Field Strength Instrument is usually used to test the field strength of the instrument. The size of the field strength meter is a unit of V / M, which contains the unit of length m. In principle, a level meter (or voltmeter) measures the voltage at the input port of the instrument, while a field strength meter (or potential) measures the voltage at a point in the air caused by the antenna. Strictly speaking, the field strength meter consists of a level meter and an antenna. It is mainly used to measure the electric field intensity of high-voltage transmission and transformation system, distribution room, induction furnace, subway, electric locomotive, medical equipment, drying equipment, computer, etc. . For Labor protection, Occupational Disease Prevention and treatment, environmental testing, environmental health and other work.