Adjustable axial ratio of single-layer circularly polarised patch antenna for portable RFID reader

Author

Lin, Yeou-Fu ; Chen, Hou-Ming ; Pan, S.-C. ; Kao, Y.-C. ; Lin, Chun-Yu

Author_Institution

Inst. of Photonics & Commun., Nat. Kaohsiung Univ. of Appl. Sci., Kaohsiung

Volume

45

Issue

6

fYear

2009

Firstpage

290

Lastpage

292

Abstract

A novel single-layer, proximity-fed technique for a slot-coupled circularly polarised square patch antenna operated in the ultra-high frequency band is presented. In the proposed design a pair of radiating square patches with a cross-slot and a microstrip feed line are both etched on the top of a microwave substrate, and a coupling arrow-shaped slot is etched on the bottom of this substrate. Simulated and measured results indicate that the proposed structure can achieve circular polarisation operation. Proper adjustment of the feed coupling gap distance between the patch and the feed line results in good impedance matching and circularly polarised radiation, and an impedance bandwidth (VSWR les 2) of about 3.74 and a 3 dB axial-ratio bandwidth of about 1.62% were obtained.

Keywords

antenna feeds; antenna radiation patterns; electromagnetic coupling; electromagnetic wave polarisation; impedance matching; microstrip antennas; radiofrequency identification; slot antennas; adjustable antenna axial ratio; coupling arrow-shaped slot; feed coupling gap distance; impedance bandwidth; impedance matching; microstrip feed line; microwave substrate; portable RFID reader; proximity-fed technique; single-layer slot-coupled circularly polarised patch antenna; square patch antenna radiation; ultra-high frequency band;

fLanguage

English

Journal_Title

Electronics Letters

Publisher

iet

ISSN

0013-5194

Type

jour

DOI

10.1049/el.2009.3569

Filename

4800372