Quarter-mode circular cavity substrate integrated waveguide filtering power divider with via-holes perturbation

A compact filtering power divider composed of two quarter-mode circular cavities based on the substrate integrated waveguide is proposed. Two extra perturbing via-holes added in each side of the quarter-mode circular cavity achieve a selective bandpass filtering response and improve the performance of the upper stopband. The proposed FPD operates at 9.1 GHz with a 3 dB fractional bandwidth of 19.8%. The insertion loss in operating band is <1.6 dB and the input return loss is better than 16 dB. The amplitude and phase imbalances between the two outputs are measured better than 0.6 dB and 3.5 degrees, respectively. The measured results exhibit good agreement with the simulated ones.