Three-Dimensional Printed Dual-Band Filter Based on SIR-Loaded Sleeve Coaxial Resonant Cavity

In this letter, a dual-band filter based on a stepped impedance resonator (SIR)-loaded sleeve coaxial resonant cavity (SCRC) has been proposed for the first time. The high-order spurious modes can be suppressed when the sleeve is closer to the center metal cylinder. In addition, by designing the cylinder as an SIR structure, dual controllable passbands can be generated without enlarging the original volume. To validate the feasibility of the proposed method, a dual-band filter prototype with wide stopband is fabricated by multijet printing (MJP) 3-D printing technology. The measured results exhibit good consistency with the simulated ones, demonstrating the advantages of the dual operation passbands and wide-stopband performance.