Metal-Only Additive-Manufactured in Monolithic Piece Array for Sum/Difference Pattern in Ka-Band

The laser powder-bed fusion (LPBF) technique is evaluated to manufacture monolithic antennas in metal, which permits the production of metallic antennas reducing the conventional procedure based on, first, manufacturing a dielectric skeleton, and then, applying a coating process to obtain the radio frequency (RF) performance of the device. To validate the technique, an array of $4 \times 4$ horn antennas is designed to operate at mm-wave frequencies. The antenna is based on a complex structure to obtain a sum radiation pattern, although it is also designed and simulated its counterpart, considering the different pattern versions. This validates the proposed technique to obtain complex monolithic structures that can be used in several applications. Both array designs are explained together with numerical results. Then, the LPBF is detailed, and the sum version prototype is presented. The prototype is manufactured in a monolithic piece of steel, providing a single structure that includes both radiating elements and feeding network, including twisters and power dividers in waveguide. The prototype is evaluated in anechoic chamber, obtaining a good agreement with full-wave simulations within the operational bandwidth (34 to 36 GHz). The results demonstrate that the technique LPBF is a suitable candidate to produce monolithic metal-only devices with complex designs.