A time domain based method for the accurate measurement of Q-factor and resonance frequency of microwave resonators

TL;DR

This paper introduces a rapid, stable, and conceptually simple time domain method for accurately measuring the resonance frequency and Q-factor of microwave resonators using Fourier transformation of emitted signals after excitation is switched off.

Contribution

The paper presents a novel FT-based technique for microwave resonator measurement that offers advantages in speed and stability, with accuracy comparable to existing methods.

Findings

Method is faster and more stable than existing techniques.

Fourier transform yields the resonance curve in a single shot.

Achieves similar accuracy to traditional methods.

Abstract

We present a novel method to determine the resonant frequency and quality factor of microwave resonators which is faster, more stable, and conceptually simpler than the yet existing techniques. The microwave resonator is irradiated at a frequency away from its resonance. It then emits an exponentially decaying radiation at its eigen-frequency when the excitation is rapidly switched off. The emission is down-converted with a microwave mixer, digitized and its Fourier transformation (FT) directly yields the resonance curve in a single shot. Being an FT based method, this technique possesses the Fellgett (multiplex) and Connes (accuracy) advantages and it conceptually mimics that of pulsed nuclear magnetic resonance. We also establish a novel benchmark to compare accuracy of the different approaches of microwave resonator measurements. This shows that the present method have similar accuracy to the existing ones.