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The development of a reliable Wireless Body Area Network (WBAN) relies significantly on the quality of wearable antennas. Therefore, this paper proposes a low-profile four-element Multi-Input-Multi-Output (MIMO) antenna for wearable millimeter-wave (mm-wave) WBAN applications. The MIMO antenna structure incorporates a standard Vivaldi antenna and a frequency-selective surface that encompasses the 28 GHz and 30 GHz of the mm-wave band with a 36.44% fractional bandwidth. It offers inter-element isolation of less than −20 dB in a compact space of $16\times 20$ mm2. Conformability analysis, along with testing on Gustav’s model chest, hand, and leg, was evaluated in terms of the antenna impedance bandwidth, gain, efficiency, and radiation pattern. The simulated characteristics of the MIMO antenna were tested through measurements in free space and on the human body using a prototype of the antenna. Furthermore, the MIMO antenna exhibits a low envelope correlation coefficient of less than 0.24, high diversity gain of greater than 9.95 dB, and an acceptable total active reflection coefficient of less than −10 dB. To ensure safety, the Specific Absorption Rate (SAR) analysis revealed acceptable levels of 0.397 and 0.267 (W/kg) at 28 GHz and 30 GHz, respectively. The proposed MIMO design is suitable for wearable WBAN applications owing to its small size, consistent gain, and compatibility with the human body in terms of a constant impedance bandwidth and end-fire radiation pattern.

In this paper, a compact dual-band radiator with a modified ground structure is presented for on/off body communication. The antenna is capable of resonating in the ISM-I (2.4 GHz) and WLAN (5.15–5.85 GHz) bands. The proposed antenna consists of a novel compact ring loaded with a C-shaped radiator for dual-band operation. To improve impedance matching and shifting of the lower band at the ISM-I band, a modified ground structure is used. This suggested antenna has a small footprint of 0.24λ0×0.22λ0×0.016λ0, wherever λ0 is the free space wavelength at the lower operational frequency. The proposed antenna is parametrically studied, as well as the analysis of electric field and SAR at different positions on the arm are also carried out to check its utility for medical applications. The proposed antenna's specific absorption rate (SAR) meets IEEE standards and the prototype's measured findings validate the simulation results. [ABSTRACT FROM AUTHOR]

A compact co-planar waveguide (CPW) based triple-band printed conformal antenna for on-body applications is presented in this research. In order to accomplish impedance matching, a coplanar structure is employed with the ground on the same plane, and this is printed on the top layer of a polyimide substrate of 0.6 mm thickness. The proposed conformal antenna consists of two identical patch elements. The radiating element is made up of two split ring resonators positioned on the top of the feeding element. The suggested on-body antenna has an overall miniaturized size of only 35 37.5 mm², making it ideal for use in the biomedical field. The designed antenna is capable to cover various spectrum spanning from 2.387-2.618 GHz, 4.2-4.64 GHz, and 6.23-6.56 GHz with a 2:1 voltage standing wave ratio. The designed antenna is fabricated and antenna parameters are measured which is correlated with simulated results. The antenna achieves a total gain of around 5 dBi with radiation efficiency of up to 95 % over the various operating spectrums. To validate the conformality over curved surfaces, the fabricated prototype of the proposed antenna is bent at 30°, 45, 90° angles and the measured results are compared with simulation results of the bending analysis. Furthermore, to validate the on-body performance of the antenna Specific Absorption Rate has been calculated through simulation and it is found to be lower than 1 W/Kg over all three bands of spectrums which proves that the proposed bio-medical antenna could be a viable candidate for microwave imaging applications. [ABSTRACT FROM AUTHOR]

Human deep core temperature is a vital health condition parameter. Human body temperature change begins from the deep core followed by change in skin temperature. Measuring deep core temperature is the first action for rapid detection of health condition. Infrared thermometer can measure temperature; however, the only measures the skin temperature. The use of microwave radiometer for measuring deep core temperature has garnered attention. The antenna, an important component of the microwave radiometer, has rarely been focused upon in studies on measurement of deep core temperature. This study proposed compact dual-band on-body near field antenna with a reflector for measuring deep core temperature using a microwave radiometer. The proposed antenna size is 13 mm $\boldsymbol {\times }\,\,13$ mm with a 20 mm $\boldsymbol {\times }\,\,20$ mm reflector 3 mm above the radiator. The proposed antenna was simulated and designed on a full 3D body model and simplified flat phantom and measured on real human wrist. It achieved sufficient bandwidth and volume loss density can be used in microwave radiometers for measuring deep core temperature.

