GHz Wireless Body Area Networks Research Articles

Wearable Polarization Conversion Metasurface MIMO Antenna for Biomedical Applications in 5 GHz WBAN

This paper presents a wearable metasurface multiple-input multiple-output (MIMO) antenna for biomedical applications in a 5 GHz wireless body area network (WBAN) with broadband, circular polarization (CP), and high gain. The physical properties of the MIMO antenna element and the principles of polarization conversion are analyzed in-depth using characteristic mode analysis. For the proposed MIMO antenna, the measured -10 dB impedance bandwidth is 34.87% (4.76-6.77 GHz), and the 3 dB axial ratio bandwidth is 22.94% (4.9-6.17 GHz). By adding an isolation strip, the measured isolation of the two antenna elements is greater than 19.85 dB. The overall size of the MIMO antenna is 1.67λ0 × 0.81λ0 × 0.07λ0 at 5.6 GHz, and the maximum gain is 7.95 dBic. The envelope correlation coefficient (ECC) is less than 0.007, with the maximum diversity gain greater than 9.98 dB, and the channel capacity loss is less than 0.29 b/s/Hz. The specific absorption rate (SAR) of the wearable MIMO antenna is simulated by the human tissue model, which proves that the proposed antenna conforms to international standards and is harmless to humans. The proposed wearable metasurface MIMO antenna has CP, broadband, high gain, low ECC, and low SAR, which can be used in wearable devices for biomedical applications.

Wearable Pattern-Diversity Dual-Polarized Button Antenna for Versatile On-/Off-Body Communications

A wearable dual-port button antenna that excites pattern-diversity dual-polarized waves is proposed for on-/off-body applications. Its simple structure comprises of two radiators and a common ground plane designed into two substrates. The crossed-dipole radiator is made by two symmetric bowtie dipoles printed on a circular-shaped semi-rigid substrate, which covers an ultra-wideband (UWB) application with circular polarization and directional radiation patterns, high gain, and high efficiency suitable for off-body communication. The annular-ring radiator and common ground plane are made by a conductive textile on the square-shaped flexible-felt substrate. The annular-ring radiator is shorted to the ground plane using four vias, which generates triple TM modes covering the 2.45/5.85 GHz wireless body area networks (WBAN) with omni-directional radiation patterns and a 3.8 GHz C-band with a directional radiation pattern suitable for on-/off-body communications. The fabricated antenna is verified by measurement in both free space and phantom body environment. Measurements agreed well with simulations. Simulated specific absorption rates (SARs) under US and EU standards are below the safe level, making the proposed antenna suitable for on-/off-body communications.

A Wideband Metasurface Antenna With Dual-Band Dual-Mode for Body-Centric Communications

A wideband wearable metasurface antenna with dual-mode (on-body and off-body mode), dual-band, designed for the 2.45 and 5 GHz wireless body area network (WBAN), is proposed in this communication. The TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode of the circular patch is used for the off-body mode in the 2.45 GHz WBAN band because of its broadside radiation pattern, meanwhile, the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> of the circular patch and metasurface mode are chosen for on-body mode due to their omnidirectional radiation pattern in the second band. A shorting pin is used to tune these modes to the desired operating frequencies and using polydimethylsiloxane (PDMS) makes the antenna easier to be integrated into wearable devices. The prototype is fabricated, and a good performance is realized with a measured <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> < −10 dB functional bandwidth of 4.9% and 15.7% which can cover the 2.45 and 5 GHz WBAN band, respectively. Moreover, the measured peak gain achieves 5.5 dBi for off-body mode and 5.3 dBi for on-body mode, as well as the specific absorption rate values are lower than the limitation standards of U.S. and Europe throughout the operating band. The acquired performance demonstrates that the proposed antenna has a great potential in the wearable applications.

