Is SWR?

SWR is short for 'Standing Wave Ratio'.  It's a very important measurement because it indicates how well your radio system is performing.  The typical radio system is comprised of a transmitter, antenna, coax cable, antenna mounting device, and ground plane. Ideally the entire system should be matched in a manner that allows the transmitter to radiate all of it's power through the antenna.  A perfect match, would measure 1:1 on a SWR meter.  A SWR reading of 2:1, or higher, indicates power is being reflected back to the radio. This is undesirable and could possibly damage the transmitter.

What causes high SWR?

• Incorrect coax cable, type, length, quality, or damage.
• Poor installation, or location.
• Antenna not properly tuned.
• Insufficient ground plane.
• Damage to the antenna.

How do I measure the SWR of my antenna?

Measuring SWR and tuning an antenna may vary from system-to-system but it's usually not difficult.  Below are the basic instructions:

• Connect the SWR meter between antenna and radio.
• Measure the SWR of lowest frequency in your band and then measure the SWR of the highest frequency. For example, on the 2-meter ham band (144-148 MHz) measure the SWR at 144 MHz and take another measurement at 148 MHz.
• Raise or lower your antenna whip so both SWR readings are equal. If the SWR for 144 MHz is too high, lower the whip. If the SWR for 144 MHz is too low, raise whip.
• Adjust the antenna in 1/8" increments.
• For mobile installations it is recommended that you keep the doors closed because your ground plane will change when your door is opened. Stay away from buildings or high fences.

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