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This paper presents a method to reduce the size of a compact antenna for MICS and IEEE 802.11a/b applications. Initially a monopole antenna (45 × 40 × 1.6 mm³) is designed for the ISM band (2.4–2.5 GHz). A spiral meandered single patch is incorporated to lower the operational frequency to 600 MHz assuring significant antenna size reduction. Further enhancements include a two-sided spiral extension and a T-shaped arm around the microstrip feed, enabling operation across three frequency bands achieving an overall 84% size reduction with improved gain. The prototype meets FCC standards for Specific Absorption Rate (SAR). To optimize gain, machine learning models along-with LASSO, Ridge, and Random Forest regression algorithm are used. The LASSO model proves most effective, achieving gains of 6.6629 dBi at 400 MHz, 7.6225 dBi at 2.45 GHz, and 8.7569 dBi at 5.5 GHz, with fractional bandwidths of 22%, 27%, and 8% respectively. [ABSTRACT FROM AUTHOR]

The design and fabrication of planar semicircular slot antennas for both wideband and dual-band sub-6 GHz 5G wireless applications are presented in this paper. A transmission line feed is included in the designed U-shaped radiating patch. To minimize the antenna size and control the bandwidth, a semicircle-defected ground structure is etched beneath the radiating patch. To allow for dual-band operation, a T-shaped stub structure is attached in the middle of the U-shaped radiating patch. If the transverse part of the T structure is connected to the two U limbs, the antenna performs as a wideband antenna (WBA). Furthermore, reducing and modifying the length of the T structure's transverse part are equivalent to constructing a frequency tunable band-stop filter that controls the two operating frequency bands of the antenna. The design has a small footprint of (0.35λ0 × 0.35λ0) where λ0 denotes the free space wavelength, peak gain, and efficiency of about 8.5 dBi and 93%, respectively. When the length of the transverse part of the T structure LB = 10.3 mm, the antenna acts as a WBA with operating frequency band from 1.8 to 6 GHz. When the length of the transverse part of the T structure is reduced to LB = 4.3 mm, the antenna is converted into a dual-band antenna with operating frequency bands from 1.8 to 3.7 GHz and from 4.05 to 5.5 GHz. In the simulations, the antenna performed adequately when both the dielectric back cover and the human head-hand model are present. The study achieved safe specific absorption rate (SAR) values that preserve good efficiencies and radiation patterns. The investigated SAR10g values at 3.3/4.5 GHz are equal to 0.121 W/kg, which are within allowable bounds. The simulations and measurements are highly matched. [ABSTRACT FROM AUTHOR]

The manuscript presents the design and development of a Microwave Hyperthermia (MHT) applicator integrated with an Electromagnetic (EM) lens. The purpose of the proposed MHT applicator is to provide non-invasive microwave hyperthermia treatment for skin cancer. The proposed MHT applicator comprises of an EM lens (133.75 × 133.75 mm3) placed ahead of a Hybrid Fractal Microstrip Patch Antenna (HFMA) (30 × 26 × 1.645 mm3), backed by a Meshedgrid-shaped Artificial magnetic Conductor (AMC) (48 × 48 × 3.27 mm3) reflector at an optimal distance of 16 mm The prototype of the HFMA is fabricated on a Rogers (RT5880) substrate and offers an impedance BW of 278 MHz, for a frequency from 2.316 to 2.594 GHz. To improve the front-to-back ratio (FBR) of the proposed HFMA, an EM lens that reduces the beam width and concentrated the energy in the desired direction is integrated with the AMC-backed HFMA. The final MHT applicator configuration provides a 3 dB beam width of 49.6° and a gain of 7.35 dBi at 2.45 GHz. The testing and validation of the proposed MHT applicator is carried out in a simulation environment using Computer Simulation Technology (CST) Multiphysics for thermal analysis to check the temperature rise in the phantom. An in-vitro sample of skin phantom with a tumor is prepared using chemicals mimicking skin properties is exposed to the EM radiations emitted by the proposed HT applicator excited using a RF signal generator and power amplifier. the temperature rise in the phantom is recorded using optical temperature measurement probe. A temperature rise in the cancer-affected area up to 44 °C (Effective Temperature Area (ETA) 36 × 20 mm2) is observed in the simulation environment for an exposure time of approx. 45 min and in the measurement environment after a span of 25 minuites. A reported Specific Absorption Rate (SAR) value of 10 W/Kg shows that the proposed MHT applicator is safe for human exposure, and also reduces hot spots by enhancing the focus with controlled temperature, thus making the proposed applicator safe for human exposure. [ABSTRACT FROM AUTHOR]

