A Ka-band waveguide bandpass filter designed by transmission zero resonator pairs (TZRPs)

In this paper, a Ka-band waveguide bandpass Alter is designed by transmission zero resonator pairs (TZRPs). A waveguide TZRP is designed and analyzed with two transmission zeroes and a transmission pole. The lower transmission zero can be flexibly designed by the sizes of the C-shaped resonator while the upper one is determined by the sizes of the straight stripline resonator. Then, proposed bandpass filter is formed by coupling two waveguide TZRPs. Four transmission zeroes are induced by at both sides of the passband, for improving the band shirt. For enhancing the couplings, two short striplines are used between the TZRPs. The operating frequencies of the proposed bandpass filter can be flexibly deigned by adjusting the locations of transmission zeroes of the waveguide TZRPs. A good agreement between the simulated and measured results is obtained. The proposed filter has the properties of low cost, compact size and mass production.