A wideband circularly polarized <i>S</i> ‐shaped slot antenna

Abstract

This article introduces a simple wideband circularly polarized (CP) S-shaped slot antenna for ISM band wireless communication applications. By using a wide curve S-shaped slot patch on the top side and a T-shaped feeding line on the bottom side of the substrate, the wideband CP wave is generated. The overall size of the proposed antenna is 0.85λ × 0.85λ × 0.011λ (λ is the wavelength of the lowest operating frequency) and it has a broad impedance bandwidth of 68.1% between 1.66 and 3.44 GHz for S11 < –10 dB and a 3 dB axial-ratio bandwidth of 57.1% between 1.68 and 3.06 GHz. Within the axial-ratio bandwidth, the measured gain of the proposed antenna ranged from 2.1 to 5.4 dBic. The measured results are in good agreement with simulated results. The new type of slot antenna with wide bandwidth and simple structure is a good candidate for various RFID applications.