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Old May 29th 04, 07:19 AM
Rick Frazier
 
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Rich:

Well, as 2m transmit is 144-148, the antenna will be too short for the
2m band, and the spacing of the 4 bays will be too close.

Generally speaking, it's usually easier to cut down element length on a
lower frequency antenna to bring it up to a higher frequency. Depending
upon the design, this may not result in a reasonable gain figure for an
individual antenna...

I'm assuming that when you say 4-bay, you mean an antenna array with 4
separate antennas in a 2x2 (square) configuration, which for the
original design frequency range, would have yielded nearly 6db of gain
over a single antenna of the array.

If you are serious about making the array work on 2m, the first thing
you will need to do is to increase element lengths to bring resonance of
the individual antennas within the 2m range. This may not result in
near the gain the original antenna had at it's design frequency because
the spacing of the elements will no longer be optimal. You might be
able to model it in NEC, ezNEC or one of the other antenna programs to
see what the current antenna gain and bandwidth figures are, and then
change lengths of the elements (leaving the spacing the same) and see
what the new antenna looks like.... Of course, even if it's ok, then
you have to figure out how to "stretch" the elements to fit. Once you
figure all of this out, and get a single antenna with decent gain at
your frequency of interest, then you need to repeat it three more times,
then connect them at the optimum spacing with an appropriate phasing
harness for 2m operation....

If you haven't guessed by now, it may be easier to just sit down and
make (or buy) an antenna with about the same gain figure the existing
4-bay has, and save yourself a lot of time. However, if you're willing
to spend a bunch of time piddling around and aren't looking for optimum
results, it can be a lot of fun to modify something like what you have,
if you enjoy cut and try and have a lot of time on your hands...

Good Luck
--Rick AH7H

wrote:

I ended up with a 4 bay antenna that is resonant from 150 - 170.
How much work is it to put this on 2 meters?

Rich L
KB7YEB