In this paper, a flexible on-body antenna with frequency reconfigurability for multipurposes is proposed. The proposed antenna has a hexagon-like shape with an on/off short to the ground. It switches between the ISM frequencies 433 MHz (when the switch is on) and 915 MHz (when the switch is off). It works as an on-body receiver for Wireless Capsule Endoscopy (WCE) system implemented at 433 MHz and as a receiver for implanted arm antenna implemented at 915 MHz. The proposed antenna is simulated on a cylindrical phantom of the average dielectric constant of skin, fats, and muscle. The effect of varying the bending radii is studied as well. The proposed antenna is fabricated and then tested on a liquid replicating the average biological material and on the human arm as well. The measured reconfigurable antenna gives good matching at both 446 MHz and 934 MHz. It also matched well on the human arm at the OFF state. Moreover, the fabricated on-body antenna at the ON state is tested as a receiver for the WCE system. The proposed antenna is fabricated on Rogers 5880 laminate and attains a size of 45 × 65 mm². [ABSTRACT FROM AUTHOR]

Multiple Input Multiple Output (MIMO) antennas have shown tremendous scope for increased capacity in wireless communication systems and are investigated for on-body networks in this work. A multi-antenna system based on truncated semi-elliptical patch antennas is presented and its characteristics evaluated. These patches are placed orthogonal to each other for good spatial and polarization diversity. Moreover, Artificial Magnetic Conductor (AMC) structures are used in the design to provide high isolation. The AMC-backed MIMO antenna provides 14.4% bandwidth and 10.6 dB isolation improvement, compared to the antenna without AMC. Besides, the channel capacity is also increased when AMC is integrated with the antenna. The diversity performance of the designed MIMO antenna is also evaluated in terms of envelope correlation coefficient and capacity loss for the lossy array. The proposed antenna offers spatial, polarization, pattern diversity, and good stability over the human body with improved channel capacity. [ABSTRACT FROM AUTHOR]

In this paper, the influence of user mobility and on-body antenna placement on system loss in body-to-body communications in indoor and outdoor environments and different mobility scenarios is studied, based on system loss measurements at 2.45 GHz. The novelty of this work lies on the proposal of a classification model to characterise the effect of user mobility and path visibility on system loss, allowing to identify the best set of on-body antenna placements. To quantify the influence of visibility and mobility on the average system loss, a combined score is proposed, allowing to map system loss onto the degree of visibility and mobility that depends on the scenario being considered and on on-body antenna placements. Overall, a good agreement is observed between the proposed classification model and the average measured values of system loss, with the higher values of combined scores being associated with lower values of systems loss. For the cases under study, the average values of system loss are 61.6 dB for the cases of the antennas being positioned only on the front of the body and/or the head, and 64.5 dB if at least one of the antennas is placed on an arm.

Deep core temperature is the most basic and important information about health conditions. Non-contact infrared thermometers are widely used for human body temperature measurement. However, infrared thermometers are not suitable for deep core temperature measurement. To overcome this limitation, measuring deep core temperature with a microwave radiometer is gaining attention. In this study, we propose a dual-band on-body near-field antenna for measuring deep core temperature with a microwave radiometer application. The proposed antenna has a compact size of 20 mm $\times30$ mm $\times1.52$ mm. The negative (−) radiator is located at the top of the substrate and the positive (+) radiator is located at the bottom of the substrate. The dual-band is proposed for high temperature resolution and is achieved by a meander slot on the radiator. The antenna is fabricated on a high dielectric substrate and the stubs are proposed to reduce the size of the proposed antenna so that it can be used on various human body parts.

