A Low-Cost Via-Less Air-Filled Waveguide in Multilayer PCB for High-Frequency Circuits Based on Artificial Magnetic Conductors

This paper proposes a novel, low-cost, via-less approach to implementing air-filled waveguides (AFWs) embedded within multilayer printed circuit board (PCB) structures to achieve low propagation loss. Three low-cost FR4 substrates are sandwiched together using prepreg to form the basic AFW structure. An electroplating technology and planar artificial magnetic conductor (AMC) surfaces are employed to make the sidewalls of the rectangular waveguides. This approach eliminates the need for metalized vias as sidewalls, thereby reducing dielectric loss within the AFW. The proposed structure exhibits a theoretical insertion loss of 0.08 dB/cm at 77 GHz. A transition from the WR-12 waveguide is demonstrated. Finally, the results of different lengths of straight AMC AFW and a 90° bend are presented.