Study of a Mismatched Parallel Wire Transmission Line and its Potential Applications

TL;DR

This paper investigates a mismatched parallel wire transmission line's potential as a tunable bandpass filter and sensing device, analyzing its characteristics and demonstrating its sensitivity to dielectric variations.

Contribution

It introduces a model for mismatched transmission lines as tunable bandpass filters and explores their application in high-sensitivity liquid dielectric sensing.

Findings

Mismatched lines exhibit narrow bandpass filter characteristics with steep roll-off.

Center frequency depends on line length and dielectric material.

Tuning is achievable by adjusting dielectric profile along the line.

Abstract

In this work a mismatched section of a transmission line is examined for its utility in a bandpass filtering application. A model to analyze the situation is given. It was found that the transfer characteristics of such mismatched transmission line resemble with that of a narrow bandpass filter with steeper roll-off. It has been shown that the center frequency of the response depends on the length of the mismatched section as well as the dielectric material of the line. Further it has been shown that the center frequency can be tuned to a desired value by adjusting the dielectric profile along the length of the line. This was tested on a set of parallel wire transmission lines of three lengths and liquid dielectrics. During the study it was noticed that a sensing mechanism to detect variation in small volumes of the liquid dielectrics with high sensitivity can be developed using mismatched transmission lines.