Ultra-compact K-band microwave terminations

A new multi-material compact topology, allowed by multi-material 3D-printing, is proposed to design microwave terminations in rectangular waveguide technology. The concept is based on a Salisbury-like resonant absorber constituted of a 3D-printed Polylactic Acid 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 in order to achieve a compact and low weight component that can be directly connected to a standard metallic waveguide. Experimentally, a return loss of 24.2 dB together with a -15dB bandwidth of 23.9%, was demonstrated on a 1.6 mm-thick termination. Such components can ease the integration of terminations in massively distributed antenna array.