A Wideband Quadraxial Feed for Compact Dual Polarised Vivaldi Antenna Elements

This work presents a fully metallic dual polarised Vivaldi antenna element for K/Ka-band SatCom phased arrays. The element is fed by a novel quadraxial-to-quadridge waveguide transition, which is designed for connectorless integration with a PCB-mounted beamformer IC network. The Vivaldi unit cell has an active reflection coefficient of better than -10 dB for scanning up to 60 degrees in the E-, D-, and H-planes in the K/Ka SatCom bands. A back-to-back (B2B) configuration of the quadraxial transition is 3D-printed in metal using the laser powder-bed fusion technique. A tolerance study shows how an initial gap between the quadraxial pins of approximately 30 μm impacts the B2B insertion loss, while the zero-gap post-processed B2B structure features a reflection of -13 dB and the transmission coefficient of -0.7 dB, in both simulations and measurements and in both bands of interest.