George, VA3EF wrote:
"How important/valid is statement:
'Both verticals has to be the same' for 1/4 wave verticals/space to be
fed in phase? Can one be shunt tower and other inverted-L ?"
==========
If the shunt-fed tower and the inverted-L are matched to 50-ohm coax,
feeding them in phase ( zero degree phasing, for a bidirectional
broadside pattern) is no problem. Just run equal length coaxes to the
two verticals
Feeding them 180 degrees out of phase (bidirectional endfire pattern) is
also no problem. Just make one coax electrically 1/2 wave longer than
the other.
The problem with phasing unequal verticals arises when you want to phase
them for a unidirectional endfire pattern. Then you have to know the
mutual impedances (difficult to determine without the proper
instrumentation) between the verticals to be able to calculate the
correct length of the delay line. For verticals spaced 1/4 wavelength, a
"hybrid" coupler may be constructed to force 90 degree endfire phasing.
73, de Earl, K6SE
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