The growing need for remote healthcare monitoring and personalized treatment has driven the evolution of Wireless Body Area Networks (WBAN). This paper presents a new multiband antenna design for WBAN, featuring a dual wideband antenna that operates from 2.22 to 3.52 GHz and 4.98–11.13 GHz. The design also includes an integrated 4 × 4 artificial magnetic conductor (AMC) surface and a 4 × 3 frequency selective surface (FSS) superstrate layer that works together to reduce back radiation and improve radiation performance. The AMC unit cell produces a quintuple zero-degree reflection phase response at 2.5 GHz, 4.8 GHz, 6.5 GHz, 9.1 GHz, and 11 GHz, and the FSS superstrate generates a multiband response of the transmission coefficient at 3.24 GHz, 6.68 GHz, and 9.25 GHz, behaving as a Double Negative material at their corresponding resonant frequency. The integrated antenna design measures 0.425λ0 × 0.425λ0 × 0.17λ0 (λ0 at 2.45 GHz) and covers the most common wireless frequency bands, with an impedance bandwidth of 23.74% (2.19–2.78 GHz), 1.739% (3.99–4.06 GHz), and 72.46% (5.13–10.96 GHz). Furthermore, the integrated antenna showcases a peak gain of 11.98dBi at 7.5 GHz, a notable Front-to-Back Ratio of 25.15 dB at 8.2 GHz, and a minimal specific absorption rate (SAR) of 0.0142 W/kg at 9 GHz. These accomplishments resulted in a considerable 99.45% reduction in the overall average SAR values and achieved an 83% radiation efficiency. The effectiveness of the proposed multiband antenna design was evaluated by fabricating and testing an experimental prototype using a Vector Network Analyzer and Anechoic Chamber. Overall, the integrated AMC and FSS structures enable multiband resonance and improved radiation performance, making the presented antenna design a promising solution for future WBAN applications. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of a low-profile 8 × 8 multi-input-multi-output (MIMO) antenna with zero ground clearance, designed using an intelligent antenna recommender system. A dissimilar antenna pair is employed to achieve multi-band resonance and enhance isolation for sub-6G mobile communication. The primary antenna is a loop antenna resonating at n77, n79, and n46 bands, designed with the aid of a model developed using a support vector machine (SVM). The auxiliary antenna is a modified monopole resonating at n78 and n79 bands to minimize the antenna footprint on mobile devices. An eight-antenna MIMO array is fabricated, and measured results demonstrate that the proposed antenna has a reflection coefficient of less than − 10 dB at 3.5, 3.7, 4.5, and 5.2 GHz, with diversity gain and isolation greater than 9 dBi and 15 dB, respectively. SAR analysis conducted on a human head model shows a maximum SAR value of less than 1.6 W/kg at all sub-6G bands, compliant with FCC standards. The proposed MIMO antenna offers a viable solution, even when integrated with a battery and display, without occupying internal space within a mobile phone. [ABSTRACT FROM AUTHOR]

Purpose: To develop and test an MRI coil assembly for imaging deep brain stimulation (DBS) at 3 T with a reduced level of local specific absorption rate of RF fields near the implant. Methods: A mechanical rotatable linearly polarized birdcage transmitter outfitted with a 32‐channel receive array was constructed. The coil performance and image quality were systematically evaluated using bench‐level measurements and imaging performance tests, including SNR maps, array element noise correlation, and acceleration capabilities. Electromagnetic simulations and phantom experiments were performed with clinically relevant DBS device configurations to evaluate the reduction of specific absorption rate and temperature near the implant compared with a circular polarized body coil setup. Results: The linearly polarized birdcage coil features a block‐shaped low electric field region to be co‐aligned with the implanted DBS lead trajectory, while the close‐fit receive array enables imaging with high SNR and enhanced encoding capabilities. Conclusion: The 3T coil assembly, consisting of a rotating linear birdcage and a 32‐channel close‐fit receive array, showed DBS‐conditioned imaging technology with substantially reduced heat generation at the DBS implants. [ABSTRACT FROM AUTHOR]

Designing an electromagnetic radiating element that can enhance the capacity of a device operating with multiple frequencies simultaneously, while maintaining its compactness and compatibility with customer premise equipment, is a significant challenge. To tackle this issue, this work proposes a multiple input multiple output (MIMO) antenna with eight elements placed 45° apart on a Rogers 5880 substrate which has been micromachined from sixteen edges with a thickness of 0.252 mm. The substrate measures the area of 717.46 mm2 boasting a dielectric constant of 2.2 and loss tangent of 0.0009 with a unique star shape. The slot technique improves the return loss accompanied by defected ground structure to achieve dual-band operation at 28.1 GHz (n261) with the impedance bandwidth from 27.95 to 28.4 (0.45 GHz) and 39.5 GHz (n260) having impedance bandwidth from 38.6 to 40.4(1.8 GHz). The inter-element isolation of more than 60 dB is achieved for both bands with micromachined substrate. The measured gain at 28 GHz is 7dBi and at 39 GHz it is obtained as 7.4dBi. The 8-port MIMO is simulated for all the diversity metrics such as Diversity Gain (DG), Channel Capacity Loss (CCL), Envelope Correlation Coefficient (ECC), Mean Effective Gain, Total Active Reflection Co-efficient (TARC). The parameters evaluated for all eight ports are within the standard values with ECC of < 0.001, DG > 9.99 dB, CCL < 0.1b/s/Hz, and the TARC < − 10 dB. The MIMO has been fabricated and tested for various results which favourably aligned with the simulated results validating the applicability of the proposed mm-Wave 8-port MIMO antenna for practical 5G applications. Furthermore, the 8-port is also simulated for conformality check which showed a minor change in impedance bandwidth at 15°, 30°, and 45°. The Specific Absorption Ratio (SAR) analysis has provided values less than 1.6 W/kg for both the intended bands. The conformal and SAR analysis has added an advantage to the application of the proposed antenna for 5G as well as for wearable on-body applications. [ABSTRACT FROM AUTHOR]

