Latex based near-endfire wearable antenna backed by AMC surface

Abstract

A near-endfire, artificial magnetic conductor (AMC) backed wearable antenna is proposed in this paper for wireless body area networks operating in the 2.4 GHz ISM band. The bidirectional-endfire radiation pattern of Yagi-Uda latex antenna is changed to off-axis near-endfire radiation using an AMC reflector also printed on latex. The antenna is separated from upper AMC surface using flexible Styrofoam of thickness 0.044λ o at 2.4 GHz for best compromise between keeping the antenna structure low-profile and achieving an off-axis beam tilt radiation of ~74 o towards end-fire direction. 0 o reflection phase AMC surface is proposed to reduce downward radiations and consequently improve the antenna tolerance to positioning on the human body, and reduce the specific absorption rate (SAR) level for 2.4 GHz frequency band gap. Antenna performance in terms of return loss, radiation efficiency, extent of frequency detuning, gain and SAR level are studied for free space as well as CST MWS tissue-equivalent voxel model for proposed antenna design. The Yagi-Uda antenna backed with AMC reflector demonstrates the measured return loss bandwidth of 40 MHz (2.43−2.47 GHz) and gain of -0.2 dBi in endfire direction with improved on-body radiation efficiency of 74.82 % and reduced peak SAR level of 1.24 W/kg for 10 g tissue for the compact overall flexible latex antenna volume of 0.4λ o × 0.4λ o × 0.076λ o at 2.4 GHz.Index Terms -Artificial magnetic conductor reflector, bodyworn antennas, endfire radiation, on-body communications, specific absorption rate, voxel model.

Interaction of electromagnetic waves with humans in wearable and biomedical implant antennas

“…Various boresight radiation antennas on AMC metasurfaces [3] have been proposed earlier to reduce the back radiation and make antennas tolerant to positioning on human body, and in the process also reduce the body absorbed radiation [4 -6]. In [7], we proposed latex based fully flexible near-endfire Yagi antenna on AMC metasurface intended for on-body communications. The antenna was designed, optimized and studied at 2.4 GHz on the CST Microwave Studio voxel model 'Gustav' [8] for a close separation distance of 3 mm between the antenna and upper surface of the voxel (see Fig.…”

Wearable Antennas 3.8 and 5.6 GHZ Using for Indoor Child Monitoring

“…WBAN's applications in monitoring services have been growing. Many bands of frequencies allocated for WBAN, such the Medical Implant Communication System (MICS) where 400 MHz is used, 2.4 GHz and 5.8 GHz bands for the Industrial Scientific Medical (ISM), low and high frequencies of the Ultra-wideband (UWB) which lie between 3 and 10 GHz band [4][5][6][7].…”

“…In recent times, rapid increasing wireless equipment encouraged the development of modern wireless standards such WiFi and WiMax [6][7]. Recent communications have characterised the transmission between different antennas located around the body [8].…”

“…Recent communications have characterised the transmission between different antennas located around the body [8]. Wearable antennas have already been developed as metal patches with different shapes on textile fabric [7]. The antennas published in [8] were probe fed and linearly…”