A Tunable Filter with Different Kinds of Material for Good Electrical Performance

Abstract

Abstract A tunable comb-line filter based on series of material with different conductivity is presented and optimized to achieve proper insertion loss and bandwidth. The coupled circuit technique is used and the varactor diode parallel resonance is employed to meet the requirement for external voltage control. Based on the analysis of the tunable filter, the influence of the material with different conductivity on insertion loss and bandwidth is analyzed and it is found that the material of the resonant rib in the filter is an important factor for the electrical characters and high conductivity can effectively restrict the insertion loss and realize the narrow bandwidth. The results also show that the narrow bandwidth could not be obtained when the conductivity of the material is too low.