This article presents a parallel-plate lens beamformer for continuous wide-angle scanning. The design is based on a compact dual-lens system with extended scanning range and is optimized using a previously developed geometrical optics technique. Beam steering is accomplished with a mechanical feed system based on the noncontact characteristic of groove gap waveguides, offering large bandwidth, low profile, and mechanical ruggedness. The proposed concept is validated by an all-metal prototype of a $20.5\lambda $ lens operating in the uplink Ka-band allocated to satellite communications (27.5–31 GHz). Good agreement is obtained between the simulated and measured performances. The measured return loss is greater than 12 dB over the entire frequency band and beyond. High scanning performances are achieved over an angular range of ±50° (±14 beamwidths), with maximum scan losses in the order of 3 dB and good pattern stability over the entire band. The proposed solution is particularly suited for next-generation satellite terminals requiring compact broadband antennas with continuous beam-steering capability over a large angular range.

In this paper, shaped continuous parallel plate waveguide delay lenses are proposed. The previous configurations introduced by the authors displayed a residual side lobe imbalance, showing the limitations of elliptical delay lens profiles, derived from a starting bifocal constrained lens. Polynomial profiles are proposed here as a way to enhance the scanning performance and the pattern shape. Optimized configurations demonstrate a reduction in the phase aberration levels over a large scanning range ([-30°, 30°]). The associated radiation patterns demonstrate lower and more balanced first side lobe levels (SLLs) (≅ -18 dB), as compared to the previous elliptical approach (≅ -13.2 dB). A validation has been proposed through the manufacturing and test of a prototype over the downlink Ka-band ([27.5-31] GHz). Excellent radiation performance [half-power beamwidth (HPBW), SLL] has been experimentally obtained over a wide angular range ([-31.5°, 31.5°]), including low scanning loss and high radiation stability over the entire frequency range. High radiation efficiencies are demonstrated with this fully metallic design, particularly suitable for space applications. The mechanical simplicity offered by the concept is also quite attractive for low-cost multi-beam platforms.

This article presents a 3-D polarizing screen that converts linear to circular polarization in a broadband frequency range. The conceived unit cells are fully metallic and based on structures that support transverse electromagnetic modes. Such cells have been specially conceived to be manufactured through metal 3-D printing based on selective laser melting. This is the first time that a polarizing structure presents such a broadband behavior without the use of dielectric materials. In addition, this is the first successful proof of concept of additive manufacturing in the context of metallic periodic surfaces, which is enabled by the use of a codesign approach. The present proposal is validated through the design and manufacturing of a prototype operating in K- and Ka-bands. Successful experimental results are reported.

This communication discusses a generalized analytical formulation for the design of doubly curved reflectors fed by line sources of any shape, including straight, circular and even elliptical profiles. The proposed hybrid array fed reflector antenna configuration produces pencil beams from line sources which may be either passive multiple beam line sources or reconfigurable linear phased arrays. The proposed formulation, based on parabolic strips derived from Geometrical Optics considerations, reduces significantly phase aberrations which were responsible for beam squint and side lobes imbalance with the previous simpler formulation. Numerical results are presented at Ka-band. This doubly curved reflector design is considered of interest in combination with linear phased arrays to introduce some level of coverage reconfigurability (one-axis beam steering) for on-board broadband satellite communication payloads with a much simpler focal array design when compared to existing planar phased array fed reflector antennas.

A novel compact and highly efficient dual-polarized horn-like antenna is presented. It exploits a radiating aperture that is fed by four smaller waveguides via a quad-furcated junction. The antenna also comprises the full feed network for the feed waveguides including an integrated 4-way orthomode power divider. Design principles are described in detail and illustrated by means of an example involving an antenna with aperture size of 2.6 $\lambda _{0} \times 2.6\lambda _{0}$ ( $\lambda _{0}$ the wavelength at the central frequency of operation) intended primarily for Geostationary Orbit (GEO) satellites. The antenna feed was designed to comply with the Additive Manufacturing rules and exhibits aperture efficiency levels close to the theoretical maximum ones over the entire transmit Ku band (10.7 – 12.75 GHz), while at the same time its profile is highly compact (6.4 $\lambda _{0}$ ). The measured results of a prototype 3D-printed in Selective Laser Melting (SLM) verified experimentally the calculated high aperture efficiency (over 90%). The total antenna feed attains return loss > 19 dB and maximum cross-polarization isolation (XPI) > 24 dB over a bandwidth of 18%. In light of the favorable electrical performances and compact size, the proposed solution constitutes an appealing alternative to profiled (or spline) horns for satellite antenna systems used either as reflector feeds or direct radiating arrays.

In this paper a new concept to improve the angular stability of linear-to-circular polarizing reflectors is presented. It is first explicitly demonstrated that existing design approaches heavily rely on the adjustment of the design stack-up, namely the substrate height and relative permittivity, to the desired operating frequency. An approach is then proposed for decoupling the performance from the substrate parameters. The proposed approach provides increased design flexibility, resulting in performance improvement. Insight on the operating principle is provided resorting to equivalent circuit models. Subsequently, the benefits of the angularly stable reflection polarizer are demonstrated by a practical example involving a multiple beam antenna implemented using materials and processes compatible with satellite missions. The antenna exploits an innovative quasi-optical beam former as primary feed combined with a cylindrical polarizing reflector. Numerical and experimental results from this antenna architecture are presented to confirm the improvements achieved with the proposed concept over existing designs. The close comparison of simulations with measurements that is achieved validates the concept and the design approach.