A Sub-THz Low-Cost Additive Manufactured Monolithic Geodesic H-Plane Horn Array Antenna

A monolithic geodesic H-plane horn array antenna that operates up to 170 GHz is achieved for the first time using a low-cost additive manufacturing (AM) technique. To reach high gain and symmetric beam, a truncated geodesic H-plane horn is used to obtain a narrow beam in the H-plane, while a 1 : 8 power divider built on parallel-plate waveguides is constructed to narrow the beam in the E-plane. A ray-tracing and physical-optics model is developed to facilitate the design, which is capable of computing the full radiation pattern, directivity, and gain (considering conductive losses) of geodesic H-plane horn array antennas with significant time efficiency and high degree of accuracy. The adopted metal-only laser powder-bed fusion AM technique is especially suitable for fast prototyping structures with intricate shapes at a low cost. However, special adaptations are still considered in the design to ensure a successful fabrication of the prototype operating at the D-band. The prototype maintains good frequency stability from 110 to 170 GHz with a return loss better than 10 dB and a symmetric pencil beam. The measured data show a maximum realized gain of 29 dBi, a maximum aperture efficiency of 67% (calculated using <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">realized gain</i>), and a maximum radiation efficiency of 86%.