Design of a novel L-band high selectivity miniaturized planar filter

In this paper, a novel compact microstrip cross-coupled bandpass filters achieved by miniaturized stepped impedance resonators (SIR) is proposed. The SIR structure contributes to making the filter miniaturization and the cross-coupled line helps filter to have a better selectivity. Compare with the Chebyshev filter, quasi-elliptic function filter has a better selectivity. This article has introduced a Chebyshev filter and a quasi-elliptic filter, through the design and analysis, finally achieve the quasi-elliptic filter working form 1.88GHz to 1.98GHz, the insertion loss is less than 1.8dB within the operating bandwidth, and return loss is more than 15.9dB, two transmission zeroes are located at 1.75GHz and 2.05GHz.