Wearable Metasurface Antenna based on Electrically‐small Ring Resonators for WBAN Applications

This letter proposes a novel wearable metasurface antenna (MSA) based on electric ring resonators (ERR) for 5.8 GHz wireless body area network (WBAN) applications. All substrates of the proposed design are made from the semi-flexible Rogers RT5880 material. To achieve size miniaturization, 6 × 8 ERR elements are placed on a flat surface connected through a corporate-feed network. The total dimensions of the proposed MSA are 120 × 90 × 1.574 mm3 (2.2λ0 × 1.69λ0 × 0.029λ0). Furthermore, an average efficiency of 79.9%, and a peak gain of 12.82 dBi with a stable radiation pattern have been realized in the operating band. The performance of the proposed MSA is analyzed in close proximity to the human body tissue. The experimental results show good agreement with the numerical data. With all these features, the proposed design is a good candidate for wearable WBAN applications.

Microstrip monopole antenna with a novel UC‐EBG for 2.4 GHz WBAN applications

A microstrip monopole antenna backed with a novel uniplanar compact electromagnetic bandgap (UC-EBG) structure for 2.4 GHz wireless body area network applications is proposed here. The proposed antenna has a size reduction of 50% when the number of EBG array is optimised from 3 × 4 to 2× 3, while the radiation performance is almost invariable at the same time. The operating frequency band under different conditions has the capability of covering the 2.4–2.4835 GHz industrial, scientific, and medical band. Due to the addition of 2×3 UC-EBG on the back, the radiation patterns become unidirectional, and the measured average gain increases from 2.1 to 5.6 dB. Meanwhile, the cross-polarisation of the monopole antenna can be suppressed prominently by the EBG array. The simulated specific absorption rate values are 0.0536 W/kg under 1 g standard and 0.0296 W/kg under 10 g standard, which are far below the limitation of USA and Europe. These results can manifest the reliable wearable performance of the proposed antenna.

A Wearable PIFA With an All-Textile Metasurface for 5 GHz WBAN Applications

In this letter, a wearable all-textile metasurface antenna (MSA) for 5 GHz wireless body area network (WBAN) applications is proposed. All the components of the proposed MSA are made of the comfort textile materials. A metasurface with high permittivity values is placed right above a wide-bandwidth planar inverted-F antenna to realize size miniaturization and gain enhancement. The proposed MSA has a profile of 4 mm (0.07λ0) and occupies an area of 42 mm × 28 mm (0.77λ0 × 0.51λ0). Moreover, this antenna realizes a measured peak gain of 6.70 dBi, an average efficiency of 77%, and an operating band from 4.96 to 5.90 GHz that covers the 5 GHz WBAN band. In addition, the on-body studies show that the MSA is suitable for wearable applications.

Optimal Design of a Planar Textile Antenna for Industrial Scientific Medical (ISM) 2.4 GHz Wireless Body Area Networks (WBAN) with the CRO-SL Algorithm.

This paper proposes a low-profile textile-modified meander line Inverted-F Antenna (IFA) with variable width and spacing meanders, for Industrial Scientific Medical (ISM) 2.4-GHz Wireless Body Area Networks (WBAN), optimized with a novel metaheuristic algorithm. Specifically, a metaheuristic known as Coral Reefs Optimization with Substrate Layer (CRO-SL) is used to obtain an optimal antenna for sensor systems, which allows covering properly and resiliently the 2.4–2.45-GHz industrial scientific medical bandwidth. Flexible pad foam has been used to make the designed prototype with a 1.1-mm thickness. We have used a version of the algorithm that is able to combine different searching operators within a single population of solutions. This approach is ideal to deal with hard optimization problems, such as the design of the proposed meander line IFA. During the optimization phase with the CRO-SL, the proposed antenna has been simulated using CST Microwave Studio software, linked to the CRO-SL by means of MATLAB implementation and Visual Basic Applications (VBA) code. We fully describe the antenna design process, the adaptation of the CRO-SL approach to this problem and several practical aspects of the optimization and details on the algorithm’s performance. To validate the simulation results, we have constructed and measured two prototypes of the antenna, designed with the proposed algorithm. Several practical aspects such as sensitivity during the antenna manufacturing or the agreement between the simulated and constructed antenna are also detailed in the paper.

