A novel Spur Stepped Impedance Resonator

This paper propose a novel Spur Stepped Impedance Resonator (SSIR). Developed from the classical Stepped Impedance Resonator (SIR) without additional or complicated circuit occupying, almost keeping the same compact size and quality factor, the SSIR has tunable spurious resonances while keeping fundamental resonance frequency almost unchanged, and a tapped SSIR will produce tunable transmission zeros without interfering with the fundamental resonance or the loaded quality. A simple demo application of SSIR on designing bandpass filter with extended stopband is proposed, fabricated and measured.