SAR reduction and gain enhancement of compact wideband stub loaded monopole antenna backed with electromagnetic band gap array

Abstract

This article discusses a design of compact wideband stub loaded monopole antenna (CWSLMA) backed with 3 × 3 array of hexagonal shaped electromagnetic band gap (EBG) cell operating at 2.45 GHz with enhanced gain and low specific absorption rate (SAR) for wireless body area network (WBAN) applications. The split ring rectangular shaped radiator is designed with protruding stub to miniaturize the antenna size of monopole antenna (34 × 18 × 1.6 mm3) at resonance frequency 2.45 GHz. The proposed CWSLMA is fabricated on glass epoxy FR4 substrate supported with 3 × 3 array of hexagonal shaped EBG cell over Kapton polyimide flexible substrate. The proposed antenna consists of simulated 10 dB return loss (RL) bandwidth (BW) of 16.7% (2.3–2.72 GHz). The proposed 3 × 3 array of hexagonal shaped EBG cell enhances the realized gain of proposed CWSLMA to 7 dBi by reducing the back-lobe radiation. The EBG array also increased the isolation between fabricated wearable antenna and human body and thus, reduced SAR to 0.44 W/kg (tested over 10 g of human tissues) at frequency 2.45 GHz. The fabricated proposed CWSLMA with EBG achieved a measured 10 dB RL bandwidth of 17.3% (2.27–2.7 GHz) and a measured group delay below than 1 ns in entire operational band with measured gain of 6.8 dBi. The proposed CWSLMA with EBG is designed, fabricated, and tested. The measured results of fabricated antenna prototype are verified and validated with simulated ones.