Scientists mostly follow a trial-and-error approach using simulators for designing implantable antennas which may increase time complexity and memory usage. In this article, the Transmission Line Model (TLM) is utilized to design a miniaturized meander-line implantable antenna at 2.45 GHz for reducing time and memory requirements. The meander-line antenna is first decomposed into different segments – x-directed, y-directed, and bends. Each segment is considered a transmission line and each line is replaced by its equivalent lumped LC network. The lumped parameters are calculated using the dimensions of the segment and guided wavelength inside the body. Here, a three-layered body model is represented by a T-type resistor, inductor and capacitor (RLC) network. The antenna within the human body is then simulated using Finite Element Method (FEM)-based CST Microwave Studio software. FEM technique is taking 4.94-MB memory space and 13-minutes time to analyze this implanted system whereas TLM is analyzing the same system by considering 726-KB memory within 52 s. TLM is predicting implanted antenna performance considering ∼0.8% error concerning simulated response. The designed antenna is fabricated and measured within a homogeneous body phantom and minced pork to verify the simulated response. The effect of chamfering of the corners of the meander-line antenna is also analyzed here. From this study, it is observed that TLM can predict implantable antenna response efficiently with low memory and less time requirement with respect to FEM which is helpful for antenna engineers. Analysis of implantable antenna with low memory and time requirements using TLM is a novel approach to this work. [ABSTRACT FROM AUTHOR]

This work deals with the effect of polyaniline (PANI) coating layer on structural and magnetic properties of copper–zinc ferrite nanoparticles (Cu0.5Zn0.5Fe2O4). For this purpose, Cu0.5Zn0.5Fe2O4 nanoparticles were synthesized by sol–gel method and coated with PANI. Here, it was found that PANI plays an important role in improving the magnetic properties and heating efficiency of Cu0.5Zn0.5Fe2O4. In this regard, the structure of Cu0.5Zn0.5Fe2O4 nanoparticles and Cu0.5Zn0.5Fe2O4/PANI nanocomposite was confirmed by FTIR and XRD analysis. The average size of Cu0.5Zn0.5Fe2O4 and Cu0.5Zn0.5Fe2O4/PANI was calculated by transmission electron microscopy to be 21 and 27 nm, respectively. Measurements of magnetic properties by vibrating sample magnetometer confirmed the improvement of superparamagnetic property with negligible coercivity and persistence after adding PANI coating. Also, zero field cooling and field cooling curves showed that the blocking temperature increases significantly after adding PANI coating. Induction heating efficiency of Cu0.5Zn0.5Fe2O4 nanoparticles under alternating magnetic field was studied using specific absorption rate measurement and compared with Cu0.5Zn0.5Fe2O4/PANI nanocomposite. Also, in the cytotoxicity (MTT) analysis (at the recommended concentration of PANI/Cu0.5Zn0.5Fe2O4) on normal breast fibroblasts (MCF-10A) (in vitro), more than 70% of the cells survived. These results showed the application of PANI/Cu0.5Zn0.5Fe2O4 nanocomposite for use in therapeutic/diagnostic methods such as magnetic hyperthermia or magnetic resonance imaging. [ABSTRACT FROM AUTHOR]

The relentless drive towards miniaturization and seamless integration of electronic components in wireless communications and wearable devices has significantly increased the demand for flexible, cost‐effective composites with high dielectric constants and low losses. This study presents a wideband, low‐profile, and flexible antenna with excellent on body radiation performance for wearable applications. The antenna is designed using a low‐loss composite film based on PMMA‐PVDF‐HFP‐PZT and silver‐based ink. The proposed flexible antenna exhibits a wide bandwidth of 132.16% with a voltage standing wave ratio (VSWR) of less than two. It achieves a peak gain of 2.76 dBi at 2.92 GHz and maintains a maximum radiation efficiency of 80% across the 1.26–6.17 GHz frequency range. These characteristics demonstrate that the antenna is an effective solution for achieving high data rates and reliable communication links. The antenna's suitability for wearable applications is assessed by testing it on a simulated human body and analyzing its behavior under physical deformation. The results under bending showed only a minimal frequency detuning, which is negligible given the antenna's wide operational bandwidth. The specific absorption rate (SAR) analysis shows values of approximately 1.88 W/kg at 3.5 GHz with an input power of 0.5 W, and 0.279 W/kg at 5.8 GHz with an input power of 0.45 W, which complies with established safety limits for exposure. Overall, these results suggest that the proposed antenna is a viable solution for integration into wearable medical devices, such as a doctor's chest badge, enabling noncontact interactions and reducing the risk of bacterial contamination. [ABSTRACT FROM AUTHOR]

