Evaluation of a Dielectric-Only Transmitarray for Generating Multi-Focusing Near-Field Spots Using a Cluster of Feeds in the Ka-Band

Abstract

A transmitarray antenna is evaluated to generate a multi-focusing spot area in the Fresnel region of the antenna in the Ka-band. The antenna is designed to focus the radiated field at a certain point using a central feeding configuration. The number of feeds is increased to create as many focusing spots as feeds. The feeds are placed along an arc defined in the principal planes of the transmitarray, radiating independent near-field spots and providing a solution with a wide-angle spot scanning without an antenna displacement and a high isolation between feeds. To validate this concept, a transmitarray based on dielectric-only cells is designed and simulated under full-wave conditions. Then, this design is manufactured using a 3D printing technique, and the prototype is measured in a planar acquisition range. Measurements are performed for different feed positions in order to validate the multi-focusing capability of the antenna. Measurements and simulations show a high agreement and validate the proposed design technique.

Radar near-field sensing using metasurface for biomedical applications

“…Examples illustrating this concept include an optically transparent reflectarray antenna operating at 5.8 GHz 32 and a bi-layer resonant wires transmitarray antenna at 157 MHz 33 , both designed to enhance wireless power transfer in the near-field. Moreover, near-field multi-focus reflectarray and transmitarray apertures, illuminated by numerous horn antennas, are designed with a distance of 9.6 λ at 5.8 GHz 34 and 9.3 λ at 28 GHz 35 . A folded transmitarray structure fed by a horn antenna at a spacing of 2.2 λ is proposed to concentrate power in both the near- and far-field at 2.45 GHz 36 .…”

Fast Transmitarray Synthesis with Far-Field and Near-Field Constraints

“…One case of interest is short-range millimeter wave communications for indoor small cells or femtocells, which could correspond to an office or meeting room. In such a scenario, there might be several devices and sensors closely distributed in the near field (NF) of the base station antennas, and different NF spots are, hence, required to provide coverage to the different devices [3,4], for transfer of information, power (wireless power transfer or WPT), or both (wireless power and information transfer or WPIT). Furthermore, it may also happen that some wireless devices are in the nearby regions of the base station antenna, while others are located in farther positions.…”

“…At the same time, transmitarrays (TAs) have received much attention in the last decade [4,[8][9][10][11][12][13]. They are planar array lenses characterized by their high efficiency and gain, low profile, and light weight, and they have attracted great interest as a feasible solution for beam steering and 5G multibeam antennas [13][14][15][16].…”

“…They are planar array lenses characterized by their high efficiency and gain, low profile, and light weight, and they have attracted great interest as a feasible solution for beam steering and 5G multibeam antennas [13][14][15][16]. In parallel, also in recent years, 3D printing technology has emerged as a fast, low-cost, low-loss alternative for the fabrication of reflectarrays [17], lenses [18,19], and, in particular, TAs [4,11,[20][21][22].…”