A wideband and high rejection multimode 60 GHz GaAs bandpass filter using open-loop CMRC with controllable transmission zeros technique

This work presents a novel compact open-loop resonator V-band bandpass filters with compact microstrip resonator cell (CMRC) controllable transmission zeros for 60 GHz. The filter, which has a high and wide rejection band, has two functions, which are: (1) perturbation for multimode operation and (2) zero point generation at the stopband to control the stopband. Proper input/output open-loop coupling is conducted using two additional poles. The CMRC distances between resonators and the positions of the open gaps in the open-loop-coupled filter can be adjusted to change the coupling coefficients and generate controllable transmission zeros in the upper stopband. The design and fabrication of the proposed open-loop and CMRC open-loop resonator filters provide such advantages as a wider passband and a higher rejection level, and precise control of the locations of the transmission zeros.