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Author Topic: Question about Par Endfedz and end feed antennas in general.  (Read 14088 times)
W9KDX
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Posts: 771




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« on: August 22, 2011, 05:29:33 AM »

Every time I look for comments and suggestions about building any type of end fed dipole, there are a lot of problems and issues with a host of things that can cause less than stellar performance.  Most people suggest going to some sort of balanced dipole.

However, all the reviews  I read of the Endfedz are nearly 5/5.  I am wondering how Par can do such a great job while most home brew end fed antennas seem to have so much trouble.  I have a receiving only Par and I find it works very well and I am planning to get the new 40/20 when it is finally available, but I was wondering what the magic is that Dale pulls out of his hat that home builders don't seem to be able to pull off.


Thanks,

Sam
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Sam
W9KDX
AD4U
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« Reply #1 on: August 22, 2011, 05:38:05 AM »

Sam:

First I know absolutely nothing about any of the Par antennas.  However ANY end fed wire antenna MUST operate "against" a good ground plane to be effective.  This means installing numerous "radials" which will act as a counterpoise (for the lack of a better term) which will act as the other half of the antenna.

An end fed wire antenna or a vertical will typically receive OK without a ground plane - your SWL antenna for example.  However transmitting a decent signal will require one.

It does not matter what the reviews posted here say, the laws of physics have not changed.

I think most people recommended that you try some kind of balanced dipole antenna, because they are much easier to get up and going.  If an end fed antenna is your only option, it can be made to work, but it will take a lot more effort to do so.

Dick  AD4U
« Last Edit: August 24, 2011, 07:31:10 AM by AD4U » Logged
K5LXP
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« Reply #2 on: August 22, 2011, 07:55:17 AM »

ANY end fed wire antenna MUST operate "against" a good ground plane to be effective. 

How do the end fed half waves at each end of a G5RV work then?


Quote from:  link=topic=77049.msg533884#msg533884 date=1314016173
I am wondering how Par can do such a great job while most home brew end fed antennas seem to have so much trouble.

Have you looked at AA5TB's site?  Many in the QRP community have duplicated his results with good success:

<http://aa5tb.com/efha.html>


Quote
I am planning to get the new 40/20 when it is finally available

Try it, you'll like it.  End fed antennas have been in use long before it was determined they couldn't work (much like SWR didn't matter until there were meters to measure it).


Mark K5LXP
Albuquerque, NM

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AD4U
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« Reply #3 on: August 22, 2011, 08:33:33 AM »

ANY end fed wire antenna MUST operate "against" a good ground plane to be effective. 

How do the end fed half waves at each end of a G5RV work then?


Mark K5LXP
Albuquerque, NM


I guess it is all in how one defines "work".  IMO a G5RV does not work well when compared to even a half wave dipole. A G5RV is a compromise antenna that enables one to radiate a signal on all bands.  I have never "seen" where a G5RV is a high performance antenna nor have I ever "seen" where it out performs a half wave dipole.

Dick  AD4U
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W9KDX
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« Reply #4 on: August 22, 2011, 10:01:20 AM »

Thanks for the interesting link and thanks for the information on ground planes.  I am in no position to disagree with all of my experience heretofore being in listening rather than transmitting.

The thing that keeps getting to my logic is the massive number (209) of reviews here for these antennas with not a single thing to say other than WOW and a 5.0 rating.  I guess I'll have to see  for myself as any balanced dipole I put up with be bent in weird ways and way to low to the ground.  I agree that you can't argue with physics, but Dale has something going on in that box at the end that seems to work for a lot of people.

Sam
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Sam
W9KDX
WB2WIK
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« Reply #5 on: August 22, 2011, 10:16:03 AM »

What he has going (users have taken the little matching unit apart by cutting it open, and the results have been posted on the web) is a matching transformer that works well but isn't very large, hence the "power restriction" on the Par End-Fedz.  If he made the transformer a lot bigger the antenna could handle more power.

It still uses the outer conductor of the attached coax as an RF path (as well as the wire antenna itself), so performance can still vary with the length of the coax and its routing.  It's already been determined if you use this same antenna installed at ground level with the wire sloping up into a tree (so, fed at the "lowest" point in the assembly) and bury the coax underground from that point all the way back to the station, the antenna doesn't work as well.  That's because half the antenna that normally radiates won't do that when it's underground.

