Radials? and the end fed 1/2 wave (EFHW)

[Marconi]

This thread is planned to use a poll to get opinions on the need for radials, slanted, horizontal, 1/4 wave, or less than a 1/4 wave on the A99. After a few days for the poll, I will post a recap result for this work, and we'll see what my Exnec models show us in the regard, OK?

JJ, our buddy from Columbia SA, talked to me a while back about what Eznec5 suggested about radials on the A99. He had a project in mind, and wanted to know what would be the best length for radials made of 1/2" tubing compared to the 72" stock radials. I agreed to model several scenarios that he could consider. I just sent those models along with my recap results to JJ.

I told him I didn't think, based on my real world testing and some modeling, that radials would make much difference in just about any configuration and explained why.

Well, I did an A99 with 4 x 105" inch radials...both slanted at about 45* degrees, and horizontal. I also did the same model with 72" radials slanted down, and another model with no radials at all, just like a lot of A99s are installed, except for the isolated mast maybe.

JJ, planned to mount his antenna on a non-conductive 38' foot mast, so these models do not include the mast. I also did these models in free space, and over Eznec's real world Earth, set to average soil conditions. The recap, to be posed later, is broken down into two groups, real world, and free space, showing both the maximum angle lobe in degrees, and gain.

As comparison, I have posted below a Free Space (FS) model that I did a while back for a thread where Bob85 presented his idea for shortened radials with a system that retains the full 1/4 wave length along with Multimode 200, the owner of the antenna. I did alter this model a bit for height to equal JJ's idea, and made sure all settings were similar.

View attachment Bob's .50w radial idea FS.pdf

 

[nav2010]

Using radials on an half wave end fed will not show any significant improvements unless you isolate the antenna from the mounting pole and choke the antenna. The reason behind this is because if you don't isolate and choke this kind of arrangement then the mast will change the electrical length of the radials and the coax will do exactly the same. At the end of the day we are trying to force current into those radials and by isolating and choking you leave no alternate path for those currents to run apart from the radials.
Two years ago I did exactly this and during testing on FM (SSB is too unstable to do any testing at all) and I had significant improvements. Local station four files away, had a clear 2 S point improvement. Other improvements locally were 1-2 S points. Had a 4 S point improvement at 20 miles away and a massive RX improvement on my south side which I previously was unable to hear.
I believe that adding radials in this way, you lower the angle of radiation in a half wave and more of your RF is concentrated where you need it. Your own tests Marconi on such arrangements are unfortunately null and void, in fact all your tests on all your antenna's are null and void because [a], you failed to use the same mounting pole, coax, pl plugs, location, , you used SSB instead of FM which is totally unstable from one minute to the next, [c], you failed to isolate the antenna from the mast and were only testing your masts ability to act as a counterpoise, [d], your choice of participants in your tests was incompetant because you never arranged with anyone for the tests to take place, you havn't got a clue if any of those participants were using beams, altering their power on the radio, if they were trust worthy or any of them were mobile in some cases. Then when someone else gets a different set of results you start arguing the toss and making silly threads like this to try and prove me wrong. You can model this arrangement till you are blue in the face but the fact of the matter is - it works!
Take your finger off that antenna switch button, step back from the Kenwood and get yaself sat in a Shackletons high seat chair (they're lovely) and stare at the birds out the window.

 

[HomerBB]

Two years ago I did exactly this and during testing on FM (SSB is too unstable to do any testing at all) and I had significant improvements.

nav2010,
please explain exactly what you did within the parameters of the poll/thread.

You said you added radials,isolated the antenna from the mast, and put a choke beneath the feedpoint (I assume based on the previous paragraph), but no where did you reply to the choices in the poll, so I don't know whether you did this

72" slanted down radials?
this
1/4 wave slanted down radials?
this
1/4 wave horizontal radials?
this
72" horizontal radials?
or this
Another configuration like Bob85's model posted?

Could share this with everyone?

 

[BOOTY MONSTER]

i picked 1/4 wave slanted down radials because some folks do report slightly , to much better performance adding ground elements . and because i had better results using 1/4 WL ground elements on my 5/8s than i did with more shorter ground elements . it would be interesting to see real world results using 1/2 wave 3/4 wave and full wavelength ground elements .

 

[nav2010]

nav2010,
please explain exactly what you did within the parameters of the poll/thread.

