Specific Absorption Rate Analysis Research Articles

Embroidered textile antenna with dual‐band capability for body‐centric communication systems

AbstractThe integration of health monitoring and wearable antenna technologies has enhanced patient assessment and the provision of healthcare. Traditional health monitoring methods have evoked a surge in interest toward embroidered antennas as a viable solution for constant physiological monitoring in a noninvasive way. This study examines the performance of an embroidered wearable textile (EWT) antenna intended for breathing rate applications. The antenna is seamlessly integrated into a commercially available T‐shirt, extending the confines of “smart” textiles. The compact (45 mm × 26 mm) EWT antenna operates in 2.4 and 5.8 GHz with gains of 2.07 and 5.85 dBi, respectively. Crumpling and stretching analysis have also been investigated to ensure antenna's mechanical stability and reliability. Subsequently a specific absorption rate analysis has also been performed to quantify the radiation within specified limits.

Simulation and Design of Three 5G Antennas

In the context of 5G networks, this paper investigates microstrip array antennas and mobile terminal MIMO array antennas. It introduces two innovative designs and, based on these, develops and fabricates a mobile terminal antenna. The first of these designs, a 4 × 4 microstrip array antenna operating in the LTE band 42 (3.4–3.6 GHz), is researched and fabricated and an innovative approach, combining embedded and coaxial feeding methods, is proposed and employed. Measurement results indicate a bandwidth of 373 MHz (3.321–3.694 GHz), achieving a relative bandwidth of 10.7%. The antenna exhibits a high gain of 12.7 dBi, with an undistorted radiation pattern, demonstrating excellent directional characteristics. The second of these designs, a “loop-slot” MIMO antenna designed for 5G mobile devices with metal frames, is investigated. By opening slots in the metal frame and integrating them into the antenna’s feeding structure, the decoupling principle is analyzed from the perspective of characteristic mode theory. This design shares resonant modes between the loop and slot antennas, allowing for the overlapping placement of the two antenna units. Experimental results confirm an isolation level exceeding 21 dB, with significantly reduced dimensions. Finally, an eight-unit MIMO antenna is designed and fabricated for 5G mobile devices with metal frames. Continuous optimization of the “loop-slot” module layout and unit spacing leads to a compact and miniaturized antenna structure. Measurement results show an isolation level exceeding 17 dB, radiation efficiency ranging from 65.8% to 73.7%, and an envelope correlation coefficient (ECC) below 0.03. Finally, an analysis of specific absorption rate (SAR) demonstrates excellent MIMO performance in terms of human body radiation exposure.

Design of a novel compact low specific absorption rate multiple input multiple output antenna for 5G sub-6 GHz terminals

This investigation presents a new design and analysis of a fourteen elements massive multiple input multiple output (MIMO) compact low specific absorption rate (SAR) antenna system for 5G and beyond terminals. The MIMO antennas are realized for sub-6 GHz LTE-band 46 (5.1-5.8 GHz) long-term evolution 5G wireless communication services. The proposed antenna system is designed on an FR-4 dielectric constant 4.3 substrate consisting of the main board and four sideboards. The radiating elements are developed on the sideboards consisting of a monopole antenna and two metamaterial unit cells, as well as the feed line is designed on the principal board. The overall volume of the proposed structure is 150×80×7.5 mm. Through the use of the metamaterial unit cells, the proposed antennas have been arranged in close proximity without developing a strong mutual coupling. The results obtained were very important in terms of impedance matching, isolation among the antennas, and good gain. Even, the SAR analysis at the operating frequency band of 5.5 GHz proves that the proposed MIMO antenna system satisfies safety standards set for human exposure at the international level. Therefore, the proposed massive MIMO antenna structure is a potential solution for future communication applications.

