A tunable filter with long hole resonance structure

In this paper, a new type of electrically tunable filter is designed based on the long hole structure. The results show that the frequency adjustable range of the new filter is from 210MHz to 350MHz, the bandwidth is more than 3%, the insertion loss is not more than -3dB and the insertion loss is better than - 14dB, respectively. The electrical performance of the new filter is better than that of the original comb line filter and the weight is 0.3Kg, which is only 30% of the original electrically tunable filter. The results show that the design method of the long hole structure is reasonable and has excellent performance. This new kind of filter would have good application prospect in EMC design.