A Compact Microstrip Tunable Filter Based on Metamaterial *

Abstract

Filter can prevent electromagnetic interference in the communication system and ensure the effective transmission of signals. In this paper, a tunable filter is designed. By loading a varactor diode in the gap of metamaterial structure, the operating frequency band of the filter is changed. The tunable filter is made and measured in this paper. Experiment results show the filter is in the X-band (7.9GHz-12.1GHz) continuously adjustable, the operating bandwidth is 42%, the minimum insertion loss is 27dB, and the maximum return loss is 0.67dB. The filter designed in the paper has multi-band and wide-band filtering characteristics, and solves the problems of integration” multi-band and broadband in communication systems.