Ham Radio Tip of the Day
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Today’s tip is from Bob, KG6AF. For submitting this tip, Bob will get one of my e-books. Thanks, Bob!
Low SWR isn’t the “be all and end all” it’s sometimes made out to be. Just because you measure a low SWR, it doesn’t mean that your antenna is radiating efficiently. Conversely, a high SWR doesn’t mean that an antenna won’t radiate. Remember that a 50-ohm dummy load has a 1:1 SWR.
Most modern rigs will reduce or cut off transmit power if the SWR the transmitter sees is higher than 2:1, so you do have to make sure that the impedance the transmitter sees at the antenna connector is close to 50 ohms. To do that, we often use an antenna tuner. An antenna tuner will make the transmitter happy, but that doesn’t mean that the transmitter’s output power is being radiated by the antenna. There are many other factors that come into play.
Take the time to read reliable material on the subject. The ARRL Guide to Antenna Tuners, by Joel Hallas, W1ZR, is a good starting place. You can also find lots of solid information in the QST archives.
73!
Dan KB6NU
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