Circular Quarter-Mode SIW Antenna for WBAN Application

ABSTRACTIn this paper, a miniaturized Substrate Integrated Waveguide (SIW) antenna is designed for 5.8 GHz Wireless Body Area Network application. The proposed antenna is based on a quarter-mode concept, which is acquired by cutting a circular patch into four quarters along the perfect magnetic walls. Later on, by etching a tilted-rectangular slot on the top of a quarter-mode SIW cavity, two modes TM210 and TM020 get coupled and in results, an enhancement in bandwidth is achieved. The performance of the fabricated antenna has been validated on pork tissues. The measured impedance bandwidth and the radiation efficiency of the antenna are 400 MHz [5.52–5.92 GHz] and 88.5%, respectively. The evaluated value of specific absorption rate on pork tissues is 1 W/kg averaged over 1 g mass of tissue, with the input power of 250 mW. The simulation results and the measurement results examined on pork tissues agree well with each other.

Experimental study of a wearable aperture-coupled patch antenna for wireless body area network

A new type of the wearable aperture-coupled patch antenna for 2.4 GHz wireless body area network (WBAN) application is proposed. The H-shaped slot in middle ground plane and rectangular ring microstrip feed line are optimized, so that it realizes the efficient electromagnetic coupling with the radiating element. The substrate layers are 2 mm thickness felt layers with relative permittivity of 1.2, and the other layers are copper foil tape (CFT) to ensure the performance of the antenna. Furthermore, the return loss, radiation pattern and gain are investigated in detail for the antenna under different bending curvature radius. Experimental results show a good agreement with simulation results. (C) 2017 Wiley Periodicals, Inc.

Reconfigurable antenna options for 2.45/5 GHz wireless body area networks in healthcare applications.

This paper presents electronically reconfigurable antenna options in healthcare applications. They are suitable for wireless body area network devices operating in the industrial, scientific, and medical (ISM) band at 2.45 GHz and IEEE 802.11 Wireless Local Area Network (WLAN) band at 5 GHz (5.15-5.35 GHz, 5.25-5.35 GHz). Two types of antennas are investigated: Antenna-I has a full ground plane and Antenna-II has a partial ground plane. The proposed antennas provide ISM operation in one mode while in another mode they support 5 GHz WLAN band. Their performance is assessed for body centric wireless communication using a simplified human body model. Antenna sensitivity to the gap between the antenna and the human body is investigated for both modes of each antenna. The proposed antennas exhibit a wide radiation pattern along the body surface to provide wide coverage and their small width (14 mm) makes them suitable for on-body communication in healthcare applications.

Hardware Implementation of (63, 51) Bch Encoder and Decoder for Wban Using LFSR and BMA

Error Correcting Codes are required to have a reliable communication through a medium that has an unacceptable bit error rate and low signal to noise ratio. In IEEE 802.15.6 2.4GHz Wireless Body Area Network (WBAN), data gets corrupted during the transmission and reception due to noises and interferences. Ultra low power operation is crucial to prolong the life of implantable devices. Hence simple block codes like BCH (63, 51, 2) can be employed in the transceiver design of 802.15.6 Narrowband PHY. In this paper, implementation of BCH (63, 51, t = 2) Encoder and Decoder using VHDL is discussed. The incoming 51 bits are encoded into 63 bit code word using (63, 51) BCH encoder. It can detect and correct up to 2 random errors. The design of an encoder is implemented using Linear Feed Back Shift Register (LFSR) for polynomial division and the decoder design is based on syndrome calculator, inversion-less Berlekamp-Massey algorithm (BMA) and Chien search algorithm. Synthesis and simulation were carried out using Xilinx ISE 14.2 and ModelSim 10.1c. The codes are implemented over Virtex 4 FPGA device and tested on DN8000K10PCIE Logic Emulation Board. To the best of our knowledge, it is the first time an implementation of (63, 51) BCH encoder and decoder carried out.