> There were (and may still be) a few stations that used the Franklin
> antenna, or two half-waves in phase.
Here's the Brittish patent by C.S. Franklin:
http://www.aktuellum.com/circuits/antenna-patent/patents/242342.pdf
There's aren't many commercial Franklins around due to the serious amount of
steel and property required. As in the case of WHO, some are "modified
Franklins." KFBK, KSTP, WOAI, KNBR have, or at one time had been using
Franklins. I believe WOAI, San Antonio has a 180/120 modified Franklin.
Stacking two half-waves results in a full-wave vertical dipole, but the two
elements are phase-cancelled. The Franklin employs a 90-degree network to
bring the top and lower elements in phase.
Here's a very simplistic diagram that shows the perils of using a 5/8-wave
vertical in the AM broadcast service.
http://www.radiomagonline.com/media/ar/0701/107br0703lg.jpg
Paul, W9AC
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