Asymmetric Ground Structured Circularly Polarized Antenna for ISM and WLAN Band Applications

This article presents the design and analysis of a dual-band antenna with circular polarization for ISM and WLAN band applications. The proposed antenna operates at two frequencies ranging from 2.1-3.1 GHz and 4.4-7.7 GHz with resonating frequencies at 2.45 GHz industrial, scientific and medical band (ISM) and 5.8 GHz wireless local area network band (WLAN). The antenna is fed by coplanar waveguide feeding (CPW) with an asymmetric ground structure, and the radiating element consists of 24 spokes in the design. The current antenna providing the impedance bandwidths of 38.4% and 49% at two operating bands. The proposed antenna exhibiting circular polarisation with 3 dB axial ratio bandwidth of 150 MHz at 2.33-2.48 GHz and 1600 MHz at 5.14-6.74 GHz. The designed antenna is fabricated on an RT Duroid 5880 substrate with dimensions of 40 x 28 x 0.4 mm(3). The intension behind the design of this antenna is to use it for wearable applications in conformal nature with low specific absorption rate (SAR). The SAR values observed at two operating frequencies are 1.09 W/Kg and 1.47 W/Kg on hand and 0.946 W/Kg and 1.12 W/Kg on head, respectively. The placement and radiation characteristics analysis is done with Ansys Savant tool, and the subsequent measured results provide good correlation with simulation results.