency and is, in my opinion, a much better design (at least for the single band versions) that still fits in a very small space. Did the new owner drop the series?

73,
Dave AB7E
 
Homebrew Tak-tenna  
by KB2NAT on January 12, 2009 Mail this to a friend!
Thanks for a great article. I've wondered about the Tak-Tenna and wanted to do what you did. Articles like this sure make enjoyable reading as well.
 
RE: Homebrew Tak-tenna  
by KE7VUX on January 12, 2009 Mail this to a friend!
I wonder if something like this has a future as a mobile antenna.

Ham-stick or TakTenna? There's a comparison to make. (for that matter, a "hamstick dipole" for a fixed installation)

Mobile = compromise, so which would be a better performer for a mobile installation?
 
RE: Homebrew Tak-tenna  
by N6EY on January 12, 2009 Mail this to a friend!
"A ham sez "Isn't it odd how about $20 or $30 of parts and a little prefabrication can add up to a 300 or 400 percent profit? Only in America!"

Hopefully, this is a joke. The cost of running a business that makes anything means a profit margin barely in double digits. That PC you bought at Fry's gave the manufacture 7-9% margin on the sale, if they were lucky.

The lack of knowledge of how a business runs is staggering. "

Sure, the PC's have almost no profit, but have you seen the markup on accessories? On the order of 500-1000%!
 
RE: Homebrew Tak-tenna  
by N4KC on January 12, 2009 Mail this to a friend!
Well, in my opinion, the inaugaration of President Obama will...no, wait, that's over on that other goofy (and decidedly frightening) thread.

If the object of the article is to get some folks to experimenting with an antenna to see what it can do, to suggest a weekend project for somebody as N3OX noted, then the author accomplished that in spades. Great job! Well organized and documented.

I'm with K6CRC and WA8MEA on the profit ham manufacturers (or any small business) make, tho I see the original poster retracted his "tongue-in-cheek" criticism.

Yes, there may be a place for this antenna--commercial version or homebrewed--but seems like a small-gauge-wire dipole or loop or a vertical could offer much better performance. The G5RV is a good choice as described by someone up the way there, too, if you have a hundred feet and a center support.

This stuff is fun! Too bad some of these posts aren't.

Don N4KC
www.n4kc.com
www.donkeith.com
www.n4kc.blogspot.com
(A blog dedicated to rapid technological change and
its effect on society, media and amateur radio)



 
Homebrew Tak-tenna  
by G0GQK on January 12, 2009 Mail this to a friend!
I knew this antenna was designed by somebody else and Alan has said it was PT Barnum. I've been trying to find if there is a site showing designs which appeared in 73 magazine many years ago because there were many experimenters during the 1960-70's period.

g0GQK
 
Homebrew Tak-tenna  
by WA8EBM on January 12, 2009 Mail this to a friend!
Nice article. At least it got us thinking about limited space antenna designs. I think the real future in this is in fractal antennas. I was fascinated when I first saw some amateur radio HF designs several years ago but any new information has disappeared. I would assume it is either patents or military applications that squashed them. I was especially interested in fractal hf ground systems for verticals.
 
RE: Homebrew Tak-tenna  
by N4JTE on January 12, 2009 Mail this to a friend!
Thank you for nicely presented article. When you become dissappointed with your tak I suggest you turn it into a very effective 2 meter quad as I did about 3 days later. I respect Steve's entrepenurial spirit and his getting a product out there in a tough market, he makes no ridiculous claims for gain and such, the problem is with the reviews on eham that are at best misleading unless it's the only antenna they have or had. Hope the author keeps on building and sharing his results, tnx.
Bob
 
RE: Homebrew Tak-tenna  
by AB7E on January 12, 2009 Mail this to a friend!
WA8EBM: "I think the real future in this is in fractal antennas. I was fascinated when I first saw some amateur radio HF designs several years ago but any new information has disappeared. I would assume it is either patents or military applications that squashed them. I was especially interested in fractal hf ground systems for verticals."

Not so. Scientific debunking is what rightfully tossed those overhyped claims for fractal geometries (at least for offering any advantage for size reduction) in the trash heap. Search around the web and you'll find all sorts of discussions on it that will (or should) change your mind. I'm not saying that a fractal geometry compression doesn't electrically shorten a wire antenna ... I'm saying there's no magic in it that has any advantage over any other compression technique, and mechanically it's a grossly inferior approach.

73,
Dave AB7E
 
RE: Homebrew Tak-tenna  
by N3OX on January 12, 2009 Mail this to a friend!
"Ham-stick or TakTenna? There's a comparison to make. (for that matter, a "hamstick dipole" for a fixed installation) "

If I had to give a wild guess, 40m Hamstick Dipole vs. TakTenna type as constructed here, or hamstick on the mobile vs Half TakTenna type both with well choked-off feedlines?

Hamstick dipole wins.

If you considered the *same overall length* for both types of antenna, and used high conductivity wire like copperweld or just plain copper, the end loaded TakTenna type one would handily win.

And I think KL7AJ is probably more or less right that this antenna is *close* to about as good as you can do for the size. A slightly better optimization of the loading could make it a little less lossy but a little narrower 2;1 SWR bandwidth.

The problem I have with using a 30 inch antenna on 40m for home station use is that it's only 30 inches long ;-)

If you use a 30 inch long dipole at N feet off the ground, for N>5 or 6ft or so, I bet you do better with an N foot tall top loaded vertical fed against whatever radials you can put down.

You mount this thing at 15 or 20 feet like some people do, that means you have a mast and coax going up 15 or 20 feet, and it would be a snap to lay down radial wires to the best extent of your abilities and build a good 15 or 20 foot top loaded 40m vertical. If you're really married to spiral pancake end loading you can probably even do that.

On a mobile, it might make sense to use a 3 or 4 foot top loaded antenna fed against the vehicle, but at home most ultra-short loaded dipole installations would be vastly improved by just using their support mast for the antenna and throwing out the dipole.

I feel the same way about Isotrons and EH antennas, which really are basically tank circuits that excite the coax, as is probably a 40m TakTenna and even a hamstick dipole to a large extent. If you replace their coax with a wire or pipe and load to resonance with a simple capacitance hat and coil assembly and lay down even a modest radial field for your small backyard, you go up 10dB in signal.

I have a 40m tank circuit:

http://n3ox.net/files/40mtank_1.jpg

If I installed that at the top of a 33 foot piece of coax and grounded the coax at the base to a good RF ground, I would have built a really fancy 1/4 wave vertical that was voltage fed at the top, with the capacitance of the tank circuit to the universe as the "counterpoise". That's what a lot of people end up with when they use an antenna like this.

73
Dan



 
RE: Homebrew Tak-tenna  
by KA6KBC on January 12, 2009 Mail this to a friend!
Hi All,

Thanks for the comments. I build this back in June 08, but just completed this write up during Christmas. It was fun to do some Antenna research/testing. Hope you consider doing your own testing/posting.


I did note that one of my links did not work:

"From what I have read the Antenna has problems in that most of the performance is based on feedline radiation (See the links below)".

http://groups.google.ie/group/rec.radio.amateur.antenna/browse_thread/thread/167fb7a34305cf3e

http://lists.contesting.com/_antennaware/2008-04/msg00021.html


73's,

Bill - KA6KBC

http://www.myhamshack.com/KA6KBC/





 
radial wires  
by W7COM on January 12, 2009 Mail this to a friend!
n3ox: ..it would be a snap to lay down radial wires to the best extent of your abilities..

I'll remind my lower back of that when I'm done :)
 
RE: Homebrew Tak-tenna  
by KC8VWM on January 12, 2009 Mail this to a friend!
The spiral coils have experimentation potential.

I wonder if this design would work any better if you droop a 10 foot or so section of the wire from the ends of the spiral and reorient the wire into a sort of spiral with hanging bobtail wire attached to the bottom of the cross member?

73 Charles - KC8VWM



 
RE: Homebrew Tak-tenna  
by KC8VWM on January 12, 2009 Mail this to a friend!
... and make the spiral coil a bit larger for more capture area?

 
RE: Homebrew Tak-tenna  
by KB6QXM on January 12, 2009 Mail this to a friend!
The scary thing is that someone spent that much time on this project. How about using a high Q antenna such as a Texas bug catcher on a car in your driveway? At least you have a reasonable antenna.

In RF, there is no "free lunch".

As a bug catcher is a mobile antenna, it is still not even close to ideal, but at least the antenna is a high Q antenna and has reasonable performance. Omni-directional, but without the real estate for a real antenna, all you will get is marginal performance.

Physics is Physics!!!
 
RE: Homebrew Tak-tenna  
by LNXAUTHOR on January 12, 2009 Mail this to a friend!
to the author:

try not to take the unkindly comments regarding your antenna experiment too hard - it is true that $5 worth of wire can work wonders and provide an efficient antenna - but you have to have the space and height to do so (simple wire dipole)

in your situation, i'd go with others' recommendations, such as a good mobile antenna or short vertical...

if you have a little bit of space, two Lakeview hamsticks in a dipole adapter attached to an SD20 or other type of vertical support can also work well

(and you can then use the inexpensive Armstrong rotator!)

:-)

good luck with your antenna experiements - i've built some good ones, some bad ones, some cheap ones and some expensive ones - they all weren't good and cheap, but they were all fun!
 
RE: Homebrew Tak-tenna  
by KA6KBC on January 12, 2009 Mail this to a friend!
Hi Robert,

"....The scary thing is that someone spent that much time on this project..."

Not scary - That's what Hams/Engineers do - Right ? We build things and figure out how they work (or Why they don't work) ? Also try to figure out how we can make a better or cheaper mouse trap :o)

- 73's - Bill - KA6KBC
 
RE: Homebrew Tak-tenna  
by KB6QXM on January 12, 2009 Mail this to a friend!
Bill,

Not dogging how much time you spent on the project, but the simple fact is that you cannot cheat physics. Any good engineer knows that.

If someone is not technically knowledgable, I can understand that, but antenna theory is antenna theory based on physics.

I understand that some people do not have the means or desire to live in the country with a lot of land to put up the proper antenna.

I appreciate that some people try to "cheat" the system by making an antenna for 40 meters the size of an antenna for say 2 meters.

Your response from people in the know is to try to make an antenna that will not act as a large radiating dummy load. If you want to experiment, then get a field strength meter, work with other materials, try other antenna designs or try smaller wavelengths.

I am not putting you down for your construction of a home brew antenna. I just was wondering about the return on investment from a time perspective with an antenna that is 20 db down from a simple coil loaded dipole.

Just food for thought.

Good luck in your experimentation.

73
 
Mobile Tak-tenna  
by WA5UHK on January 12, 2009 Mail this to a friend!
Taking bugcatcher to a whole new level..
 
RE: Homebrew Tak-tenna  
by WB2WIK on January 12, 2009 Mail this to a friend!
>RE: Homebrew Tak-tenna Reply
by KC8VWM on January 12, 2009 Mail this to a friend!
... and make the spiral coil a bit larger for more capture area?<

::That won't really help. The spirals are just end loading, the antenna itself is the short horizontal dipole between them.

I tried the "commercial" version of this antenna and it was 20-30 dB down from everything else I have (like my full-sized 40m inverted vee at 55 feet).

However, that doesn't mean it won't make contacts: It certainly will. 40m is an amazing band! I recall working a station in Florida from here in Los Angeles on 40m SSB when I was mobile...pretty decent signals...to discover my antenna was just the Hustler foldover mast because I forgot to screw on the 40m resonator. SWR was probably 40:1. It made the contact, anyway: 54" aluminum mast on the back of the car.

WB2WIK/6
 
RE: Homebrew Tak-tenna  
by KC8VWM on January 12, 2009 Mail this to a friend!
I think some people are forgetting this is not about building a maximum performance antenna. The main objective is about designing a limited space antenna - so of course, it's going to exhibit limited performance charateristics.

