Author(s) :

Ibrahim, Shehu Gajo, Babale S. A., Yusuf Z. Y, Lawan S. H, Lawan M. B.

Volume/Issue :

Abstract :

This paper proposed a design of flexible compact microstrip patch antenna with enhanced bandwidth and capable of supressing higher order harmonics. The design employed the use of two quarter-wavelength (λ/4) resonators coupled in close proximity to radiating patch. The wideband was achieved by parametric study of the distance between the radiating patch and the pair of λ/4 resonators thereby combining the resonances from the rectangular patch and λ/4 resonators. The proposed capacitive couple feed and shorting pin between the resonators effectively eliminating the spurious radiations caused by harmonic resonant modes of the patch radiator. The proposed design 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 plans. The antenna was studied and analysed using CST Microwave Studio. Different parameters such as Return Loss, Gain and Efficiency were studied and compared with inset-fed microstrip patch antenna operating at same 2.45GHz ISM band. The antenna’s bandwidth is enhanced to about 2.3 times that of the inset-fed with fractional bandwidth of 9.4% and the higher order resonances were effectively eliminated. 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 with SAR values of 0.203W/kg for 1gram and 0.0721W/kg for 10grams. The proposed antenna can be used in many wearable electronic devices operating at 2.45GHz ISM band.

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