Broadband Circularly Polarized Annular-Ring Microstrip Antenna

• Published in: IEEE transactions on antennas and propagation Vol. 57; no. 8; pp. 2474 - 2477
• Main Authors: Guo, Yong-Xin, Bian, Lei, Shi, Xiang Quan
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-08-2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Antenna feeds; Antennas; Applied sciences; Bandwidth; Broadband; Broadband antennas; Circular-polarization; Circularity; Current distribution; Cutting; Exact sciences and technology; Frequency; General equipment and techniques; Impedance; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Microstrip antennas; Organization, operation and development plans; Patch antennas; Phases; Physics; Polarization; Radiocommunications; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Telecommunications; Telecommunications and information theory; Wideband; wideband antennas; Circular polarization; wideband antennas; Printed antenna; Bandwidth allocation; Broadband antennas; Proximity detector; Wide band; Microstrip antennas; Current distribution; Axial ratio; Resource management; Annular antenna; Circular-polarization
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2009.2024584

A wideband circularly polarized (CP) annular-ring patch antenna with two proximity-coupled L-probe feeds orientated to have phases of 0 deg and 90 deg , using a broadband 90 deg hybrid feed, is proposed. It is found that the current distribution for CP operation can be improved by cutting a smaller concentric circular slot on the original larger circular patch to form an annular-ring patch. With such an arrangement, the proposed antenna delivers a wider axial ratio (AR) bandwidth than that of the conventional circular patch with the identical feeding technique. Considering the common overlapped bandwidth limited by the impedance, AR and gain, the proposed annular-ring patch antenna exhibits an effective bandwidth of 38% from 1.5 to 2.2 GHz, which is wider than the corresponding bandwidth of 29.7% from 1.35 to 1.82 GHz for the conventional circular patch. Moreover, the effective bandwidth of 38% for the proposed annular-ring antenna is also much wider than those for the other annular-ring patch antennas in the literature.