Circularly polarized slotted‐ground microstrip antennas for radiofrequency identification readers

Abstract

The single‐feed, circularly polarized microstrip antennas (CPMAs) based on the slotted‐ground plane are investigated for radiofrequency identification readers.The conventional CPMA with truncated corners is also studied to compare with the proposed CPMA's performances. In the proposed designs, four square slots with asymmetrical configuration are etched in the diagonal directions on the ground plane of the antenna to achieve circularly polarized radiation. The proposed CPMAs are designed with low‐cost FR4 substrate and RO4003C substrate and their performances are compared. The antenna bandwidth is also studied on thin and thick dielectric substrates. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2304–2309, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27075

A compact multi‐slots loaded gap coupled CP antenna with DGS for WLAN/WiMAX applications

“…13 Four symmetrical square slots was etched from the square ground plane to obtain the 0.83% ARBW. 14 Three triangular defects were embedded in hexagonal radiating patch as well as in square ground plane to realize the CP BW upto 1.8%. 15 An annular ring slot with linked L-slot, fractal slot and dumbbell shaped slots were introduced in the ground plane to obtain the ARBW's of 9.68%, 1.28% and 1.06%, respectively.…”

“…A hook shaped microstrip antenna with multiple narrow slits in the ground plane 12 and concentric circular fed patch with parasitic sectored annular ring microstrip antenna having semi‐ring slot in the ground were investigated to obtain the CP radiation 13 . Four symmetrical square slots was etched from the square ground plane to obtain the 0.83% ARBW 14 . Three triangular defects were embedded in hexagonal radiating patch as well as in square ground plane to realize the CP BW upto 1.8% 15 .…”

Compact broadband circularly‐polarised antenna with a backed cavity for UHF RFID applications

“…Many patch antennas with CP are presented in the literature. CP patch antennas are commonly designed with current perturbations because of the compact profile and easy fabrication [4][5][6][7]. However, the impedance bandwidth and CP bandwidth of these patch antennas are relatively narrow, and are therefore unable to cover the entire UHF RFID frequency range from 840 to 960 MHz.…”

Circularly polarized monopole slot antenna for UHF RFID reader

“…Generally, an RFID system consists of a tag, a reader and a data processing system. Usually, the tags are linearly polarized (LP) and randomly oriented [1,2], so the reader antennas are often designed as circularly polarized (CP) to establish reliable communications between the reader and the tags. Microstrip antennas have the merits of low profile, low cost, easy to produce, and many circularly polarized microstrip reader antenna designs have been published in the literature.…”

“…One commonly used feeding methods for CP microstrip antennas is coaxial probe feed. This kind of feeding structure is easy to fabricate and match, but the 3-dB axial ratio CP bandwidth is typically narrow, and cannot cover the UHF RFID operating band (902-928 MHz) [1][2][3][4]. Another feeding method is microstrip line coupling feeding [5][6][7].…”