In this letter, a parallel-plate waveguide half-Luneburg geodesic lens multiple-beam antenna optimized for additive manufacturing is designed and validated experimentally in the K $_{\mathrm{a}}$ band. Two prototypes were manufactured in AlSi10Mg through laser powder-bed fusion and measured in an anechoic chamber. The compact and lightweight prototype optimized for additive manufacturing demonstrates excellent RF performance while significantly reducing mass and mechanical complexity. Specifically, misalignment errors present in previous studies are solved, improving side lobe level by up to 10 dB. A maximum realized gain of 22.1 dBi is measured at 28 GHz. This single-piece, compact and lightweight design is particularly attractive for applications having mass restrictions and limited space like millimetre-wave systems on board small satellites.

Fully metallic geodesic lens antennas are popular for millimetre-wave band applications due to their simplicity, robustness and low loss. Here, we report the experimental results of a geodesic lens array antenna, which was specifically designed to be additive-manufactured in one single piece using Laser Powder-Bed Fusion (LPBF). LPBF in aluminum alloy AlSi10Mg is able to produce high conductivity and relatively low surface roughness, so the antenna is highly directive and efficient. In addition, LPBF increases the robustness of the design since the lens array is monolithic, i.e., the risks associated to the assembly, including misalignments and undesired air gaps between pieces, are totally eliminated.

This paper applies an in-house generalized ray-tracing model to efficiently compute both the radiation pattern and the efficiency of geodesic lenses with non-rotationally symmetric shapes. Losses due to ohmic effects and surface roughness are included in the model. These losses are very relevant for monolithic geodesic lens antennas as postprocessing techniques cannot be applied to reduce the surface roughness of the internal part of the metallic plates. The model is validated by comparison with full-wave simulations for three different lenses: a circular flat parallel-plate waveguide, an elliptically-compressed geodesic lens, and a water-drop lens. These results show a reduction in computational time by a factor of 600 using the ray-tracing model. A non-rotationally symmetric water drop lens has been manufactured in a monolithic piece using the laser powder-bed fusion technique with successful experimental results.

This article delves into the industrial evolution of lens antennas for future millimeter-wave and sub-THz radio access applications. Here, we address the potential advantages of applying lens antennas with respect to traditional phased array antennas, which are widely used in base station products, and we also describe how lens antennas may fulfill the strict requirements of next-generation radio access systems in a cost-effective and sustainable way. A comparative study of several in-house experimentally validated parallel-plate fully metallic Luneburg lens antennas in terms of radiation performance and manufacturability is finally provided.

This paper reports on the design and experimental validation of a fully-metallic double-ridged waveguide 10 × 10 Rotman lens additively manufactured as a single part. The wide band operation of this quasi-optical beamformer enables us to cover the uplink and downlink frequencies allocated to satellite communications in the K/K${}_{\mathrm{a}}$-band, from 17.3 GHz to 30 GHz. The feeding port design was adjusted to enable vertical printing, thus minimizing the use of supporting structures. A prototype was manufactured and tested. The reported results indicate losses in the range of 0.5 dB in the lower-frequency band and 0.8 dB in the upper-frequency band, including the waveguide transitions added for test purposes. The measured reflection and coupling coefficients remain below −11.5 dB over the operating band. The standard deviation of the residual phase error across the array ports is below $5°$ in simulation and below $10°$ in measurements. Array factors synthesized using the scattering parameters confirm the good stability of the beamforming functionality over the wide frequency band analyzed. This monolithic design is a promising step toward more integrated antenna systems, such as a compact dual-stack configuration for planar array design.

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 radiofrequency performance of the device. To validate the technique, an array of 4 × 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 difference pattern version. 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.