However, if one thinks outside the box for a moment, it may be possible to capitalize on maximizing the space available with this spiral design. They make antenna's using slinkies, so why not build a parasitic array using spiral loops?

I am really feeling this design is more than capable of outperforming a set of hamsticks in a dipole configuration because the overall physical dimensions and capture area is larger and/or similar with respect to physical size. In addition and unlike a hamstick, the spiral wire coil is not "bunched up" together like a hamstick which seems to suggest it may exhibit lower losses and better overall performance.

Also unlike a hamstick dipole arrangement, I am suspecting there is likely to be some gain exhibited if a reflector is used in conjunction with the driven spiral element.

Not sure how this can be measured/modeled exactly but then again you can't simply ignore the principles and physics of a parasitic element array regardless if it design is a yagi, loop, it has traps, coils, capacity hats or even if it's designed into a spiral configuration.

73 de Charles - KC8VWM
 
RE: Homebrew Tak-tenna  
by KC8VWM on January 12, 2009 Mail this to a friend!
by KC8VWM on January 12, 2009 Mail this to a friend!
... and make the spiral coil a bit larger for more capture area?<

::That won't really help. The spirals are just end loading, the antenna itself is the short horizontal dipole between them.

----

I dont understand. I thought the spiral was a 1/4 wave legnth of wire with a reflector constructed behind it and spaced accordingly for 40m similar to a quad?

Are you suggesting the design is based a dipole - meaning equal lengths exist for both spiral elements?

I will have to look at that again...

73 de Charles - KC8VWM


 
RE: Homebrew Tak-tenna  
by KC8VWM on January 12, 2009 Mail this to a friend!
Can't really tell how or where this antenna is fed in this article.

"b.) Connect the Coax via the Alligator Clips about 2 inches from the end of the smallest inner Spiral Coils."

This suggests the coax is fed only to the center of the quarter wave spiral coil at the front of the array right? I am assuming the rear coil is unattached and functions as the reflector? ... or are we just constructing an elaborate coiled dipole here?


ie.

O---V---0

0 = coil#1 - "v"= feedpoint - 0 = coil #2

0v-----0

?

73 de KC8VWM
 
RE: Homebrew Tak-tenna  
by N3OX on January 12, 2009 Mail this to a friend!
"I dont understand. I thought the spiral was a 1/4 wave legnth of wire with a reflector constructed behind it and spaced accordingly for 40m similar to a quad? "

Nope.

It's essentially just a combined capacitance hat/loading coil structure.

The spiral-end antenna I modeled shows maximum radiation broadside to the thing that for some unknown reason is called the "boom"

I would call that the "element"

http://n3ox.net/files/N3OX_spiral.jpg

I went back and checked something, though, and there is one pretty interesting property of this antenna vs. a normal coil loaded dipole. I found the resonance of this model empirically after thinking I was in the ballpark of the 20m version (I was just guessing lengths)

So the spacing between the coils is 36" and the coils were a guess. Since I thought I was guessing approximately right for 20m, I looked in the vicinity of there for resonance, and actually found it was resonant more on 17m. I tweaked it a little bit in the model to tune it for 18.15MHz.

But I went back and looked. It also has a resonance near 6.13 MHz and one near 30.4 MHz, and probably higher ones. It's got a fundemental and is resonant close to odd harmonics. However, on all three of its resonant frequencies that I checked, the pattern is the simple broadside pattern consistent with a (loaded) dipole.

A spiral appears to be a multiband resonator (a big enough conventional looking inductor could also be that) It does happen that the total wire length in the spiral is 1/4 wavelength long at 6.1MHz ...

So the end spiral doohickeys do have the interesting property of being able to provide multiband resonance (possibly not the most useful set: close to f, 3f, 5f,etc) in a simple form factor. But they don't radiate. In fact, the antenna has extremely nice nulls off the ends, especially on 6.1MHz.

On the higher bands, the field cancellation from the spirals is less complete, but this only makes the nulls shallower! It never becomes the primary mode of radiation.

The best conventional analogy to the spirals that I can think of at the moment is a slightly less than 1/4 wave shorted transmission line stub in series with a capacitance hat. Since it's slightly less than 1/4 wave shorted at f, it's also slightly less than 3/4 wave near 3*f and slightly less than 5/4 wave near 5*f and will be inductive at all those frequencies.

It does appear that the spirals support standing waves of current (there's actually a null and phase reversal in the currents on the higher bands). But the radiation from the nearly completely cancels as can be seen by the radiation pattern in the picture I posted.

If I think about it long enough I think I can find the transmission line stub and unfold it... it's there I suspect, just like the "velocity factor" antenna.

Unlike the velocity factor antennas, this antenna has a shot at radiating an OK signal, but a problem with it (and the VF antenna) is that the loading mechanisms are operating very close to self resonance (as evidenced by the standing waves of current on the spirals).

In a resonant circuit like that, you can find ***any value of inductive reactance you need*** in between a few hundred ohms inductive and tens of thousands of ohms inductive reactance as you approach self resonance from the inductive side. You need 3000 ohms to load a 3 foot antenna on 6 MHz? You got it.

But the problem comes in as you get very close to self resonance. EXACTLY at resonance in a shorted 1/4 wave transmission line stub, the input impedance is a very high ***pure resistance*** (If the line were lossless it would be infinite, but with loss it's merely high).

On the inductive side of resonance, you can get 12000 ohms or 3000 ohms of inductive reactance, but there will also be a large resistive part... so the Q of that inductor might be 1 or 2 or 5. It'll load the antenna to resonance, but adds a large amount of resistance. How bad it is depends on the loss in the line, and if I can find and unfold a 1/4 wave stub out of this antenna, at least it'll be made from copper wire (in my design... ) and it won't be coax like a V.F. antenna.

But no matter how interesting the ends are, I can say two things:

1) they're at least slightly more lossy than an optimum lumped LC resonator made of a good coil and a capacitance hat, even if they're made of copper and not steel or "special wire"

and

2) the bit that does the radiating is the wire that goes between them, it has constant and fairly high current and is just a short dipole.

73
Dan



 
Homebrew Tak-tenna  
by W5HLP on January 12, 2009 Mail this to a friend!
Very nice essay and of course it touched some nerves but there has been SOME very good open minded debate.

For anyone interested in an engineering viewpoint of the Tak-Tenna, Antennex (www.antennex.com) has a two part analysis complete with modeling over the last couple of months. Not as simple a system as you might think. Worth a look. An very nice objective look without a lot of diatribe.

I have been using the Tak-Tenna at about 20 feet - just one of many "experiments" in the antenna farm - and I personally like some of the results. First - I use it on 40m only. Second - low noise. I use it basically in NVIS and it does a nice job. Some feedline radiation is present - installation matters.

It particularly seems to like digital modes (PSK31) for short hops - maybe a light bulb would work as well but this is cuter. I'm keeping mine.

Oh BTW - fractal antennas are still a hot topic. Just because its not the current rage in Amateur circles doesn't necessarily mean all research has stopped. Other folks do use RF. Similarly - not all physics stopped with Maxwell.

73
Herman
W5HLP
"There are two kinds of ships; submarines . . .and targets."
 
RE: Homebrew Tak-tenna  
by KC8VWM on January 12, 2009 Mail this to a friend!
I dont understand. I thought the spiral was a 1/4 wave legnth of wire with a reflector constructed behind it and spaced accordingly for 40m similar to a quad? "

Nope.

It's essentially just a combined capacitance hat/loading coil structure.

The spiral-end antenna I modeled shows maximum radiation broadside to the thing that for some unknown reason is called the "boom"

I would call that the "element"

http://n3ox.net/files/N3OX_spiral.jpg


-----

Thanks for the information, very informative discussion. FB on the .jpg very helpful.

But "what if" it was redesigned and the antenna was fed as I originally thought?

ie.

0v---0

When fed as depicted above, the short "boom dipole" would no longer be the radiating antenna element.

Is it true the first spiral would then essentially become a 1/4 wave driven element and the rear spiral element would become the reflector.

What if we then unwound a portion of the spiral at the end (like a bobtail) and let it hang down below the mast? Would that help to improve overall efficiency while utilizing the same amount of physical space?

Hmmmm.. Just thinking.

73 de Cahrles - KC8VWM
 
Homebrew Tak-tenna  
by KI4WCA on January 12, 2009 Mail this to a friend!
Thanks for the article!I have always been fascinated by tiny antennas and also huge ones!I saw an article years ago where a guy made a pancake loop about 2 feet across with a capacitor for resonating it and used it with great effect on 40.It hung over his operating position!
Efficient...no.But he made contacts and apparently reveled in the people who did not believe what he was using.It had a microscopic bandwidth of course.
Again, thanks for the article.
73 DE KI4WCA
 
RE: Homebrew Tak-tenna  
by QRZDXR2 on January 12, 2009 Mail this to a friend!
hey I wouldn't say yours looked too bad. After all its the performance that counts. Had you made yours out of PVC pipe I think it would look about the same as the store bought one. Think of the money you saved making your own.

Wood works so long as it stays dry. PVC works in all weather so long as it doesn't get hot and start to droop as well as the sunlight eventually turns the plastic to junk.

The better material to use here would be fiberglass that has a UV coating to keep the sunlight from damageing it eventually.

I have always wondered about the new engineered woods that are used for decks. They are plastic as well as some wood I think. Should lend themselves to being used for antenna applications.

Looking good from my view.. keep up the good work
 
RE: Homebrew Tak-tenna  
by N3OX on January 12, 2009 Mail this to a friend!
Yeah, I think I actually like the wood better too ;-)
 
RE: Homebrew Tak-tenna  
by KB3HJK on January 13, 2009 Mail this to a friend!
N3OX - you have really cleared up alot of my misconceptions about these compromise antennas. I have owned both the Tak and Isotron, and performance is as you say - very spotty, at best. I wonder what your opinion on another compromise antenna is, a vertical - the Ventenna HPF vertical (http://www.ventenna.com/HFp-V.html) Another dummy load? And worse, another feedline radiator? Maybe it would be better than the previously mentioned contraptions. God, I would really like to get back on 40 with a bit more reliability.

Kevin
 
RE: Homebrew Tak-tenna  
by AB7E on January 13, 2009 Mail this to a friend!
KB3HJK: "I wonder what your opinion on another compromise antenna is, a vertical - the Ventenna HPF vertical (http://www.ventenna.com/HFp-V.html)"

I don't have any personal experience with the Ventenna, but it appears to be simply multiple sections of "hamstick"-type elements with wire spiral wrapped around pieces of fiberglass. The seller claims 200 KHz bandwidth on 40m (without a tuner) and a height of only 10.5 feet, which means there is a lot of loss.

A good indication of the level of technical understanding behind the Ventenna is to read the designers discussion of radials at

http://www.ventenna.com/files/Radials.pdf

In it, he states that three ground mounted radials represent the optimum configuration for a ground mounted vertical in general, and that any more than that degrade performance. He bases that silly claim on SWR measurements made with the Ventenna. The truth, of course, is that as the number of radials increases the ground losses would decrease (to a point), the Q of the antenna would go up, the bandwidth would decrease, the feedpoint impedance would likely decrease to a few ohms, and the SWR would indeed go up.

So yes, it sounds to me basically like a dummy load in its recommended configuration, or at best a difficult-to-feed very short antenna if you put a proper number of radials under it.

73,
Dave AB7E
 
RE: Homebrew Tak-tenna  
by KB3HJK on January 13, 2009 Mail this to a friend!
Dave, thanks. Ahh, there are just no shortcuts, are there! 468/freq in mhz. Like a fool, I will keep trying to beat nature though.
 
RE: Homebrew Tak-tenna  
by AB7E on January 13, 2009 Mail this to a friend!