Microwave ablation has become a viable alternative for cancer treatment for patients who cannot undergo surgery. During this procedure, a single‐slot coaxial antenna is employed to effectively deliver microwave energy to the targeted tissue. The success of the treatment was measured by the amount of ablation zone created during the ablation procedure. The significantly large blood vessel placed near the antenna causes heat dissipation by convection around the blood vessel. The heat sink effect could result in insufficient ablation, raising the risk of local tumor recurrence. In this study, we investigated the heat loss due to large blood vessels and the relationship between blood velocity and temperature distribution. The hepatic artery, with a diameter of 4 mm and a height of 50 mm and two branches, is considered in the computational domain. The temperature profile, localized tissue contraction, and ablation zones were simulated for initial blood velocities 0.05, 0.1, and 0.16 m/s using the 3D Pennes bio‐heat equation, temperature–time dependent model, and cell death model, respectively. Temperature‐dependent blood velocity is modeled using the Navier–Stokes equation, and the fluid–solid interaction boundary is treated as a convective boundary. For discretization, we utilized HcurlΩ elements for the wave propagation model, H1Ω elements for the Pennes bio‐heat model, and H1Ω3×L02Ω elements for the Navier–Stokes equation, where Ω represents the computational domain. The simulated results show that blood vessels and blood velocity have a significant impact on temperature distribution, tissue contraction, and the volume of the ablation zone. [ABSTRACT FROM AUTHOR]

Summary: This article investigates the mutual coupling reduction of a compact two elements wearable ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna. The ground plane of the proposed wearable MIMO antenna structure consists of three connected square ring‐shaped stubs and two rectangular slots of narrow height. These ground stubs and slots minimize the mutual coupling effect between antennas and provide high isolation. The suggested MIMO antenna functions from the 1.87 to 13.82 GHz frequency spectrum covering WLAN (2.4–2.484 GHz), UWB (3.1–10.6 GHz), and X band (8–12 GHz) with 152.32% fractional bandwidth. It sustains port isolation above 27 dB throughout the 2 to 13.82 GHz frequency band. Inside the whole working frequency band, the suggested antenna offers a tiny envelope correlation coefficient (ECC < 0.098), greater diversity gain (DG > 9.93 dB), minimum channel capacity loss (CCL < 0.32 bits/s/Hz), and slight magnitude variation in mean effective gain of antenna ports (< 0.1 dB). The recommended antenna yields a SAR level below the designated threshold (<1.6 W/kg), affirming its suitability for body‐worn applications. The designed MIMO antenna structure has an overall volume of 32 × 48 × 1.5 mm3. [ABSTRACT FROM AUTHOR]

In this study, at ultra-wideband (UWB) frequency band (3.1–10.6 GHz), we propose the use of compact 2:1 and 3:1 nonuniform transmission line Wilkinson power dividers (NTL WPDs) as feeding networks for simple 2 × 1 linear UWB Vivaldi tapered and nonuniform slot antenna (VTSA and VNSA) arrays. The 2:1 and 3:1 tapered transmission line (TTL) WPDs are designed and tested in this work as benchmarks for NTL WPDs. The VTSA array provides measured S11 < −10.28 dB at 2.42–11.52 GHz, with a maximum gain of 8.61 dBi, which is 24.39% higher than the single element. Using the VNSA array, we achieve 52% compactness and 6.76% bandwidth enhancement, with good measured results of S11 < −10.2 dB at 3.24–13 GHz and 15.11% improved gain (8.14 dBi) compared to the VNSA single element. The findings show that the NTL and Vivaldi nonuniform slot profile antenna (VNSPA) theories are successful at reducing the size of the UWB WPD and VTSA without sacrificing performance. They also emphasize the Vivaldi antenna's compatibility with other circuits. These compact arrays are ideal for high-resolution medical applications like breast cancer detection (BCD) because of their high gain, wide bandwidth, directive stable radiation patterns, and low specific absorption rate (SAR). A simple BCD simulation scenario is addressed in this work. Detailed parametric studies are performed on the two arrays for impedance-matching enhancement. The computer simulation technology (CST) software is used for the simulation. Hardware measurement results prove the validity of the proposed arrays. [ABSTRACT FROM AUTHOR]

Printed electronics, fueled by graphene's conductivity and flexibility, are revolutionizing wearable technology, surpassing copper's limitations in cost, signal quality, size, and environmental impact. Graphene-based inks are positioned to lead in this domain, offering cost-effective solutions directly applicable to materials such as textiles and paper. However, graphene encounters a primary drawback due to its lack of an energy band gap, constraining its potential applications in various electronic devices. In this study, we present a novel formulation of a superconductive, flexible leather graphene antenna utilizing a tri-nanocomposite structure of Graphene Nanoplatelet/Silver/Copper (GNP/Ag/Cu), covering a wideband bandwidth from 5.2 GHz to 8.5 GHz. The electrical conductivity of the GNP/Ag/Cu sample was assessed using the four-point probe method. With each additional layer, conductivity increased from 10.473 × 107 S/m to 40.218 × 107 S/m, demonstrating a direct correlation between conductivity and antenna gain. The study evaluates the efficacy of various thicknesses of conductive Graphene (GNP/Ag/Cu) ink on drill fabric. Safety assurance is provided through specific absorption rate (SAR) testing, indicating 0.84 W/kg per 10 g of tissue for an input power of 0.5 W, in compliance with ICNIRP standards for wearable device safety. Additionally, a morphological analysis of the antenna was conducted, showcasing its potential for efficient signal transmission in wearable electronic devices.

