This item is a vintage Micronta Field Strength/SWR Tester, model 21-525B.
Function: It is used to measure the Standing Wave Ratio (SWR) of radio transmissions and the intensity of electromagnetic fields emitted by radio transmitters.
Purpose: Helps optimize antenna performance, ensuring efficient signal transmission and minimizing interference.
Key Features: Includes a analog meter for SWR and Field Strength readings, a Calibration (CAL) knob, and a switch for Forward (FWD) and Reflected (REF) power readings.