To KB3HJK,

Please don't get me wrong ... I don't want to imply that high-efficiency small antennas can't be designed and built. Far from it, and I think that experimenting with such things would be a lot of fun. N3OX suggested he might try to come up with something and I hope he does. In fact, I wonder why we HF'ers don't organize field events to see who can build an antenna with the best signal-to-size ratio, kind of like the VHF'ers do for raw gain. It could even be done from a distance ... design the antenna so that it could be shipped and assembled by someone else at a common site, and announce the event ahead of time so that hams everywhere could contribute to the signal comparisons. I wonder how many commercial vendors of ultra-small antennas would participate ;)

In theory, a short antenna can be made efficient enough to compare very well to a full size version, but the tradeoffs (lower impedance, narrower bandwidth) are inescapable and you need to address them carefully to make it work well in practice. In most cases, that requires some pretty careful measures to prevent your RF from being wasted ... either in the antenna itself, the matching scheme used to feed it, or in the ground underneath it.

The antennas that sound too good to be true, or rely only on endorsements from users with no direct standard of comparison, should be avoided.

73,
Dave AB7E
 
RE: Homebrew Tak-tenna  
by W9OY on January 13, 2009 Mail this to a friend!
Dan's analysis got me thinking, you could do this by planting 2 poles at opposite sides of the lot. Attach some L/C capacity hats to the poles and then join them with a wire, and feed the thing with something like a hairpin match in the center. It would be mechanically easy to implement and should be pretty efficient, and pretty cheap to build.

73 W9OY

 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"In theory, a short antenna can be made efficient enough to compare very well to a full size version, but the tradeoffs (lower impedance, narrower bandwidth) are inescapable and you need to address them carefully to make it work well in practice"

And the *most important thing* for hams who need small antennas like KB3HJK does is to never forget that those tradeoffs are fundamental.

In order to radiate a certain amount of RF power into the universe with a short dipole, you *have to increase the current* flowing along the straight bit many times over what has to flow in a half wave dipole.

If you make a very short/small antenna and want to *radiate* the same amount of power, that *requires* a much higher current flowing in the radiating part of the antenna, period.

In order to pump more current through the antenna without causing significant losses, you have to reduce the loss resistance significantly compared to a big antenna.

And an antenna that needs lots of current to radiate a given amount of power is said to have a "low radiation resistance"

The power lost to heat in an antenna is basically I^2*Rloss (the antenna current squared times the loss resistance) The power radiated is I^2*Rrad (current squared times radiation resistance).

So what does this have to do with bandwidth? Well, a couple of things. One is that when you make an antenna smaller and drive high currents in it, you make a LOT more electrons slosh back and forth in a small physical space. To focus on a short cap hatted dipole, there's a LOT of magnetic field caused by the very strong current (lots of electrons per cycle) flowing through the horizontal dipole part, and there's a LOT of electric field caused by lots of electrons piling up on the capacitance hats, first one and then the other, as the RF cycle progresses.

A capacitance hat charges up on one part of the RF cycle, a quarter cycle later, all those electrons are rushing at maximum speed toward the other hat, another quarter cycle later, they're piled up on the 2nd hat, and another quarter cycle later they're rushing back toward the first hat. Energy is exchanged between the electric field, largely between the hats and the magnetic field as the electrons are rushing through the horizontal conductor.

Since everything is so compact, the electric and magnetic fields are very strong, and store a lot of energy near the antenna.

But we also know something else... we know that the radiation resistance is very small, and to make the antenna efficient, we must reduce the loss resistance. So the *total resistance* is very low. The resistance is associated with the energy lost per cycle of RF. Some goes to heat in the loss resistance, some goes to radiation, "dissipated" in the radiation resistance.

But if you compare the energy *stored in the fields around the antenna* vs. the energy *lost per cycle*, you find that there's a lot of energy stored vs. how much is dissipated in the radiation and loss resistances. The strong fields make the stored energy high, the low resistances make the dissipation small.

So the antenna is very "high Q." If you cut power to a very high Q antenna, it will ring down for a relatively long time as the stored energy is damped by the dissipation into loss and radiation. But we know from other circuits that high Q resonant circuits are very sharply tuned, and a small antenna is no exception. It has a very narrow bandwidth over which you can slosh current back and forth effectively in a resonant way.

Since the radiation resistance and the stored energy in the fields is fixed by the size and shape of the antenna, the only way to broaden the response of a certain size antenna with fixed tuning is to add losses!!!

This is fundamental, and will steer you away from very small, broad bandwidth antennas if you keep it in mind. You absolutely, positively must give up bandwidth to keep efficiency at small size.

This is why the very best tiny antennas will all be motor driven. Magnetic loops and mobile screwdriver antennas with capacitance hats are two great examples of how to get around the narrow bandwidth problem. Sure, the antenna is 10kHz between the 2:1 SWR points, but if you can tune that 10kHz anywhere you want between 5 and 21 MHz, who cares?

But there's even a point where motor drive doesn't save you. There's even a point where superconducting antennas don't save you.

There's a lower limit that few talk about (except a few crazy magloop guys who come close to running up against it)

If you make a very very tiny, extremely low radiation resistance antenna and you stamp out almost all the losses by welding together huge conductors, your antenna's bandwidth could become so narrow as to not pass even a SSB signal. ;-)

You'd actually roll off your audio if you had a 1kHz wide magnetic loop and could make the tuning stable!

But this is the basic fact you need to remember when antenna shopping. Quite small antennas should be easily retunable in small steps across a ham band, otherwise they are required to be *quite* lossy to give good SWR bandwidth. No matter what any manufacturer says, a tiny antenna needs to be VERY small in bandwidth for it not to be lossy.

And KB3HJK, as far as that particular HF-p antenna goes? It's nearly impossible to know exactly but I expect that since it covers 200kHz of 40m with no retuning and is only 10 feet long, it's probably going to be about 1% efficent.

For comparison, I built a 40 foot long 40m dipole with a loading/matching coil at the feedpoint that should have been about 80% efficient (-1dB) and was about 70kHz between the 2:1 SWR points. End loading could improve that, but the HFp isn't end loaded.

If you really need to get on 40m better than you have been in the sort of 3-10 foot antenna class, your next antenna should have a motor.

Or if you're worried about feedline radiators because you can put the antenna 20 feet up on a pole, just go ahead and make the pole the antenna instead. N0LX has some interesting voltage fed "loaded end fed half waves" on his website, and they actually model reasonably well.

And even a Tak-Tenna type antenna is maybe OK, the problem with them is that there's NO REASON to use a 30 inch antenna on 40m. It's too short. Do the same thing but make it 15 feet long and you'll be much better off.

73
Dan








 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"Attach some L/C capacity hats to the poles and then join them with a wire, and feed the thing with something like a hairpin match in the center. It would be mechanically easy to implement and should be pretty efficient, and pretty cheap to build. "

Yeah, you should *always* use all the space you've got. That's the first rule of efficiency for short antennas, bigger is easier ;-)
 
RE: Homebrew Tak-tenna  
by AJ4DW on January 13, 2009 Mail this to a friend!
Reviewing Bill Johnson's article I note that the performance/bandwidth improves as the distance between the two coils increases and as the radii of the coils increase... in other words, as it approaches a dipole.

I was excited about this antenna when it first came out... it looked very interesting and it had some great reviews. But when I ran A/B tests (as others have done) there was always a big signal loss (as others have found). As someone mentioned, "anything gets out", but that's no reason to settle for a lousy antenna. I don't believe that the TakTenna is a good solution for anyone.
 
RE: Homebrew Tak-tenna  
by WI7B on January 13, 2009 Mail this to a friend!
Dan N3OX,

But do the best small antennas have to have a motor, or just a way of adjusting the Hi-Q coil inductor to vary the tuning range of your narrow transmission band? I'm thinking specifically of Texas Bugcatcher-type coils that our manually "tapped".

Thanks for the insight on short-form antennas. Qualitatively, I always believe it helps to "think" like an RF photon: (1) how can I "escape" from through this too-small door?, and (2) what can I actually "see" since I'm bigger than any structure around me, save the earth or a house?

73,

---* Ken
 
RE: Homebrew Tak-tenna  
by KB3HJK on January 13, 2009 Mail this to a friend!
Dan, that was a GREAT explanation. Has me thinking of a motoroized hi-q dipole. Or maybe something a bit cheaper but similar.

I would assume the motor is for convienence, as opposed to having to run outside and make manual adjustments every 20-30 khz or so.
 
RE: Homebrew Tak-tenna  
by W4VR on January 13, 2009 Mail this to a friend!
Sounds like it's not worth the trouble buying or making one, according to your tests. You would be better off using a snake antenna laying on the ground!
 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"But do the best small antennas have to have a motor, or just a way of adjusting the Hi-Q coil inductor to vary the tuning range of your narrow transmission band?"

If you want to beat 5% or 10% efficiency or so on 40m with a 3 or 4 foot antenna, you need to retune a LOT. Probably on the order of 10 coil taps to get you across the 40m phone band?

And they need to be presets because just putting your hand near the loading coil will detune your antenna plenty that when you bring your hand away, you won't be on frequency any more, so the alligator clip kind of tuning procedure is difficult.

Since you're weaker than most stations, your best bet at making QSOs is probably to answer the CQs of loud stations.

Very short dipoles, at least, probably tend toward extreme sensitivity to getting wet. A magloop is better, but it's also much, much narrower for a given size (excessively low radiation resistance for the size).

Any antenna is going to work best as far out in the clear as you can put it.

Those things add up to remote actuation, in my book. No, you don't *really* need a motor, but I think there won't ever be a really wildly popular commercial antenna or homebrew project for a maximum-efficiency 3 or 4 foot 40m antenna that doesn't have a remote actuator in it. People will try it and after the eightieth trip outside, they'll go back to something lossy.

Depends on your operating habits, of course... if you really, really like to call CQ until you get an answer, or if you've got three nets you love, or if you operate PSK31, a fixed tuned or multiple tapped discrete tuned antenna with five or six taps you can plug in easily could do the trick.

If you're building an antenna for camping and are sitting at the picnic table running QRP with the antenna five feet away, maybe you can run over real quick and adjust taps or manual inductors or capacitors, or even use some sort of tuning rod or rope to get further from the antenna so you can hit resonance on the nose.

And you can probably stretch back into a good operating point tap in foul weather by using a tuner inside without too much of a performance hit, but that depends on how you match the thing to the feedline.

So you're right, what I *strictly* mean is you need some way to adjust the coils or whatever to resonate the antenna... but the antenna becomes infinitely more usable and operating time becomes much more fun if all you have to do is tap a little button next to the radio to run the motor for a split second and tweak it up to the next 20kHz block...

My magloop has a 2:1 SWR bandwidth of something like 10kHz or 15kHz on 40m. EZNEC says it's about 25% efficient with respect to a full size 1/4 wave vertical... which beats the pants off the couple percent you probably get with a 40m vertical that is only 10 feet long and covers the whole phone band.

But you're going to make a LOT more contacts with a 2% efficient antenna and no running outside than with a 25% efficient antenna that has 15 to 20 different settings across the phone band which change slightly depending on the environment.

73
Dan
















 
RE: Homebrew Tak-tenna  
by UC1AWX on January 13, 2009 Mail this to a friend!
Hmm. Loading up those utility lines will give you a really long antenna for 160m.
 
RE: Homebrew Tak-tenna  
by KI9A on January 13, 2009 Mail this to a friend!
RE: Homebrew Tak-tenna Reply
by WG8Z on January 12, 2009 Mail this to a friend!
Amazing the effort some will put forth to build a lousy performing antenna

Thats no the point. Just look at the antenna. Obvioulsy, if you have room, most anything will out-perform this antenna, thats a given. BUT, if you live in an apartment, or under the neighborhood ghestappo, this might be the difference between getting on the air, and just being an SWL.

