A Novel Tri-band Balanced Bandpass Filter Based on SIW with Double-sided Complementary Split Ring Resonators (DS-CSRRs)

In this paper, we propose a novel SIWR (Substrate Integrated Waveguide Resonator)-the ESIWR (Elliptical Substrate Integrated Waveguide Resonator) and use it to design a tri-band balanced filter with DS-CSRRs (Double-Sided Complementary Split Ring Resonators). The two resonators are overlapped by layer-on technology, and most of the resonant modes are preserved based on reducing the size of the traditional single-layer SIW filter by 50%. According to the distribution of the propagation modes in the ESIWR, two pairs of 50 Ω balanced feedlines loaded with CPW. It improved common-mode rejection by effectively cutting off common-mode transmission from the source to the load by opening circular arc-shaped holes in the symmetry layer. The simulation results show that this tri-band filter performs well while meeting miniaturization requirements and is suitable for modern communication systems.