Design of a Broadband Microstrip Bandpass Filter

In order to design a filter with good frequency selectivity and wide stopband, a notch H-Shaped DMS (defected microstrip structure) microstrip filter is applied. The DMS structure is cascaded with two 1/4 λ terminal short resonators. The filter is designed and analyzed by using HFSS. Measurement results show that the bandwidth of the filter is 0.95GHz-1.45GHz, the stopband below -20dB is 1.6-3.7GHz. The insertion loss of the filter over the whole bandwidth is less than 0.57 dB.