http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=1&f=G&l=50&co1=AND&d=ptxt&s1=ploussios .INZZ.&s2=antenna.TTL.&OS=IN/ploussios+AND+TTL/antenna&RS=IN/ploussios+AND+TTL/antenna

See US Patent 4,924,238



(Fred) wrote in message . com...
A few years back I read a paper which described an electronically
tuned HF Helical antenna. It was a shunt fed Helical monopole which
employed electronically switched PIN diodes to add or subtract helix
turns. As far as I remember a 6ft helix antenna was resonant between 4
to 30 MHZ by switching the PIN diodes. Diameter = 19", 20 turns, Q50,
average power = 400W.
Now the question to the antenna experts: was such an antenna ever
developed and manufactured. If yes, who did.
Thanks es 73
Fred
wb6iiq / dh1nwr