The ever-growing miniaturization of electronic devices is foremost due to a wide range of changes in shrinking the wearable devices. This article focuses on a small, wearable antenna with dual bands for 5G and Wi-Fi communications. The Frequency Selective Surface (FSS) is made of denim Jean and has a top- loaded stubs-inspired radiator and a modified ground plane structure to induce the resonance frequencies at 3.5 and 5.8 GHz within a compact 31.5 mm × 26 mm size. With the FSS integrated antenna, you can cover the N-78 5G band-width of 620 MHz (S11 × −10dB) in the 3.28–3.9 GHz range, as well as the Wi-Fi bandwidth of 600 MHz (S11 × −10 dB) in the range of 5.65–6.25 GHz. The antenna presented has a peak gain of 7.07 dB at 3.5 GHz and 6.02 dB at 5.8 GHz. This antenna is mounted near a human arm model lowering the Specific Absorption Rate (SAR) to 0.370W/kg at 3.5 GHz and 0.870W/kg at 5.8 GHz. The simulated values are validated with measured results and are suitable for body area communication. The designed FSS antenna provides stable impedance bandwidth for conformal applications with enhancing radiation performance.

In this study, at ultra-wideband (UWB) frequency band (3.1–10.6 GHz), we propose the use of compact 2:1 and 3:1 nonuniform transmission line Wilkinson power dividers (NTL WPDs) as feeding networks for simple 2 × 1 linear UWB Vivaldi tapered and nonuniform slot antenna (VTSA and VNSA) arrays. The 2:1 and 3:1 tapered transmission line (TTL) WPDs are designed and tested in this work as benchmarks for NTL WPDs. The VTSA array provides measured S11 < −10.28 dB at 2.42–11.52 GHz, with a maximum gain of 8.61 dBi, which is 24.39% higher than the single element. Using the VNSA array, we achieve 52% compactness and 6.76% bandwidth enhancement, with good measured results of S11 < −10.2 dB at 3.24–13 GHz and 15.11% improved gain (8.14 dBi) compared to the VNSA single element. The findings show that the NTL and Vivaldi nonuniform slot profile antenna (VNSPA) theories are successful at reducing the size of the UWB WPD and VTSA without sacrificing performance. They also emphasize the Vivaldi antenna’s compatibility with other circuits. These compact arrays are ideal for high-resolution medical applications like breast cancer detection (BCD) because of their high gain, wide bandwidth, directive stable radiation patterns, and low specific absorption rate (SAR). A simple BCD simulation scenario is addressed in this work. Detailed parametric studies are performed on the two arrays for impedance-matching enhancement. The computer simulation technology (CST) software is used for the simulation. Hardware measurement results prove the validity of the proposed arrays.

The paper deals with an efficient procedure to study human exposure to vertical dipole antenna above a flat lossy half space. The closed form expressions for the corresponding irradiated electrical field are obtained assuming the sinusoidal and triangular current distribution along the antenna, respectively. The corresponding integral field expressions are evaluated by means of numerical integration and analytical procedures. The computations have been undertaken in the far field zone for various antenna parameters and compared to rigorous numerical model. Provided the field radiated from the vertical dipole is determined, whole body average Specific Absorption Rate (SARWB) is computed in a simple parallelepiped model of the human body and cylindrical model of the human body, respectively.

This research paper presents a compact dual-band polyester-based wearable bandpass microstrip filter using stepped impedance resonator. In the proposed wearable filter, pass band of 1.85 GHz to 2.66 GHz is useful for ISM band and 3.74 GHz to 7.42 GHz is appropriate to Wi-Fi, WLAN and Wi-Max frequency band applications respectively. In this filter, insertion loss of 0.147 dB and return loss of 32.6 dB at 2.38 GHz insertion loss of 0.469 dB and return loss of 32.3 dB at 4.54 GHz with fractional bandwidth of 34% and 81% is respectively achieved. The proposed wearable filter is fabricated using polyester cloth substrate and selfadhesive copper tape. The Agilent vector network analyzer is used to test the fabricated polyester filter. Good agreement is obtained between the simulated as well as measured insertion loss and return loss of the proposed wearable filter. Equivalent circuit and SAR analysis of this filter is also presented in this paper. Novelty of this research paper is fabrication of high bandwidth dual band wearable filter that can be integrated with wearable antenna to be a wearable Filtenna. Modified equivalent circuit of SIR is prepared and validated. Simulated and measured results are found to be in good agreement. [ABSTRACT FROM AUTHOR]

This work presents a study where a sinusoidal corrugated antipodal Vivaldi antenna (SC-AVA) operating in the ultra-wideband (UWB) region is employed as a transducer for microwave imaging (MWI) of a cancerous breast. The functionality of the antenna within the UWB range is confirmed based on performance parameters like return loss, gain, radiation pattern, fidelity factor, and group delay. E-field distribution, H-field distribution, and near field directivity simulations in the presence of the breast phantom have also been carried out and reported. The practical application of the developed antenna for biomedical imaging is evaluated by measuring the specific absorption rate (SAR) readings at multiple frequencies within its operating range. The SAR readings are obtained from an electromagnetic simulator by modelling a realistic heterogeneous breast phantom with multiple embedded tumors, and placing them in close proximity to the transducer. The modelled SC-AVA is further utilized for imaging multiple tumors hidden inside the gland layer of the heterogeneous breast phantom developed in-house. The fabricated breast phantom is scanned using the in-house developed multistatic MWI setup. Based on the data obtained from the scanning setup the images are reconstructed using both the delay multiply and sum (DMAS) and iterative DMAS imaging algorithms. Furthermore, a comparison of the reconstructed images is done to check in which case the obtained images are closer to the fabricated breast phantom. [ABSTRACT FROM AUTHOR]

