Substrate integrated waveguide filter with embedded mixed source-load coupling

A compact substrate integrated waveguide (SIW) filter with an improved stopband using multilayer embedded mixed coupling (MC) is presented. By implementing MC into the input/output SIW, the filter not only exhibits good rejection for the upper stopband, owing to an additional controllable transmission zero, but also has a miniature size of 18 ?? 12 mm^{2 by profiting from its low-temperature co-fired ceramic structure. An experimental second-order filter with three TZs has been designed and fabricated. The measured results show good agreement with the simulated ones.}