Don, thank you for the reference. I know I read this back when you wrote it. I have saved as a reference for other operators, who seem to need a bit more understanding.
73, Bill K9YEQ -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Don Wilhelm Sent: Tuesday, February 20, 2018 8:10 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Antenna tuning or matching unit On this subject, it may be of interest to point to the article on my website www.w3fpr.com "Antennas, Transmission Lines and Tuners". This article first appeared in QRP Quarterly in July 2001. I am pleased that DXzone has also recognized that article and has included it in its Antennas/Theory category - see https://www.dxzone.com/dx19232/antennas-and-transmission-lines-myths.html There is not much math in the article, but you may find the concepts valuable. The sections on "SWR as a friend" and "Antenna Tuners" is particularly relevant to the current topic. 73, Don W3FPR On 2/20/2018 8:16 PM, Alan B via Elecraft wrote: > This all depends on what is meant by antenna tuning. > When teaching newbies the wrong phrase can cause problems that are not seen > till later. > Antennas are tuned with wire cutters or a hacksaw so the feed impedance is > the desired value, ideally 50 ohm resistive or at least a match for the > feeder concerned. > Of course that is not always practical so an antenna matching unit brings the > antenna or antenna plus feeder input impedance to the value wanted by the > transmitter. > Too often I have seen students believe the ATU alters the current and voltage > distribution on the antenna so it looks exactly like the distribution on a > dipole of the correct length for the frequency concerned. > Granted the currents and voltages might change as the ATU is adjusted but > that does not make the antenna radiate more efficiently. The reflection at > the feeder/antenna junction is unchanged. > In training we use the term antenna matching unit, AMU, to avoid best we can > the students starting off with the wrong impression. > Amongst ourselves we can get away with slack terminology, we all know what is > meant; in front of trainees it is a different story. ______________________________________________________________ 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 k9...@live.com ______________________________________________________________ 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
