A Novel Wide Stopband PBG Structure with Fractal Features and Its application to the Design of Microstrip Low-pass Filter

A novel wide stopband one-dimensional PBG structure with fractal features is proposed, which is useful for microstrip circuits. The proposed structure is with the same size as the conventional PBG structures, but boasts the characteristic of ultra-wide stopband and low ripple level in the passband. In this paper, a microstrip low-pass filter is designed employing the proposed wide stopband PBG structure. The simulation results show the low-pass filter is able to achieve a 3-dB lower passband of 4.65 GHz with a ripple level of 0.78 dB and a maximum reflection loss of-15dB and a20-dB stopband of above 15 GHz with an attenuation of over 50.00 dB. The measurement results are found to be in good agreement with the simulation results.