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How to Put a Power Meter to My Antenna

Amateur radio enthusiasts need to measure the power transmitted into antenna systems as well as the power "reflected" back to the transmitter. Making contacts with the minimum power necessary is always a good amateur radio practice, and for some license categories, a maximum power limit must be observed. Several types of measuring devices are available for this task, offering different levels of complexity and different operating frequencies.

Things You'll Need

Wattmeter
Wattmeter/SWR meter
Antenna analyzer

Instructions

- 1
  Use a commercial grade wattmeter like the classic Bird 43 for precise measurements of output and reflected power. This type of meter is the simplest, as it measures only power. It requires plug-in elements for different frequency ranges. The Bird 43 handles frequencies from 450 KHz to 2.7 GHz and power up to 10 kilowatts. To measure output and reflected power, simply rotate the frequency element in the desired direction.
- 2
  Use a hand-held wattmeter to measure power output and SWR on a 2-meter radio. The MFJ-841, for example, connects between the radio and antenna. To read power output, just switch the MFJ-841 to PWR, key the radio and read the power from the meter. To read SWR, switch the meter to SEN (sensitivity), key up and adjust the the meter for maximum needle deflection. Key down and set the switch for SWR. Key up and read the SWR. Many other meters on HF and VHF follow these same principles by first peaking a meter and then reading the reflected power.
- 3
  Use an antenna analyzer for a wide range of measurements, including power, SWR, resonance and impedance. Some antenna analyzers will measure antenna resonance -- the center frequency of an antenna -- without any transmitted power. Units such as the Comet CAA-500 use a dual-meter movement to measure output power and SWR simultaneously. These meters are easy to use because the user need only select the frequency.

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