  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.
