International Journal of Antennas and Propagation 
Volume 2007 (2007), Article ID 76793, 8 pages
doi:10.1155/2007/76793
Research Article

A Broadband Circularly Polarized Stacked Probe-Fed Patch Antenna for UHF RFID Applications

Hang Leong Chung, Xianming Qing, and Zhi Ning Chen

 Institute for Infocomm Research, 20 Science Park Road, 02-21/25 TeleTech Park, Singapore Science Park II 117674, Singapore
Received 1 March 2007; Revised 22 May 2007; Accepted 15 August 2007

Recommended by Hans-Erik Nilsson

Abstract

A broadband circularly polarized stacked probe-fed antenna suitable for UHF RFID applications is presented and studied. The proposed antenna is fed by two probes which are connected to a hybrid coupler. Two parasitic patches are stacked above a primary probe-fed patch to enhance the bandwidth of the antenna. The optimized antenna prototype achieves gain of more than 6.5 dBic, axial ratio of less than 3.0 dB, and return loss of less than −15 dB over the UHF band of 820–980 MHz (17.7%). Parametric studies are carried out to demonstrate the effects of antenna geometry parameters on the performance. The proposed antenna can be a good candidate for UHF RFID applications.