Tuesday, November 23, 2010

SWR again

I have long noticed that many new-time and old-time amateur radio operators alike hold the idea of low SWR (standing wave ratio) for antenna systems very near and dear to their hearts. High SWR has been blamed as being the cause of TVI, poor transmitted signals, burned finals and antenna system problems. Low SWR has been the most sought-after and trusted measurement among hams for antenna system adjustment and monitoring. So let's consider what SWR measurements are, why we make them in the first place, and how we can best interpret the readings we measure. The whole story here.


  1. I agree, Paul. All a low SWR means is that the transmitter finals are not going to see a harmful load. It says nothing at all about how well an antenna will radiate. It frustrates me to see articles about antennas that report a low SWR as proof that the design works, and give no indication of how well it performs on-air at all.

  2. Yes, as we all know, a dummy load has a very low SWR *and* a *very low* efficiency ;)

  3. Hello Paul, nice article with some nice examples. I got 2 antennas as you know, and never measured the SWR direct. I'm not interested in that as long as the results are like expected. And as long as my 500mW PSK signal is heard at a attic dipole in England I'm more then satisfied :-). By the way I never had a coax cable that bad that it shows a 1,5:1 SWR without a antenna, I wonder what that coax lokked like then. 73, Bas


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