On that note, another book by Collin ("Antennas and Radiowave Propagation) that isn't in my work office has this to say about parasitic arrays:
Parasitic arrays have usually been designed by experimental methods because of the difficulty of calculating the mutual impedances, the element lengths, and the optimum spaces, since these parameters are all interrelated in a complex nonlinear way.
I certainly don't think discussing the possibility of coming up with an analytic proof is a waste of time, but such a proof will be hard to say the least.
Sean
On Sun, Mar 14, 2021 at 01:14 PM, David Kirkby wrote:
On Sun, 14 Mar 2021 at 01:47, Reginald Beardsley via <pulaskite=
[email protected]> wrote:
If anyone knows of a rigorous proof that the Yagi-Uda is the "sharpest beam" I am *very* interested in reading it.? On inspection it seems plausible, but mathematics at that level is rather a black art to mere applied math people like me.
Thanks and..
Have Fun!
Reg
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I find it extremely unlikely that such proof exists. You would of course need to start by defining what is the "sharpest beam". The diffraction limit puts a limit on the first sidelobe and some Yagi-Uda antennas have the first sidelobe approximately that.
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I find it worrying that the ARRL no longer sell Lawson's book on Yagi-Uda antennas. It was an ARRL publication.? It was the book that taught me enough to write my own program to analyze the antenna. It is a fairly different concept to NEC. You could argue it give you an analytical expression for the far-field, as the far-field pattern depends on the self impedance of elements and the mutual impedance between them. But the formula for mutual impedance in Lawson's book makes the assumption the elements have zero diameter and are a half-wave long.
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The National Bureau of Standards (NBS)? made lots of careful measurements on Yagi-Uda antennas. Lawson shows that one of them must be wrong - probably just a typo.
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Dave
