Cqtestk4xs@aol.com wrote:
> In a message dated 3/26/2009 5:39:51 PM Greenwich Standard Time,
> nq4u@mtars.org writes:
>
> Plans are to add a stack match.
>
> Both antennas will be fed with 75 ohm hardline cut to proper length. Wire
> antennas will also be located on this tower.
>
> Will there be some pattern distortion due to different antenna spec's?
>
> What are some problems that others have had in stacking two different
> antennas such as these?
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>
>
> Anecdotal here:
>
>>From what I've heard stacking dissimilar Yagis has been met with mixed
> success. I'm not sure of the reasons. Boom length and phasing problems
> come to
> mind.
>
> I've been stacking IDENTICAL antennas since the 80's and have always been
> successful.
>
>
I think a way to summarize this is that stacking dissimilar antennas is
trickier (i.e. less predictable from casual analysis) than stacking
identical ones. Identical ones have easier analysis math to predict
what they'll do. Dissimilar ones will have "different" patterns as you
switch the various configurations. It will probably work (and
realistically, you may not be able to identify any differences, since
it's not like you can A/B it).
You could probably, without a huge amount of trouble, run some models in
NEC to see what you'd get, pattern wise.
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