Don, Yes, I know, that's why I said "at the proper height".
73, Ken WA8JXM On Dec 8, 2011, at 8:49 PM, Don Wilhelm wrote: > Ken, > > Actually, the feedpoint impedance for a half wave center fed dipole is 70 > ohms if it is "in the clear". The proximity to earth and other physical > objects will lower that impedance. For antennas typically used at HF, yes, > the feedpoint impedance will be closer to 50 ohms than the ideal of 70 ohms. > > 73, > Don W3FPR > > On 12/8/2011 8:14 PM, Ken wrote: >> On Dec 8, 2011, at 6:47 PM, Jim Brown wrote: >> >>> Virtually all the loss in transmission lines at HF (and even VHF) is due >>> to copper (that is, I squared R). Open wire line (and window line) has >>> much lower loss than coax because it has much higher impedance, so the >>> current for the same transmit power is much less than for coax. >> >> The impedance of the feedline does not change the impedance of the antenna. >> A half wave length dipole at the proper height is still a 50 ohm feed >> regardless of whether it's fed with 50ohm line or 600 ohm line. >> >> Ken WA8JXM >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