I think some of these old farts that poo-poo every "compromise" antenna, here on EHAM, should actually try living in an antenna restricted area once. Sometimes, compromise antennas are the only thing able to let folks enjoy our hobby. Time to stop being such crabby old bastards, and start actually encouraging others to be active.

Just look at that thing. You can stick out on the porch, and, for 30 bucks, you can make QSO's.

73- Chuck KI9A
 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"Has me thinking of a motoroized hi-q dipole. Or maybe something a bit cheaper but similar. "

That would be an excellent antenna for its size. But like you say, not cheap.

A couple of really good screwdriver antennas fed as a dipole, especially with large capacitance hats, would be a nice thing, but the kilobuck price tag sort of stops people in their tracks ;-)

Magloop is the same way once you find out that it's $200 for the vacuum variable capacitor

My experience with my magloop, though, is that if I were stuck with no other antenna besides the magloop, I'd still be a reasonably happy ham. Mine tunes continuously from 5MHz through about 21.3MHz with a little box next to the rig, and at least theoretically comes in quite a bit better than hamstick dipoles and things like the TakTenna, etc.

A motorized coil loaded dipole of similar size should actually beat a magloop because the radiation resistance is much higher but the conventional designs are essentially impossible to build without a lathe.
A magloop, at least, is a tractable home construction project.

I do see that Surplus Sales of Nebraska has some $99 3-30uH roller inductors though ;-)

One question that's worth keeping in mind is "how many $100 antennas am I going to buy before I build a $300 one I'm happy with?"

It's not a question I can answer, of course, because depending on your operating habits a $300 25% efficient antenna might not really be that much better than a $50 2% efficient one. A better transmitting antenna isn't going to help a noisy receiving situation at all (unless you have some problem like AM broadcast trashing your receiver)

Optimum efficiency probably isn't worth the money and work for a lot of folks, but I feel like there should at least be a few more options to consider. There are a lot of homebrew projects that aren't even close to optimum.

73
Dan



 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"BUT, if you live in an apartment, or under the neighborhood ghestappo, this might be the difference between getting on the air, and just being an SWL. "

Chuck, the thing I don't buy is that a 30 inch antenna is a good thing to bother with on 40m. If you can put this on your porch without getting funny looks, you can also string a dipole up under your porch roof without getting funny looks or build an eight foot tall vertical version to sit on your porch that doubles as a plant holder.

If all you can really fit is 30 inches for 40m, well, OK, yes you can make contacts, but 90% of the time I think there's a creative solution that could buy someone 10dB.

Just making your homebrew TakTenna type antenna as long as you can swing is a great start!

73
Dan
 
RE: Homebrew Tak-tenna  
by KI9A on January 13, 2009 Mail this to a friend!
RE: Homebrew Tak-tenna Reply
by WG8Z on January 12, 2009 Mail this to a friend!
Amazing the effort some will put forth to build a lousy performing antenna

Thats no the point. Just look at the antenna. Obvioulsy, if you have room, most anything will out-perform this antenna, thats a given. BUT, if you live in an apartment, or under the neighborhood ghestappo, this might be the difference between getting on the air, and just being an SWL.

I think some of these old farts that poo-poo every "compromise" antenna, here on EHAM, should actually try living in an antenna restricted area once. Sometimes, compromise antennas are the only thing able to let folks enjoy our hobby. Time to stop being such crabby old bastards, and start actually encouraging others to be active.

Just look at that thing. You can stick out on the porch, and, for 30 bucks, you can make QSO's.

73- Chuck KI9A
 
RE: Homebrew Tak-tenna  
by KI9A on January 13, 2009 Mail this to a friend!
"RE: Homebrew Tak-tenna Reply
by WG8Z on January 12, 2009 Mail this to a friend!
Amazing the effort some will put forth to build a lousy performing antenna "

I dunno, Dan, without actually trying it. For years, guys have used Hustler mobile antennas, that are actually shorter than that, with decent results.

My whole thing is this. We are lucky we have yards large enough for real dipoles, and, if we ever had to go back to such a poor antenna, we would be pretty disappointed. But, for the guy who has no choice, it might mean the world to get on the air.
 
RE: Homebrew Tak-tenna  
by AB7E on January 13, 2009 Mail this to a friend!
KI9A: "I think some of these old farts that poo-poo every "compromise" antenna, here on EHAM, should actually try living in an antenna restricted area once. Sometimes, compromise antennas are the only thing able to let folks enjoy our hobby. Time to stop being such crabby old bastards, and start actually encouraging others to be active. Just look at that thing. You can stick out on the porch, and, for 30 bucks, you can make QSO's. "

That's not the point. You could drape 65 feet of center-fed #18 wire across the roof of most homes and get better results than that $30 "thing". A 33 foot piece of #18 wire sloping up to the highest nearby support and properly fed against some radials on the ground will provide better results than that $30 "thing". Neither one would be visible to neighbors. As I and several others here have mentioned, unless you're absolutely constrained to mounting an antenna on a balcony railing almost anything else is going to be a better choice than a five cubic foot tank circuit at the end of some coax.

What is the point is that many hams spend a bunch of bucks (or time) putting up a grossly inferior antenna, and then because they don't have anything to compare it to, proudly announce how great it is without ever knowing what they're missing ... thereby misdirecting other hams down the same flawed path. If that's your idea of encouragement, you and I grew up in different circles.

By the way, you may want to go back and read KA6KBC's article. He built the antenna but HE'S the one who pointed out the 20 db differential to a simple dipole at the same height in the same back yard. The rest of us merely reinforced his observations with some technical background. If that fits your definition of a crabby old bastard, count me in.

73,
Dave AB7E
 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"
I dunno, Dan, without actually trying it. For years, guys have used Hustler mobile antennas, that are actually shorter than that, with decent results. "

I know, Chuck... that's the great thing about the fact that there's 50, 60, 70dB dynamic range among what would workable signals on a full size antenna on a HF band. You can still work the top signals.

But there are other people frustrated with their teeny-tiny antenna and I feel like they need to know why.

Someone who fully recognizes that their antenna is radiating 1W or 500mW of their 100W is one thing, but someone who bought an antenna that was advertised as "only 4 S-units down from a full size dipole," or even worse, "almost as good as a full size dipole" might really be bashing their head against the wall wondering why no DX one can hear their 100W compared to the friend down the road who has a trap dipole. They'll figure it out eventually, but I don't mind heading it off at the pass too.

The original Tak-Tenna on the Tak-Tenna site is advertised like this:

"...no heat sensed on antenna wire or coax feedpoint when touched by hand after power tesing

NO lossy matching components anyplace in system"

C'mon. It's a 30 inch 40m antenna with 200kHz 2:1 SWR bandwidth.

I don't want to pick on the TakTenna too hard, it's just topical. I've covered Hamstick dipoles elsewhere on the site recently too.

What I want people to take away from my comments is this:

- - - - - -

The antennas I'm coming down hard on will turn you into a QRPer.

- - - - - -

Now, QRP is FUN and if the choice is 1W ERP or no ham radio, you know where I'm going to be. I was making DX contacts with 2.5W ERP on 80m CW the other night.

But the idea that the latest, greatest ultra-short antenna radiates most of your 100W is always false, and the decision to use one is probably best made with that in mind. If it's just a few feet long and covers most of 40m, it will turn your 100W almost entirely into heat.

73
Dan













 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"That's not the point. You could drape 65 feet of center-fed #18 wire across the roof of most homes and get better results than that $30 "thing"."

The worst part of this, of course, is the possibility that someone might buy a -20dBi antenna and add on a $1000 1500W amplifier to make it the equivalent of 100W to a -8dBi antenna ;-)

I know the amplifier goes inside, etc,etc, but it doesn't take too much work or money to build a -8dBi stealth antenna.

Fortunately for the ham world, most -20dBi antennas don't stand off enough voltage or handle enough current without fusing open to stand up to 1500W. But I know one that does.

;-)

73
Dan

 
RE: Homebrew Tak-tenna  
by GW1MCD on January 13, 2009 Mail this to a friend!
Hi. The profit level in the UK would be much-much higher. This is "RIP OFF" Britain.73.
 
RE: Homebrew Tak-tenna  
by KC8VWM on January 13, 2009 Mail this to a friend!

"3.) 1 - 25 foot RG8 coax with PL259 - Radio Shack - Close Out - $5 "

------

Ahhh. I see the root of the performance issue now...

1) I would suggest removing the 25 foot run of RG-8 feedline and replace it with a 32ft. 6 - 1/32in. length of #14 AWG wire cut for 7.200 mhz operation.

2) Connect the wire directly to the SO-239 connector on the back of your rig. Proceed to run the wire to the top of one of the speaders. (top right or top left spreader - not critical).

3) Remove both spiral loops from each speader and return them back to the neighbors BBQ grill where they belong.

Viola!...Problem solved and you even trimmed $5 bucks off final production costs! :)

73 de Charles - KC8VWM
 
RE: Homebrew Tak-tenna  
by N1YRK on January 13, 2009 Mail this to a friend!
I used to be in the antenna business. Made 2.4 ghz co-linear verticales., mostly for the wifi market, before there were a lot of antennas out there for this purpose. There's more to the production aspect than a lot of people realise. What's fun as a hobby becomes tedious as a business. Then, there's the customer expectations. I would deal with the biggest idiots, like the ones who would let 50' of coax hang without any sort of mechanical support. Then there's those who ask 'what kind of distance can I get'? - As though there's some magical formula. The problems with lost and damaged shipping, with malformed parts from subcontractors, with taxes and insurance, with not know whether to invest in tooling and having to depend on volume to make up the capital cost, at the same time worrying what someone in China is going to do (thanks to the US government sabotaging our industrial base).

It's not easy. That being said, I wonder if, for amateurs, it's not best to leave the antenna screwing around for the ham radios and leave professional antennas to those who will pay hundreds of dollars for something and have no problems with hand-holding the customers.
 
RE: Homebrew Tak-tenna  
by KI9A on January 13, 2009 Mail this to a friend!
Dan, I still contend this is a better antenna than 60' of wire on the roof. Here is why. Apartments. Apartments. Apartments.

Yes, your house, there might be better options. But, putting wire on the roof presents issues such as TVI, RFI, ect. I've been there. It happens.

78 reviews on EHAM, 4.8 out of 5. I question that big time. But, if we went from our setups, to that, we would score it a 1 or 2. If a guy goes from nothing to that, it maight be a 4.

Be interesting to do a test of random wire on the roof, and this beast. Heck, I might just make this a club project!
 
RE: Homebrew Tak-tenna  
by N3OX on January 13, 2009 Mail this to a friend!
"Dan, I still contend this is a better antenna than 60' of wire on the roof. Here is why. Apartments. Apartments. Apartments.
"

Well, when I lived in an apartment I stealthily put up 100 feet of magnet wire for a HF antenna.

I do understand what you're saying about the stealth appeal of this thing: people probably think this wacky looking and relatively tiny thing is probably easier to pass off as a TV antenna, etc.

And maybe, just maybe, this sneaks under the radar in a few situations where a 10 foot or 15 foot antenna wouldn't.

But I bet most places either don't care unless you bother someone or are strict about anything and are going to give you a hard time unless you jump through hoops and plug it in to your TV.

In my apartment complex (980 units, mixed garden and high rise, I lived in the former), if you had a grill or a couple of other banned items on the balcony, you'd get a note demanding their removal for fire code reasons, but anything else you had out there went totally unmentioned... including a 6m Moxon clamped to the side of the building:

http://n3ox.net/projects/sixmoxon/

I started only putting it up when I wanted to operate, but found that to catch openings, I needed to leave it up as much as possible, so I would take it down for work but it stayed up over most summer weekends and I'd put it up as soon as I got home in the evening and leave it up overnight so it was there in the morning.

