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I have a 4 element 10 m yagi antenna. If I point it at the sky, will its azimuth radiation pattern then become the same as its elevation radiation pattern when horizontally polarized?

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  • $\begingroup$ Pointing it up gives you NVIS propagation, but you asked about radiation pattern which just rotates and isn't special. $\endgroup$ – user10489 Jan 14 at 12:27
  • $\begingroup$ I think this is a good question, since the elevation pattern of many types of antenna is heavily influenced by ground effects and may not translate directly to azimuth. $\endgroup$ – natevw - AF7TB Jan 14 at 18:40
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Short answer: yes, provided there are no ground effects in either orientation. That's how azimuth and elevation are defined.

If there are ground effects in either orientation, then it is likely that the radiation patterns will change as the orientation of the antenna, in relation to ground, is changed. In this case it is likely that changing the orientation of the antenna will not cause the azimuth pattern to become to the elevation pattern and visa versa.

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    $\begingroup$ With the caveat that the antenna must be free of ground influences in both cases. If not, the azimuth pattern from the normal orientation will not necessarily be the same as the elevation pattern when it is rotated. The same for the converse. $\endgroup$ – Glenn W9IQ Jan 14 at 17:33
  • $\begingroup$ But that's basically the same as saying that the horizontally mounted Yagi musn't be mounted directly in front of a wall; the difference that ground is typically inevitable :) but as long as that ground is not in reactive near field, you'd only get the reflection of the reverse beam, which hopefully is low-power for any useful Yagi-Uda to begin with. $\endgroup$ – Marcus Müller Jan 14 at 17:47
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    $\begingroup$ Here is what I am thinking. Mounting yagi's at different heights above ground changes their pattern. If you start with a horizontal yagi antenna pointing at the horizon (all elements equidistant to ground) within 0.5 wavelengths to ground, the ground effects are observable in the pattern of the antenna. If you now point the antenna at the sky, the former ground effects will not be translated because that ground effect is no longer there to the same extent (since the director is now closest to the ground). $\endgroup$ – Glenn W9IQ Jan 14 at 18:11
  • $\begingroup$ that's true! I simply overread the "10m" part of the question and assumed wavelength << distances involved! Want to add your own answer or edit mine? $\endgroup$ – Marcus Müller Jan 14 at 19:50
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    $\begingroup$ Thanks, Marcus. I edited your answer - please make sure you are OK with it. $\endgroup$ – Glenn W9IQ Jan 14 at 23:38

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