A highly miniaturized miniaturised meander-shaped implantable antenna is proposed for biomedical applications. The antenna has a volume of 12.29 mm3 and is designed with slots only. Using only slots on patch and ground surface, the fabrication of proposed implantable antenna is quite effortless unlike using techniques of sorting pin, metamaterial, and multiple patch stacking. The analysis shows that the proposed antenna has excellent impedance bandwidth of 140 MHz (2.39 GHz to 2.53 GHz) with resonating frequency of 2.41 GHz, circular polarisation with an axial ratio bandwidth of 80 MHz (2.45 GHz to 2.53 GHz), gain of −23.45 dB, acceptable SAR 901 W/KG in industrial, science and medical band (ISM). The detail parametric study of the designed antenna with substrate/superstrate materials, different human body tissues, different depth of penetration in human tissues, and thickness of substrate/superstrate have been analysed successfully. For the authenticity purpose, the results are correlated with the prepared skin mimicking gel (saline solution) in vitro model. The fabricated antenna indicates similar performance as provided by the proposed simulated antenna design. [ABSTRACT FROM AUTHOR]

The ever-growing miniaturization of electronic devices is foremost due to a wide range of changes in shrinking the wearable devices. This article focuses on a small, wearable antenna with dual bands for 5G and Wi-Fi communications. The Frequency Selective Surface (FSS) is made of denim Jean and has a top- loaded stubs-inspired radiator and a modified ground plane structure to induce the resonance frequencies at 3.5 and 5.8 GHz within a compact 31.5 mm × 26 mm size. With the FSS integrated antenna, you can cover the N-78 5G band-width of 620 MHz (S11 × −10dB) in the 3.28–3.9 GHz range, as well as the Wi-Fi bandwidth of 600 MHz (S11 × −10 dB) in the range of 5.65–6.25 GHz. The antenna presented has a peak gain of 7.07 dB at 3.5 GHz and 6.02 dB at 5.8 GHz. This antenna is mounted near a human arm model lowering the Specific Absorption Rate (SAR) to 0.370W/kg at 3.5 GHz and 0.870W/kg at 5.8 GHz. The simulated values are validated with measured results and are suitable for body area communication. The designed FSS antenna provides stable impedance bandwidth for conformal applications with enhancing radiation performance. [ABSTRACT FROM AUTHOR]

This paper proposes a slotted patch antenna with wide bandwidth covering ISM frequency band (2.40-2.48 GHz) for implantable biotelemetry applications. A homogeneous skin phantom (HSP) model proves the usability of the proposed antenna in in-body environments. At a resonance frequency of 2.42 GHz, the design shows an S11 parameter of-35.56 dB, a percentage impedance bandwidth of 66.6% (2-4 GHz), and the maximum peak gain of-24.80 dBi. To validate the simulated results, the designed antenna was fabricated and measured, showing good compliance with the expected results. To ensure tissue safety, a specific absorption rate (SAR) is simulated for the proposed antenna which satisfies the requirements of IEEE standards, with a value of 87.75 W/kg for 10 g of tissue. The proposed antenna shows a telemetry range of 11 and 6.3 m at 7 kbps and 100 kbps data rates, respectively. The key features of the proposed antenna include the following: miniaturization, good S parameters, wide bandwidth, low SAR, good telemetry range, and high gain. [ABSTRACT FROM AUTHOR]

This article presents a compact implantable antenna for biomedical use in the ISM band (2.4–2.48 GHz). The antenna is designed with Roger RT/duroid 6010.2LM high permittivity substrate of thickness 0.25 mm, and feed with a 50 Ω co-axial feed. A hybrid-loop resonator slot structure and C & I-shaped slots in the radiating patch has enabled the antenna to work in the ISM band. Via less ground makes this design simple, easier to fabricate, and a suitable candidate for implantable application. The proposed antenna occupies a small volume of 0.0984 λ0 × 0.082 λ0 × 0.00468 λ0 and retained 152 MHz bandwidth (2.4077–2.5599 GHz with FBW 7.64 %) with a maximum gain of −22 dBi where λ0 is guided wavelength. The projected antenna has good performance in the multi-layer tissue model, male human head voxel model, frequency-dependent skin model, and in muscle phantom by maintaining a minimum −20 dB return-loss in the ISM band. The proposed antenna's Device Integration using a frequency-dependent skin phantom was performed and the results are well-suited for biomedical applications in the ISM band. The bare antenna was used to study the Specific Absorption Rate (SAR) in the human scalp. Where for 1 g and 10 g tissues the investigated results are 626.05 W/kg and 84.4 W/kg for an input power of 1 W, however the input power is limited to maximum 2.55 mW (for 1 g tissue) and 23.56 mW (for 10 g tissue) to comply with IEEE SAR guidelines. The qualities of the manufactured antenna are verified in a skin-imitating gel and animal tissue that exhibits good agreement with the simulation outcomes. [ABSTRACT FROM AUTHOR]

