SWR, also known as Standing Wave Radio, is an important concept for ham radio operators. SWR is what allows us to know whether our antenna is performing as designed.
If you have a good SWR reading, you can rest easy knowing your antenna is receiving and transmitting the best that it can.
What is SWR?
SWR is sometimes called VSWR, for Voltage Standing Wave Ratio. The typical ham shack consists of a transmitter connected to a feed line, which is then connected to the antenna. When you key your radio, it develops a radio frequency (RF) voltage on the transmission line. The voltage travels down your coax to the antenna — this is called the forward wave. Sometimes that forward wave is reflected back towards the radio — and that relationship between forward vs. reflected power is what SWR measures.
What is a good SWR reading?
A good SWR reading is as close to 1:1 as possible. If you’re SWR is 1:1, that means 100% of the power from your radio will be transferred to your antenna.
If you’re SWR is 2:1, that means you’re losing 14% of your output power at the antenna. If you’re at 3:1 you’re losing 25% of your power.