A Broadband Adjustable Filter Based on Metamaterial
The traditional filter requires a filter combination of different central frequencies to realize the adjustable frequency. In this paper, based on the principle of metamaterial phase compensation, miniaturization and high integration filter are designed. And by using the varactor diode loading technology to change the electromagnetic parameters, the filter can be tuned in frequency. A square loop metamaterial filter is designed in this paper. The filter can be continuously tunable in the X band by loading varactor diode on the unit structure. The measured results show that: when the varactor diode increases from 0.15pF to 0.70pF, the center frequency of the filter is decreased from 11.7GHz to 10.3GHz, the bandwidth is 17.2% (10.1GHz-12.0GHz), and the return loss minimum is 25dB, the insertion loss maximum is 0.5dB.