Split-ring Microstrip Research Articles

A Wideband Circularly Polarized Antenna with Characteristic Mode Analysis

A wideband circularly polarized (CP) antenna is presented to achieve enhanced impedance, axial ratio (AR), and gain bandwidths. The antenna consists of two circular patches, a split-ring microstrip line with six probes, and a circular ground plane. By using these six probes which are placed in sequence on the split-ring microstrip line, the operating bandwidth of the proposed antenna is increased. The characteristic mode method is used to analyze different modes of the antenna and reveal the mechanism of extending the 3-dB AR bandwidth. Measured results show that the proposed antenna obtains an impedance bandwidth of 1.486–2.236 GHz (40.3%) for S11 ≤ −18 dB, a 3-dB AR bandwidth of 1.6–2.2 GHz (31.6%), and a boresight gain of 8.89 ± 0.87 dBic.

DESIGN OF DUAL CIRCULARLY POLARIZED ANTENNA WITH HIGH ISOLATION FOR RFID APPLICATION

In this paper, a dual-fed circularly polarized antenna design with high isolation is presented for radio frequency identiflcation (RFID) reader. The proposed antenna is excited by two fed ports connected with a circular split-ring microstrip line underneath the ground plane. A radial aperture in the ground plane provides coupling between the split-ring microstrip and radiating patch. For multiple RFID band requirements, the dimension of the aperture can be modifled to obtain high isolation on difierent RFID Band. Finally, an antenna prototype for China RFID Band (920{925MHz) is fabricated. The measured results agree well with simulation, and show 10-dB matching bandwidth of 18% (820{1000MHz), 3-dB axial ratio (AR) bandwidth of 11% (854{960MHz), and 25-dB isolation bandwidth of 11MHz (917{928MHz).