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Author Topic: Antenna in small, urban lot: 2nd try  (Read 3704 times)
KD4LLA
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Posts: 463




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« Reply #15 on: April 02, 2008, 07:48:58 PM »

You might want to sell your radio equipment to me, as your wife will never be happy with any antenna.  String the wire up around the house on a day when she is shopping and she will never know the difference.
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KC8HQX
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« Reply #16 on: April 03, 2008, 06:29:52 AM »

I've read a lot of good suggestions so far. I hadn't thought of using a capacity hat.  

As for the ladder line, it's not just a matter of asthetics (though I'm not to keen on screwing stand-off into our "new" house either); to get ladder from a dipole to my shack, it'd have to make at least seven 90 degree bends to get around the turrets and gables to my window.

Though my lot is 50x135, I have to use the 50 foot dimension if I want an East/West radiation pattern. Using the long end of the property would require me to put a pole in the front yard and would put the antenna close to both my house and the neighbor's.

I was at the house last night cleaning up in anticipation of moving in and found that the neighbors have changed the chain link fence to wood privacy. I also closely eyeballed the trees back there. The branches are so intermingled that stringing a dipole would be extremely difficult at best. I could manage to snake a vertical up there, but a capacity hat would have to be of robust construction to survive the rough trip up through the branches.  

Correct me if I'm wrong, but my understanding is that most of these wide band doublets will load up, but their take-off angles vary from high to NVIS. I'd rather trade off a few dB of gain for a pattern that puts the signal where I want it and a vertical seems to fit the bill in that respect.

Finally, there are some attractive off the shelf solutions, but I tend to be a DIYer. Where's the fun in grabbing a several grand of equipment off the shelf and just plugging it in?

BTW, since I already have a cheap/free supply of LMR-400, can I get away with burying it rather than purchasing the gel filled version?

Doug
KC8HQX
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N3OX
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« Reply #17 on: April 03, 2008, 06:59:36 AM »

"but my understanding is that most of these wide band doublets will load up, but their take-off angles vary from high to NVIS"

Please draw your own conclusions about *gain* at various elevation angles from books or EZNEC instead of the constant mention of "angle of radiation" here on eHam.

Anywhere I've been soil-wise, a 40 foot high doublet will kick the pants off a vertical on 20m and up, probably will do so on 30m and may very well compete on 40m.  For DX on 80m, a vertical will do better.  For 40m, having both is useful.  I'd never choose a vertical for 30m and up vs. a 40 foot high horizontal antenna unless I tried both and found that my local ground conductivity gave the vertical enough of a boost.

But be aware that over average soil, a vertical can be MUCH LESS EFFICIENT than a doublet.  The angle of maximum radiation doesn't matter worth a darn for transmitting if the total radiation is so much less that the vertical has lower gain at that elevation angle.  Over ordinary dirt, a lot of that high angle radiation gets *cancelled* and *absorbed* instead of being redistributed.  

You want to work the Middle East on 20m?  You need the best gain at the takeoff angles most common for the Middle East.  Check your 40 foot doublet in EZNEC vs a ground mounted vertical over average ground.  You'll probably find that the doublet has 3dBi gain at 11 degrees elevation and the vertical has -1dBi gain at 11 degrees elevation.  

On 40m, the angle of *maximum radiation* might be really high... but the difference in strength between a 40 foot doublet and a ground-mounted 1/4 wave vertical at low angles might not be all that much, or anything at all!!  The only real advantage is on receive, where a vertical picks up less high angle interference... but you can do that with small receiving antennas and you'll have a bigger signal stateside on transmit, and why not?  Fun for  participation in domestic contests and ragchews.


Point taken about branches getting in the way of putting up the doublet... that's another issue altogether.

But don't fall for the party line that "verticals are good for DX because of their angle of radiation."  It's not that simple, and a 40 foot high doublet is FAR from a cloud burner on the higher HF bands... it will probably be several S-units stronger than a ground mounted vertical on 20m and up at least... unless you have stellar soil conductivity.  

Don't design your antenna system based on sound bites. Look at gain at desired elevation angle, not angle of maximum gain.  5dBi at 10 degrees from an antenna that has a gain of 9dBi at 45 degrees is 6dB better than -1dBi at 10 degrees from an antenna that has 0dBi of gain at 25 degrees !!!!

