The Para Dynamics PDC5 is a multi-purpose meter, that can test SWR and power output as well as an antenna matcher.
SWR (Standing Wave Ratio) or VSWR (Voltage Standing Wave Ratio) is a measurement of your antenna systems efficiency, using this meter will allow you to determine if you need to tune your antennas for increased performance.
The power meter portion of this meter is designed to give you a reading on your transmitters modulated output power.
The antenna matcher function is what sets this meter apart from others, antenna matchers will allow you to adjust the impedance of your antenna system, thereby allowing you to attain a 1:1 SWR no matter what. This is especially useful for stock antenna systems that come with semi trucks, if after tuning the antennas you are still not able to achieve a low enough reading, using the antenna matcher will allow you to attain a 1:1 SWR. Keep in mind, you must keep the meter inline to maintain this low reading.