A half-mode substrate integrated waveguide filtering power divider with Fourier-varying via holes

In this article, a novel design methodology of a half-mode substrate integrated waveguide (HM-SIW) filtering Wilkinson power divider is proposed. The width between the two metallic rows of vias in the conventional HM-SIW divider is governed by a truncated Fourier series expansion to obtain specific passband/stopband performance. The optimized varying width is obtained using the even-mode analysis, whereas the odd-mode analysis is used to find the optimum values of three isolation resistors that achieve acceptable isolation and output ports matching over specific frequency range. For validation, a HM-SIW divider with a center frequency of 12.3 GHz and 3.7% 10-dB fractional bandwidth is designed, simulated, and measured. Simulated and measured results show a good agreement with passband return loss and transmission losses better than -15 and -3.0 dB, respectively.