This article presents an in-depth investigation of wearable microwave antenna sensors (MASs) used for vital sign detection (VSD) and lung water level (LWL) monitoring. The study looked at two different types of MASs, narrowband (NB) and ultra-wideband (UWB), to decide which one was better. Unlike recent wearable respiratory sensors, these antennas are simple in design, low-profile, and affordable. The narrowband sensor employs an offset-feed microstrip transmission line, which has a bandwidth of 240 MHz at −10 dB reflection coefficient for the textile substrate. The UWB microwave sensor uses a CPW-fed line to excite an unbalanced U-shaped radiator, offering an extended simulated operating bandwidth from 1.5 to 10 GHz with impedance matching ≤−10 dB. Both types of microwave sensors are designed on a flexible RO 3003 substrate and textile conductive fabric attached to a cotton substrate. The specific absorption rate (SAR) of the sensors is measured at different resonant frequencies on 1 g and 10 g of tissue, according to the IEEE C95.3 standard, and both sensors meet the standard limit of 1.6 W/kg and 2 W/kg, respectively. A simple peak-detection algorithm is used to demonstrate high accuracy in the detection of respiration, heartbeat, and lung water content. Based on the experimental results on a child and an adult volunteer, it can be concluded that UWB MASs offer superior performance when compared to NB sensors. [ABSTRACT FROM AUTHOR]

Radiofrequency (RF) heating utilizes high-frequency electromagnetic waves to induce heat within materials via molecular friction. This method offers rapid, even heating, deep penetration, and energy efficiency. Nevertheless, there is a dearth of research on RF exposure parameters concerning food processing. Investigating these parameters is crucial for RF process optimization, setting safety guidelines, and guaranteeing product quality. This research clarifies RF exposure parameters through the one-pass drying of high moisture content (MC) long-grain paddy rice (cultivar [cv.] XL-753) at an initial MC of 20.4% wet basis (w.b.) to a final of MC of ≤ 13.5% w.b. (safe MC for storage). The specific objectives of this research were to: 1. Advocate the utilization of standardized RF exposure parameters (Specific Absorption Rate, SAR; Electric Field Intensity, E; and Power Density, S) of food and agricultural products, aiming to simplify RF processing, fostering consistency and safety in operations. 2. Estimate the RF exposure parameters associated with the one-pass RF drying process. 3. Determine the RF exposure parameters’ influence on rice physicochemical attributes of Milled Rice Yield (MRY), Head Rice Yield (HRY), Color Parameters (L* a* b*), Surface Lipid Content (SLC), and Pasting Properties. Using a pilot-scale parallel-plate RF heating system (6 kW, 27.12 MHz) with a 105 mm product-to-emitter gap, RF exposure parameters were determined: E = 46.82 V/m; EEff = 33.11 V/m; S = 300,000 W/m²; SAR = 2,224.95 W/kg. Rice samples underwent RF exposure durations of 360, 600, and 840 s, resulting in SARAdjusted levels of 0.80 × 106, 1.33 × 106, and 1.87 × 106 J, respectively. Half of the RF-processed paddy rice underwent tempering, which involved immediately transferring paddy rice after RF treatments into sealed glass jars and then into an incubator set to a constant temperature of 60°C for a duration of 4 h. RF processed samples at the highest SARAdjusted tested (1.87 × 106 J) followed by tempering resulted in MC reductions of 6.7% pt. w.b., final MC of 14.0% w.b., MRY, HRY, and SLC of 70.80%, 47.38%, and 0.47%, respectively. Non-tempered samples at the same SARAdjusted level had MC reductions of 7.34% pt. w.b., final MC of 13.1% w.b., MRY, HRY, and SLC of 60.91%, 4.53%, and 0.43%. Tempering and SARAdjusted values slightly affected rice physicochemical characteristics of color and viscosity. However, the differences were minor and inconsistent. To ensure optimal quality in largescale RF drying of rice, it is crucial to avoid SARAdjusted levels exceeding 1.33 × 106 J. Exceeding this threshold has been shown to cause overheating, adversely impacting the grain’s quality. Moreover, implementing a tempering process postdrying is also essential in mitigating these detrimental effects. [ABSTRACT FROM AUTHOR]

The paper deals with an efficient procedure to study human exposure to vertical dipole antenna above a flat lossy half space. The closed form expressions for the corresponding irradiated electrical field are obtained assuming the sinusoidal and triangular current distribution along the antenna, respectively. The corresponding integral field expressions are evaluated by means of numerical integration and analytical procedures. The computations have been undertaken in the far field zone for various antenna parameters and compared to rigorous numerical model. Provided the field radiated from the vertical dipole is determined, whole body average Specific Absorption Rate (SARWB) is computed in a simple parallelepiped model of the human body and cylindrical model of the human body, respectively. [ABSTRACT FROM AUTHOR]

