At 06:29 AM 6/14/2007, Bob Maser wrote:
>Surely you don't expect a 4 element on a 26 foot boom to be
>competition for a 4 element SteppIR on a 32 or 34 foot , do you? I
>was just leveling the playing field by taking the boom from a 205BA
>and taking away one of the directors.
>The day that some company comes out with an antenna that can vary
>the length of the elements and change spacings between the elements,
>then I will consider buying one,
Presumably this is because you want "optimum" spacing between
elements (i.e. a boom length optimized for 20m will be too long on
10m, and vice versa)?
What about a long boom with, say, 6 SteppiR elements spaced along
it. On 10m, one just "turns off" the elements (retract them all the
way, or change the length enough to eliminate the interaction) that
are too far away and turn it into a "short boom".
But, as a practical matter, I suspect that 4 adjustable elements on a
longish boom can get very, very close to the performance (however you
want to measure it) at a single frequency, as any other antenna of
the same overall length. The challenge would be in specifying what
you actually want from "performance".. is it gain, directivity, null
placement, F/B, F/R, peak sidelobe level, integrated sidelobe level, or what?
The only limit would be that the element spacing can't be more than,
probably, 1/4-1/2 wavelength at the highest frequency of use.
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