On Mon, 30 Aug 2004 10:36:57 -0500, (Richard Harrison)
wrote:

Roy, W7EL wrote:
"Notice that I said that the wire was most likely to be a problem with
antennas on the order of an 80 meter dipole length."

80 meters isn`t the lowest nor the highest frequency ham band, but could
be a problem for various reasons. Loss is directly proportional to
resistance in the familiar current squared times resistance formula.

Resistance increases due to skin effect only as the square root of the
frequency while resistance varies directly with the conductor length
which varies inversely with frequency.

Loss gets worse for a given wire size as frequency drops because you
need longer wire for a 1/4 wavelength. It doesn`t get worse as fast as
it would if there were no skin effect because as frequency lowers,
current penetration grows and wire resistance drops due to reduction of
the skin effect. But, the longer wire is inevitable along with its
higher resistance at the lower frequency.

At RFE, as soon as a new frequency became available we would often erect
a Signal Corps rhombic kit and start broadcasting. These weren`t made
for 100KW so the dissipation lines soon melted and the rhombics became
bidirectional.

At the end of WW-2, many Central Europeans fled to South America. When
we strengthened and replaced our dissipation lines, we discovered we had
built a large loyal audience among the fugitives. Not too surprising
since we were programming with some of their favorite entertainers who
were also exiles. Too bad we had to eliminate the signal flooding South
America, but other broadcasters had claims on the frequencies we were
using for a South American audience.

Best regards, Richard Harrison, KB5WZI

Very interesting, Richard. Were the rhombic dissipation lines made of high
resistance wire? And where were the transmitters located that flooded SA? And
what SA countries did the fugitives concentrate in?

Walt