On Sat, Feb 11, 2017 at 3:46 PM, Don Wilhelm <donw...@embarqmail.com> wrote:
A halfwave dipole is a halfwave dipole whether fed at the center or at an > end or somewhere in between. > The radiation pattern and efficiency is the same. > ============ This is 100% correct. Two minutes spent with EZ-NEC will verify that the radiation pattern of a dipole antenna is more or less independent of the feedpoint location.The idea that an end-fed antenna is "less efficient" is wrong. Antenna efficiency is a function of radiation resistance and ohmic losses, not of feedpoint location. The power has to go somewhere, and where it goes is into radiation. In the days before most hams had an antenna simulator program, Cebik was a big proponent of EFHW and had a nice analysis on his website. He made the qualitative point that since the impedance at the end is high, there is little current flowing in the unbalanced feedline at that point; if the antenna is fed with open-wire line, the return current in the unterminated leg is small and it's not hard to match. He followed this up with some actual calculations. Although Mr. Cebik is no longer with us, nowadays serious hams have antenna programs, so they can do their own analysis. The role of folklore in antenna design has diminished considerably. Tony KT0NY ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
