Study on Low Resistance Permanent Joints for Assembly of PCB-Integrated Additively Fabricated Air-Filled Waveguide

In this paper, permanent joints are investigated for assembly of the recently introduced Printed Circuit Board (PCB) integrated air-filled waveguide (AF-WG). The joints provide low-resistance contact between the metal-coated 3D-printed U-shaped waveguide shell and the on-PCB ground plane that serves as one of the guide walls. The above is an alternative to the originally proposed through-hole screw joint and studied snap-fit joints, which are a better choice at higher frequencies. Joints employing conductive glue and low-temperature solder were assessed by measurement of test vehicles being a long WR-42 sized waveguide section in-between two through-patch microstrip to AF-WG transition operating within 18 GHz to 26.5 GHz bandwidth. The obtained results show that solder joints might be attractive in terms of minimizing power losses, however, special care must be taken during the assembly process.