Low-temperature cofired ceramic (LTCC) was used for a novel band-pass filter design. The filter is based on metallic strips parallel to the E-plane and mounted in a substrate-integrated waveguide (SIW). A new iterative technique based on the variation principle was used to obtain the inductive reactance of equivalent T-network of the metallic strip. The design method of the filter was derived by applying the equivalent network of the metallic strip to the usual method of the filter design. A set of curves relating the various filter parameters is introduced. This filter was designed such that it is electromagnetically isolated inside the SIW and excited using grounded coplanar waveguide (GCPW) to SIW transitions; therefore, it can be easily integrated with MMICs. The design steps are explained and verified by examples and results. Three-dimensional electromagnetic field modeling and simulation was carried out using a high frequency structure simulator (HFSS). A comparison between different types of SIW is presented showing the resulting S-parameter curves for each case. By following the design steps, similar filters for various frequency bands using any dielectric material can be easily designed.
Compact balanced bandpass filter design using miniaturised substrate integrated waveguide cavities