In most installations, even though the coax will radiate, as long as you restrict transmitter power there won't be problems, or at least not many problems.  People do seem to like them.
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KK7KZ
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« Reply #6 on: August 22, 2011, 12:04:47 PM »

I believe the thing that the End Fedz have going for them is portability and convenience. I have operated the Par End Fedz (PEF) on 17 and 20 and done extensive comparisons with inverted vee wire dipoles and rotatable dipoles on the same bands. The PEF were installed with the matching unit near the ground and with the unit at the top of the pole in vertical, horizontal and sloping configurations.

First off, the PEF uses the shield as the counterpoise the antenna works against. The PEF usually ran an S4-S5 noise (dependent on your particular location, sometimes more, sometimes less) compared to an S0-S1 noise level for the dipole - same bands, same location. Since the shield is vertical in the config where the matching unit is up top, it picks up noise just as a typical vertical will do. Signal levels were typically 1-2 S units below the dipoles (sometimes more) and when the Par is installed with the matcher near the ground, signal levels suffer additional loss compared to traditional dipoles. Sometimes, however, the vertical component (shield) improved reception of low angle signals, but they could only be heard when signal strength was above the S4-5 noise level.

Don't get me wrong, they do perform but not quite as well as a simple dipole. I doubt many of the 200+ reviews were done with any comparisons to other antenna configurations. So, if that's all you know and you haven't done any quantitative/qualitative comparisons then most likely it gets a '5.' Most folks are happy with them and the 'I can work 'em if I can hear 'em' yardstick seems to be the measure of performance most used. You must realize it's a 'relative' rating system on eHam reviews.

However, if you spend the time to do some A/B comparisons, I suspect the ratings would change.

I used them for several months and was somewhat satisfied but once I compared with traditional dipoles, the PEF are now now resting quietly in coffee cans in the basement.

Again, these were casual tests by using the antennas for several weeks at a time (separately and in A/B mode) and keeping track in the log which antenna was used with sig reports recorded. Propagation will play a big part in performance but these tests were run during that huge dry spell when the SFI was hovering forever around 70 so I think prop wasn't a significant factor.

For me, the signal to noise ratio differences between the dipoles and the PEF and the increased noise levels with the PEF antennas made listening/operating a less than satisfactory experience because of the 'tiring' factor the noise causes when blasting one's ears. Horizonatal dipoles are much quieter and more pleasant to use. A lot of stations heard with the dipoles were covered up by the inherent vertical noise of the PEF.

Just my .02 and a lot of hours listening to both systems. The choice is up to you.

R.
« Last Edit: August 22, 2011, 12:07:56 PM by KK7KZ » Logged
W9KDX
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Posts: 771




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« Reply #7 on: August 22, 2011, 12:58:50 PM »

KK7KZ,

Thanks so much for your great run down of the issues with the Par EFs.  That is exactly what I needed to know and it explains just what is lost and what is gained which make perfect sense.  I just knew that you couldn't get something for nothing and added noise is definitely something I need to consider.  My Par EF-SWL is very noisy but I have never listened to a good center fed Dipole so I just assumed that is the way things are.

An additional question is I could; can a center fed dipole be set up as a horizontal V.  As in one radiator heads north and the other heads east?

Sam

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Sam
W9KDX
2E0OZI
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Posts: 270




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« Reply #8 on: August 22, 2011, 01:02:32 PM »

As stated above the thing missing from the reviews is usually a comparison against a standard design. Steve Nicholls G0KYA in his book "Stealth Antennas" DOES compare all of the designs he tries out against a few references, so that makes it a step up from just "I tried it and it works" IMHO. Of course what is missing from other peoples suggestions is an intimate knowledge of your own QTH, finances, and whether your partner will be entirely happy with a forest of aluminium in the air. Or the neighbours. My own situation lends itself very well to an end fed wire + counterpoise so thats what I use at the moment. Beams, yagis, verticals are not on at this QTH, so its some sort of wires for me all the way. Maybe later in the year I will try a doublet, if I can keep the feed away from metal stuff. Mabe not. Its all fun.  Grin
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Men can only be happy when they do not assume that the object of life is happiness.
George Orwell
W9KDX
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Posts: 771




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« Reply #9 on: August 22, 2011, 01:24:23 PM »

Well, I lost my spouse 15 years ago so it is just me.  However, I have to set up in the back yard, fastened to my deck and trees, so I can't get much above 20 feet.  I need the pulley system to counter balance stress under the deck so any center feed would be 30-40 feet out in the middle of the yard.  Given that neighbor kids run through there all the time, I can't just drop down, so the feed would have to travel back along the antenna wire.  While I can get away with black wire as subtle, RG-8 is just not going to pass with the neighbors.  The end fed would work perfectly with the layout, but my coax would only be 25 feet long or so and almost all horizontal as it runs under the deck.

