> Kris Kirby <[EMAIL PROTECTED]> wrote:
> What if you took two 1/4 wave ground planes, mounted
> the RX antenna up top, fed with hardline, and mounted
> the TX antenna pointing down, 1/2 wavelength (or 4/2
> wavelegths) down from the mounting point of the first
> antenna?
Did this on my first 6 meter repeater without a duplexer
and just one folded - loaded bandpass cavity made from
an old ARRL Handbook. I converted a 5/8 wave cb antenna
for rx, and use a half wave converted adjustable rod
scanner antenna for the tx at the bottom of an 80' pole.
Worked great at 2.5 watts output, sucked wind at 25
watts out using what one now would say is a fairly
wide front end Hamtronics R76 receiver. Feedline was
only rg-8, which was all I could give to the low budget
project back when I had a full head of hair. :-)
> This, it would seem, would put the image of the
> antenna 180-out from the first antenna, plus the
> isolation of having to go through a common ground
> surface as it were. That might give you a few DB of
> seperation, if there aren't too many near-field
> or far-field reflections to have to overcome.
finding wave-length and distance nulls in antenna
patterns in vertical sep repeater antennas used
on low band is a real chore.
Simple good setups work, getting greedy doesn't
have as much fudge room.
cheers,
skipp
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