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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. [ABSTRACT FROM AUTHOR]

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) ($\cong -18$ dB), as compared to the previous elliptical approach ($\cong -13.2$ dB). A validation has been proposed through the manufacturing and test of a prototype over the down-link 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. [ABSTRACT FROM AUTHOR]

This letter proposes an efficient design process to reduce the cross polarization of linear-to-circular reflection polarizers illuminated by practical feeds. In particular, we propose a two-step process, where first a geometrical optimization of the unit cell is applied along one plane of the reflector, followed by a progressive rotation of the unit cell in the orthogonal plane. An offset flat polarizer comprised of dipole unit cells fed by a standard gain horn has been used to illustrate the process. Significant improvements in cross-polarization discrimination are demonstrated by simulation. Two breadboards have been manufactured, and their response is compared in order to demonstrate the validity of the design process. Good agreement with measurements is observed corroborating the proposed technique. [ABSTRACT FROM AUTHOR]

This communication introduces a novel periodic reflector which provides linear to circular polarization (CP) conversion in two frequency bands. Significantly, the reflector converts a slant 45° linearly polarized wave into two orthogonal CPs over two separate frequency bands while further the unit cell dimensions are maintained below the critical grating lobe limit of half wavelength. Unlike previous designs providing this performance, which are based on linear dipole elements, miniaturization is here achieved by exploiting resonances in both TE and TM polarized waves. The operating principle of the polarizer is discussed and a parametric study is presented to derive design guidelines. A prototype working in the satellite Ku-band has been designed and tested to validate the proposed design. The proposed polarizer can find applications in multiple-beam satellite antenna systems in order to reduce the number of reflector apertures in a single-feed-per-beam configuration. [ABSTRACT FROM AUTHOR]