DESIGN OF BAND-PASS FILTERS USING STEPPED IMPEDANCE RESONATORS WITH FLOATING CONDUCTORS

A new type of miniaturized stepped impedance resonator (SIR) for bandpass fllter applications is proposed in this paper. The new resonator incorporates a ground plane window with a ∞oating conductor in the backside of the substrate. The ground plane window increase the characteristic impedance of the lines used to implement the inductive region of the quasi-lumped resonator, thus allowing some size reduction. Moreover, the presence of a ∞oating conducting patch printed below the capacitive region of the resonator pushes up the flrst spurious band of the fllter. A meaningful improvement of its out-of-band rejection level is then achieved. The coupling between adjacent resonators is also enhanced thus leading to wider achievable