The design and development of a small-sized, high gain ultra wide band (UWB) antenna based on different substrate materials are presented for on body wireless body area network (WBAN) applications. In the present scenario, on-body wearable antennas wave propagation and radiation pattern characteristics have been rigorously explored for study along with the growth of wireless body area networks. The major focus of the presented work is to perform comparative analysis of different substrate materials on performance of a novel, small sized, high gain UWB antenna design suitable for on body WBAN applications. The comparative investigation of the effect of different substrates materials i.e. FR4, Jeans, Rubber, Fleece, Polyester and Rogers RT 5880 on the designed antenna performance for has been performed. The FR4 substrate material found to optimum for proposed UWB antenna that has an overall measurement of 30 mm × 35 mm × 1.2 mm, possesses a large impedance bandwidth of 119.3%, and exhibits high gain and directivity. The peak measured gain and directivity are realized as 6.0 dB and 6.739 dBi respectively at 11.1 GHz. The performance parameters results of designed and fabricated antenna have been investigated and found to be in good compliance. The simulation and evaluation outcomes of the fabricated antenna demonstrate the suitability of the presented FR4 based antenna for WBAN utilization to be operable for communication in the UWB band. [ABSTRACT FROM AUTHOR]

Circularly polarised multiple‐input‐output antennas embedded in wearable wireless devices attract importance in the individual security and beauty fabric modelling industry involving technology embedded on‐clothes wearables. A circularly polarised wideband is designed and analysed in the present design‐study where a wearable application uses a multiple‐input‐output. It adds 2 symmetric 'Multi‐Input‐Multi‐Output' antennas that are good looking design like a swan‐shaped, and the ground plane is similar to the shape of a swan. The designed novel antenna comprises a ground plane having a line feed and a rectangular inverted L‐type micro‐strip which is supporting circular polarisation. The antenna element is spanning at 3‐DeciBell (dB) Axial Ratio Band‐Width of 5.2–7.1 GHz and an impedance bandwidth (S11 less than or equal to −10 dB) of 3.6–13 GHz. The proposed antenna manifesting a channel capacity loss less than 0.2 b/s/Hz, and envelope correlation coefficient less than the value 0.02, total active reflective coefficient less than −10 dB, and diversity gain greater than the value of 9.96, Mean Effective Gain (also represented as MEG) ratio is within ±0.5 dB. There is a twin‐sense circular polarisation in this antenna and superior isolation between resonating elements (greater than 18). The proposed antenna for human tissues specimens is also discussed with its specific absorption rate (also pronounced as SAR) in different situations that pertain to the living body. The overall size of the proposed 'Circularly Polarised' textile 'Multi‐Input‐Multi‐Output' antenna is 34:5 × 42 × 1 mm3. Because of its textile layers, reasonable performance, and compact size, the designed 'Multi‐Input‐Multi‐Output' antenna may be useful for wearable applications. The presented novel antenna can be made unrecognisable with a beautiful swan‐shaped design that can simply comingle with the other designs of fabric (in the fashion dress). The simulated antenna was made‐up following regular and general manual techniques and verified in the proposed conditions. The corner‐to‐corner distance between the 'Multi‐Input‐Multi‐Output' antennas is 14.2 mm, and the achieved isolation is beyond 18 dB after suitable adjustments of the designed final antenna. [ABSTRACT FROM AUTHOR]

This paper presents a wideband, low-profile and semi-flexible antenna for wearable biomedical telemetry applications. The antenna is designed on a semi-flexible material of RT/duroid 5880 (Er = 2.2, tanδ = 0.0004) with an overall dimensions of 17 mm × 25 mm × 0.787 mm (0.2λ0 × 0.29λ0 × 0.009λ0). A conventional rectangular patch is modified by adding rectangular slots to lower the resonant frequency, and the partial ground plane is modified to enhance the operational bandwidth. The final antenna model operates at 2.4 GHz with a 10-dB bandwidth (fractional bandwidth) of 1380 MHz (59.7 % at the centre frequency of 2.4 GHz). The proposed antenna maintains high gain (2.50 dBi at 2.4 GHz) and efficiency (93 % at 2.4 GHz). It is proved from the simulations and experimental results that the antenna has negligible effects in terms of reflection coefficient, bandwidth, gain, and efficiency when it is bent. Moreover, the antenna is simulated and experimentally tested in proximity of the human body, which shows good performance. The proposed wideband antenna is a promising candidate for compact wearable biomedical devices.

