Design of Wide Stopband and High Suppression Cavity Filter

Radio frequency filter is the core device to improve the signal to noise ratio of radar. A cavity filter for suppressing high harmonics in Ka band millimeter wave (MMW) radar is presented. The structural parameters of the filter are obtained by theoretical calculation. A cavity filter with the center frequency of 8.1 GHz and the relative bandwidth of 9.80% is designed by using HFSS electromagnetic simulation software. The spurious passband is above twice the frequency of the center frequency. The attenuation of the stopband is greater than 78 dB in 9.2 ~16 GHz, which can well meet the demand of the need of Ka band MMW radar to suppress high harmonics.