Evaluation and SAR Analysis of Low Frequency and Broadband Electric Field Exposure Measurement Values in the Home Environment

In this study, the effective value of low-frequency (50 Hz) and high-frequency (700–2500 MHz) broadband electric field exposures was measured for 24 h in four different selected environments in a house. All the statistical values of 1000 data points recorded with two measuring devices for 24 h in each environment are calculated, the most appropriate curves are fitted to the data, and the curves are plotted by expressing their changes with respect to time. All statistical and parametric values of the density and cumulative probability functions of the curves are calculated and plotted. In broadband measurements, the broadband is divided into fifteen sub-bands, but the data are available in only six of these sub-bands. The six-layer human head model is created by using the middle frequencies of the six sub-bands used, and taking the permittivity (εr) and conductivity (σ) of each layer into consideration. The specific absorption rate (SAR) value in the brain is calculated by using the total transmission coefficient of six layers. The SAR value surrounding the head is obtained. These SAR values are interpreted by considering the Federal Communications Commission (FCC) and the Community European (CE) occupational and general public SAR limits.

A DODECAGON SLOTTED CIRCULAR TWO-ELEMENT SUB-6 GHZ FLEXIBLE ANTENNA FOR WEARABLE APPLICATIONS USING MODAL ANALYSIS

The sub-6 GHz 5G band has opened doors for a seamless and high-data-rate communication system connecting multiple devices. Multiple-input/multiple-output (MIMO) antennas are the backbone of such reliable communication systems with enhanced channel capacity. In this paper, a flexible two-element antenna is proposed for wearable applications. The dodecagon-slotted modified circular patch antenna with a defective ground structure gives isolation of 18 dB over the bandwidth. The antenna exhibits a gain of 3.38 dBi at the operating frequency of 4.8 GHz. A characteristic mode analysis was performed to investigate the resonance behavior of the antenna. Furthermore, specific absorption rate analysis was performed and found to be 0.790/0.314 W/kg for 1/10 g of tissue at 4.8 GHz. The MIMO diversity metrics exhibited an envelope correlation coefficient < 0.001, total active reflection coefficient < -10 dB, diversity gain ≈ 10, mean effective gain < -3 dB, channel capacity loss < 0.40 bps/Hz, and multiplexing efficiency < 0 over the operating frequency band.

4G based SAR analysis for anatomically based human head model using mobile phone antenna

Mobile phone handsets utilized by individuals of all ages been heavily grows popular as a wireless communication device. Every mobile phone produces electromagnetic radiation at radio frequencies (RF). The specific absorption rate is used to calculate how much of this energy is absorbed by the human skull. Standard guidelines state that sold phones must fall below a specified SAR. This paper aims to evaluate the Specific Absorption Rate (SAR) and E-field strength for mobile phone radiation exposure on a head model who is 40 years old and a 5-year-old child. The human skull is represented in this model as a six-layered sphere made up of the brain, CSF, dura, bone, fat, and skin. Various layers of the head's SAR distribution have been measured as an impact of radiation from mobile phones exposure using the 1800 MHz frequency. Earlier research were used to consider the dielectric properties of tissue layers. The human head and mobile phone antenna is modelled in this research using ANSYS HFSS. A hand-held mobile phone's dipole antenna type is considered for RF exposure. It is seen how EM absorption in various tissue layers for both adults as well as child head. SAR comparisons between the adult and child head reveal that the child head absorbs greater power due to the distinctive layerwise head shape, conductivity, permittivity, and permeability of the two head models. Excess EM absorption may have negative physiologic implications for human health specifically impact on child physical and mental health.

Design of a compact sigma slotted dual-mode UWB antenna for wireless body area network applications

Abstract This article presents the design of a novel sigma slotted circular monopole antenna for wireless body area network applications. The design is proceeded with a sigma-shaped slot etched on the circular radiator with Rogers 4003C substrate. The size of the proposed antenna is 30 × 30 × 1 mm3. With partial ground plane, the bandwidth characteristics of the antenna have been enhanced. The designed antenna covers 2–10 GHz of the ultra wideband, thereby providing more than 106% bandwidth. The antenna exhibits high gain values of 1.95, 3.23, 3.46, and 5.95 dB at 2.45, 3.45, 5.8, and 9.5 GHz, respectively. The proposed design operates on off-body mode at 2.45 GHz and on-body mode at 5.8 GHz, thus acting as a dual-mode antenna. To ensure the health and safety measure, specific absorption rate analysis was done for both low and high values of input power and also with Cartesian and cylindrical human arm models. Bending analysis was also done. The time domain parameter group delay was also analyzed for the proposed antenna for on- and off-body scenarios. The prototype was fabricated, and validation of simulation results was done for free space and on-body scenarios.