Ultra-wideband (UWB) technology can offer broad capacity, short-range communications at a relatively low level of energy usage, which is very desirable for wireless body area networks (WBANs). The involvement of the human body in such a device poses immense difficulties for both the architecture of the wearable antenna and the broadcast model. Initially, the bonding between the wearable antenna and the human body should also be acknowledged in the early stages of the design, so that both the potentially degrading output of the antenna as a consequence of the body and the possibility of exposure for the body may be handled. Next, the transmission path in WBAN is affected by the constant activity of the human body, leading to the time-varying dispersion of electromagnetic waves. Few researchers were interested in this field, and some substantial progress has recently been considered. On the other hand, this paper covered both wearable and Non-wearable UWB antenna designs and applications with respect to their substrate characteristics. Finally, this review prospectively exposes the upgraded developments of (ON-OFF) body antennas in the area of wearable and Non-wearable UWB and their implementations in the WBAN device and aims to evaluate the latest design features that inspire the performance of the antennas.

A hybrid dual-band antenna, consisting of an L-shaped radiating slot and a cylindrical dielectric resonator antenna (CDRA) is proposed, simulated and experimentally validated in this paper. The microstrip transmission line excites the fundamental mode (TM10) of the slot that generates the lower frequency resonant band (2.4 GHz) and slot below the CDRA excites HEM11 mode of the CDRA to generate higher frequency band (5.8 GHz). The slot and CDRA modes are quasi-independent of each other and the resonant frequency of both modes can be adjusted quasi-independently. An equivalent circuit model of the independent modes and hybrid system is extracted to show the real behaviour of the modes and overall system. The on-body analysis of the antenna shows that the antenna is suitable for use in wearable biomedical devices.

A millimeter-wave (mm-Wave) multiple input multiple output (MIMO) antenna operating at 24 GHz (ISM band), suitable for wearable applications, is proposed in this paper. The proposed MIMO antenna consists of two elements, designed with an edge-to-edge distance of 5.14 mm, backed by a 5 × 5 cell electromagnetic bandgap (EBG) structure. The antenna is fabricated on a flexible Rogers 6002 material (ϵr=$ 2.94, tanδ = 0.0012, thickness = 0.254 mm). The proposed antenna retains its performance when bent along the x-axis and y-axis. The performance of the antenna in term of s-parameters and radiation properties is studied in free space as well as on a human phantom. Good impedance matching of the antenna at the resonating frequency (24 GHz) is observed when it is bent and when worn on the body. The introduction of the EBG improves the gain by 1.9 dBi, reduces the backward radiation by 8 dB, reduces the power density on the back towards the body from > 200 W/m2 to 2, and also enhances the 10 dB bandwidth by 100 MHz. The antenna possesses a low envelope correlation coefficient (ECC) of 0.24, high diversity gain (DG) of 9.7 dB, reasonable multiplexing efficiency of -0.684 dB and a good peak gain of 6 dBi at 24 GHz. The proposed antenna is suitable for wearable applications at mm-Wave range due to its simple geometry and good performance in bending and on-body worn scenarios.

This article investigates how the creeping wave propagation around the human thigh could be used to monitor the leg movements. The propagation path around the human thigh gives information regarding leg motions that can be used for the classification of activities. The variation of the transmission coefficient is measured between two on-body polyethylene terephthalate (PET) flexible antennas for six different leg-based activities that exhibit unique time-varying signatures. A discrete wavelet transform (DWT) along with different classifiers, such as support vector machine (SVM), decision trees, naive Bayes, and K-nearest neighbors (KNN), is applied for feature extraction and classification to evaluate the efficiency for classifying different activity signals. Additional algorithms, such as dynamic time warping (DTW) and deep convolutional neural network (DCNN), have also been implemented, and in each case, SVM with DWT outperforms the others. Simulation to evaluate a specific absorption rate (SAR) is carried out as the antenna is positioned on the human thigh leaving no gap. The results show that the SAR is within the threshold as per the Federal Communications Commission (FCC) standard. [ABSTRACT FROM AUTHOR]

Wireless Body Area Network (WBAN) requires only a minimum amount of drive procedure with small array message and wide volume is obtainable by Ultra-Wide Band Technology. The humanoid physique presence carries tremendous difficulties for the plan of the propagation model as well as the wearable antenna in this system. To start with, the combination amid the wearable aerial and the humanoid physique must be considered even within the preliminary stages of the layout, with a purpose to be able to cope with each in all likelihood degrading performance of the antenna due to physique and the probability of revaluation for the physique. Later, the transmission medium of the Wireless Body Area Networks is controlled through the non-stop motion of the human body, as a result of the dissipation of the electromagnetic waves at different intervals. Many scholars are involved in the above subject then certain considerable development has been completed lately. The present article recollects today's consequences in the zone of aerials fixed in the physiques, transmission medium and then individual software in Wireless Body Area Network systems. This review discloses the major improvements of physique aerials involved by the part of fixable in the physiques and non-fixable in the physiques Ultra-Wide Band method then their applications in the Wireless Body Area Network device and methods for reducing SAR in them. [ABSTRACT FROM AUTHOR]

