At 11:29 AM 4/8/2007, Clint Talmadge wrote:
>Jim is correct. The Phase shift is 180 degrees and is added to two
>equal lengths of coax making the antennas In-Phase with the switch
>in one position and Out-Of-Phase in the other position.
OK.. there's a fairly easy way to do this with 1 SPDT relay...
Antenna one: some number of halfwavelengths of coax: contact A:
halfwave of coax: contact B: some number of half wavelengths of coax:
Antenna B.
You feed either at Contact A or Contact B...
Since you're always halfwavelengths, all the Z's sort of work
out. (bearing in mind that the feedpoint is going to look like
Zantenna/2 (because they're in parallel)..
ALmost any relay would work here. There's leakage C and Ls, but not
huge, and probably there's that much stray reactance on the antennas
that you'd have to deal with anyway.
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