Topband: Dipole and Ladder Line
Mon, 13 Nov 2000 19:41:12 -0500
> Can anyone tell me if the 70 ft. vertical length of ladder line that feeds
> my 160 meter dipole contributes anything to my reception of signals.
1. Antennas are "reciprocal," meaning transmit and receive characteristics
are identical. Reciprocity is a fundamental antenna principal.
2. Radiation from a balanced feedline (or from coax in most situations)
results from imbalance in the system -- physical or electrical asymmetry,
coupling to nearby objects, variations in height, local ground variations,
etc. With excellent symmetry, the feedline will contribute very little to
the total radiation. With poor symmetry, it can contribute a lot.
Ergo, if you have a nice straight 160 meter dipole that is pretty much in
the clear, and if the feedline runs at a right angle to/from the antenna for
a good distance, you will have minimal radiation (and reception) from the
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