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In this article, 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 beamformer 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 are achieved validates the concept and the design approach. [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]

An analytical model based on geometrical optics is proposed to design and analyze continuous parallel plate waveguide (PPW) lens-like antennas. The proposed design is based on a transversal PPW section working as a lens-like beamformer. By simplifying the propagation inside this transversal section, a bifocal constrained lens model is first defined; it provides a relevant starting point to design the proposed beamformer. A refined model based on ray tracing and with an enhanced performance prediction is achieved by accounting the wave propagation inside the transversal cavity. The numerical analysis of phase aberrations and radiation demonstrate the performance of the proposed beamformer. The results of the ray-tracing model are in a very good agreement with the corresponding full-wave model, while providing a significant reduction in the computational effort, making the proposed model more suitable for advanced optimization processes. [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]