73,
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N0CGF
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Posts: 29




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« Reply #18 on: April 03, 2008, 11:17:17 AM »

I used to live in a residential area with houses around my small lot. I first installed a 4btv vertical ground mounted. For the 30 radials I had a hard time getting each radial out 5 - 10 feet each. Performance was Poor even on cw. Then I went to the dipoles and those I could not get up higher than 30 feet, and 40 meter performance has been poor for 25 years.
Then I purchased ON4UN's Low Band DX'ing Book. From reading this I installed a 6BTV vertical elevated at roof level with 4 elevated tuned radials for each band. This antenna on 40 meters has been FANTASTIC !!
I just need more operating time to compare the elevated vertical with tuned elevated radials to my dipoles on the higher bands. That has been my experience so far with elevated vertical with elevated radials at this location. 73's N0CGF Dennis

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KC8HQX
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« Reply #19 on: April 03, 2008, 01:29:09 PM »

"Please draw your own conclusions about *gain* at various elevation angles from books or EZNEC instead of the constant mention of "angle of radiation" here on eHam. "

N3OX,

I *have* drawn my own conclusions about *gain* at various angles from various books, EZ-NEC, Cebik and other web available sources of antenna analysis. Please don't draw your own conclusions about what I might or might not have done except from what I've already stated. "Angle of radiation" or "Take off" angle is the angle of maximum gain from horizontal, no? Are you arguing semantics just to be a curmudgeon?


I'll be on the the same HF bands you likely occupy soon enough; do you treat people with this much disdain on the air to? Verbal floggings in real life or on the internet really don't encourage me to believe the effort to rejoin Ham radio and get my General is worth it if this is what I'm going to experience as a "Newbie" to HF. I've never been treated like this by folks on the oft maligned 2 meter repeaters.

Given the bands I'm wishing to work (80/40/20), space and feeding limitations, every doublet and modified doublet I've investigated that could possibly be crammed into my backyard has been passable on 20, less than stellar on 40 and downright awful on 80m. I think I'm going to have to accept 80m is a pipe dream unless I install a large vertical or huge tower, but never the less, on 40m for example, where most doublets hoisted as I has I can get them will be burning the clouds, the model of a 33 ft. vertical wire shows a nice vertical gain maxima (take-off angle) at 20-25 degrees and a giant null overhead. Not perfect for long DX, but far better than the 45-80 degrees and huge overhead lobe of the doublets I've looked into.

Sure, the only real way I can know is to try, which is what I intend. Since I've stated multiple times I'd rather build than buy my first HF antennas, chances are pretty low that I'm going to plunk down significantly more $$$ for a Hustler or Gap than I did for my 20 year old used Kenwood rig.

I'm warming up to the idea of a remote tuner/match hidden under a rock in the back yard with which to feed a doublet or non-resonant vertical.  I'm sure I have a long road of experimentation ahead, but I'll figure something out. That's the fun part. It's my way to gather as much information as possible from print, internet and human resources *before* blowing my hard earned cash.

Doug
KC8HQX
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KC8HQX
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Posts: 177




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« Reply #20 on: April 03, 2008, 01:34:58 PM »

BTW, I really do appreciate the advice given here on eHam.  However, I have been experiencing real negativity from people I deal with about being a "newbie" or "*&%! No-Code" and am irritated by it.

Doug
KC8HQX
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WB2JNA
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Posts: 94




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« Reply #21 on: April 03, 2008, 02:13:31 PM »

Doug:
This was mentioned before, but maybe it bears mentioning again. The simple solution may be a long wire tuned with a manual tuner at the station (with a ground or counterpoise of course), or a horizontal loop of wire (it can be pretty thin and almost invisible) that runs around the perimeter of your yard or the perimeter of the house (or even wrapped around the house) and fed in the middle with a short length of coax or ladder line into the tuner. Hope this helps.
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N3OX
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« Reply #22 on: April 03, 2008, 03:15:24 PM »

"N3OX,

I *have* drawn my own conclusions about *gain* at various angles from various books, EZ-NEC, Cebik and other web available sources of antenna analysis."

Excellent.


"Verbal floggings in real life or on the internet really don't encourage me to believe the effort to rejoin Ham radio and get my General is worth it if this is what I'm going to experience as a "Newbie" to HF."

Umm.  Verbal floggings?  I apologize if what I said came off as insulting to you.  I was merely trying to convey that advice here on eHam tends toward "verticals = DX" with little to no qualification.

I have no idea of your background or your exact design process.  I do know that some on this site tend to recommend verticals as DX antennas when, in fact, high horizontals are much better... and in fact, "high" isn't necessarily all that high.  

"I've never been treated like this by folks on the oft maligned 2 meter repeaters."

I can understand how you could construe my first sentence as curmudgeonly insulting.  The written medium doesn't convey tone well.

