Elliptic function filters designed in LTCC

A 35GHz elliptic function four poles bandpass filter that is compatible with multi-layer substrate integrated wave-guide (MSIW) technique based on low temperature co-fired ceramics (LTCC) is presented. The filter consists of four MSIW cavities in a multi-layer design, with evanescent-mode coupling between adjacent cavities and a cross coupling between the first and last cavities, and are fed by micro-strip lines through slot apertures. The simulated filter response has a bandwidth of 1.6% centered at 35 GHz with an insertion loss of 1dB, and two poles at 34.39 GHz and 35.73 GHz, respectively.