Good answer Mike, but I think you made a typo below...
If the antennas are 50 ohms and you feed them with odd
quarter waves of 75 ohm coax, the impedance is transformed
to 100 ohms... divided by 2 at the T connector is 50 ohms,
not 37.5.
In theory I agree with the comment about not moving too far
from the design frequency, but in practice I suspect it
will be a little more forgiving. I have built phasing
harnesses this way for 2 and 4 dipole arrays (base /
repeater antenna) and they cover a fairly wide range before
the impedance gets out of hand. BUT, the bandwidth of the
antennas themselves will be a BIG factor here...
Paul N1BUG
Mike Perryman K5JMP wrote:
> You can create a 50ohm "match to split" by using RG-59 is
> 75ohm (and is lossy as hell at 2m, but for the sake of
> argument please bear with me.) cable cut to an odd
> multiple of a 1/4 wave length combined with a
> T-connector.
>
> Feed the T with standard 50ohm line. Assuming a purely
> resistive load, the two lines in paralell will present a
> resistance of approx 37.5 ohms. This is close enough.
> And I am NOT going to get into complex impedances here.
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