Transient response of an open resonator in the time domain

Abstract

In the present paper a time response of a quasi-optical open resonator when exciting it by a pulse signal with a radiofrequency filling has been investigated using an inverse Fourier transformation. The radiofrequency filling corresponds to millimeter wavelengths region. Fourier image of the time response of the resonator is calculated from a product of two frequency’s functions. One of these functions is the Fourier image of a pulse signal at the resonator input, and the second is a calculated or measured amplitude — phase characteristic of the resonator. When calculating the amplitude- phase characteristic of the resonator (a complex transfer coefficient) a plane — layered model of the resonator was used.

Experimental investigation has been conducted in millimeter wavelengths with Fabry-Perot type open resonator. Amplitude- phase characteristic of the resonator were measured in “on passage“ regime in wide frequency band.

It was shown that presence of weakly absorbing layer in the resonator leads to changing of the time response of the resonator. The obtained results can be used in the dielectric measurements, defectoscopy of stratiform materials, relaxometry, non-destructive control of materials and structures, etc.