A 40-110-GHz Precision Delay Scanner System

A broad-band microwave measurement system has been designed to measure envelope delay distortion on a swept basis at millimeter-wave carrier frequencies. The delay scanner ultilizes the envelope phase-shift technique with a 10-MHz envelope frequency to measure delay distortion. The set operates from 40 to 110 GHz in three waveguide bands. The accuracy of delay distortion measurements is 30 ps with a resolution of 10 ps and the measurement accuracy for insertion-loss distortions is 0.08 dB with a resolution of 0.01 dB. The delay scanner meets the stated accuracy for unknowns with an insertion loss less than 10 dB. The measurement system features signal averaging for random noise reduction and baseline subtraction. The paper gives an electrical description of the delay scanner and discusses in some detail those operating principles and design approaches that were used to minimize measurement errors. Overall performance characteristics are summarized with a listing of error contributions.