Comparing unloaded Q-factor of a high-Q dielectric resonator measured using the transmission mode and reflection mode methods involving S-parameter circle fitting

TL;DR

This paper compares two high-precision methods for measuring the unloaded Q-factor of a sapphire dielectric resonator, highlighting their accuracy and the impact of delay compensation on measurement results.

Contribution

It introduces a delay compensation procedure applicable to both transmission and reflection measurement methods for improved Q-factor accuracy.

Findings

Both methods yield comparable Q-factor measurements after delay compensation.

Delay compensation significantly improves measurement accuracy.

The study demonstrates the effectiveness of circle fitting in high-Q resonator analysis.

Abstract

A comparative study of unloaded Q-factor measurements of a TE011 mode sapphire dielectric resonator with unloaded Q-factor value of 731,000 at a frequency of 10 GHz and temperature of 65 K using two best Q-factor measurement methods are presented. The Transmission (TMQF) and Reflection methods are based on relevant multi-frequency S-parameter measurements and circle fitting procedures to compute the unloaded Q-factor of the resonator. For accurate comparison of the methods a delay compensation procedure (introduced in the TMQF technique to remove delay due to non-calibrated cables) has been applied also to the reflection data.