DESIGN AND ANALYSIS OF FLEXIBLE MICROSTRIP PATCH ANTENNA AT 2.45GHz ISM BAND

Abstract

The paper presents a design and performance analysis of an in-set feed rectangular wearable patch antenna at 2.45GHz for ISM band. The antenna is made of polydimethylsiloxane (PDMS) flexible substrate with dielectric constant of 2.7, loss tangent of 0.02 and thickness of 2.5mm which is conformal and robust solution to wearable applications. Zelt, a nylon-based material, with surface resistivity of 0.01 ohm/sq and thickness of 0.063mm was used for radiating planes. The proposed antenna was studied and analysed using CST Microwave Studio, where different parameters such as Return Loss, Gain and Efficiency were observed. As the antenna is expected to be worn in close proximity to human tissue, the Specific Absorption Rate (SAR) was investigated on a three layered body model of Skin, Fat and Muscle. The proposed antenna achieved a 100MHz impedance bandwidth (4.08%), Gain of 3.11dB and Efficiency of 51%. The proposed antenna on flat body phantom gives acceptable SAR of 0.615W/Kg and 0.281W/Kg over 1gram and 10gram of tissue which are below the SAR threshold limits of 1.6W/kg and 2W/kg respectively. The proposed antenna can be incorporated in to various wearable devices.