However, I fail to see how the rest of my post is a "verbal flogging."  If you thought it was, my sincere apologies for a post that sounded like I was berating  you.  Now, let's get to the facts.

You said this:

"I'd rather trade off a few dB of gain for a pattern that puts the signal where I want it and a vertical seems to fit the bill in that respect."

and

"most doublets hoisted as I has I can get them will be burning the clouds, the model of a 33 ft. vertical wire shows a nice vertical gain maxima (take-off angle) at 20-25 degrees and a giant null overhead. Not perfect for long DX, but far better than the 45-80 degrees and huge overhead lobe of the doublets I've looked into. "

- - - - - - -

The point of my post was this:

For transmitting, what matters is the gain at the desired elevation angle, not the angle of maximum gain.

You might try to overlay the plots of the cloudburner and the vertical as you've calculated them.

When I do that over Real/High Accuracy "Average" Ground with a 50 foot long doublet at 40 feet vs. a 33 foot wire vertical on 40m, I find that the "cloudburner" pattern of the doublet gives stronger response than the vertical all the way down to 12.5 degrees or so.  They're equal response at 12.5 degrees.

At 20-25 degrees, the "cloudburner" doublet is 3dB stronger than the vertical.

Now this is a vertical that is connected directly to MININEC ground, giving it basically the equivalent of 60 33 foot radials or better as a ground system and it's installed in a clear, flat open space.

A real ground mounted vertical hung from a tree is down among the ground clutter, especially that tree.  There probably isn't that much loss, but the vertical is only very marginally beating the doublet at very low angles anyway.

My point is that over some types of soil, most of the power that's warming the clouds with the doublets you're looking warms the soil when you run a vertical, even with a very good ground system.  There's some dissipation involved in forming that nice vertical pattern.

Over EZNEC "Average" soil you can only get a doublet up 1/8th wavelength, then verticals start to have an impressive advantage.

If you can get the doublet up 1/4 wavelength, there starts to be little advantage to the vertical, and other factors like ground system losses and near-field ground clutter losses might play a role in actually swinging the advantage toward the doublet.

If the doublet is a half wavelength or more up, it may very well kick the snot out of the vertical.  

And remember, stray losses in vegetation and ground clutter are going to go up with frequency.

My experience in real life in places with sort of average soil quality has been that ground mounted verticals or low ground planes on 20m and up are really very poor compared to easily erected horizontal antennas at a half wavelength or higher.  This is what I was imagining you might be comparing on 20m... some vertical vs. a 30-40 foot high doublet... maybe even a 40 to 50 foot high doublet.  I'd take a 30 foot high dipole over a ground mounted vertical on 20m any day due to my experiences with both.  

My relevant experience in real life on 40m is that a slightly-less-than-1/4 wave high doublet antenna and a somewhat elevated vertical dipole antenna worked about the same for the DX I could hear, sometimes favoring one or the other.    

My relevant experience on 80m is that a quarter wave vertical with a minimal radial system is the best 80m DX antenna I've ever, ever had.  I've also never had the opportunity to try a dipole free and in the clear at, say, 60 to 80 feet.  I can't argue with your cloudburner conclusion on 80m, but that's because the gain of the doublet at low angles is quite a bit less than that of the vertical, so the vertical wins....

- - - - - -

Again, sorry if you thought I was being condescending.

I just wanted to get the point across that even though a sort-of-low doublet is a cloudburner, there are a lot of circumstances where a ground mounted vertical is a dirtburner, even if you put down a lot of radials.  

I feel that this is not thoroughly recognized among the internet advice community, but it's something I've noticed in models and in my own installation.

Gain at a given elevation angle *is* what matters for transmitting at least, not the angle of maximum response.  

All I'm saying is that if I had 40-50 foot high antenna supports and wanted to optimize 80/40/20, I would seriously consider having the 40m/20m antenna be horizontal.



73,
Dan






 
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N2IK
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« Reply #23 on: April 03, 2008, 03:28:50 PM »

This is my second time being a ham. First time was in 1963 for one year when I was snot-nosed high schooler. Even back then, there were the crusty codger minority.

I remember hearing one calling "CQ No Lids, Kids or Space Cadets." I shrugged my shoulders and spun the dial. Could not answer him anyway as I was a CW only Novice with a homebrew transmitter, two rocks and a dipole a paltry twenty feet high.

Most of the hams I met then and meet now, are fine people like those who made me welcome and helped me transition from clueless newbie to ham. They lent me code records, taught me theory, gave me parts for my rig and antenna, etc. I had the great pleasure to meet my old elmer, Julie Hoffer W1DL(SK) from 1963 again in 2000 after I got relicensed. I got a chance to thank him for all he did way back when and to work him on the air for a few years.