You said you added radials,isolated the antenna from the mast, and put a choke beneath the feedpoint (I assume based on the previous paragraph), but no where did you reply to the choices in the poll, so I don't know whether you did this

72" slanted down radials?
this
1/4 wave slanted down radials?
this
1/4 wave horizontal radials?
this
72" horizontal radials?
or this
Another configuration like Bob85's model posted?

Could share this with everyone?

Quarter wave horizontal electrically but not straight physically.

 

[Marconi]

nav2010,
please explain exactly what you did within the parameters of the poll/thread.

You said you added radials,isolated the antenna from the mast, and put a choke beneath the feedpoint (I assume based on the previous paragraph), but no where did you reply to the choices in the poll, so I don't know whether you did this

72" slanted down radials?
this
1/4 wave slanted down radials?
this
1/4 wave horizontal radials?
this
72" horizontal radials?
or this
Another configuration like Bob85's model posted?

Could share this with everyone?

Homer, you'll be surprised at these Exnec model results. You already know my opinion regarding shortened 1/4 wave radiators with a noticeable top hat attached, and how they can compare favorably with a full 1/4 wave radiator. For me, this idea also applies to radial elements too.

IMO, this idea that Nav2010's is describing is sort of like the model I posted for Bob85 up above, as a result of his post sometime back concerning what he and Multimode200 found out with MM200's end fed 1/2 wave. I think his antenna might have been a Silver Rod or Thunder Pole antenna rather than an A99 however. http://www.thunderpole.co.uk/1-2_wave.htm

i picked 1/4 wave slanted down radials because some folks do report slightly , to much better performance adding ground elements . and because i had better results using 1/4 WL ground elements on my 5/8s than i did with more shorter ground elements . it would be interesting to see real world results using 1/2 wave 3/4 wave and full wavelength ground elements .

BM, in my opinion there is a big difference in how a 5/8 wave radiator is affected by radials and a 1/2 wave. The same applies to a 1/4 wave, but it needs radials even more so. Since Imax is a 5/8 wave, one might ask how it performs without radials? If you doubt this then you are Homer try your 5/8 wave ground planes without radials...and you'll see they don't work so good. The answer is in the matching device, just like Shockwave told us some time back.

 

[BOOTY MONSTER]

http://www.worldwidedx.com/cb-antennas/71031-half-wave-antennas-not-needing-ground-elements.html

another thread on ground elements on 1/2 waves .

*******************************************

"BM, in my opinion there is a big difference in how a 5/8 wave radiator is affected by radials and a 1/2 wave. The same applies to a 1/4 wave, but it needs radials even more so. Since Imax is a 5/8 wave, one might ask how it performs without radials? If you doubt this then you are Homer try your 5/8 wave ground planes without radials...and you'll see they don't work so good. The answer is in the matching device, just like Shockwave told us some time back."

i agree with you OGP . but the poll question is "Which works best for the A99" not what will work . i think it's more than obvious that the A99 does a excellent job for many people just as it is and some folks have better results with it than they do bigger 5/8's . some folks need the ground elements and a choke along with mast isolation to get good performance from them in their installations . i don't recall any comments from anyone saying that adding ground elements , choking and isolating ended up degrading the performance of there A99 . some have said it made no difference though .

IMO location (where it's at and whats around it) will dictate what a A99 (or any other) antenna will do . if i feel a antenna needs ground elements i'd add some that were resonate for the frequency/band it will be used on . just my thoughts ............

 

[Marconi]

http://www.worldwidedx.com/cb-antennas/71031-half-wave-antennas-not-needing-ground-elements.html

another thread on ground elements on 1/2 waves .

*******************************************

"BM, in my opinion there is a big difference in how a 5/8 wave radiator is affected by radials and a 1/2 wave. The same applies to a 1/4 wave, but it needs radials even more so. Since Imax is a 5/8 wave, one might ask how it performs without radials? If you doubt this then you are Homer try your 5/8 wave ground planes without radials...and you'll see they don't work so good. The answer is in the matching device, just like Shockwave told us some time back."

i agree with you OGP . but the poll question is "Which works best for the A99" not what will work . i think it's more than obvious that the A99 does a excellent job for many people just as it is and some folks have better results with it than they do bigger 5/8's . some folks need the ground elements and a choke along with mast isolation to get good performance from them in their installations . i don't recall any comments from anyone saying that adding ground elements , choking and isolating ended up degrading the performance of there A99 . some have said it made no difference though .

