Download the MFJ-801 Manual This easy-to-use MFJ antenna meters show the strength of the actual field being radiated from your antenna. You can use it to determine the basic radiation pattern of your antenna and see which direction your signal is strongest. You can make changes to your antenna and instantly know if it radiates better or worse. You can compare one antenna to another find out which HT antenna radiates the strongest signal. Measure your HF antenna now and compare it later to make sure its performance is still up to par. Adjust a ground lead, artificial ground, counterpoise or tune your transmitter or antenna tuner for maximum field strength. You can check for RF floating around the shack that may be caused by faulty antennas or poorly shielded equipment. Demonstrate the concept of gain or antenna polarization. Find hidden transmitter bugs at office or house. Usable from 100 KHz to 500Mhz.