Study on the performance of novel planar dual-mode microstrip bandpass filter

A novel planar dual-mode elliptic-function microstrip bandpass filter with two triangle corner cuts and a square notch is proposed, and the performance of the designed filter is studied in detail. The proposed filter structure uses a single patch without coupling gaps. The center frequency is about 2.13 GHz. The 3 dB fractional bandwidth is 9.86%, and the minimum insertion loss in the passband is 0.13 dB.There are two transmission zeros on both sides of the passband. The insertion loss is <; 1 dB and return loss is >; 10 dB within 2.08-2.22 GHz. The effect on the filter´s performance by changing filter parameters is studied. The results show that this new filter can provide a low insertion loss and reduce uncertainty in fabrication. It also makes miniaturization easy.