Any particular way to minimize the noise issue?

You guys are great.  This place is a phenomenal resource!
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Sam
W9KDX
KY6O
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Posts: 6




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« Reply #10 on: August 22, 2011, 03:20:05 PM »

I almost ordered an End-Fedz, after talking with a few friends who own them, and swear by them, plus reading all the 5/5 reviews here. But, like the first posting here, I kept asking myself "What is the magic?" No matter how hard you try to deny it, you're not going to be able to change the laws of physics, and "wire is just wire". The electrons don't care Wink

So, several hours of deep research later (Thanks, ARRL Antenna Book!) I just ordered a few torrids to experiment with. The key thing is to perform a deep web search for a "9:1" balun. That seems to be the best way to couple 50 ohm coax (The radio end) with anything from 450 ohms to several thousand ohms. Palomar Engineering sells a complete kit (Minus a box) for $25, or you can order the part dirrectly from them for less than $7 (Shipping not included)

-Rich, KY6O


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W9KDX
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Posts: 771




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« Reply #11 on: August 22, 2011, 04:25:58 PM »

Well guys, based on some very savvy postings from people who know way more than I do, I have decided to give up on the end fed and go with a balanced dipole.  I spent the last hour in the back yard and I have a way to do it so I need your advice.  I will have to put it about 15 feet above ground, behind my house, and about 10 feet from the back of the house (aluminum siding 2 story) running East-West in Minnesota.  This way I can get the center feed supported with the deck and run the coax straight down to the basement where the shack is.  I could look at two versions, one is a Windom with offset feed point working 40,20,10, and 6 meters at 66 feet long.  The other is a standard dipole center feed with traps for 40 and 20 meters at 44 feet.  Either one can be made to fit although the 44 foot version will have about 30 feet of rope.  I am partial to the Windom only based on the lack of traps which will make it less visible to the neighbors, however it will cost substantially more and I only plan, for now, to work 20 and 40 meters.

What will be the likely problems with my plans.  Any suggestions welcome.

Much thanks,

Sam
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Sam
W9KDX
KK7KZ
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« Reply #12 on: August 22, 2011, 05:34:04 PM »

Chas,

I bought some white coax a while back (RG-8X) and it is hardly visible against the sky. Can't remember who I bought it from but I think it was AES. With your short run, RG-8X ought to be just fine for HF purposes.

Check some of the antenna books/internet pages for configurations; dipoles are extremely tolerant of zig zags, droops, bends, etc. Just hang some wire the best way you can and you'll be on the air. My buddy in FL runs a dipole that is inverted vee and also is a vee in the horizontal axis looking west. Works just fine.

R.
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W1JKA
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« Reply #13 on: August 23, 2011, 04:17:07 AM »

     Practical use and observation only.I operate mostly qrp-cw dx,using a 40m endfedz,dipole with 20/40m radiators and efhwfor 20/30m.All 3 are ideal for qrp.

      Dipole: longer set up time,support considerations,no tuner needed

       Par endfedz: Less set up time,less support considerations,more directional than dipole and no coupler needed.

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K5LXP
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« Reply #14 on: August 23, 2011, 07:14:24 AM »

I could look at two versions, one is a Windom with offset feed point working 40,20,10, and 6 meters at 66 feet long.  The other is a standard dipole center feed with traps for 40 and 20 meters at 44 feet. 

At 15' up and 10' behind the house, it probably doesn't matter, neither one will be remarkable and they may not even tune right.


Quote
I am partial to the Windom only based on the lack of traps which will make it less visible to the neighbors,

They must be living in your back yard if they can see a wire 10' away from your house.

If an end fed would get the wire up higher and in the clear I would take that over a low doublet next to an aluminum sided house.


Mark K5LXP
Albuquerque, NM
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