">Besides the loss problem you mentioned, a more fundamental problem is that a
half wavelength line is only a half wavelength at one frequency, presumably the
center of the band. As you tune away from that frequency, the 1/2 wave line is
no longer just an attenuator as you report, but it acts to reduce the bandwidth
of the system. The more multiples of a 1/2 wave, the more reduction."
Rick,
Very true. In some fairness to the author, he did set the 1/2-wave section
length based on the lower frequency where the correction occurs, as the antenna
is cut for the upper frequency where it's resonant.
>"What I have been doing for a long time is to instead locate a capacitor at
>the feedpoint with the normally closed contacts of a relay across it."
That's the elegant solution if one wants to pass DC power on the line.
However, just using an RG-11 variant of cable pretty much solves the problems
with reasonable efficiency and all the switching components can remain at
ground level for easy servicing.
Paul, W9AC
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