A Novel Wideband Circularly Polarized Antenna for Worldwide Uhf Band Rfid Reader Applications

Abstract

Abstract-This paper presents the novel design of a wideband circularly polarized (CP) Radio Frequency Identification (RFID) reader microstrip patch antenna for worldwide Ultra High Frequency (UHF) band which covers 840-960 MHz. The proposed antenna, which consists of a microstrip patch with truncated corners and a cross slot, is placed on a foam substrate (ε r = 1.06) above a ground plane and is fed through vias through ground plane holes that extend from the quadrature 3 dB branch line hybrid coupler placed below the ground plane. This helps to separate feed network radiation, from the patch antenna and keeping the CP purity. The prototype antenna was fabricated with a total size of 225 × 250 × 12.8 mm 3 which shows a measured impedance matching band of 840-1150 MHz (31.2%) as well as measured rotating linear based circularly polarized radiation patterns. The simulated and measured 3 dB Axial Ratio (AR) bandwidth is better than 23% from 840-1050 MHz meeting and exceeding the target worldwide RFID UHF band.

A Circularly Polarized Antenna Array with Gain Enhancement for Long-Range UHF RFID Systems

“…Many studies have been conducted to achieve high-gain RFID reader antennas which can cover the universal ultra-high frequency (UHF) RFID band [6][7][8][9]. A maximum CP gain of 9.3 dBic is demonstrated in [7] with a single antenna configuration and the use of a structure with a high profile (35 mm).…”

Design of Dual Circularly Polarized Antenna With High Isolation for Rfid Application

“…If the antenna or reader is not well matched with the isolation component, the Tx leakage will be increased. Another guaranteed and low-cost solution is the antenna structure integrated with a branch line coupler as feed network [14,15]. However, the use of complex branch-line coupler is an inconvenience for mass production and make the overall antenna dimension larger.…”

A Broadband Circularly Polarized Antenna Fed by Horizontal L-Shaped Strip

“…Circularly polarized (CP) antennas are widely used in wireless communication applications such as navigational systems, radar tracking and radio frequency identification (RFID) readers [1][2][3][4] because they allow more flexible orientation between the transmitter and receiver antennas. Circular polarization can be realized by exciting two orthogonal modes of equal amplitude and 90 • phase difference.…”