Analyzing the SAR in Human Head Tissues under Different Exposure Scenarios

This paper deals with the assessment of induced specific absorption rate (SAR) in various human models under different exposure scenarios, including both laboratory measurements and simulations. Firstly, SAR values were measured in a standardized SAR laboratory using a phantom for two radiofrequency electromagnetic field (RF-EMF) sources at 900 MHz and 1800 MHz. These laboratory measurements served as a reference for SAR calculations conducted on a specific anthropomorphic mannequin (SAM) using a computer simulation technology (CST) program, thus enabling the determination of antenna location and excitation signal levels for further evaluation. Subsequently, simulations were carried out with CST to evaluate average SAR for the head and for specific head tissues such as the brain, muscles, and fat. Realistic computational human models were also used alongside SAM in CST to explore the influence of gender, age, and tissue type on SAR. Various power levels representing low, moderate, and high RF-EMF exposure were applied to the human models to compare against basic restrictions and reference levels. The simulation results indicate significantly higher SAR values calculated for 1800 MHz compared with 900 MHz. The ratio of the highest SAR values at 1800 MHz to 900 MHz is approximately 1.70 for a baby, 2.59 for a child, and 2.84 for both adult female and adult male. While the SAR values for the brain, fat, muscle, and head are comparable at 900 MHz for the baby, the brain’s SAR value at 1800 MHz stands out significantly from the other tissues. In contrast with the baby, the difference in SAR values between 900 MHz and 1800 MHz is more pronounced for the child, adult female and adult male. The lowest SAR values at 900 MHz and 1800 MHz were obtained for brain tissue in all human models, while the head has the highest SAR value. The maximum SAR change ratio between the brain and the head is calculated to be 4.44 for the male at 1800 MHz. The results reveal that, although the applied electromagnetic field levels were below reference levels for general public local exposure, some local SAR values exceeded the International Commission of Non-Ionizing Radiation Protection’s basic restriction for the general public at certain power levels, particularly at 1800 MHz. The SAR analysis derived from this study is significant in understanding the impact of wireless technologies on health, establishing safety standards, guiding technology advancement, conducting risk assessments, and increasing public awareness.

SAR Analysis Using a Dipole Antenna in a Non-layered and Multi-layered Human Head Model

The public complaints about health are on the rise as a result of mobile phone usage. Limits on the radiation strength emitted by these devices have already been recommended by standard bodies such as The Federal Communication Commission (FCC) of the United States and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) to safeguard public from excessive exposure to electromagnetic fields. Some recent research have found that long-duration use of calls on mobile phones increases the incidence of health hazards and has negative consequences. After survey the research on investigation of specific absorption rate (SAR) in the human head is becoming increasingly essential. In proposed work, Investigations were done on how human head model and electromagnetic source interacted. The goal of this work is to demonstrate that the one layer head model is not a good model rather appear to be unreliable to evaluate SAR since genuine human skull tissue is not modelled in the same way. But investigation of SAR in six layers (Brain, CSF, Dura, Bone, Fat and Skin) human head appears better and reliable. Affection to the six layered human head may be dominant when exposed to electromagnetic (EM) fields.

