An instrument for the precision measurement of attenuation in a waveguide network

Abstract

A precision instrument for the continuous monitoring of the unidirectional loss in an overmoded circular waveguide communication system is described. The unit is capable of measuring an attenuation in the range 36-56 dB with an absolute accuracy of ±0.4 dB at any frequency in the range 51.85-52.05 GHz. The instrument is implemented as a switched heterodyne radiometer, which continually compares the power level received from a remote CW source via the waveguide network against power generated by a local reference source at the same frequency. The received power reference is an accurate, stable, thermocouple power meter.