So whatever you do, don't pay attention to those crusty idiots who can't remember how clueless they were when they started out.

73 de Walt N2IK

 
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N3OX
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« Reply #24 on: April 03, 2008, 03:38:05 PM »

By the way, how did I come across as someone who was interacting with you on the basis of you being a "newbie" or a "no-code" anything?

But I couldn't care less what your licensing history is.  A license is an authorization to use our frequencies.  

I realize now that I may have insulted you based on the fact that *you* also came to the conclusion that what mattered was take-off angle rather than gain at a given angle...

I was reacting to that, and that alone.  I can build an antenna with a 2 degree takeoff angle that has -10.3dBi gain at that angle... a very lossy beam a couple wavelengths in height, for example.  That's a terrible antenna.  

If I try for the sake of rhetoric, I could probably design an antenna array that has **maximum gain** straight up at 90 degrees but also has 10dBi gain at 5 degrees elevation.  I'm sure it would be very contrived (two yagis fed in phase, one pointed straight up and one pointed horizontally both at a high height might be an example)

It would be very good for talking to space, and very good for working DX ;-)  Not as good at working DX as if you just shut off the yagi pointing straight up, but that's not the point.  Its "takeoff angle" is 90 degrees.  Its gain at low angles is very substantial.

Takeoff angle is not what you want to look at.  Gain at a given angle is.


73,
Dan





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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N3OX
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« Reply #25 on: April 03, 2008, 03:39:12 PM »

I'm interested to see how much more of this thread will tend toward discussing my crusty-idiothood ;-)

It'll be fun.

Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KC8HQX
Member

Posts: 177




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« Reply #26 on: April 04, 2008, 01:26:48 PM »

Actually, I haven't received negativity on eHam, yet I let comments from other sources irritate me enough to over-react to posts here. Plus, the (new home) moving process has me on the edge of burning out. I apologize.

I'm sure at 20m and shorter a doublet can be tuned to outperform a vertical, but I'm primarily concerned with 40 and 80m with the vertical. 20 and up and the space requirements aren't so much of a problem.

*Given my space limitations*, it looks like going UP rather ACROSS will allow me to achieve reasonable performance easier. No matter what approach I take, I'm really thinking hard about the remote tuner solution.

Cebik's writings suggest a strong case for the 30ish foot vertical with a spiral capacity hat. Though a hat would be a big structure, I could conceivably make it robust enough to be "force hoisted" through the tree branches. Trying to weave an 80m capable doublet into the same space (2 trees 50 ft. apart) would be far more difficult I believe. Maybe I could construct a semi-rigid doublet using CPVC pipe? Perhaps I should learn to scale trees? OR a semi-rigid, tree supported vertical using CPVC pipe sprayed brown!

Either way, a real antenna will be far more effective than one constructed of bits and bytes. My first contact will probably be using chicken-fence, random wire, my gutters or the neighbor's dog anyway.

Doug
KC8HQX
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K9WJL
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« Reply #27 on: April 05, 2008, 07:49:53 AM »

I do have the Zero Five 43' Vertical. It works great on 10-20 and pretty good on 40-80. I dont run a tuner on 10-20, but 40-80 does require a tuner.
 It's installed over a 180 degree (semi circle) radial field with 31 radials between 10 and 20 feet long. The radials are stapled to the ground and the grass is already starting to hide them.
 The tilt over mount works very well and the XYL actually told me she dosent think the antenna looks that bad. (she doesn't have it in her nature to be nice concerning radio stuff, so it's an honest opinion) I think my G5RV works better on 40-80 but it may be that I use it more on those bands because it's alot quieter than the ZF.
 If you like I can send pics and a SWR chart I made for my installation here, just send me an Email to my address on QRZ.
 73,
 Bill K9WJL
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LU6FAE
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« Reply #28 on: April 10, 2008, 07:12:08 PM »

DEar Doug,KC8HQX

I have the same constraint at my backyard (my available space is 26 x 10 meters including my house). I was testing some dipoles to 80 m band. One of them, a homemade folded dipole worked sucessfully on this band and also on 40 & 20 m bands. This kind of antenna has a resistive load about 600 ohms- 70 watts but I could contact some stations 1200 km away from my position. I have a TS520 30 years old- tube type transceiver. Of course you will have a swr value of 1.1-1.2 on the worst condition -  that means folding the folded dipole on the roof as I made.
If you are interested on this antenna I can send you the dimensions of this. This kind of antenna is named as a non-resonant type.

Regards,
Aldo
LU6FAE
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