Quad-port electromagnetic band gap (EBG)—backed non-isomorphic multiple-input-multiple-output (MIMO) antenna for wearable applications

This paper presents the design of a quad-port orthogonal ultra-wideband (UWB) monopole antenna backed with an electromagnetic band gap (EBG) structure. The EBG structure provides band stop/band reject characteristics in the entire UWB range. The overall dimension of the diversity antenna is 70 × 70 × 1 (), where corresponds to the lowest resonating frequency. The proposed monopole antenna offers good impedance bandwidth of 8.67 GHz (2.93–11.6 GHz). The estimated diversity characterization metrics observed over the obtained frequency range are envelope correlation coefficient < 0.11, mean effective gain (MEG) < 1 dB, effective diversity gain < 9.88 dB, apparent diversity gain < 9.99 dB, channel capacity loss < 0.19 bits (s Hz)−1, and total active reflection coefficient < −20.95 dB. Also, specific absorption rate analysis is realized for the antenna in seven different tissues of the body (forehead, forearm, upper arm, chest, abdomen, thigh and lower leg) to check radiation exposure towards the human body.

A Low-Profile Compact Meander Line Telemetry Antenna with Low SAR for Medical Applications

A low-profile Compact Meander Line Telemetry Antenna (CMLTA) operating at 402.5 MHz for the Medical Implant Communication System (MICS) band medical applications is introduced. The proposed antenna focuses specifically on pacemaker telemetry applications. The meander line technique with an open loop configuration and simple transmission line feeding mechanism has been used for achieving the compact design. Based on the theory of surface current distribution, the proposed technique provides the opportunity to increase the electrical dimensions while decreasing the physical dimensions of the antenna. Further design optimization is carried out to optimize the overall antenna size to a maximum volume of 4080 mm3. By introducing CMLTA, the size of the antenna is reduced by 79% as compared to the previous work. The proposed antenna demonstrated satisfactory performance with 10 dB bandwidth of 6.17%, a maximum gain of -22 dBi and an EIRP of -25.28 dBi. The analysis of Specific Absorption Rate under premise use of 1 W input power provided the maximum 1 g and averaged 10 g SAR of 74.7 W/kg and 17.7 W/kg, respectively, demonstrating a satisfactory level according to the IEEE standard safety guidelines. Fabrication and measurements are carried out where measured results are found to be in good agreement with the simulated results. With the optimized dimensions, satisfactory gain, EIRP, and SAR performance, the proposed CMLTA is deemed suitable for pacemaker telemetry applications for effective communication.

A Compact On/Off-Body Dual Band Antenna with Modified Ground for Healthcare Applications

ABSTRACT 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's results.

Wall-Meshed Cavity Resonator-Based Wireless Power Transfer Without Blocking Wireless Communications With Outside World

In order to address the issue of wireless communication signal blocking in the traditional cavity resonance wireless power transfer (CR WPT), a wall-meshed cavity resonator constructed of the meshed metallic walls is proposed together with an analytical design method. This cavity resonator can not only generate and confine the electromagnetic waves of natural resonant modes inside the cavity resonator, but also support wireless communications with outside. The wall-meshed cavity resonator is analytically designed by the known theoretical equations without time-consuming optimizations and verified by electromagnetic simulations and experiments. The results show that the proposed CR WPT system can achieve simultaneous wireless power transfer in the cavity and wireless communications with outside. The maximum power transfer efficiency is higher than 85%. The power transfer efficiency exceeds 60% within about 70% areas inside the wall-meshed cavity. For wireless communication signals passing through the wall-meshed cavity, the attenuation at 2.1 GHz (4G), 2.45 GHz (Wi-Fi), and 3.5 GHz (5G) is about 6.0 dB, 5.1 dB, and 3.8 dB, respectively. Additionally, the safety performance of the proposed CR WPT system is numerically investigated by the specific absorption rate analysis of a human torso model.

Wireless, Battery-Free, and Fully Implantable Micro-Coil System for 7 T Brain MRI.

