On 10/17/2010 1:40 AM, Jan Erik Holm wrote: > This will go nicely with my K3 > http://www.youtube.com/watch?v=9tIZUhu21sQ
Seawater has electrical conductivity of seven *orders* of magnitude lower than copper! As a quick and dirty check, I created a simple 10m ground plane antenna in NEC-4. Four counterpoises and a vertical radiating element that is bottom fed, all of equal lengths, with the counterpoises and the feedpoint 1m above seawater (natch!) ground. All elements 0.5" in diameter. With perfectly conducting elements, the feedpoint impedance is just about 35 ohms, with a gain of 4.7 dBi. When I changed the conductivity of the vertical element to 5 mhos/ meter, while keeping the counterpoises as perfectly conducting, the computed gain dropped to -8.2 dBi and the feedpoint impedance is capacitive at 320 -i*250 ohms. I.e., something like 13 dB loss compared to using copper elements. BTW, I could not achieve resonance by extending the length of the radiating element -- I guess you will need a KAT500 in addition to that KPA500 which you use to make up for the missing 13 dB. This could make a good water heater. All that power has to go *somewhere* :-). 73 Chen, W7AY ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
