H-Band Multilayer Waveguide Incorporating a Locally Glide-Symmetric Electromagnetic Bandgap Structure

This letter presents an H-band (220-330 GHz) fully-metallic multilayer waveguide (MLW), that consists of five stacked metallic layers forming an air-filled groove. The waveguide is surrounded by a locally glide-symmetric holey electromagnetic bandgap (EBG) structure that prevents electric field leakage across the interlayer gaps. A diamond-shaped unit cell is selected for the EBG due to its high effectiveness in suppressing leakage. To enable practical characterization, a well matched vertical transition is developed using a discretized stepped corner via a novel design process, crucial to achieve good impedance matching at high frequencies. The prototype exhibits a measured reflection coefficient lower than-10dB in the entire H-band, and an average loss of the waveguide channel of 0.032dB/mm.