A miniaturized inset‐fed on‐body meandered bowtie antenna designed for brain microwave imaging systems is presented in this article. The proposed on‐body antenna can contribute to the realization of a wearable and portable brain microwave imaging system. The size of 18 × 18 mm2 is achieved at a frequency range of 0.75 to 4 GHz by the simultaneous use of self‐complementary structures and meandered lines. The frequency band is a trade‐off between penetration depth and spatial resolution. The proposed antenna performance was studied at different positions on the human head voxel model in terms of several parameters such as reflection coefficient, near‐field directivity, and fidelity factor. In addition, the antenna bandwidth was surveyed on several volunteers using a wearable measurement setup. It has been found that the averages of measured reflection coefficients in different scenarios are in good agreement with the corresponding simulation results, and the antenna shows stable performance under different practical situations. The proposed antenna takes advantage of a small footprint and body matching, which make it an eligible choice for compact, portable, and wearable head microwave imaging systems. [ABSTRACT FROM AUTHOR]

Body Sensor Networks (BSN) have emerged as a particularization of Wireless Sensor Networks (WSN) in the context of body monitoring environments, closely linked to healthcare applications. These networks are made up of smart biomedical sensors that allow the monitoring of physiological parameters and serve as the basis for e-Health applications. This Special Issue collects some of the latest developments in the field of BSN related to new developments in biomedical sensor technologies, the design and experimental characterization of on-body/in-body antennas and new communication protocols for BSN, including some review studies.

This work addresses the design and experimental characterization of on-body antennas, which play an essential role within Body Sensor Networks. Four antenna designs were selected from a set of eighteen antenna choices and finally implemented for both passive and active measurements. The issues raised during the process of this work (requirements study, technology selection, development and optimization of antennas, impedance matching, unbalanced to balanced transformation, passive and active characterization, off-body and on-body configurations, etc.) were studied and solved, driving a methodology for the characterization of on-body antennas, including transceiver effects. Despite the influence of the body, the antennas showed appropriate results for an in-door environment. Another novelty is the proposal and validation of a phantom to emulate human experimentation. The differences between experimental and simulated results highlight a set of circumstances to be taken into account during the design process of an on-body antenna: more comprehensive simulation schemes to take into account the hardware effects and a custom design process that considers the application for which the device will be used, as well as the effects that can be caused by the human body.

ABSTRACT In this article, a combination of an elliptical UWB monopole with a series of Sierpinski triangle iterations inscribed in the planarized radiator is used to develop a highly-impedance stability UWB antenna, performing from 700 MHz to 9 GHz. The fractal iteration is introduced in order to obtain a radiator size reduction and to improve the current distribution stability. With this implementation, a 31% radiator area reduction is obtained compared to a conventional circular or elliptical radiator. The antenna impedance matching is maintained over the entire bandwidth, even when an external lossy dielectric body is around or even in contact to the radiator. The antenna presents quasi-omnidirectional radiation patterns and a gain around 0 dBi and group delay variations lower than 2 ns, making it suitable for short-pulse communications systems and on-body communications applications. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:635-641, 2017 [ABSTRACT FROM AUTHOR]

This paper presents a novel miniaturized antenna with a dual-band resonance covering the medical body-area network (MBAN) and a 5.8-GHz industrial scientific medical band. Owning to its stacked-patch structure, the proposed antenna generates an omnidirectional radiation pattern with vertical polarization and a broadside radiation pattern with circular polarization at the two bands, respectively, thus fulfilling the requirements for both on- and off-body channels simultaneously. This antenna is designed on a multilayer tissue model, and is then validated on the Gustav voxel model. The footprint of the proposed antenna is only 0.18\lambda 0 \times 0.18\lambda 0 \times 0.04\lambda 0 . The proposed design is fabricated and its performance is investigated in various scenarios. When measured on the pork trunk, impedance bandwidths of 2.8% at the lower band and 9.0% at the upper band are achieved, fully covering the two bands. Besides, the transmission performance at the MBAN band is also studied by conducting measurements on the human body, and the measurement results agree well with the simulation. The obtained robust antenna performance reveals that the proposed design is suitable for MBAN applications. [ABSTRACT FROM AUTHOR]

