Staired-Slitted Flag Central Resonator Based Wide Band Bandpass Filter for Super Spurious Harmonic Suppressions

Abstract

A novel staired-slitted flag central resonator based wide band bandpass filter with sharp selectivity and super spurious harmonic suppression is proposed in this paper. Input-output ports based on three line edge coupling with ground plane aperture cutting contribute to the rejection of harmonics in the lower stopband. The spurious harmonic at the upper stopband is rejected with the help of embedded open stub suppression cells. The generation of two transmission zeros at the lower and upper cut-off frequencies are due to the staired slitted-flag main resonator, which contributes to the better selectivity of the filter, and it is verified with the help of mathematical equations. The fractional bandwidth of the developed filter is 107.2% with 7.82 GHz centre frequency. This work demonstrates the design, theory, and implementation aspects for the realization of bandpass filters with sharp selectivity and very good spurious suppression.