Tunable Microstrip Band Pass Filter with Simple Loss Compensation Method

Abstract

The tunable filter with a hairpin line resonator and a loading capacitor is designed. The filter is modified by adding varactor diodes to the coupling part for loss compensation. The designed filter has a simple structure and the characteristics of the wide band tuning range of 87.9 % from 430 MHz to 1105 MHz and low insertion loss of less than 4.42 dB.