A scalable multi-allowed band bandpass filter demonstrating ultra-wide-bandwidth, excellent efficiency, and sharp band-edge transition

By introducing both cavity mode and plasmonic resonance simultaneously in the designed sandwiched metamaterials, we present a scalable bandpass filter to demonstrate ultra-wide bandwidth, excellent efficiency and sharp band-edge transition. Our results show that this bandpass filter possess ultra-wide bandwidth (UWB) of 20 GHz centered at 60.5 GHz, with almost zero reflectance (0.0042) and present transitions within 0.6 GHz from -3dB to -20dB for upper and lower transmittance band-edge transition. Such an UWB bandpass filter is applicable for the commercialized unlicensed 60 GHz spectrum with a bandwidth exceeding 9 GHz, an unanswerable question for conventional passive bandpass filters to possess wide bandwidth and high quality factor simultaneously.