Marconi's A99 test...does the match fail if the antenna has no feeline or mast attached?

[Marconi]

222, here is a video of my test demonstrating how an A99 responds without a feed line attached, and with the antenna Isolated from the mast, feed line, and ground using my Autek VNA 1 connected directly at the feed point. The video is not too good...I had shaking in my hands that day, and there is a lot of plant life in the view that makes the video even more difficult to watch.

But IMO it does demonstrate that the A99 will work without a feed line or mast attached, producing nearly the same match whether the antenna is directly connected to the Earth or not.

For a while now I have hoped to one day do a similar test with and without the GPK attached, but my ill-health doesn't permit me.

I would expect similar results however.

Below is a PDF file for my Antenna Notes on the test several years ago. I've also include a video I made...to show how simple the test is.

Ole Grampa tries to keep his ideas simple.

Earlier I posted this idea, noted above, for a test on the A99 to 222, where I asked him to try and duplicate my idea. This thread belonged to NewYork714, so I decided to make my own thread on the subject for the A99, and it did not quite turn out like I had hoped.

The idea here is to test the A99 and see if the match noted on my VA1 antenna analyzer goes bad...if the antenna has both the feed line and the mast removed from the feed point...which is noted by many to essentially serve as the other 1/2 of the antenna, and be necessary for providing return currents for the antenna. I asked myself...what will happen if these return currents don't have radials...and we hear much discussion about this issue.

We frequently hear this claimed, and thought...could I prove otherwise.

Well, what I did is noted above.

 

[222DBFL]

Marconi I am truly sorry I haven't been able to get to the antenna and perform the tests. Between work and taking care of my father who has Alzheimer's disease, I truly haven't had time for much else! I'm on my lunch break at the moment and that is the only reason I am posting right now. Again, many apologies sir. Times are hard for me at the moment! Hope you can understand sir. Have a good day and hope you get the results you are after.

 

[gamegetter]

greetings marconi;
How can one operate a radio through the antenna without a feed line? Once the feed line is introduced, the cmc is introduced. While some may have luck in their installations, others may be unlucky and can never tame the cmc. Power amount being one variable that adds to the mix.

Isolation is one of those things along with antenna height, feed line length, feed line routing, feed line grounding point and counter poise at feed line that may aid in controlling the cmc.

I hope this is what you are talking about.

 

[Marconi]

Marconi I am truly sorry I haven't been able to get to the antenna and perform the tests. Between work and taking care of my father who has Alzheimer's disease, I truly haven't had time for much else!

If and when you can Sean.

greetings marconi;
How can one operate a radio through the antenna without a feed line? Once the feed line is introduced, the cmc is introduced. While some may have luck in their installations, others may be unlucky and can never tame the cmc. Power amount being one variable that adds to the mix.

Isolation is one of those things along with antenna height, feed line length, feed line routing, feed line grounding point and counter poise at feed line that may aid in controlling the cmc.

I hope this is what you are talking about.

GG, I don't think I can disagree with your words, but in light of this test...how do you explain my test results and the video that supports the results on the EFHW A99?

Long ago I tried removing the radials off of my 5/8 wave I-10K, and the antenna match failed completely. In that situation a feed line and a mast we attached to the antenna. My lingering question has always been: why didn't the coax and the mast work to compensate for the bad match like it does for the A99?

This simple test showed me that a 5/8 wave antenna does not work well without radials, and the mast and feed line will not mitigate for the mismatch...that works to provide the match in one case and not the other. I realize a 5/8 wave is a little different from a 1/2 wave, mostly in the radiator length, but why does the A99 seem to work with the controlling conditions you noted above and the I-10K-------No-Way-No?

I think my test shows us something else to consider and I also believe this idea about EF 1/2 waves is supported somewhat by an article published by Steve Yates AA5TB, entitled "The End Fed Half Wavelength Antenna" http://aa5tb.com/efha.html

Yates leads me to believe the idea for the element necessary for and EFHW antenna to show sufficient return currents is only 0.05 wavelength in length at the working frequency.

I've talked to Steve personally about his impression on the A99 design, and he said he is not familiar with that particular design, but if it allows the 1/2 wave radiator to radiate by it self, and without additional radials...then the designs must be similar. He added however..."...there are several EFHW designs out there in the market, but for sure efficiency is also a necessary feature needing consideration."

Link: http://aa5tb.com/efha.html

My request for someone to try and duplicate my test and video results is based solely on Nothern1, sometime in the past in another thread, reporting his similar test showed him terrible results I claim. It was raining where Norther1 was at the time, and I'm still waiting on him to report back his follow up test.

I maybe talking about something else, but I'm open to changing my mind on this.

 

[gamegetter]

marconi:

i believe the difference to be in the wire vs the aluminum, but i could be wrong. once the ground plane was removed from the aluminum tube i10k, the antenna became much more sensitive to it's environment and all the before mentioned variables greatly affected it and to a greater degree. this can also partly be the reason that some set ups work well for folks and not for others when trying to install the same type antenna at different locations and under slightly different variables.

 

[gamegetter]

marconi:

regarding this link you posted above: http://aa5tb.com/efha.html
at the very end of the article, the author states "I can usually rack up 500 contacts using only 4 or 5 Watts. DX is very easy with this arrangement as well".
My thought on that is that low power is not likely to affect the cmc as much as higher power would affect the end fed, and DX can be accomplished with just about anything, as you are well aware it is all about conditions. To paraphrase a good friend: "We're just lucky that Mother Nature doesn't require our antenna systems to be perfect in order to work our radio."

 

[Marconi]

marconi:

i believe the difference to be in the wire vs the aluminum, but i could be wrong. once the ground plane was removed from the aluminum tube i10k, the antenna became much more sensitive to it's environment and all the before mentioned variables greatly affected it and to a greater degree. this can also partly be the reason that some set ups work well for folks and not for others when trying to install the same type antenna at different locations and under slightly different variables.

You may be right GG, but

maybe I should try this wire vs. tubing idea out on a CFHW dipole and see it makes any difference in performance or match...at least to the extent in difference I reported with the A99 in my video.

Is that fair? on your previous post also.

 

[gamegetter]

marconi, if you modeled a 5/8 wl end fed with thick tubing such as the I10k vs a 5/8 of thin wire the size such as the a99 uses, i wonder what that would show?....on a center fed, i would think the ground or counterpoise currents would be balanced, but much higher on the end fed, but i could be wrong, the model may help.

just some thoughts. good day.