An SWR meter is used to measure the Standing Wave Ratio of a CB antenna. Setting the SWR for your CB antenna is essential for good range. Essentially you are checking for two things when you check your SWR; to make sure the reading on channel 1 is the same as 40, and that both readings are at a safe level. If your SWR readings at channel 1 and channel 40 are even, than the readings for channel 2 through 39 are going to be in line as well. You want your SWR on all channels to be as close to 1:1 as possible. Ideally, you're aiming for less than 2:1 across all channels. A reading of 3:1 is too high. You know you have a problem when your SWR is over 3. See our CB antenna tuning guide for more information.
Be sure to pick up a short CB coax for connecting the meter to your radio, if you don't already have one. Some meters have the short coax included! If you're in the market for a new CB antenna, or simply want to consider other options to ensure you have the best antenna for your needs, we recommend reading our guide to choosing the right cb antenna.