Design, simulation and fabrication of a varactor tunable combline microwave filter

This paper devotes to design, simulation and fabrication of a varactor tunable combline microwave filter in L band. The filter is of cavity type with tapline external coupling with varactors as tuning elements. The design method used here is important because it enables the designer to use a variety of different varactors. The simulation has been done using the full wave method of finite elements in conjunction with a linear circuit analysis software, and in spite of simplicity is quite accurate. Good agreement between the results from the simulation and measurements shows this accuracy.