This is what my Eznec horizontal model with results noted by comparing the matching values for R, X, SWR. This suggest what results we might expect when tuning near the Earth, and then on raising to installed height.
The model I used is my best optimized horizontal 4 element yagi model installed @ 36' feet. My modeling idea here was to maximize gain at the best match and resonance possible, and minimize the need for gamma matching.
The first two models are horizontal at 9' and 36' feet above Earth which might be considered a typical tune and then install scenario. Then I rotated this model with the reflector 8" and 32" above Earth standing on the reflector end. This was done in order to compare the two methods and how the match changed if any.
Assuming there is little environmental effects on this antenna, I see very little change in the match results if tuned either way and at these two particular heights.
I did not check, but I suspect if the antenna was mounted vertical such results might not be as similar, and thus more tuning work at the installed height might be necessary.
I learned something new here I think, and I was surprised at these results.
View attachment Robb's tuning a yagi beam #1.pdf
If you see something I might have missed, let me know.
The model I used is my best optimized horizontal 4 element yagi model installed @ 36' feet. My modeling idea here was to maximize gain at the best match and resonance possible, and minimize the need for gamma matching.
The first two models are horizontal at 9' and 36' feet above Earth which might be considered a typical tune and then install scenario. Then I rotated this model with the reflector 8" and 32" above Earth standing on the reflector end. This was done in order to compare the two methods and how the match changed if any.
Assuming there is little environmental effects on this antenna, I see very little change in the match results if tuned either way and at these two particular heights.
I did not check, but I suspect if the antenna was mounted vertical such results might not be as similar, and thus more tuning work at the installed height might be necessary.
I learned something new here I think, and I was surprised at these results.
View attachment Robb's tuning a yagi beam #1.pdf
If you see something I might have missed, let me know.
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