Losses in substrate integrated waveguide band-pass post filters

Insertion loss is a crucial specification to judge the quality of a substrate integrated waveguide (SIW) band-pass filter. In this paper, six Chebyshev band-pass post filters in SIW technology are firstly designed with a lossless mode-matching code. The considered filters are designed with various orders for a center frequency of 10.5 GHz and a fractional bandwidth of 9.52%. These filters are then simulated with a full-wave electromagnetic solver in order to investigate the various contributions of ohmic and dielectric losses affecting the performance. In particular, the influence on the insertion loss of the variations of the metal cladding and vias conductivity, the dielectric loss tangent and the thickness of the substrate is quantitatively analyzed. For validation, one prototype filter is fabricated to compare the simulations to experimental results.