This paper presents a high gain antenna with a nearly unidirectional radiation pattern. The antenna is composed of concentric complementary split ring resonators (CSRRs) that radiate at different frequencies as determined by the circumference of each ring slot as well as the mutual coupling between them. The antenna is optimized for operation at 2.45 GHz, which is one of the frequencies commonly used for body-worn communication devices. It is found that the concentric CSRRs behave like a filter in the radial direction and prevent surface currents from reaching the edges of the ground plane resulting in broadside radiation. The antenna shows a return loss of higher than 25 dB in both measurement and simulation. The front-to-back ratio (FTBR) is improved by backing the ring slots with a metallic rectangular cavity yielding FTBR of 21.2 dB and gain of 7.87 dB in measurements. The achieved radiation characteristics prove that the designed antenna is a good potential candidate for body-worn communication devices, where human body exposure to radiation must be minimal. [ABSTRACT FROM AUTHOR]

In this paper, performance of a Swastika slot-ultra-wideband (SS-UWB) patch antenna for an on-body application is investigated. This antenna is intended for the use in UWB wireless body area network (WBAN) applications, between 3.1 and 10.6 GHz. The proposed antenna is a SS-UWB patch antenna of dimension 27 mm × 27 mm × 1.6 mm. It is fabricated and tested in free space scenario instead in anechoic chamber to obtain more realistic on-body measurement results. This SS-UWB patch antenna covers the ultra-wide frequency spectrum in the range 4.25–12.5 GHz [8.25 GHz] with a quasi-omni directional gain from 1.77 to 5.6 dB. This antenna's efficiency is from 81.3% to 90.67% (−1.8 to −0.85 dB) over free space. The antenna is characterized in free space as well as on body model with and without antenna body gap. Measured results obtained from the antenna like S 11 , radiation pattern, antenna efficiency, and gain are matched with the simulated results. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a performance analysis of beam-reconfigurable in/on-body antennas. Both antennas operated within the Medical Device Radio Communications Service band (MedRadio band: 401-406 MHz) and were designed to steer the beam directions. To implement the beam-steering capability, the two antennas used two artificial switches. The in/on-body antennas were fabricated on FR-4 and fabric substrate, respectively. A skin-mimicking model ( εr = 46.74, σ = 0.69 S m−1) was adopted for the simulations and measurements of the two antennas. We performed transmission and reception tests between in/on-body antennas in an antenna chamber. The test was implemented in various cases, with different antenna distance and angle values. In addition, we compared received power between the calculated results (by virtue of the Friis transmission equation) and the actual measured results, and summarize these findings herein. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1163-1169, 2016; View this article online at . DOI 10.1002/mop.29750 [ABSTRACT FROM AUTHOR]

ABSTRACT A dual-band on-body antenna for in-on-on wireless body area network repeater applications is proposed. This antenna consists of a dual-patch antenna and a zeroth-order resonance (ZOR) element. The two patch antenna elements form dual resonances that cover the 2.4 GHz ISM band. In addition, a triangle cut made at the lower edge of patch Element 1 improves the impedance matching in the 2.4 GHz ISM band. The ZOR element operates in the 403 MHz MICS band. The antenna has near surface radiation in the 2.4 GHz ISM band and nearly omnidirectional radiation in the 403 MHz MICS band. To evaluate the performance of the antenna on a human body, the proposed antenna is placed on a human equivalent flat phantom. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:436-441, 2016 [ABSTRACT FROM AUTHOR]

In this paper, a low-profile dipole array antenna with monopole-like radiation for on-body communications is proposed. The proposed antenna, operating in the industrial, scientific, and medical (ISM) band, is designed with consideration of the human body effect. By placing eight planar dipole antenna elements symmetrically around the z-axis, the proposed antenna achieves monopole-like radiation characteristics with a low profile. The antenna has overall dimensions of 0.44 λ0 × 0.44 λ0 × 0.013 λ0 at 2.45 GHz in the ISM 2.45 GHz band (2.4.2.485 GHz) and a 10- dB return loss bandwidth of 4.9% ranging from 2.4 to 2.52 GHz. [ABSTRACT FROM AUTHOR]

