eHam.net - Amateur Radio (Ham Radio) Community

Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net



[Articles Home]  [Add Article]  

40 Meter Reversible 'String Beam' Antenna

from N4JTE on August 16, 2009
View comments about this article!

3 dBd on a Shoe String Budget

Okay, not really using shoe strings, more like a creative misuse of 300 lb test masonry string and trees in odd places. This project started when a 70 mph thunderstorm took out most of my support tree in my neighbor's yard along with a working G5RV that served well in filling in some missing lobes to the NE/ SW that my 60 ft. high EDZ lacks. So my goal was to get a broadside gain antenna in place for the NE/SW directions. I tried numerous variations until I realized that with a little creativity and a 500 ft. roll of masonry string I could accomplish a 2 element flat top full size wire beam for 40 meters in the right directions. The critical factor in this epiphany was to be the making friend's with my neighbor's newly arrived pit bull mix. When that storm came through, the first thing I noticed, besides the power being off, was all the antenna wires all over the yard. The top 25ft. of my support tree in the neighbor's yard had snapped off and fallen in front of Mr. pit bull's dog house. Before getting any closer I reviewed a couple of "Dog Whisperer" tapes and found a nice NY strip steak bone in the fridge.

0x01 graphic

Now armed and dangerous, I calmly and assertively, (yeah right,), approached the terrified dog. After some mutual bonding he came out of his little house and he and I talked about my need to use the remainder of the tree that nearly squashed him for some new antennas. So we agreed to stay in touch and he would ignore any random orange painted 2 ounce lead sinkers that were likely to land near him in the next few days.

The Plan

I wanted to make the two elements as light as possible. I was not overly concerned about the driven element as it and the coax feedline would be supported by the pole in the center. We all know there are many feedline techniques for direction shifting, but I wanted to avoid the extra weight of feedlines and the need for a remote antenna switch. I have had great success with 2 and 3 element low height quads by utilizing a stub and small relay to add needed length to a director to change to reflector. The other requirement for lightweight and simplicity was due to the fact that my neighbor's tree is about 100ft. from the driven element feedpoint and I needed a way to hang two wires on that tree without an obvious bunch of heavy ropes or too much visible out their back window, did not want to push my luck, invisible is good! I got lucky - first with the dog/ owner and secondly the remaining tree limbs were 50 ft high and wide enough apart to get the needed 20 ft spacing. My big concern was with the director wire as it would have to free span more than 140 ft, and with the added weight of the relay and the 12v supply wires I knew that extreme sag was gonna be a factor, especially considering one end was gonna be attached to a catenary string between a 40ft. pole and another tree, (mine this time). So looking around in my own yard I realized that if I used my big maple tree for one end of a support string that could go back to feed pole, it could end up as a support string under the director wire. I looped it under the director/ reflector and after every thing else was pulled tight I yanked on the string till the director wire was as close as possible to even height with the driven element at 40 ft.

0x01 graphic

Because everything here is in full bloom, I knew it was gonna be a major chore to get this sucker up in the air with all the spacing strings and wires getting stuck in the trees, and it was! Knowing what was in store trying this by myself, I did not attempt the reversibility concept till I made sure the thing worked at all. (DUMB) It worked like a light switch to the SW compared to the EDZ, not totally surprising but impressive to my old ears. So after a week or so I figured why not lower the thing and add the reverse capability to the mix and harass the Europeans . Well as any antenna experimenter knows, once you get the sucker in the air free of branches, leaves etc. it's probably best to consider yourself lucky and have a beer and enjoy your new antenna, WELL, I don't like beer, so I loosened about 6 strings with the goal of getting to the center of the director and splicing in the stub and relay for reversibility. With all the trees/ limbs/ spacing strings etc. hanging up , the best I could do was get the relay stub spliced in about 15 ft. off the center of the director wire, and was pleasantly surprised that the eccentric placement works fine.

