E-band Waveguide Filter Based On TE₃₀₁ High Submode

This paper introduces and analyses an E-band waveguide filter based on the TE301 higher-order mode. Based on the traditional linear waveguide filter, an H-plane processed single mode waveguide filter based on the TE301 mode resonant cavity is designed by incorporating a novel resonant cavity structure using higher order modes. This design achieves high out-of-band rejection while ensuring a lightweight and compact structure for the filter. By exploiting mode cancellation between the main and spurious resonances, two transmission zeros are generated above and below the passband using two TE301 asymmetric resonant cavities. The position of these transmission zeros relative to the passband can be controlled by adjusting the size of the resonant cavities, greatly facilitating filter tuning. Physical test results show that the filter has excellent performance with a center frequency of 83.5 GHz, insertion loss less than 1.5 dB, return loss greater than 15 dB and in-band ripple less than 0.5 dB in the 81-86 GHz passband.