An elegant solution for the concurrent transmission of data and power is essential for implantable wireless magnetic resonance imaging (MRI). This paper presents a self-tuned open interior microcoil (MC) antenna with three useful operating bands of 300 (7 T), 400, and 920 MHz, for blood vessel imaging, data telemetry, and efficient wireless transmission of power, respectively. The proposed open interior MC antenna contains two mirrorlike arms with diameters and lengths of 2.4 mm and 9.8 mm, respectively, to avoid blood flow blockage. To wirelessly show LED glow on a saline based phantom, the MC was fabricated on a flexible polyimide material and combined with a miniaturized rectifier and a micro-LED. Using a path gain, the power transfer efficiency (PTE) of the MC rotation was also analyzed. Additionally, the PTE was calculated for a range of distances between 25 and 60 mm, and a -27.1 dB PTE attained at a distance of of 30 mm. Based on the recommendations of the International Commission on Non-Ionizing Radiation Protection for human brain safety when exposed to radio-frequencies from external transmitter, a specific absorption rate analysis was analyzed. Measurements of the s-parameters were noted using a saline solution and blood vessel model to imitate a realistic human head. They were found to correlate reasonably with the simulated results.

Analysis of tumor in the breast using UWB textile antenna

AbstractCancer is the most frequent and deadly disease, with an increasing number of cancer patients and deaths. Breast cancer is becoming the most common type of cancer among women. This paper describes an octagonal‐shaped ultrawide band patch antenna with a denim substrate having a dielectric constant of 1.7. Various positions of the tumor inside the breast phantom are analyzed by the designed antenna using computer simulation technology (CST) Microwave Studio. Multiple tumors are traced by specific absorption rate analysis. The frequency range covered by the antenna is 2.4–10.1 GHz.

Towards durable and efficient antenna with SAR reduction analysis for on-body applications

Abstract This paper is focused on providing a viable solution to wearable antenna performance disconcertment caused by the underlying human body. Direct placement of the antenna on the body yields undesired results owing to the frequency detuning effect. The simplest possible way out is to make use of a metallic reflector. Hence, a reflector backed antenna is presented for 5.8 GHz ISM band with total lateral dimensions of 28 × 28 × 13.58 mm3. The reflector makes use of a conformal high dielectric laminate coated with a thin copper layer owing to which the assembled design achieves low SAR (Specific Absorption Rate). The prototype provides excellent results at the cost of some extra volume occupation in an off-body direction. Another AMC (Artificial Magnetic Conductor) backed technique is followed and implemented separately to have the structural compactness lacking in the former case. The antenna at hand is backed by a 2 × 2 array of AMC unit cells. The overall design dimensions are reduced. The reflector backed design achieves 8.2 dB gain, above 90% efficiency, and 99% bandwidth overlap with the primary antenna. The AMC backed design provides good spectrum coverage from 5.73 to 5.94 GHz with high gain. Free space response, on-body performance, and investigation of SAR analysis of the proposed designs substantiate effective wireless data transfer in body-centric communication.

The significance of nanoparticles in brain cancer diagnosis and treatment: modeling and simulation

A numerical analysis of specific absorption rate (SAR) and temperature distributions in a realistic human head model is presented in this study. The key challenge is to rise cancer temperature to an optimal temperature without heating nearby healthy tissues. The model’s uniqueness is that it captures the effect of nanoparticles on both brain cancer diagnosis and treatment. A realistic human head model with a cancerous brain segmented from 2D magnetic resonance imaging (MRI) gained from an actual patient using 3D Slicer, modeled, and simulated using CST-Microwave Studio, and illuminated by Archimedes spiral antenna. At frequencies of 2450 MHz and 915 MHz, the model simulated the absence and presence of various nanoparticles. The obtained results suggest that when using nanoparticles, it is possible to achieve sufficient energy deposition and temperature rise to therapeutic values (greater than 42 °C) in brain cancers using the proposed noninvasive hyperthermia system at 915 MHz frequency, especially for gold nanoparticles, without harming surrounding healthy tissue. Our research might pave the way for a clinical applicator prototype that can heat brain cancer.

