Toward Ultracompact Multi-Materials Rectangular Waveguide Terminations

A new multi-materials’ compact topology, allowed by multi-materials 3-D-printing, is proposed to design microwave terminations in rectangular waveguide technology. The concept is based on a Salisbury-like resonant absorber constituted of a 3-D-printed polylactic acid (PLA) dielectric spacer and a lossy dielectric in the form of a pad whose dimensions allow controlling the frequency of maximum absorption. The flange of the termination is also printed with a lossy dielectric to achieve a compact and low-weight component that can be directly connected to a standard metallic waveguide. The concept has been validated experimentally in K-band (18–26 GHz) and X-band (8–12 GHz) with relative bandwidths (RBWs) around 20% for both frequency bands. These components demonstrate a quite stable temperature behavior. The power-handling capability (PHC) has been investigated through simulations and experiments. It was demonstrated that the maximum power than can support the termination is around 4–5 times lower than a more standard and bulky termination made with the same materials.