QUAD-BAND WEARABLE SLOT ANTENNA WITH LOW SAR VALUES FOR 1.8 GHZ DCS, 2.4 GHZ WLAN AND 3.6/5.5 GHZ WIMAX APPLICATIONS

In this paper, a quad-band wearable slot antenna with low specific absorption rate (SAR) is presented. By cutting an inverted V-shaped slot with its arms further extended towards the center of the circular patch, multiple resonant modes of the antenna can be excited to operate on 1.8 GHz DCS, 2.4 GHz WLAN and 3.6/5.5 GHz WiMAX bands. The measured peak gains and impedance bandwidths are about 4.91/7.84/2.58/4.12 dBi and 320/60/80/180 MHz for the 1.8/2.4/3.6/5.5 GHz bands respectively. The SAR of the proposed antenna has been measured using a three layer human tissue model. The estimated SAR values at all the resonant frequencies are well below the threshold limit of 2W/kg, which ensures its viability for wearable applications. In order to approximate different parts of the human body, the SAR values have been estimated for three surface sizes, 120 × 120 mm2, 220 × 220 mm2 and 320 × 320 mm2, of the human tissue model, and results are compared. Frequency detuning of the proposed antenna due to bending along x, y and x-y planes has also been carried out and discussed. Further, on arm effect on the antenna performance is investigated, and results are presented. The simulated and measured results are in good agreement, which validates the use of proposed wearable antenna in DCS/WLAN/WiMAX bands.