A very compact low-profile (37.6\ mm\times 27\ mm\times 3.1\ mm) unidirectional UWB antenna is proposed for wireless body area network (WBAN) localization applications by focusing on its ranging performance and impulse fidelity in time domain in addition to frequency domain characteristics. The antenna is immune to direct skin contact, and also demonstrates very good frequency and time domain properties in free space or at any distance to a body: reflection coefficient and radiation pattern resilience to body influence; flat transfer function amplitude and linear phase over the desired frequency band from 6 GHz to 9 GHz. Superior time domain performance is demonstrated in simulation and measurements with average impulse fidelity of 97% in both free space and when placed at 0 mm or 3 mm over the body. Off-body ranging measurements show accuracies of the order of 5 cm and achievable range higher than 5 m for almost all frontal directions (16 m being the maximum), with transmitting power complying with the international regulation. [ABSTRACT FROM PUBLISHER]

ABSTRACT A higher order mode (TM31) circular-ring patch on-body antenna with shorting pins for on-body communications in wireless body area network is proposed. Using shorting pins, TM31 resonance mode was generated, while achieving compact low-profile structure with monopole-like radiation characteristics. To obtain wide bandwidth, an annular ring with shorting pins having TM31 mode is closely located around the circular patch. The antenna has the overall dimensions of 0.49 λ0 × 0.53 λ0 × 0.025 λ0 at 2.45 GHz in the industrial, scientific, and medical 2.45 GHz band (2.4-2.485 GHz) and the 10-dB return loss bandwidth is 7.3% ranging from 2.35 to 2.53 GHz. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1543-1547, 2014 [ABSTRACT FROM AUTHOR]

One of the major challenges faced by passive on-body wireless Internet of Things (IoT) sensors is the absorption of radiated power by tissues in the human body. We present a battery-less, wearable knitted Ultra High Frequency (UHF, 902-928 MHz) Radio Frequency Identification (RFID) compression sensor (Bellypatch) antenna and show its applicability as an on-body respiratory monitor. The antenna radiation efficiency is satisfactory in both free-space and on-body operations. We extract RF (Radio Frequency) sheet resistance values of three knitted silver-coated nylon fabric candidates at 913 MHz. The best type of fabric is selected based on the extracted RF sheet resistance. Simulated and measured performance of the antenna confirm suitability for on-body applications. The proposed Bellypatch antenna is used to measure the breathing activity of a programmable infant patient emulator mannequin (SimBaby) and a human subject. The antenna is highly sensitive to respiratory compression and relaxation. Fluctuations in the backscatter power level/Received Signal Strength Indicator (RSSI) in both cases range from 6 dB to 15 dB. The improved on-body read range of the proposed sensor antenna is 5.8 m, about 10 times higher than its predecessor wearable knitted strain sensing Bellyband antenna (0.6 m). The maximum simulated Specific Absorption Rate (SAR) on a human torso model is 0.25 W/kg, lower than the maximum allowable limit of 1.6 W/kg.

Body Sensor Networks (BSN) have emerged as a particularization of Wireless Sensor Networks (WSN) in the context of body monitoring environments, closely linked to healthcare applications. These networks are made up of smart biomedical sensors that allow the monitoring of physiological parameters and serve as the basis for e-Health applications. This Special Issue collects some of the latest developments in the field of BSN related to new developments in biomedical sensor technologies, the design and experimental characterization of on-body/in-body antennas and new communication protocols for BSN, including some review studies. [ABSTRACT FROM AUTHOR]

This work addresses the design and experimental characterization of on-body antennas, which play an essential role within Body Sensor Networks. Four antenna designs were selected from a set of eighteen antenna choices and finally implemented for both passive and active measurements. The issues raised during the process of this work (requirements study, technology selection, development and optimization of antennas, impedance matching, unbalanced to balanced transformation, passive and active characterization, off-body and on-body configurations, etc.) were studied and solved, driving a methodology for the characterization of on-body antennas, including transceiver effects. Despite the influence of the body, the antennas showed appropriate results for an in-door environment. Another novelty is the proposal and validation of a phantom to emulate human experimentation. The differences between experimental and simulated results highlight a set of circumstances to be taken into account during the design process of an on-body antenna: more comprehensive simulation schemes to take into account the hardware effects and a custom design process that considers the application for which the device will be used, as well as the effects that can be caused by the human body. [ABSTRACT FROM AUTHOR]