Design of Wideband, Circularly Polarized Patch Antennas for Rfid Applications in the FCC/Etsi Uhf Bands

Abstract

Abstract-The primary objective of this paper is to design a high-gain, circularly polarized patch antenna suitable for Radio Frequency Identification (RFID) readers that operate in the FCC and ETSI bands . These designs will be used in a healthcare application to provide tag identification for thousands of medicines stored on shelves inside a pharmaceutical warehouse. Consequently, it is important that these antennas provide sufficient electromagnetic coverage and polarization diversity in order to boost tag readability and minimize item identification errors. The proposed RFID reader antenna design begins with a single patch with truncated corners on air substrate in order to help us understand the effect of various geometrical parameters on critical antenna figures of merit. A stub is introduced in order to improve the impedance matching characteristics of the antenna. The wideband characteristic of the design, for both impedance matching and axial ratio, is achieved by a second truncated-corner patch antenna positioned on top of the first one. An optimum design is achieved by changing the heights of the main and parasitic patches, the size of the truncated corners, and the probe position. The final antenna designs are verified by comparing measurement and simulation results.

An ultra-thin double-functional metasurface patch antenna for UHF RFID applications

“…The proposed MPA dimensions and radiation characteristics are compared to the state-of-the-art RFID reader antennas operating in the UHF band; a summary is provided in Table 2. As it can be seen, not only the commercially available reader antennas [15][16][17] but also most of the developed designs in literature [18][19][20][21][22][23]25 are bulky and cumbersome, and may not be appropriate for portable RFID applications. They, however, have a higher gain mainly due to using air substrates in their configurations.…”

“…The UHF RFID reader patch-based antennas are generally thick, bulky, and heavy, especially the commercially available ones [15][16][17] . With the aim to possibly cover the entire worldwide UHF RFID bandwidth (860-960 MHz), techniques such as (1) including several air gaps in the antenna design [18][19][20][21][22][23] , (2) utilizing high dielectric permittivity materials 24 , and (3) using thick substrates [25][26][27] were employed. Unlike (1) that enhances the antenna matching bandwidth and gain at the expense of the bulky profile, both (2) and (3) not only lead to narrower antenna bandwidth but also excite more the surface waves in the structure leading to decreased radiation efficiency and directivity.…”

2-Dipoles Circularly-Polarized Antenna Integrated in Lamp Holder for Fixed RFID Reader

“…Till now, we have seen store employees armed with handheld RFID readers and the research has been focused on finding a compact, low-profile, lightweight, and cost-effective solution for the antenna [5]- [10]. However, handheld RFID readers still require personnel to use them.…”

A Compact Low-Profile Ring Antenna With Dual Circular Polarization and Unidirectional Radiation for Use in RFID Readers

“…Two major types of them are microstrip patch and ring antennas. The microstrip ring antenna is the better candidate since its side length is about one quarter-wavelength and one half of the conventional patch antenna [4]- [6] when they both operate at its fundamental mode. The circular polarization can also be easily obtained with the ring antenna [7]- [9].…”