New highly narrowband miniature microstrip bandpass and bandstop filters based on SIR components for wireless systems

Abstract

ABSTRACT This study presents new miniaturized designs of microstrip multiband bandstop filter (BSF) and multiband bandpass filter (BPF) employing step impedance resonators (SIRs) and RT/Duroid 6010 substrate. The projected bandstop filter can be adopted in applications for removing the interference of narrowband signals from the allocated bands of other wireless systems operated under 2.5, 5.84, and 9.79 GHz. On the other hand, the designed bandpass filter can be used in RF transceivers operating in various isolated narrow frequency bands at operating frequencies of 5.35, 5.555, 6.36, 7.84, 8.385, and 9.5 GHz. The novelty of this paper comes from the considerable smallness of the designed filters and extremely low fractional bandwidths (less than 1%) as compared with numerous reported filters in the literature, especially the superconducting filters. Both filter designs have been verified through measurement, and the measured consequences are in line with the simulation ones.