This paper presents novel approaches for dual-band bandpass filter design utilizing stepped impedance simplified cascaded quadruplet resonators (SI-SCQRs) with slot coupling. A pair of SI-SCQRs forms a cross coupled dual-band filtering path to provide high selectivity passband response, and a slot coupling structure provides SI-SCQRs with another filtering path for improving and controlling the performances of the dual-band filter such as insertion loss and bandwidth. Measured insertion losses are 0.26 dB and 1.2 dB and return losses are better than 16.3 dB and 15.2 dB at the first and second passband frequencies, respectively, with a mid-stopband attenuation around 30 dB.
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