Design of Miniaturized Quadrupole Waveguide Filter Based on Spatial Multiplexing

In this work, a miniaturized 2.11GHz quadrupole waveguide filter based on spatial multiplexing has been developed. The fourth-order bandpass filter consists of two compact waveguide structures, which multiplexes two concave waveguide elements in the z-axis direction and reduces the volume of traditional rectangular waveguide at the same frequency. The electromagnetic simulation analysis of the waveguide filter with this structure is presented in detail. The waveguide filter has a size of $60^{\ast}60^{\ast}37\ \text{mm}^{3}$ and Q value reached 1967, which shows the excellent selectivity. For the compact bandpass filter, the insertion loss is lower than 0.15 dB and return loss is higher than 17.7dB.