0x01 graphic

Execution

First of all it's nearly impossible to photograph wire and strings in the air, nice for stealth not good for articles. Anyway; I first put up the driven element as a basic dipole and pruned the insulated wire to get to 7.185. I ended up at 64 ft. length. For the director I cut it 3 ft. shorter, 61 ft. and strung it up with 20 ft. spacing strings at each end and the centers. When using the fishing rod and 2 ounce sinker, I went for the outside limbs on the tree above Fido's house so I knew I would have a nice taut 20 ft. spacing between the two wire elements. The ability to reverse directions in a heartbeat has always been fun for me, especially when you're getting 3 dBd of gain, in other words, your 500 watt amp now sounds like a 1000 watts, and you get some nice front to back to boot. It is a very simple procedure of splicing in a DTDP relay, about $8 from Radio Shack, and shorting out the at rest position and putting a 6 ft. loop of wire into the active pins so the application of the 12 volts puts the stub into the circuit. For more detail on the relay wiring check out www.n4jte.blogspot.com and check on the quad experiments. There is no need for high priced relays in this design as the induced power in the parasitic wire is well within the limits of the relay at full legal power.

On The Air

Rather than presenting a boring list of reports from the many stateside and DX stations I contacted during this experiment, Just know this; IT WORKS. I consistently hear the "Light switch" reference when changing directions with 3 to 5 S units gain in the chosen directions.

Final Comments

Trust me, I am totally aware that what I detailed here is nothing earth shaking to most of us. What I hope I conveyed was a simple, cheap and highly efficient wire beam. In my case, after walking around my backyard, and others, for 8 years I found a way to get a nice flat top 40 reversible beam in useful directions. For the "How to hang a wire antenna properly" purists out there, my use of masonry string might seem a little crude. However, by luck or serendipity, my 165 ft. zepp has survived two years in upstate NY. That and the fact most of my wire antenna experiments are short lived unless I am totally amazed with the outcome, might skew my argument. For a permanent installation use the string to pull back through something more substantial and allow for limb movement with a counterweight or a strong spring. Well there you have it, the theory and application presented here will work for any band, and if your neighbor is a little hesitant about an almost invisible string in their tree, give them a steak bone, works every time!

Thanks for reading, N4JTE

Member Comments:
This article has expired. No more comments may be added.
 
40 Meter Reversible 'String Beam' Antenna  
by N3AWS on August 16, 2009 Mail this to a friend!
Great article! Now tell us about your EDZ.

73, Jim N3AWS
In the Land of the Morning calm
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by K0BG on August 16, 2009 Mail this to a friend!
Talk about your doggedly search for more effective antennas.....

The only problem I see is, not too many will even try such an undertaking. And, unfortunately, not too many of us have understanding neighbors. Most of them just have loud, unfriendly, and obnoxious dogs.

Good job in any case.

Alan, KBG
www.k0bg.com
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by W4VR on August 16, 2009 Mail this to a friend!
I can attest to the fact that your antenna is loud up here in Northern Maine, and when you switch to the other direction it's 15 dB down. Good work, Bob. Simple but effective.
 
40 Meter Reversible 'String Beam' Antenna  
by W4FCC on August 16, 2009 Mail this to a friend!
Great article!

Always enjoy reading your stuff.

73,

Rick
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by WB2WIK on August 16, 2009 Mail this to a friend!
Nice article!

Now, did the dog ever get his ticket?
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by HAMMYGUY on August 16, 2009 Mail this to a friend!
VG article!
 
40 Meter Reversible 'String Beam' Antenna  
by K9ZF on August 16, 2009 Mail this to a friend!
Great article!

I wish I had your trees:-)


73
Dan
--
Amateur Radio Emergency Service, Clark County Indiana. EM78el
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: 40 Meter Reversible 'String Beam' Antenna  
by N4KC on August 16, 2009 Mail this to a friend!
Just goes to show you, when something important is at steak, the ham will doggedly meat the challenge.

Sorry.

Very good article, though, if not for the specs but for the ingenuity. So many guys hesitate putting up anything but the perfect antenna, thus depriving themselves of the fun of being on the air and the pleasant surprise of sometimes getting lucky.

Don N4KC
www.n4kc.com
www.donkeith.com
www.n4kc.blogspot.com
(A blog about rapid technological change and its effect
on society, media and amateur radio)
 
40 Meter Reversible 'String Beam' Antenna  
by N2RRA on August 16, 2009 Mail this to a friend!
Excellant article!

All the elements to fill the imagination to what could be possible if you apply your self. Look forward to your next article much like this one.

73's!
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by KB2NAT on August 16, 2009 Mail this to a friend!
Really good article, though I imagine that dogs have reasons to also like trees.
 
40 Meter Reversible 'String Beam' Antenna  
by W4FCC on August 16, 2009 Mail this to a friend!
"Just goes to show you, when something important is at steak, the ham will doggedly meat the challenge."


Ugh. Ha!
 
