An Automatic Gain Control System for Microwaves

This paper describes a system which can keep the power level in a microwave set-up constant with good accuracy in spite of variations of the input power level. The system uses a variable attenuator based on the Faraday rotation in magnetized ferrite and thereby achieves a frequency response up to about 500 cps with the present equipment and much better potential response. Variations in input power are reduced by a factor varying from 10 to 400 depending on available power and on the detector used to detect the output power.