Simultaneous Wireless Power Transfer and Data Telemetry Using Dual-Band Smart Contact Lens

An efficient noninvasive system for simultaneous transmission of wireless power and data is vital for continuous human health monitoring. In this article, we present a self-tuned spiral-shaped antenna with dual-band characteristics operating at 920 MHz and 2.4 GHz for efficient wireless power transfer (WPT) and data telemetry, respectively. To avoid vision blockage, the proposed smart contact lens (SCL) dipole antenna comprises two symmetrical spiral arms with inner and outer diameters of 10 and 14 mm, respectively. The SCL antenna was printed on a thin flexible polyimide substrate with a biocompatible polydimethylsiloxane (PDMS) coating. The influence of dispersed dielectric properties of PDMS on SCL antenna performance was investigated. Furthermore, the antenna was combined with a miniaturized rectifier and a micro-LED to demonstrate wireless LED illumination on a saline-filled model head. The power transfer efficiency (PTE) as a function of eye movement in the form of a path gain was also investigated. In addition, the PTE across the distance variations from 10 to 30 mm was computed, and a &#x2212;17.85 dB was achieved at a separation of 12 mm. A specific absorption rate analysis was performed to determine human eye safety under radio frequency exposure from the external transmitter and the results complied with the International Commission on Non-Ionizing Radiation Protection guidelines. Furthermore, a theoretical link power budget analysis was experimentally validated using software-defined radio. Measurements of s-parameters were noted through the use of a saline solution to mimic a realistic human eye and were found to have a reasonable correlation with the simulated results.

Opportunistic control of vertical stub compact pentagonal slot circular polarized implantable antenna with SAR analysis for bio-medical applications

A Compact Implantable Pentagonal Slot (CIPS) antenna with coaxial fed used for biomedical applications in industrial, scientific and medical (ISM) 2.4–2.5 GHz frequency band. This coaxial fed implantable antenna is designed using biocompatible substrate and superstrate layers of Rogers 6010 material with permittivity (εr) = 10.6 and loss tangent (tan δ) = 0.0036 to achieve human body insulation. The proposed CIPS antenna with substrate and superstrate volume is (10 × 9.2 ×1.27 mm3) 116.84 mm3. The S11 of the proposed antenna in homogeneous and heterogeneous environments are − 43 dB and − 42 dB, respectively. The major progress includes the CIPS antenna, implanted into the simulated muscle layer of a human arm comprising a three-layered cylindrical model for which several parameters are analyzed like return loss, radiation pattern, and specific absorption rate (SAR). The fabricated antenna parameters have been measured with the in-vitro test by immersing the antenna inside single layer tissue emulating gel, as well as, inside a chicken breast slab.

An Investigation Using Specific Absorption Rate Analysis to Diagnose Early- stage Breast Tumor using UWB Antenna.

This work was focused on the detection of early-stage breast tumors and their location. The most frequently seen disease progression and mortality in women's lives is Breast Cancer. Because of breast cancer/tumors, the risk of mortality for women has risen exponentially. From the 2020 deadline for breast cancer, women who died from carcinoma were 123.8 cases per lac women between 2006-2010. This problem is also overcome by the early identification of the tumor using different detection procedures like X-ray mammography, computerized tomography, ultrasound imaging technique, Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), microwave imaging. Researchers carried out multiple studies in these areas. To detect early-stage breast tumors and their location using SAR analysis. The major dielectrical difference between cancerous breast tissues and normal tissues in this technique is the microwave frequency range. The term Specific Absorption Rate (SAR) describes the amount of energy which is absorbed (W/kg) in the breast tissue. This segment illustrates the usefulness to diagnose the tumor position in the breast by means of maximum SAR value coordinates. Changes in breast and tumor size are important for the risk of diagnosis. The power absorbed in connecting with a normal breast and a tumor breast is measured and equivalent for different breast masses. The maximum SAR is also analyzed at distinct tumor locations at various frequency ranges. It is observed that max SAR coordinates are very close to the actual tumor location. So, the maximal value of SAR coordinates indicates the existence of a tumor in the breast phantom. The simulated data above strongly suggests that the Max SAR values were higher in the breast phantom with tumor as compared to the breast without tumor. With different tumor radius (3 mm and 5 mm) analyzed with different resonant frequencies like 3GHz, 4GHz and 5GHz at the actual tumor location of (0, 0, 35). Even though a model representing the real properties of breast tissue is required to assess the validation of any imaging process, so the real-time development of an equivalent breast phantom and its execution is needed.