A novel filter structure for suppressing spurious responses and producing attenuation poles

This paper proposes a novel bandpass filter that can suppress spurious-resonance responses over a wide frequency range. The basis of this idea is to reduce the coupling between a resonator and the external circuits at frequencies at which spurious resonances might occur. On the other hand, the filter structure proposed here is realized as a multi-path transmission-line filter, so that it is easy to produce attenuation poles near the passband. In this paper, we demonstrate the performance of such a filter theoretically and experimentally