IMO location (where it's at and whats around it) will dictate what a A99 (or any other) antenna will do . if i feel a antenna needs ground elements i'd add some that were resonate for the frequency/band it will be used on . just my thoughts ............

Yep, you may be right that location always makes a difference in real world results, but this project is intended to be theoretically lossless, using free space models, with no loss due to resistance, other objects in the near field, mast, feed line, mismatch, or Mother Earth, all of which removes the variable you're suggesting.

My point was that we can't just assume that the radial effects on a 1/4 wave, 1/2 wave, or 5/8 wave will be the same.

Maybe I misunderstood your point.

 

[BOOTY MONSTER]

"but this project is intended to be theoretically lossless, using free space models, with no loss due to resistance, other objects in the near field, mast, feed line, mismatch, or Mother Earth,"


so in other words it has no basis in reality or application in real world use ?

 

[Marconi]

When I post the results, you'll be able to see that I also did the models over Eznec's real Earth condition as well. But don't be confused, because technically these too are not the same as real world use either. This is the nature of models, the inability to evaluate every possible material influence...the same flaw that exists in our personal real World testing.

No mater what we do with our antennas, we'll never be able to perfectly duplicate what every other operator might do, so we might ask, "...what's the point of doing any comparison work over real Earth?"

We do it, because we can.

 

[Needle Bender]

Well I didn't vote because I didn't see my option on the list.
I would place a 5.5 turn x 4" diameter choke in the coax 26" down from the antenna connector and install it on a 5'-6' fiberglass rod to isolate both the antenna and coax choke from the mast. Somewhere I remember reading that a 1/2 wave only needs a .06 wave length long counterpoise, but it would be a good test to build it and the full 1/4 wave radial version to see if one outperformed the other in the real world.

 

[Marconi]

Here is JJ's recap for the models I made for JJ's idea.

View attachment Recap of JJ's A99 models .pdf

 

[Robb]

Using 1/4 wave length radials AND isolating the antenna from the mast has been done by Hams with this antenna. Just look up the A99 on eHam and read some comments there. Anecdotal evidence at best - BTW. Some guys have used 1/4 wave length radials for 20m and have made it work with a tuner. Same with 17m and 15m too. Not that I would do that with it; there are better ways to get on 20m than a vertical built primarily for 10m, 11m, and 12m respectively. . So, using a 'slanted' 1/4 wave length radials for 11m should be best. Or perhaps horizontal radials; whatever looks best with EZNEC radiation pattern - I guess . . .

Simply put, because it needs that much counterpoise to balance the vertical for the freq being used. The RF on whatever freq will need it. If it isn't there; then it will end up using the coax as the counterpoise. Found that out when using it on 17m - BTW. I don't know about the claims of 2 S-units gains previously mentioned though, unless the antenna was already otherwise compromised in some way. AS in - having no radials at all.

 

[Needle Bender]

2 s units loss compared to an Imax and even more compared to a metal 5/8 has always been my experience with the a99, so maybe this isolation and radial thing is what it needs, but being an end fed 1/2 wave the entire cycle is completed from the base to the tip and back to the base so it doesn't really need the complimentary 1/4 wave radial system a 5/8 requires to complete the 2nd cycle after it goes up and back down through the effectively 1/8 wave matching network & 5/8 radiator.

 

[Marconi]

2 s units loss compared to an Imax and even more compared to a metal 5/8 has always been my experience with the a99, so maybe this isolation and radial thing is what it needs, but being an end fed 1/2 wave the entire cycle is completed from the base to the tip and back to the base so it doesn't really need the complimentary 1/4 wave radial system a 5/8 requires to complete the 2nd cycle after it goes up and back down through the effectively 1/8 wave matching network & 5/8 radiator.

I got the part I marked in red, but I've never had such results in my real world experience comparing these two. The rest I don't get at all, but it might help if you drew me a picture.

I was curious about your claim, so I took JJ's Free Space model of the A99 with 4x105" slanted radials at 38' high and extended the radiator by 60" inches to 22.5' feet just to check the difference. Here are the results as a comparison.

View attachment NB's claim for gain.pdf