The Reduction of Errors in a Precise Microwave Attenuator Calibration System

Refinements have been made to the parallel-substitution heterodyne method of attenuation measurement. These are provision for small fixed frequency differences between the IF signals to improve the sensitivity of tests for leakage, a switched reference path to reduce errors from drift and to assess "flange scatter," a flexible waveguide in the measuring path to accommodate attenuators of different lengths, a steady flow of dry air through the system to remove moisture, and an electronic system for fine-balancing the two channels.