Furthermore, I left the clamp there 24/7 for a year or more. I fully recognize I was very, very lucky that I didn't have anyone breathing down my neck, but I bet most people renting an apartment have one of three situations:

1) one like mine was where, basically, it is no one's job to talk to the guy who clamps an antenna on the wall or strings up some wire. If you don't ask and just do it, you can just do anything you want.

2) one where the landlord/rental company is fine with whatever you can fit on a balcony as long as you ask, *don't* attach anything to the building, and don't annoy the neighbors too much.

3) one where there is a STRICT no antennas policy and a very active policing.

The kind of place that does #3 is probably the kind of place where you can fake an OTARD exemption and pretend your TakTenna is primarily a TV antenna (and, in fact, you could even use it as a TV antenna), but if they *really want to come after you* all they have to do is figure out that you're transmitting. A whiff of RFI to the neighbor and you're sunk.

And even if you are going to fake OTARD, even a 1 meter diameter magloop is probably a better antenna ;-)

You have a point in that not everyone can afford a magloop, and not everyone wants to build something, and if you're in a really tough spot regarding enforcement, whatever thing you can put out there that radiates even 1 watt might be the ticket.

But I don't see those users in the reviews:

I see a guy in a private home with no trees.

I see a guy in a private home with this antenna on the roof.

I see a guy who sees fit to mention his 36 foot long balcony using a 20m version.

I see S52CC with a cool sidearm thingy who could almost certainly stretch the antenna out to three times its length:

http://www.taktenna.com/Balcony%20photos%20Vince%20and%20Denis.htm

Someone's using the 40m TakTenna on top of a 20 foot flagpole.

I'm not saying the choice is wrong for them. CLEARLY people love these things. We're all free to use whatever we like. I'm just saying it's suboptimal in the vast majority of cases and when someone comes along and finds that their version is 20dB down on a full size dipole, that the readers of the article and the ensuing thread recognize that as *typical* and *predicted,* and KA6KBC didn't screw up, he just knows the truth ;-)

Every antenna has its niche but I don't see a whole lot of people who are actually saying they're restricted to 30" of space on 40m. You double the length to 60" and you're going to do better in a way that's probably noticeable.

"Be interesting to do a test of random wire on the roof, and this beast. Heck, I might just make this a club project!
"

If you do this, can you please, please do a favor for hams everywhere? Beg, borrow, build, or buy a current meter and measure your feedline current, especially if you mount the thing many many feet in the air? I'm not above accepting this antenna as a useful top feeding transformer for long vertical runs of coax in addition to its likely abysmal performance as a horizontal dipole, but we do need to sort out the two effects.

And I personally am going to be building a short dipole project but it's going to be a bit different.

I would, however, be really interested in hearing from apartment dwellers. Can you really only do 30" or would you be able to do a 5' long antenna or a 10' long antenna?



73
Dan
















 
RE: Homebrew Tak-tenna  
by KC7MF on January 13, 2009 Mail this to a friend!
Let's see. Someone said that the 78 folks who reviewed this antenna were too new to ham radio to know the difference or some such. What an arrogant position to take. The poster decried the assumed fact that the folks who reviewed the Tak Tenna didn't do A/B tests. I am certain that everyone who reviews on eham does extensive testing or they wouldn't dare make their opinions known.

I am one of the folks who reviewed the Tak on Eham. (I thought one of us worms ought to come out of the woodwork.) I rated it 5/5. I rated the antenna based upon what I expected. Which was frankly not a whole lot. It was easy to assemble, cheap, and wouldn't put my homeowners association in a full blown, double rectilinear panic. I could have thrown a wire over the roof but, you know, when you live in a Santa Fe style stucco house you are throwing the wire on top of a few miles of chicken wire. Well I could also have tried sticking some wire up a tree but to find one I would have to go a few miles from my Arizona home and couldn't afford the coax. So I stuck up the Tak and tried some phone. The darned thing is that people started talking to me. Some in Oregon, another in Michigan. Then some guy in Mexico had the temerity to call me and we had a nice chat. Then some guy on ship called me from were there be dragons and I was impressed. It appears most of the folks who called me must have been contesters taking a break because they all kept saying 599. That or they could tell my helical signal that I was on a TAK and they didn't want to hurt my feelings. So for about an hour of time, a hundred or so bucks, and safety from the antenna Nazis in the HOA I was talking to folks. I liked that. I stuck a tuner on the thing and it messed up and started working on 17 20 and 80 meters. I'm going to try it on 160 meters if I can get the sheep dog to sit on the coax but I will have to let you know about that. In fairness I should say I was pouring the power to it alternating between about 70 watts on the 735 to right at 100 watts on the HW-101. (Folks tell me it won't work either but that is for another thread.) So, anyway, for doing all this stuff it shouldn't do I gave it a 5/5 on the review.

I want to apologize to all of the folks with their double jointed, parallel circuited, modified Moxon arrays up 150 feet who, probably correctly for all I know, get 1000db gain and can cook a chicken in Maui from their mountain top home in Idaho. No doubt they are the only ones who deserve 5/5 on an eham review.

But here is the deal. How many people here have an antenna more efficient than an inverted V up 40 or so feet? A few? A lot? How many people here spent more than it takes to wire a trailer park in Alabama to put up a vertical that won't work as well as some wire you got out of the dumpster shot into a tree with a spear gun you borrowed from the neighbor?

I think it is great for folks to experiment with antennas. There is little else with which we can experiment these days. The guy who sells the Tak Tenna knows all that stuff about how we could build on cheaper. He also knows that there are some of us who are having fun playing with his toy. So the TAK gets 5 for fun and 5 for all the folks who give me 599. Some day I will tell you all about my R-5 that is flat on 80 meters. I wish all those folks would stop telling me how good I sound when we all know full well that it just isnt possible.
 
RE: Homebrew Tak-tenna  
by KI9A on January 14, 2009 Mail this to a friend!
" Someone said that the 78 folks who reviewed this antenna were too new to ham radio to know the difference or some such"

Do you work in the media?

Check your facts. Re-read my post. I said 78 folks had reviews, and said NOTHING about being too new...

Wow.

And I was defending the design. And this guy wants to turn into a new ham vs old ham conversation?

 
RE: Homebrew Tak-tenna  
by N3OX on January 14, 2009 Mail this to a friend!
"But here is the deal. How many people here have an antenna more efficient than an inverted V up 40 or so feet?"

Very few. An inverted V up 40 or so feet is nearly 100% efficient. Some people have more gain or less coax loss, but you can expect a good dipole up at that height, or even a tad lower, to clock in around 90% efficiency.

But KA6KBC's A/B test suggests that his homebrew version is more like 1% efficient.

Some people don't find that. There's one review of the TakTenna that says the antenna compares favorably to his dipole on 40 and 20.

But he goes on to admit that it has no directionality at all. To me, that's a sure sign that the feedline is radiating. There's nothing wrong with using your 20' vertical run of feedline or whatever as a 40m antenna by exciting it at the top with a resonant circuit. But if you *recognize* that's happening, and want to stick with it, you can still improve the system in a number of ways (like putting radials at the base of the coax, or moving the feedline away from the house to reduce noise pickup)

And if you don't have significant feedline radiation, you can't possibly exceed much more than a few percent radiation efficiency with a 30 inch antenna on 40m and still keep sufficient bandwidth to pass a SSB signal.

That's a fact.

Now, do I know you are running a 1% efficient antenna system? Nope? Maybe you've got a sweet length of feedline in the clear that's participating in the process.

And, even if you were running a 1% efficient antenna, you could be extremely happy and get plenty of 59 and 599 reports, even honest ones.

What I do know is this: if the antenna itself is doing most of the radiating that gets done, 99% of your radiated power goes to heat. It just has to. No way around that.

And if the antenna itself isn't doing most of the radiating, but is exciting the feedline to radiate, the results that other users will get in other installations will vary wildly. Your particular installation could be quite good and within a couple dB as good as a well grounded vertical in some special situations, but others won't have the same thing.

I don't think hams should feel a pressure to build the biggest, baddest antenna array out there, but I do feel pretty strongly that hams should know that to get even 1% efficiency out of a 30 inch long antenna on 40m is a fairly difficult task. And they need to know that the feedline is very likely the antenna if they're having an easy time making contacts.

I'll say it again, I'm happy to admit that the TakTenna could be a fancy transformer for top feeding verticals, but the users could benefit from knowing that... they can run their coax vertical a little further from the TV, maybe put some radials at the bottom.

73
Dan








 
RE: Homebrew Tak-tenna  
by KT8K on January 14, 2009 Mail this to a friend!
As a dyed-in-the-wool QRPer who almost never cranks the Orion above 5 watts, I get a good laugh from all the hams who run 100 or more watts and are unaware they have a smaller ERP than I do. No wonder I get picked first as often as I do in pile-ups. I'd always rather put up a truly-invisible 18 gauge magnet wire dipole for 40m and get that 90+% efficiency than any antenna that has such poor efficiency.

People blame the antenna when it's really the ionosphere, too. Back in the 80's I made a QSO into a neighboring state on 40m CW with my Argonaut 509 (5-6w max) only to realize afterward that I was connected to my Heathkit CanTenna through a couple of 3' RG8 jumpers and a B&W antenna switch. I heard him first, running 100w to his low dipole several hundred miles away, and he gave me a 579 or something - no problem. We had a nice chat and then I smacked myself on the forehead afterward when I looked at the antenna switch.
The efficiency of an antenna is far more important than gain, but the ionosphere can beat that by many more tens of decibels.

Run what you will, folks, but be realistic. You can always do better than a mag-loop or tak-tenna unless the only space you have to put it up is inside a closet. I guess a lot of people are finding out what fun operating QRP is even when they don't know they're running QRP.
Best rx to all & 73 de kt8k - Tim
 
RE: Homebrew Tak-tenna  
by KB8NDM on January 14, 2009 Mail this to a friend!
I was under the impression that small transmitting loops are quite efficient, but are difficult to construct and operate due to the need for a very high-voltage variable capacitor.
 
RE: Homebrew Tak-tenna  
by N4KC on January 14, 2009 Mail this to a friend!
Tim KT8K:

I'm with you. I leave the amp off or on standby most of the time until I need it and I can't tell you the number of times I forget to switch it on, thus sending a mighty 25 or 30 watts to the antenna. Often I work the station, get my decent signal report, and go happily along until I catch a glimpse of the wattmeter and it's barely moving.

That's why experimenting with antennas holds such interest for some of us. And why I applaud articles such as this. The author set out to recreate a popular commercial product with really good reviews here on eHam to see for himself how it worked. Compared to your dummy load (or no antenna at all), it probably works fine and might allow someone to get on the air who otherwise could not. Compared to a good dipole or vertical with a nice ground field, it is, to put it mildly, sub-par. But it is what it is, and I don't think the manufacturer makes any extravagant claims.

I've said it before and I'll say it again: even with today's complicated, surface-mount technology, those of us without EE degrees, a lot of free time, and a shop full of sophisticated test gear still have a few areas in which we can play and experiment (and learn). Vintage tube gear is one. So is kit-building. Antennas is another. I can string something up in the backyard, compare it to an existing aerial, tweak it, play with it, and if it's better, keep it. If it isn't, I recycle the materials for another experiment.

I had a great QSO the other afternoon on 20 with a JR1. He, too, had a modest station similar to mine, including the commercial version of my homebrew antenna. I could NOT have built the TS-2000 I use if I had all the parts and ten years. With some help, I might could have built the amp I used but it would have taken me a long time and some serious refreshing of my knowledge base (I don't work with this stuff everyday and never have!). I know I could build a tuner that would work okay but not the memory auto-tuner I now use.

