Title :
Compact shorted inverted-L antenna with circular polarisation for RFID handheld reader
Author :
Lin, Y.F. ; Chen, Hsuanwei Michelle ; Chen, C.H. ; Lee, C.H.
Author_Institution :
Inst. of Photonics & Commun., Nat. Kaohsiung Univ. of Appl. Sci., Kaohsiung, Taiwan
Abstract :
Two shorted inverted-L radiating elements are located on the orthogonal corner of the square substrate and connected to each output port of a Wilkinson power divider. A shorted inverted-T strip is placed on the other corner of the square for a perturbing resonator to generate circularly-polarised (CP) radiation in the UHF band. Proper adjusting of the horizontal and vertical lengths of the inverted-T strip will differentiate two orthogonal linearly modes with 90° phase difference for a good CP radiation. Simulated and measured results indicate that the proposed structure can achieve circular-degree polarisation operation. A measured impedance bandwidth (VSWR ≤2) of about 16.4% (810-960 MHz) and a 3 dB axial-ratio (AR) bandwidth of about 4.4% (890-930 MHz) at 915 MHz were obtained.
Keywords :
UHF antennas; UHF radio propagation; UHF resonators; antenna radiation patterns; electromagnetic wave polarisation; power dividers; radiofrequency identification; AR bandwidth; CP radiation; RFID handheld reader; UHF band; Wilkinson power divider; axial-ratio bandwidth; bandwidth 810 MHz to 960 MHz; circular-degree polarisation radiation operation; compact shorted inverted-L antenna; gain 3 dB; horizontal length adjustment; impedance bandwidth; perturbing resonator; phase difference; shorted inverted-T strip; square substrate orthogonal corner; two shorted inverted-L radiating element; vertical length adjustment;
Journal_Title :
Electronics Letters
DOI :
10.1049/el.2012.4296