40 Meter Reversible 'String Beam' Antenna  
by K9ZF on August 16, 2009 Mail this to a friend!
Here is a challenge guys:


An "all band" HF antenna, 160 thru 6 meters, [80 through 10 would be reasonable too] using wire, coax fed, with less than a 3:1 SWR on good portion of each band.

The idea is for an antenna to match many of the new generation HF rigs with a built in auto-tuner. Or one of the after market tuners like the LDG models.

It also needs to perform like a 5 element yagi, even when erected at 20 feet above ground. HI HI...

Sounds like the start of a neat contest, huh?


73
Dan
--
Amateur Radio Emergency Service, Clark County Indiana. EM78el
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!
 
40 Meter Reversible 'String Beam' Antenna  
by KL7AJ on August 16, 2009 Mail this to a friend!
Dear OM:

I don't know HOW I allowed this oversight, but I TOTALLY forgot to mention pit bulls in the Safety Chapter of the Opus of Amateur Radio Knowledge and Lore. I will amend that post haste. It will go nicely with my advice on lead sinkers and such. Thanks for the inadvertent suggestion!

From the Opus:

........One of the most time-honored methods for getting a wire aerial into a tree without climbing it is the use of a slingshot and sinker, or, alternatively, a bow and arrow. Either one of these devices can be used to launch a length of fishing line over an accommodating branch, which can then be used to hoist the wire aerial. Of course, each of these methods has certain hazards associated with them, as well. It's probably not a great idea to use a hunting arrow, as there is likelihood someone on the other side of the aforementioned tree might be on the receiving end. Even if the receiving party should survive, this action could result in collateral injury as described in method 12 above. So it's probably better to use an arrow with a target tipor if you're really a wimp, an arrow with one of those rubber-blob thingamajiggers on the tip.
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by KY6R on August 16, 2009 Mail this to a friend!
Great article - as usual - thanks. The only problem is trying to get such a beam up 1/2 wavelength - at least in my 'hood.

An alternative - that has just about as much broadsided gain is a Bruce Array attached to fiberglass poles. I have a 4 element 20M (4.2 db gain) and a 2 element 40M version (2 db gain) in my tiny backyard.

The bottom element (phasing lines) are 8' off the ground, and requires no radials. Fed as a vertical dipole with a short run of ladder line, and then a 4:1 balun and coax into the shack.

These are very good antennas - the elements are only 1.05 * 1/4 wl high and the space between elements are also 1.05 * 1/4 wl - so very easy to put up and maintain.

I'll re-post the picture of one of these on my QRZ page soon.
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by N4JTE on August 16, 2009 Mail this to a friend!
TNX Richard, I have to admit that my previous 2 ele reversible vertical experiment had the same or better results than the beam as described in this article, but due to summer outside activities I had to remove the raised radials and poles. I cannot attest to the Bruce array as being my first choice from here, having tried it and was not impressed, could be my bad but who knows?
If anyone can get a couple of wires up for 40,20,15,or 10 meters dedicated, and utilixe the reverse capabililities I believe it will perform well. But if space is limited I would go to phased verticals with raised radials similar to your experiments.
TNX for your comments.
Bob
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by N4JTE on August 16, 2009 Mail this to a friend!
W4VR, big tnx to you, Ron, and the others on 7168 and the Omiss net on 7.185 for putting up with my experiments. All that European DX is over your left shoulder from here in NY so your reports give me a real good clue as to what works.
"Simple and effective", I like that, gonna put on my next Resume ! Kind of sums it all up, hi.
Best regards,
Bob
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by VK6NDT on August 17, 2009 Mail this to a friend!
"Nice article!

Now, did the dog ever get his ticket?"

w0of.
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by KI4SDY on August 17, 2009 Mail this to a friend!
Good article and an excellent example of constant ham experimentation with antennas. That is how all the commercial antennas came to be.

Just out of curiosity, why not just erect a 5/8 wave 40 meter antenna (or whatever band you want) for the same 3DB gain? If you want switchable directivity, have one broadside East to West and the other broadside North to South meeting at the center with two feed lines and a switch box. That is a lot simpler and about the same price with more direction options. I love switch boxes!
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by KL7AJ on August 17, 2009 Mail this to a friend!
I believe he is now B0WOW :)
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by KG6WLS on August 17, 2009 Mail this to a friend!
He should apply for a special event call. K9R
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by KL7AJ on August 17, 2009 Mail this to a friend!
Actually, he looks more like an English bull terrier. That would make him GR0WL
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by W4FCC on August 17, 2009 Mail this to a friend!
W0OF
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by G3LBS on August 17, 2009 Mail this to a friend!
Did the dog lift a leg on the antenna?
 