But the real source of pride was that I was using a homebrew broadband hexbeam that I built in my basement and backyard with my own two hands. An antenna that enabled me to have a very pleasant QSO with Shin in Kawasaki, Japan, when other antennas in my farm were marginal at best.

THAT is a thrill!

Don N4KC
www.n4kc.com
www.donkeith.com
www.n4kc.blogspot.com
(A blog dedicated to rapid technological change and
its effect on society, media and amateur radio)


 
RE: Homebrew Tak-tenna  
by KB6QXM on January 14, 2009 Mail this to a friend!
What I do not understand is this. Anyone serious about the ham radio hobby, why would they desire to live in an apartment or on a postage stamp city lot with antenna restrictions.

I would believe that anyone serious about the hobby would try to find a rural QTH that they could put up a serious antenna system and not be concerned with limited performance antennas.

You know the old saying. If you have $10,000 to spend.

Spend $9,000 of it on an antenna system and $1,000 on the radio. Not the other way around.
 
RE: Homebrew Tak-tenna  
by AB7E on January 14, 2009 Mail this to a friend!
KB6QXM: "What I do not understand is this. Anyone serious about the ham radio hobby, why would they desire to live in an apartment or on a postage stamp city lot with antenna restrictions."

I can think of a zillion reasons why someone who seriously enjoys ham radio would end up on a small city lot, in a condo, or in an apartment. There are financial reasons, proximity (to work or school) reasons, historical (inheritance) reasons ... all of which are perfectly legitimate preemptions of the desire to have enough room for a full-size antenna.

None of that is relevant. Ham radio was never about excluding anyone because they couldn't manage to install an optimum system. The key, as KT8K so aptly put it, is not to needlessly (or obliviously) restrict yourself to an antenna that would fit in a small closet when there are so many basic, inexpensive, proven alternatives that would do a much better job within almost anyone's constraints.

That doesn't mean that hams should experiment and try various approaches. KA6KBC did just that and almost everyone has applauded his efforts, for the knowledge he (and we) gained if nothing else. I've built dozens of different verticals and wire antennas myself, and I lived on a small suburban lots with unsympathetic neighbors for 35 years. That's one of the reasons why I believe that almost no one needs to settle for something as grossly inefficient as a 30 inch end-loaded radiator for 40m.

73,
Dave AB7E

 
RE: Homebrew Tak-tenna  
by N3OX on January 14, 2009 Mail this to a friend!
"I was under the impression that small transmitting loops are quite efficient, but are difficult to construct and operate due to the need for a very high-voltage variable capacitor."

Either difficult or expensive ;-) You can buy a vacuum variable for $200 from Max Gain systems or another surplus outlet that will work well at the 100W level. Then you need the loop to be made of soldered copper tube or welded aluminum or some such. And you need a motor drive or at least a really long stick to adjust the cap. But a fairly efficient magloop can be a practical home construction project at the 100W level once you decide to spring for the vacuum variable or other large high voltage capacitor (I like the vac variables because they have a quite low minimum capacitance and a quite high maximum one, so you get wide tuning range compared to a big air variable)

A problem is that the radiation resistance of magnetic loops is a fraction of that of short dipoles, even quite short ones. I think the radiation resistance of my 4 foot octagon magloop is something like 0.03 ohms on 7MHz. So you have to have much less than 30 milliohms of RF loss resistance to get good efficiency.

The radiation resistance of a very short dipole is quite a bit higher. Seems like on the order of 0.3 ohms or so for 3' antenna on 40m, 10 times higher than the 4 foot mag loop. But there's a very large capacitive reactance to cancel, maybe 1200 ohms for a 3' dipole with 4' diameter spoked capacitance hats.

If you use practical loading coils of Q=300 or so, you are going to add 4 ohms of loss resistance with your loading coils.

The resonating component in a magloop is a very high Q object and of modest reactance. A nice vacuum variable has Q in the thousands, and maybe a couple hundred ohms reactance, so it adds a couple tens of milliohms loss by itself. I think I assumed 30 milliohms for the loss resistance of the capacitor innards and its mechanical contacts to the magloop (which are large cross sectional area silver plated clamp contacts, and are probably most of Jenning's specified loss resistance anyway)

My assumption of 30 milliohms + EZNEC's calculation of the RF resistance of an octagon gives 25% efficiency for my 4' magloop on 7MHz. Not bad. Not fantastic, but not 1% either.

In the end, a magloop can compare favorably with a very short dipole because with the short dipole the necessary loading tends to have significantly increased loss resistance so the significantly increased radiation resistance doesn't help you much.

73
Dan
 
RE: Homebrew Tak-tenna  
by N3OX on January 14, 2009 Mail this to a friend!
I'd like to add another observation.

The efficiency/bandwidth tradeoff of a small antenna is a strong function of its size.

Someone asked about not being able to hear anything on their TW2010 switched, coil loaded, end hatted dipole that's used for 20-10m.

I ran the EZNEC numbers, and lo and behold, an antenna that's about 8 feet tall with a couple big end hats loaded with Q = 200 coils in the center and hairpin matched has an efficiency of 70% (-1.5dB) and can cover about 250kHz of 20m under 2:1 swr. The higher bands will be better. Even if you assume pretty miserable Q = 50 it still stays 40% efficient.

The equivalent 40m antenna needs to be about 16 feet tall (would have to be fatter to eke out 250kHz too).

So this is not a binary system. You don't have an immediate drop off as soon as you go below 1/2 wavelength dipole. You can keep decent efficiency over usable bandwidth and still get very useful shortening! The trick is that the compensating reactance for short dipoles is a strong, nonlinear function of their length.

Here's a chart of monopole reactance as a function of monopole height, for example:

http://www.wa1mba.org/ReactanceChartSS.jpg

As the reactance falls of a capacitive cliff, you have to add lots of inductive reactance to compensate it, and even with high Q coils, you're adding a lot of resistance.



So we can't go around telling people their antenna sucks because it's shortened, and we can't go around thinking all shortened antennas are good just because some are.

The efficiency/bandwidth tradeoff has ***quantitative*** consequences, that illuminate things much more, in my opinion, than hand-wavy opinionated I-can-make-contacts-or-not ones.

The efficiency of short, loaded antennas is a nonlinear function of their length, and advice and antenna design should take that into account.


73
Dan















 
RE: Homebrew Tak-tenna  
by KA5S on January 14, 2009 Mail this to a friend!
FWIW, a pair of Hamsticks(tm) did pretty well compared to a reference dipole at the same height during HFPack shootuts at Pacificon. Loss on 40 will be higher, but it's nto as if one were buying a HiQ(also TM) dipole.

I'd listen to the advice here and use a balun at the feedpoint, though.


Cortland
KA5S
 
RE: Homebrew Tak-tenna  
by N3OX on January 14, 2009 Mail this to a friend!
"FWIW, a pair of Hamsticks(tm) did pretty well compared to a reference dipole at the same height during HFPack shootuts at Pacificon."

You talking about 40m?

Again, this is critically important. Hamstick dipole efficiency falls off the same reactance cliff that plagues all short antennas... but it's 14 feet long, right? So it's much longer in electrical degrees than a 30" antenna.

I'll go look it up.

73
Dan
 
RE: Homebrew Tak-tenna  
by N3OX on January 14, 2009 Mail this to a friend!
I looked it up... seems like HFPack shootout frequency is 14.1MHz.

A 14 to 15 foot long dipole on 14.1MHz would be matched by an equivalently loaded 28-30 foot dipole on 7MHz.

I see that the horizontal shootout's shortest antenna in the 2002 results was about 9.5 feet long.

Totally different world.

73
Dan
 
RE: Homebrew Tak-tenna  
by W8RPE on January 14, 2009 Mail this to a friend!
Nicely done. I applaud Bill for building this antenna out of curiousity and being honest about it's perrformance or lack thereof. I did the same thing with ther EH antenna. I built rather than bought one "just to see". It worked about as well as my cantenna at the same height. It's just unbelievable to me that people actually shell out a nice chunk of change for the retail versions of the magical TAK and EH antennas. Don't drink the coolaid folks!!!
 
RE: Homebrew Tak-tenna  
by AB7E on January 14, 2009 Mail this to a friend!
AB7E: "That doesn't mean that hams should experiment and try various approaches."

Sorry for the typo. That sentence should read:

"That doesn't mean that hams shouldn't experiment and try various approaches."

73,
Dave AB7E
 
RE: Homebrew Tak-tenna  
by XE3LW on January 14, 2009 Mail this to a friend!
I have a Tak-tenna, and it works, if you set the antenna properly, the height over the ground is critical, I have found that place the antenna at 27 ft over the ground the performance is a lot better than 6 ft.

An other possible use for this design, is as a ground plane for verticals.

I am using mine as a ground plane for a Shakespeare SSB Marine Antenna, performance is pretty good.

I think, that using several spiral for different bands as ground plane for a vertical will save a lot of space for radials, if you place the antenna base off the ground, to up to 0.05 lambdas over the lower operating frequency, all you need is 3 radials max. per band.

xe3lw

 
RE: Homebrew Tak-tenna  
by W4LGH on January 14, 2009 Mail this to a friend!
Just goes to show you can load anything up with your tuner in the shack and make it work somewhere. As for a Tak-Tenna over a Hamstick...I'll take the Hamstick!

I really liked the statement made that PT Barnum invented it, he really didn't, but he did say the someone would buy one every 60 seconds!

Tak-Tenna antenna for 40m ... $30
Tak-Tenna and antenna tuner for 40/20/15 & 10m ... $300
Full sized resonant dipole for 40 meters... PRICELESS!


73 de W4LGH - Alan
 
RE: Homebrew Tak-tenna  
by N3OX on January 14, 2009 Mail this to a friend!
"Just goes to show you can load anything up with your tuner in the shack and make it work somewhere"

Alan, a Tak-Tenna is a RESONANT antenna when set up properly, that, apparently, presents less than 2:1 SWR to the coax feedline over a bandwidth of 200kHz or so on 40m.

No tuner needed when you follow the tuning setup instructions.

73
Dan

 
Homebrew Tak-tenna  
by N9CYS on January 14, 2009 Mail this to a friend!
Good effort!

I applaud you for building an antenna. And learning some radio physics from other amateur physicists. I hear a lot of chatter on the bands from hams with more privileges than me who buy and operate appliances but know little how things work

As a young Novice, I could hardly contain my astonishment when I put my 40m dipole in a Vee and started easily working W6's and a KL7 on 15m. Within a few days I was working real dx. The ham down the street gave me a minute long explanation of harmonics.

Keep learning or die.

73

jim
n9cys
 
RE: Homebrew Tak-tenna  
by KI9A on January 15, 2009 Mail this to a friend!
KB6QXM: "Anyone serious about the ham radio hobby, why would they desire to live in an apartment or on a postage stamp city lot with antenna restrictions"

Pretty arrogant statement here, OM.

Are you serious? I can think of many reasons why hams live in apartments,ect.

I average about 8,000 QSO's a year. I am very active ( err, serious), and have been for over 30 years. Did I mention I live on a city lot??

By the way, my other hobby is restoring, driving old cars. Right now, I am working on a '66 Chevy II. My garage? Regular ol' 2 car attached.

You CAN be serious about your hobbies, without having top notch space...
 
RE: Homebrew Tak-tenna  
by KB6QXM on January 15, 2009 Mail this to a friend!
KI9A,

I am serious about my hobbies, that is why I have a location best suited for them. I have a ridgetop with no neighbors, so that I do not have to worry about neighbors talking about antennas/towers.

I too restore classic cars. I have a 69 Corvette presently. I have restored a 69 Big Block Mach 1 and a 1966 tri-power GTO.

I always had a place for the restoration.

Can you imagine someone with only a car port trying to restore a classic car. Cannot be done without a place to store the parts that are being taken off and to prevent them from being stolen.

