A dual‐band near‐field focused reflectarray antenna for RFID applications at 0.9 and 2.4 GHz

Abstract

This paper presents a dual‐band reflectarray antenna which operates at 0.915 and 2.4 GHz to radiate electromagnetic fields focused in the near‐zone of array aperture. The design uses two stacked feed antennas operated at 0.915 and 2.4 GHz, respectively, so that the currently available RFID systems in the market can be simultaneously used in an independent fashion. Numerical investigations on the radiation characteristics of this reflectarray, as well as an experimental validation, are presented to demonstrate its feasibility.

Near-Field-Focused Microwave Antennas: Near-field shaping and implementation

“…Fresnel zone plate lens antennas [45]- [46], transmitarrays [47] and reflectarrays [50]- [52] have also been considered to implement NFF planar lens antennas, which can be considered as devices that are able to shape the phase-front of the electromagnetic field radiated by a conventional feed antenna. All of them are suggested to avoid the complexity and losses introduced by the feeding network of electrically large NFF microstrip arrays.…”

Technologies for Near-Field Focused Microwave Antennas

“…A challenging NFF reflectarray design is the one presented by Chou et al in [43]. The final goal was the design of a dual-band NFF reflectarray suitable for RFID readers at 915 MHz and 2.4 GHz, which was required to exhibit a focal spot region at the same position (around 1 m from the reflectarray surface) at both frequencies.…”

“…As far as the multilayer 80 × 80 cm 2 reflecting surface is concerned, 36 cross-shaped and 144 rectangle-shaped periodicity cells are printed on two different substrates, to implement the required phase profile at 915 MHz and 2.4 GHz, respectively. A dual-band reflectarray as that in [43] has been designed and prototyped in [44], by using concentric square rings as reflecting elements at both 915 MHz and 2.4 GHz. An optimization procedure based on the steepest descent method (SDM) [28] has been applied in [45] to derive the phase correction required for each reflectarray element, as an alternative to the conventional conjugate-phase profile.…”

Floquet modes-based asymptotic analysis of scattering from FSS-type reflectarray/transmitarray for near-zone-focused radiations

“…The works presented in this paper perform a systematic investigation over the scattering problems, and extend the application scope to treat the reflectarray‐ and transmitarray‐type antenna structures, where the array elements are periodically distributed with different elemental structures to account for the needs of phase changes in the designs of these two types of array structure. In particular, we assume the scattering fields will focus at the near zone of array aperture [ Chou et al , ; Chou , , ; Karimkashi and Kishk , ; Buffi et al , ; Tuan and Chou , ] to resemble the characteristics of flat elliptical reflector and flat bifocal lens antennas, which have two focal points in principles and allow the energy of antenna radiation to focus at any point of interest. Thus, the solutions are very general in contrast to the solution of special case in Felsen and Ribas [].…”