Research and design of a miniaturized bandpass filter with ultra-wide stopband

This paper presents a novel miniaturized bandpass filter with ultra-wide stopband in C-band. With the assistance of 1/4 wavelength SIR (stepped impedance resonator), interdigital capacitors and suspended microstrip, this filter has small size of 15mm × 10.6mm × 1.854mm and high Q value, and can effectively suppress harmonics. Moreover, the filter is simulated by the electromagnetic simulation software HFSS (High Frequency System Simulator). The simulated results show that the center frequency of this filter is 4.7GHz and its relative bandwidth is 29.79%(1.4GHz). Most values of the return loss are below -15dB and the transmission loss is -0.5dB~-1.3dB within the passband.