DOGS  
by PLANKEYE on August 17, 2009 Mail this to a friend!
The thing that got my attention in your article is the picture of the Dog.

I thought it was a great Article!

Some folks think more Money, Big Amps, Big Beams =

You fill in the blank!

I think different than most folks!!




PLANKEYE
 
RE: DOGS  
by WI7B on August 17, 2009 Mail this to a friend!
This is a perfect article, and a great article for recession times when we are not all able to go out and buy a manufactured 40-m beam.

Does the little guy help you on phone or CW?

73,

---* Ken
 
RE: DOGS  
by G3LBS on August 17, 2009 Mail this to a friend!
I apologize for my previous post if I lowered the bone of the article
 
RE: DOGS  
by KY6R on August 18, 2009 Mail this to a friend!
G3LBS - don't worry, N4JTE is a nice guy and won't put you in the dog house for your comments.
 
20 over 9 in Europe ...WOOF!  
by N8NSN on August 19, 2009 Mail this to a friend!
Good stuff Bob,

I think the photography worked well with the added 'dots' in the pics. I am like many others in the wish to have more supports in all the right places.

The entire article is just great. I am impressed with e-ham every now and then on some of the articles that get some bandwidth in the forums and this is one article of good example.

Simplicity sure does offer it's rewards in the pursuit of having some fun with a hunk of wire and some strings, weed whacker line (they make some UV resistant stuff for weed whackers: Why UV resistant? ... no idea...), or Dacron rope.

TNX for a great read and the excellent pit pic...
did you notice the log chain restraint?

_ _ . . .
. . . _ _

Jim
N8NSN
 
RE: 20 over 9 in Europe ...WOOF!  
by AD7DB on August 21, 2009 Mail this to a friend!
The dog says he wants to go on a rover expedition with you as K9DOG! He can hear signals most of us can't!
 
RE: 20 over 9 in Europe ...WOOF!  
by WA4UF on August 23, 2009 Mail this to a friend!
You'd need a rig with a really really wide-range BFO for th' dog.

And to the poster that mentioned it, a Bruce array would be *perfect* for me, if only I could fit one into my back yard.

73, WA4UF Bruce
 
RE: 20 over 9 in Europe ...WOOF!  
by K8KAS on September 1, 2009 Mail this to a friend!
Bob, with the price of copper thru the roof do you think this antenna would work with just WET string. You know how tuff retirement is today, besides hams are cheap. 73 Denny K8KAS
 
RE: 20 over 9 in Europe ...WOOF!  
by WB9NJB on September 8, 2009 Mail this to a friend!
I had a pitbull once, and accidentally discovered that he was resonant on 160 through 6 meters. I would insert the feed line when I wanted to operate (the precise location of the feed line insertion is proprietary), and put raw hamburger around the yard when I wanted him to change the direction of radiation. At 100 watts he was pretty happy, but at 500, well, he became quite grumpy and I had to lock the shack door. Once, during Field Day a squirrel got into the back yard with the predictable result. By the time the old pooch caught and ate him, he had made 10 rounds of the back yard, and I had earned WAS. He was a great four legged antenna until he was hit by a cement truck. He survived (the driver did not) but he was never resonant on any ham band again. Such is the loss. 73 all.
 
RE: 40 Meter Reversible 'String Beam' Antenna  
by WA2JJH on September 10, 2009 Mail this to a friend!
ULTRA GREAT JOB OM. Funny how on a few topics up people are talkin about $400 Verticals that promise you the world 160-6M.

Most of us know there is no such thing as a broadband omnidirectional, no radials needed vertical that will perform great 3-30mhz.

Good 40M operation is much harder than shooting DX fish in a barrel on 20M. :)
 
Email Subscription
You are not subscribed to discussions on this article.

Subscribe!
My Subscriptions
Subscriptions Help

Related News & Articles
Your First HF Dipole
The Best First Antenna, Hands Down
Feeding an LPDA Beam Antenna
Smaller Backyard, Revised 40-Meter Beam!


Other Antennas Articles
Your First HF Dipole
Smaller Backyard, Revised 40-Meter Beam!
The Best First Antenna, Hands Down
Feeding an LPDA Beam Antenna