On Sun, 18 May 1997, Martin Ellis wrote:
> We are fortunate to have an exhaustive analysis of
> the full-Size 2-Element Yagi published by L.B. Cebik, W4RNL:
A better comparison for the announced beam might be the idealized
3-element beam I have used for some comparisons, with a max gain in the
region of 8 dBi (free space). Comparing 2 and 3 element beams is quite
difficult, since the director-reflector combination makes all the
difference in the world to performance characteristics. The antenna
becomes subject to the boom-length "axioms," whereas 2-element Yagis are
"exempt."
My own idea is simply to wait until detailed data becomes available. The
diminsional specifications are not available here; nor is the feed method.
Hence, I have not the foggiest notion of how to begin modeling the
proposed antenna, let alone what pitfalls to avoid so as not to mis-model
it.
Moreover, models cannot show some of the other crucial factors in making
Yagi decisions, such as price, structural durability, etc.
For the curious, I note that gain is said to increase with frequency on
each band, which is interesting.
Since everything is question, with too little data to begin formulating
even tentative answer and judgments, I shall wait. Since the prelimiary
announcement said that weight figures may change, it appears that certain
construction decisions were not finalized at announcement time, which
means that the wait may be considerable. But those who model commercial
beams have, in the interim, the entire Force 12, HyGain, KLM, Cushcraft,
Sommer, and sundry other lines of antennas to compare.
-73-
LB, W4RNL
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