N6BT, of F12, talks about this on p30 of his book "Array of Light". He
says that boom length is the primary item in determining forward gain if
it is "fully populated" with elements. Adding additional elements will
show little improvement in gain. "If designed carefully, the forward
gain, F/B, and VSWR can be maintained over more bandwidth by the
addition of more elements strategically placed and tuned." Good book and
well worth the $10 in my opinion.
73, Dan, N5AR
Richard Karlquist wrote:
>
> I noticed in Chapter 8 of W2PV's Yagi book, he shows that for a 20 meter
> Yagi on a 54 foot boom, there is little difference in gain whether you use
> 4, 5, or 6 elements. What I don't understand is why you never hear of a 54
> ft 4 ele Yagi, but 5's and even 6's are commonplace. This is kind of
> analogous to the question of why people bother with 4 element Yagi's on a 30
> ft boom when a 3 element on that boom has slightly more gain. I notice in
> the ARRL antenna book, there are a bunch of reference designs for Yagis.
> The 10 meter ones are more widespaced (in wavelengths) than the 20 meter
> ones. Why? Seems like they should be scale models of each other. Am I
> missing something here?
>
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