For the record... The following table gives the lost power and radiated power for a terrible ugly lossy 100 ohm ground used as a current sink for various antenna feed impedances. Using 100 watts to the feedpoint.
Ant Gnd Pwr % -dB Typ Feed Pwr to Eff gnd Ant Z loss Ant loss 30 77w 23w 23 -6.4 1/4 wave vert 50 67w 33w 33 -4.8 extended vert 450 18w 82w 82 -0.9 single wire Windom 1000 9w 91w 91 -0.4 end fed halfwave with no feedline If you can manage a 50 ohm lossy ground... 30 63w 37w 37% -4.3 db 50 50w 50w 50% -3.0 db 450 10w 90w 90% -0.5 db 1000 5w 95w 95% -0.2 db If you can manage a 25 ohm lossy ground... 30 45w 55w 55% -2.6 db 50 33w 67w 67% -1.7 db 450 5w 95w 95% -0.2 db 1000 2w 98w 98% -0.1 db >From this you can see that getting the feed Z up to 450 and above takes even a terrible ground pretty much out of the equation. 73, Guy _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
