Most of submillimeter-wave instruments, especially for space applications, make use of very high gain reflector-based antennas to fulfill the desired resolution or sensitivity requirements. This chapter covers the design and the analysis of elliptical lens antennas, providing analytical formulation to synthesize the lens and compute the radiation of the lens excited by a feed. Integrated silicon lens antennas are well suited for submillimeter-wave applications because of their focusing capabilities into a planar antenna. The chapter describes the semi-hemispherical lens antenna from its synthesis to its radiation properties while comparing it with the elliptical lens. It explains the excitation of shallow lenses by leaky-wave/Fabry–Perot feeds: starting from the analysis of the leaky-wave effect and computing its propagation constant, then analyzing its radiation into an infinite medium, and finishing up with the optimization of the shallow-lens geometry. The chapter concludes with some worked examples to make the reader consolidate and reflect on the lessons learned.@en

In this contribution, a broadband G-band leaky-wave (LW) fed lens antenna with an integrated dielectric grid polarizer is presented. The proposed wideband polarizer unit cell geometry enables its fabrication at frequencies higher than 100 GHz, presenting high transmission properties and low axial ratio (AR). A quasi-Analytic technique based on multilayer spectral Green's function combined with a numerical Floquet modes' solver is used to optimize the lens aperture efficiency and AR. The proposed technique is validated via full-wave (FW) simulations. A design is proposed in low dielectric permittivity material, achieving FW simulated aperture efficiency higher than 75% over 44% relative bandwidth, and an AR lower than 3 dB over 35% relative bandwidth. The antenna is able to achieve multiple directive circularly polarized (CP) beams when fed by a focal plane array, preserving the AR bandwidth. A prototype has been fabricated and measured, exhibiting an excellent agreement with quasi-Analytic and FW simulations.

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In order to fulfill the exponential increase in the demand of high-speed wireless links, future XG wireless networks will be developed at higher carrier signal frequencies, reaching the hundreds of gigahertz. In this contribution, a leaky-wave-fed HDPE lens antenna working at ${G}$ -band which can be useful for future XG communications is presented. The proposed lens design enables the generation of up to 40 beams, with gains higher than 30 dB. Analytical tools have been applied to optimize the lens aperture efficiency, validating the results via full-wave simulations. The reached aperture efficiency for the broadside beam is higher than 80% over a 44% relative bandwidth. The measurement results for a fabricated prototype show excellent agreement with the simulated performance.@en

A high-gain broadband leaky-wave fed lens antenna with an integrated dielectric gratings polarizer covering the whole G-band (140-220GHz) is presented. This work focuses on the polarizer gratings manufacturing and in particular on the selection of plastic materials and the fabrication process refinement. The polarizer geometry has been designed and optimized to be compatible with standard milling techniques. A quasi-analytical method based on an analysis of the lens antenna in reception is used to validate the in-lens polarizer performance. Several prototypes have been fabricated, finally obtaining an excellent match between measurements and quasi-analytical results.

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