Several linearly-polarized and circularly-polarized transmit-arrays are designed and demonstrated in the 60-GHz band. These arrays have a fairly simple structure with three metal layers and are fabricated with a standard printed-circuit board technology. The simulation method is based on an electromagnetic model of the focal source and the unit-cells, associated to an analytical modeling of the full structure. A theoretical analysis is presented for the optimization of the power budget with respect to the F/D ratio. Several prototypes are designed and characterized in V-band. The experimental results are in very good agreement with the simulations and demonstrate very satisfactory characteristics. Power efficiencies of 50-61% are reached with a 1-dB gain bandwidth up to 7%, and low cross-polarization level.

Three 400-element circularly polarized discrete lens antennas with different F/D ratios and main beam directions are studied in the 60-GHz band. They are fabricated with a standard printed circuit board technology and demonstrate excellent performance with a radiation efficiency of 53%-61%, an aperture efficiency of 15%-28%, 20-23 dBi gain, and a very good axial ratio. The typical -1-dB gain- bandwidths are above 12%, and the F/D = 0.5 prototype demonstrated a 1-dB axial-ratio bandwidth larger than 16.3%. To our knowledge, this work is the first demonstration of low-cost discrete lens antennas compatible with high-data-rate communications in V-band.

A new linearly polarized discrete lens antenna for satellite applications is designed in 42-GHz band with 1-bit phase quantization and attractive elementary cell design. This phased array has a fairly simple novel structure with only three metallic layers and exhibits compelling features for Q-band applications. The design and optimization of the power budget has been theoretically analyzed and verified experimentally. The elementary cell's impedance matching measurements show a reflection loss below -10 dB at 40.3-42.6 GHz and an insertion loss of 0.42 dB at 41.5 GHz. The proposed discrete lens antenna achieves directivity/gain values of 25.1/22 dBi. Power efficiency of 50% is also achieved with a 3-dB gain bandwidth of up to 8.7% and very low cross-polarization levels.

This paper presents a novel approach for linear to circular polarization (LP-CP) conversion in transmitarray antennas. The proposed conversion mechanism differs significantly from previous published realizations. The concept utilizes a transmission line modeling-based excitation technique, in which a centralized via excitation is split into two striplines carefully designed to balance excitations and guarantee a phase quadrature. The striplines are embedded at the center of the patch antenna allowing a compact footprint and a simple design structure. The applied true-time delay (TTD) technique assures the radiation of a wideband and low axial ratio circularly polarized (CP) field. To optimize bandwidth and transmission efficiency, a stacked patch configuration is also employed, allowing for simultaneous high polarization conversion and transmission efficiency. The unit-cell design methodology is detailed, and two transmitarray designs are realized in both X and Ka bands. Experimental results from a fabricated X-band 20×20 cell array prototype demonstrate a peak aperture efficiency of 30%, accompanied by a simultaneous 16% -1 dB gain and 1 dB axial ratio bandwidths. Furthermore, the measured wideband and highly efficient Ka-band transmitarray with a 70×70 cell array confirmed a remarkable gain of 39.8 dB and 55% aperture efficiency at 29 GHz, surpassing previous LP-CP transmitarray antennas, while maintaining axial ratio values below 1 dB in a bandwidth larger than 26%.

This paper presents a complete hybrid numerical methodology for the efficient design and optimization of large-scale Transmit-Array (TA) antennas for modern telecommunication applications. There are four main components to the proposed work and methodology: 1) the implementation through Python scripts of a hybrid scheme based on the Friis analytical formula for linking gain and phase of the primary source and elementary cells of the studied transmit-array; 2) the implementation of a Particle Swarm Optimizer (PSO) for efficient characterization of the optimal phase distribution on the in-plane lens maximizing the gain of the antenna and minimizing the side-lobe levels for multiple fed TA antennas; 3) the implementation of a full-wave Finite element and Interconnecting domain decomposition (FETI) for the final analysis of the TA radiating performance; 4) the design, optimization, fabrication and proof of concept of an X band transmit-array including the focal source. This work presents the main functionalities of the hybrid Python/CST tool associated with phase compensation PSO, FETI implementation for transmit-arrays and as an application of this numerical strategy, a new compact unit-cell operating in the X-band (thickness of 3.2 mm) able to easily generate Phase Rotations (PR) necessary for TAs with phase compensation on the aperture. The proposed unit-cell is a completely symmetric design including a metallic via interconnecting two identical square patches (including a circular hole in the center and a microstrip line) by crossing through a ground plane. A particle swarm optimization (PSO) routine is proposed as a way to quickly optimize the phase distribution of the transmit-array unit-cells. The optimization routine is tested through multiple sources and focal ratios, demonstrating a reduction of over 50% of the volume occupied by the antenna, while keeping a high gain (19.5 dBi) and overall good performance.