Narrow-Band Band-Pass Filter for Application in High Selectivity Receiver of Nonlinear Junction Detector

A narrow-band band-pass filter for application in a non-linear junction detector has been developed. An interdigital structure has been used in order to achieve 0.5% bandwidth and at the same time high rejection of interference signals. The goal was to design a narrow-band filter which ensures high sensitivity of the receiver and high rejection of signals having frequencies close to the second harmonic and high rejection of fundamental frequency. Theoretical analysis as well as measurement results are shown.