I submit to you that having the proper property to support the hobbies you choose is paramount.

I do not think it is arrogant for me to make such a statement. If you really set your priorities with your given hobbies, to have an apartment with a car or ham radio hobby is to be met with marginal results.

The same with running a business. Location, Location, Location.

People should also have the means to support any given hobby or multiple hobbies. If you do not, then again it could be met with disappointing results.

Planning for anything: hobbies, career, relationships needs to be done to ensure that your expectations are met. Anything short of that will be disappointment.

Not arrogance-Just setting and follow though of priorities.

73
 
RE: Homebrew Tak-tenna  
by N1YRK on January 15, 2009 Mail this to a friend!
In regards to antennas for restricted spaces, I found that the magnetic loop design worked pretty darned well. Because of it's high Q, it also acted pretty well as a high mounted filter! It was a MFJ-1786. To buy one new, is very expensive. I had bought it for $150 at a hamfest and sold it for about the same when I needed the cash. There are annoyances, such as having to retune because it was so narrow band (but the remote tuner worked reasonably well) and the biggest problem was not being able to operate under 10 Mhz. There were other problems, such as the fact that I couldn't simply have the antenna returned by some device that connected to the rig, and that I had to seal places where the environment had caused the protective case around the active electronics to become unsound.
 
RE: Homebrew Tak-tenna  
by KT8K on January 15, 2009 Mail this to a friend!
KB6QXM - I agree with you on the preferred ratio of investment between antennas and radio gear, but I have 5 antennas at present that have cost me under $250 all together because I got 1 cheap at a swap and fixed it, won another in a swap drawing, and built the other 3 from house wire and cheap coax also acquired at swaps. If my personal constraints allowed it I would indeed have a mountain top antenna farm like W8JI, for example. Since I DO have constraints, though, I am where I am. Here is some anecdotal evidence from my small city lot:

More than 11000 Qs just in the past 6.5 years running 5w to wires and verticals (incl. vertical dipoles). Dipoles are all tree-supported, and vertical is ground-mounted & surrounded by pine trees 6' away (yes, it's lossy). 72 countries confirmed (I'm not much of a DX chaser) and 49 states confirmed (come on North Dakota!).

I also have a few top 10 results in U.S. QRP categories in CQWW & WPX, ARRL DX & maybe SS (don't remember now) against ops with serious towers and beams, etc. (I don't ever expect to get to #1 without something better, though - but cracking the top 10 is a huge thrill.)

Note: I live in the city because my wife won't have it otherwise, and I can't afford a huge lot, so I spent about 1.5 years finding a house on the 2nd highest spot in town ... it was very much worth it.

I'd recommend to anyone: there are solutions (stealthy if need be) that can provide a >90% efficient antenna in almost *any* circumstance including apartments, HOA areas, etc., if you look for them. It is possible to be competitive and have a lot of fun in amateur radio almost anywhere if you try. A small lot in the bottom of one of those notch-like valleys in West Virginia may make HF a tough go, it is true, but you do what you can and have fun (maybe work satellites or moonbounce in that case?).

So, realistically, we all have constraints - even W8JI. Unfortunately, less experienced folks may spend significant $$ on poor solutions (like 30" end loaded dipoles for 40m) when they could do much better for much less.

(BTW - W8JI was coming in on 80m the other day and pegging the needle on my Orion-dipole setup - he's in GA and I'm in MI. I had never before seen that needle hit the stop. All I could say was ... Wow! Even stations a couple of miles away aren't that strong - the ionosphere is wonderful, but so is what one can do with good engineering.)
73 de kt8k - Tim
 
RE: Homebrew Tak-tenna  
by N1YRK on January 15, 2009 Mail this to a friend!
Performance might be improved by better quality construction. What if you fabricated the coils first? I can envision some sort of bending jig that could bend the wire as it comes off the spool to a continuing larger diameter. Then perhaps get some better insulators, or not, and either thread them on the wire or clamp them on, or even cast them on, and secure them in position on way or another. Next, take two narrow strips of wood (lathing from an old-style plaster wall comes to mine) to sandwich the insulator / wire section. The wood part should be designed to be rigid, precise, and survive the weather, without adding too much weight.

I guess the real change here would be the wire bending apparatus. Perhaps if I get the time I'll build one and make the plans available, and then you might want to reconstruct this antenna using it.
 
RE: Homebrew Tak-tenna  
by KB8NDM on January 15, 2009 Mail this to a friend!
I don't think restoring cars vs. amateur radio is a good analogy. While both are hobbies with a good amount of engineering involved, in the case of cars the space limitation is pretty non-negotiable and incidental to the actual activity.

In contrast, limited space in amateur radio is just another design parameter, like frequency, bandwidth, polarization, or even cost. Some may view it as a fun technical challenge to put together a working station within the confined space of an apartment or city lot.

Probably the ideal situation for many people is two QTHs, one urban with all of the non-ham benefits thereof, and one cabin on a big hill. ;)
 
Homebrew Tak-tenna  
by N6AF on January 15, 2009 Mail this to a friend!
An alternate antenna for consideration is the Heathkit Cantenna Dummy Load. I worked a neighboring ham with mine recently. The performance is probably similar to the Tak-tenna.
 
RE: Homebrew Tak-tenna  
by N6AF on January 15, 2009 Mail this to a friend!
How about "Monster Ether Spray". Similar to the grand improvements lent to Hi-FI stereo systems using jumper cable gauge speaker wire, you would take a can of Monster Ether Spray and walk around the yard spraying it here and there. Improves propagation dramatically by reducing free space loss. $39.95 per 12 oz can.
 
RE: Homebrew Tak-tenna  
by N3OX on January 15, 2009 Mail this to a friend!
"An alternate antenna for consideration is the Heathkit Cantenna Dummy Load. I worked a neighboring ham with mine recently. The performance is probably similar to the Tak-tenna."

Actually, the performance of the TakTenna is at least +30dBdl (decibels over a dummy load)

If your lid is on tight, it's probably more like +40dBdl

That's why they're so popular. They're 40dB better than a dummy load, which you can still make contacts on ;-)

The practical range of amateur radio station power in normal everyday use (excluding milliwatters and illegal power runners) is probably 500mW to 1500W, a range of 34dB.

The practical range of amateur radio station antenna gain in normal everyday use is probably -20dBi to +20dBi, a range of 40dB.

The biggest power to the best antenna is only 74dB stronger than the smallest power to the worst antenna, and very few people running the worst antenna actually crank down the power to 500mW just to hurt themselves further. Probably, the worst antenna stations running 100W are only 50 or so dB down from the absolute best antenna stations running 1500W.

But I hear signals over greater than a 50dB range on all sorts of ham bands, I guarantee it.

Propagation is the great equalizer in ham radio, and that makes it possible to make contacts on anything.


73
Dan
 
Homebrew Tak-tenna  
by KN4LF on January 15, 2009 Mail this to a friend!
The Tak-tenna is a close second only to the Isotron antenna.

73,
Thomas F. Giella, KN4LF
Lakeland, FL USA
http://www.kn4lf.com
 
RE: Homebrew Tak-tenna  
by KC7MF on January 17, 2009 Mail this to a friend!
Here is why I have problems with some of the sages posting here. I went to one of the links above to see what they said. How many here did? Here is a quote from the link:

"> It appears that many of these ultra compact antenna designs
> rely on radiation from the transmission line.



Thus, the reason folks who attempt to use a balun, feedline choke or
balanced line appear to have performance problems with the Tak-tenna
-- according to eham.com reviews of the antenna."

So I checked it out. I started through the reviews and here is the first one I came to mentioning a balun at all. KB3IFH posted this in his review:

"After assembly I placed the anntena on a 15' TV Antenna mast, ran with 450 ohn ladder line (as you can see in the photos) into a Palstar 4:1 Balun and into my Palstar AT1500CV tuner. Also using a TenTec ORION II for the xmtr. I am able to operate flawlessly on all bands as advertised, local and DX. QSO after QSO with no trouble."

The next mention of a balun was from NY7Q. He said,

"Taken to task by another ham over coax radiation vs antenna. I placed 4:1 balun in line, no substancial change in signals with balun in place. Took balun out of line, signals the same.
Antenna is at 20 feet with a tailtwister for direction. Using homebrew tuner, and a Alinco DX77t that a friend let me use. Varied power from 5 watts to 100 watts with and without balun, and made lots of good contacts, mostly 4 and 5s some 6s from Denver on 80 20 and 40 mtrs."


So check it out. I re-read all of the reviews and guess what? The guy referenced in the OPs links was just wrong. He could not have actually read the reviews or he would have known that not one single review spoke of a problem using a balun. Nor did anyone report "balanced-line" problems in the review. If they guy has to make stuff up he should not post at all. He might get caught. And he did.

So here is the deal. If it is not all feed-line radiation what is happening with these antennas? Why do they get better reviews than some famous, expensive and far more popular antennas?

Its true that propagation can make fools of all of us but I am going to go with the mystery. For some reason this little antenna works. And 75 or so people, who know the difference, just love it. I have heard all of the physicists telling me this just can't work. They lead me to believe that if I hook it up to my HW-101 I am really in trouble because it is too old to work as well as a Megabucks-2000/D. Yet these folks out there keep calling me back. And they give me 5/9's from Hawaii, Canada, Mexico city and all over the US. And on phone not to put to fine a point on it. (I have yet tried on data modes with this antenna.)

So just for fun I would really like to see someone do the science here. Here is a review Dan Butler N4UJW did on this antenna. He is the Hamuniverse.com guy.

http://www.hamuniverse.com/taktennareview.html

He gave the antenna 97 points.

So my point is that I have read every one of the above posts with the majotity telling me why this antenna 'can't' work or when it does it is some accident just short of God's will. When it comes to antennas I need all the help I can get. So I will accept wonderful good luck. If that is what it is.
 
RE: Homebrew Tak-tenna  
by N3OX on January 18, 2009 Mail this to a friend!
"So my point is that I have read every one of the above posts with the majotity telling me why this antenna 'can't' work or when it does it is some accident just short of God's will."

I'm not telling you it's some accident. There are two options:

If there is no feedline radiation and you're still happy with it, it is because you are happy with QRP.

***or***

If you put a current meter on the outside of your feedline you'd find it's carrying some current.

- - - - - - -

In either case, I am not telling you the antenna cannot work, I'm telling you that there are two options in the real physical world:

Option one: The antenna is 1% efficient, or even 0.5% efficient. That still works. Many people make many contacts and get many real, true 59 reports running 1W to a 95% efficient antenna. You could do that with 500mW or less...

I worked a guy on 17m once who was running 5W to a Buddipole. He was an honest 59+20dB on my meter. If he'd been running 1W, he still would have been better than 59+10dB here. He would have had to run at most ***100mW*** to get as low as a 59 report.

Option two: the main radiating bit of your antenna is actually your feedline. That *really* works. Why do I say that? Even if your feedline is not as good as a 1/4 wave vertical in the same spot, it's still going to be 10dB or more louder than the 30" long TakTenna.

And just mentioning a "balun" doesn't mean the feedline isn't radiating. You could actually put a *****perfect balun****** down at the antenna tuner with balanced line feed and have a reasonable feedline radiator driven by intentionally introduced imbalance (asymmetric clip leads) up at the antenna. And most baluns, both those at the antenna and those at the tuner, are far from perfect.

- - - - - - -

If you want to chalk your ham radio experience up to a magical mystery antenna, that's fine. I don't have much hope to convince you otherwise, and not much reason to do so.

But for the sake of others reading this thread I feel that I need to maintain that there is an actual physical explanation for **your happiness** consistent with known scientific knowledge about antennas, radiation, and propagation.

It's probably mostly that you're an optimist ;-)

I will continue to warn others away from thinking a 30" antenna can work well (in the sense of radiating more than a watt of an applied 100W), by itself, on 40m. It cannot, and if it even came close it would have an unusably narrow 2:1 SWR bandwidth.

There's no mystery here in my opinion... QRP works and so does using common mode feedline current for one's antenna. But in both of those cases, there's a lot of room for people who desire improvement to make it. You don't seem to want to improve it, so enjoy the hobby!

73, hope to hear you on
Dan




 
ISN'T IT ODD?  
by PLANKEYE on January 18, 2009 Mail this to a friend!

Considering that the "Taktenna" kit used to cost about $70 and the price doubled in the past year, the article is useful to those who wanted to experiment with the design. Isn't it odd how about $20 or $30 of parts and a little prefabrication can add up to a 300 or 400 percent profit? Only in America!

______________________

PLANKEYE:

When you throw grease at breakfast don't be surprised when the cabin is on fire!!

You don't fool everyone Brother!!


PLANKEYE
 
RE: Homebrew Tak-tenna  
by AB7E on January 19, 2009 Mail this to a friend!
KE7UXE: "So just for fun I would really like to see someone do the science here. Here is a review Dan Butler N4UJW did on this antenna. He is the Hamuniverse.com guy.

http://www.hamuniverse.com/taktennareview.html

He gave the antenna 97 points."


Uhh ... the "review" by N4UJW was hardly "science" in any sense of the word. In fact, it was appallingly subjective and arbitrary. Did you even read it? Out of 20 different categories (worth five points each) he used to rate the antenna, only three had anything to do with radiative efficiency. For the first of those, his only piece of data was that he had worked Cuba with 100 watts to the Tak-tenna. For the second, he compared the Tak-tenna to a multiband doublet 30 feet off the ground by saying he "heard" no discernible difference between the two. For the third, he compared the Tak-tenna to a ground mounted 4BTV without any radials (a notoriously bad configuration anyway) and "heard" only about a 1 S-unit lower signal with the Tak-tenna. All three categories garnered a rating of 5 for the Tak-tenna.

Some of his other categories included clarity of instructions, ease of assembly, shipping container (!), requirement for special tools, SWR (three categories, actually), cost to homebrew instead of purchase, and ease of repair. He dedicated one category to directionality if rotated, but he didn't actually test it and he still rated it a 5!

If that's your idea of objective "science", I don't think anyone here is going to influence your thinking with any rational discussion.

On the other hand, if you actually want to read an objective and semi-technically-based analysis of the Tak-tenna, try to get a copy of the two-part review written by WX7G in the Aug 2008 and Nov 2008 issues of the antenneX online magazine (www.antennex.com). The author devotes Part 1 to a theoretical analysis of the Tak-tenna and related short antenna configurations, and in Part 2 he shows some actual field measurements, with and without a balun. While I would hardly call the analysis rigorous, WX7G's model predicted less than 5% radiative efficiency if you take the feedline out of the picture, and his field strength measurements with a balun indicated a 12 db deficit compared to a dipole at the same height. He didn't specify what balun he used or where he put it, and I suspect the performance would be even worse if all shield currents were really choked off.

You may be asking yourself, "Why all this preoccupation with feedline radiation?" Because ... if most of the radiated energy is coming off the coax shield it's much cheaper and far simpler to just string up a piece of wire and feed it as a vertical.

As N3OX and others have stated, if you want to operate QRP with your 100 watt rig, you can have a lot of fun with your Tak-tenna. Or if you simply prefer to have faith in the mysteries of stuff you'd rather not try to understand, go ahead and put $125 under your pillow for the tooth fairy. On the other hand, if you want to use the hobby to learn, or if you want to operate with the best signal you can with whatever space constraints you might have, you're going to have to be a little bit more objective.

73,
Dave AB7E
 
RE: Homebrew Tak-tenna  
by W5VPU on January 19, 2009 Mail this to a friend!
Every antenna will radiate something.
 
RE: Homebrew Tak-tenna  
by WX7G on January 20, 2009 Mail this to a friend!
I recently wrote a 2-part article for AntenneX in which I analyze the Tak-tenna and reveal exactly how it works. It isn't what you think it is.

Dave WX7G
 
RE: Homebrew Tak-tenna  
by KA6KBC on January 20, 2009 Mail this to a friend!
Hi Dave,

How can I access that article ? I can't seem find it on their site with Guess level sign up ? I look forward to reading you findings. Is it posted anywhere else ?

73's - Bill - KA6KBC

 
RE: Homebrew Tak-tenna  
by VE7BDO on January 21, 2009 Mail this to a friend!
Antenna theory is just that, a set of theories. Theories aren't the "be all and end all" - they generally serve us until we have a different or more complete understanding and develop newer theories.

No such thing as "Settled Science" - by definition science cannot be settled.

Have fun experimenting and cleaning out/using up the junk box! That's what it's there for!!!
 
RE: Homebrew Tak-tenna  
by WX7G on January 22, 2009 Mail this to a friend!
Bill,

for this article you do need a subscription. It is worth is as you can access over 1000 articles.
 
RE: Homebrew Tak-tenna  
by WX7G on January 22, 2009 Mail this to a friend!
Bill,

for this article you do need a subscription. It is worth is as you can access over 1000 articles.
 
RE: Homebrew Tak-tenna  
by N3OX on January 22, 2009 Mail this to a friend!
"Theories aren't the "be all and end all" - they generally serve us until we have a different or more complete understanding and develop newer theories. "

That is correct.

And I have yet to see someone pose a hypothesis about small antennas being described by a "new theory" of electromagnetic radiation that was supported by any decent measured evidence or described theoretcially in a peer-reviewed paper. Maxwell's equations still work. They describe this antenna.

We can't discount and overturn classical electrodynamics just because someone can work Swaziland on 40m on a 30 inch long antenna. We can imagine that making a contact is a rough sort of gain measurement of an antenna.

But if you're honest about the error involved, you should probably say something like this:

"I made a contact with Swaziland, so I conclude that the gain of my antenna system is 0dBd +/- 40dB"

Those are pretty bad error bars ;-) If you hope to make the next breakthrough in antenna physics, you need to at least be able to measure, oh, +/- 2dB, not +/- 40dB.

And if you have a very small antenna, you absolutely must have a current meter to measure feedline current and some very good chokes to reduce it to a few milliamps for your tests. Otherwise, you're running a rather large antenna made of the feedline.

- - - - - - -

Trust me, if there is EVER a *real* major breakthrough in small antenna physics, you will hear about it and they will almost immediately be cranked out in quantities of millions for cell phones.

Until then, get comfortable with the current state of small antenna physics. Learn about radiation resistance and antenna Q and how you have a fundamental tradeoff among efficiency, size, and bandwidth. There are hundreds of objective and peer-reviewed scientific articles that support that point of view. I've been poring through some lately in a hope that I can cite and "translate" some of the more relevant ones.

All the major dissenters I've ever seen, those with "new theories" are trying to *sell something,* and when their antennas are finally put to the test in a controlled environment they end up 20dB down from a dipole, just like this one ;-)

The theory of small antennas is borne out well in practice in every measurement that's ever made of them. That even includes making contacts. A -20dBd antenna still radiates 1W of your applied 100W and 1W is PLENTY of power to make contacts.

It's important to remember that: making a contact, or even a *whole lot of contacts* using a 30 inch antenna on 40m does not conflict with our current understanding of how antennas work.

If you want to do experiments at home to try to discover a new approach to small antennas that might work better than an old approach, by all means do some science in your backyard. But do it scientifically.

Make a hypothesis that *can be tested* with a concrete prediction in terms of some measurable quantity.

Then measure that quantity to sufficient precision to give you evidence for or against your hypothesis.

Make conclusions that are directly supported by your evidence.

But remember that the hypothesis : "this antenna will make some contacts" will almost always gather evidence to the positive, and doesn't necessarily translate to anything in particular about "this antenna is within X dB of a full size dipole"

To gather that evidence, you need to do a measurement to somewhat better than "X dB" precision.

73
Dan












 
RE: Homebrew Tak-tenna  
by KC7MF on January 24, 2009 Mail this to a friend!
So we have one person who said they did the science but won't tell us their conclusions except "its not what you think it is". Nice. And two others who simply post "you must be wrong". Its physics.

OK. Your passion without the willingness to do the science, or at least publish it, is noted. You are certain. I understand your contention that all shorter antennas only radiate a watt or two.

So we summarize the thread. The OP says he made one but it didn't work very well. One person said the guy who sells them is a thief. And several others said that the people who use them are all self-deluded QRP operators working the world on thier feed lines. And one person said he did the science but won't publish it.

And the general tone of the thread would discourage anyone from experimenting at all. After all. There is nothing to learn from experimenting with antennas. All we need to do is wait for the cell-phone industry to tell us if there are any new developements.

I intend to continue to have fun with the hobby. I intend to continue to experiment with antennas. Even small ones. Most importantly I intend to encourage others to do it too and compare results with them. I do not intend to be one of the folks who sits back and says 'you are wasting your time' young man. There is noting new in heaven or on the earth. And I will not be the one to say 'it just can't be true'.

 
RE: Homebrew Tak-tenna  
by N3OX on January 24, 2009 Mail this to a friend!
"I do not intend to be one of the folks who sits back and says 'you are wasting your time' young man. There is noting new in heaven or on the earth. "

To discover a new idea, you have to be able to tell the difference between that and what came before.

I'm not saying *anyone* is wasting their time by building and testing small antennas. I'm just saying that no one who ever actually measures feedline current and gain has come up with something other than "this tiny antenna works much, much worse than a dipole if you choke off the feedline current"

You don't have to be a professional. You're not wasting your time. But if someone wants to publicly champion the idea that some tiny antenna could be as good as a 1/2 wave dipole or big vertical, they should probably "show their work."

And if you don't want to measure gain and feedline currents for tiny antennas, that's fine. It's not a big deal. If you want to make a list of your contacts on your weird little antenna experiment, great. I think that's fun too. I just have a problem when someone posts that list as proof that the antenna is about 95% efficient and doesn't rely on the 30 foot vertical run of feedline as the primary radiator. That's not supported by the evidence gathered.

My contention is that people running a couple-foot-long loaded "dipole" on top of a 20 foot pole would be much better served by just using the 20 foot pole efficiently fed against ground and not having bought the $100 thing that's on top of the pole in the first place.

And it's also that people running a couple-foot long antenna on their balcony would be much better served, efficiency-wise, by a ten foot long one.

I want people to experiment. I want people to run their small antenna experiment through the ringer and then post how many dB it's down from a dipole and how important the feedline current is. I want everyone's homebrew project to have an honest negative dB gain number attached to it.

It will greatly help anyone who's stuck in a really restricted situation to get the most bang for their buck; it'll help them make a rational decision about which project they should tackle or which antenna they should buy.

And yeah, I'm working on a small antenna project of my own, and it will be published, for free, on my website when I'm done with it.

73
Dan
 
RE: Homebrew Tak-tenna  
by AB7E on January 24, 2009 Mail this to a friend!
To KE7UXE:

I don't get it. There has been far more "science" presented here to support claims of low efficiency for the Tak-tenna than anything you've offered to the contrary. WB2WIK described his direct comparisons to an Inverted-V and got at least 20 db relative loss for the Tak-tenna. N3OX described mathematical considerations in great detail (feedpoint loss, radiation efficiency, etc) for short antennas. WX3G performed a theoretical analysis as well as actual comparison measurements on the Tak-tenna and published a paper on it. While WX3G is constrained from giving you a copy of his article gratis (he most likely received a payment from AntenneX for writing it), I took it upon myself to tell you his basic conclusions.

So what part of any of that do you find subjective or unconvincing? Please be specific.

And what science are you able to offer to the contrary? Please, though ... no more of this "not everything is known so that means there's room to believe what we want" nonsense.

Dave AB7E

 
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