The use of a transfer function (TF) method enables a conservative estimation for radio frequency (RF) safety assessment of active implantable devices (AIMDs). The TF approach can be applied to various scan conditions, patient populations, and device trajectories inside the human body, reducing the computational burden of full-wave electromagnetic (EM) simulation. The in vitro TF model validation process is time-consuming, requiring tests in various sample trajectories that collectively exceed eight hours. Here, we demonstrated reducing the burden of the TF approach using a low-power tabletop E-field generator. We measured the TF of the stent via the piecewise excitation method at 128 MHz and validated it by exposing the device under diverse test exposure fields using a tabletop E-field generator that requires less phantom material, lower cost than whole-body coil or MRI scanner, and with reduced experimental safety hazards or shielded room requirements. The TF approach was used to predict radio frequency (RF)-induced power near the stent tip at 128 MHz and predicted values were then compared against measured values. We also used a body transmit coil to compare the conventional in vitro TF model validation approach and tabletop E-field generator. With the tabletop E-field generator, the equivalent absolute normalized error was ( $0.37~\pm ~0.31$ dB) compared to the body transmit coil tests ( $0.43~\pm ~0.15$ dB), and the required test time decreased from eight to three hours. In summary, we showed how a low-power compact E-field generator can be used for in vitro TF model validation with reduced testing time and cost without using a shielded room.

Wearable devices are currently of great importance in developing health management and care applications and devices especially for early breast cancer detection (BCD). This is supported by the novel innovations in materials and techniques to construct highly accurate and comfortable biosensors for wearables. In this paper, the proposed flexible sensor is integrated with a Bra to realize a wearable breast cancer detection system. The proposed antenna-based sensor is composed of a CPW monopole antenna with an overall compact size of $24\times45$ mm2 on flexible PCB Roger substrate with thickness 0.17 mm. The proposed sensors have enough bandwidth from 1.5 to 8 GHz at -6 dB reflection coefficient and conformal structure for biological structures and biocompatibility. The specific absorption rate (SAR) has been calculated and measured for the proposed sensor with a value of 0.75 W/kg at 0 dBm to ensure safety level. For testing, real shaped rubber phantoms from medical school enables the dynamic combination of breast and tumor to create test scenarios for breast cancer detection. $2\times 2$ antenna-based sensors elements are placed around the breast phantom to gather data on scattering parameters for tumor characterization. Several simulation and measurement scenarios are presented to validate detection, optimum number of sensors to be used as well as training data for developed detection algorithms. Artificial intelligence techniques are used among which the CAT-Boost technique for scanning collected data and identifying the undesired tumor component inside the breast.

In this paper, a reconfigurable Multiple-Input Multiple-Output (MIMO) antenna array is presented for 5G portable devices. The proposed array consists of four radiating elements and an Electromagnetic Band Gap (EBG) structure. Planar monopole radiating elements are employed in the array with Coplanar Waveguide Ports (CWPs). Each CWP is grounded on one side to a reflecting L-shaped structure that has an effect of improving the antenna’s directivity. It is shown that by inductively connecting Minkowski fractal structure of $1^{st}$ order to the radiating element, the impedance matching is improved that results in enhancement in the array’s bandwidth performance. The EBG structure is used to provide the isolation between antenna elements in the MIMO array. The fractal structure is connected to the L-shaped reflector through four photosensitive light dependent resistor (LDR) switches. The effect of various LDR switching configurations on the performance of the antenna is investigated. The proposed array provides a novel performance in terms of S-parameters with enhancements in the radiation properties. Such enhancements

A highly bendable, and a low-profile Artificial Magnetic Conductor (AMC)-based antenna for wearable applications operating at 2.4 GHz is presented. The AMC is employed to ensure consistent antenna performance in both free space and on the body, with its safety limit complying with standards. The proposed AMC design incorporates a Jerusalem cross shape slot on its conventional patch, integrated with the antenna, resulting in overall dimensions of $60\times 60 \times 3$ mm3. The proposed low-profile AMC demonstrates superior performance under extreme bending, whether in free space or on the body, and offers a wide bandwidth, addressing the frequency detuning problem associated with deformation. In free space, the integrated design exhibited a gain of 7.61 dBi, a bandwidth of 27.13%, a front-to-back ratio (FBR) of 17.7 dBi, and an efficiency of 83.5%. When placed on the body, it resulted in a gain of 6.98 dBi, a bandwidth of 25.7%, an FBR of 18.2 dBi, and an efficiency of 70.1%. SAR analysis was conducted with different input power levels (100 mW, 500 mW, and 1000 mW) and demonstrated excellent results. The numerical and experimental results collectively suggest that the integrated design is a promising candidate for wearable applications.

This paper proposes a slotted patch antenna with wide bandwidth covering ISM frequency band (2.40-2.48 GHz) for implantable biotelemetry applications. A homogeneous skin phantom (HSP) model proves the usability of the proposed antenna in in-body environments. At a resonance frequency of 2.42 GHz, the design shows an S11 parameter of -35.56 dB, a percentage impedance bandwidth of 66.6% (2-4 GHz), and the maximum peak gain of -24.80 dBi. To validate the simulated results, the designed antenna was fabricated and measured, showing good compliance with the expected results. To ensure tissue safety, a specific absorption rate (SAR) is simulated for the proposed antenna which satisfies the requirements of IEEE standards, with a value of 87.75 W/kg for 10 g of tissue. The proposed antenna shows a telemetry range of 11 and 6.3 m at 7 kbps and 100 kbps data rates, respectively. The key features of the proposed antenna include the following: miniaturization, good S parameters, wide bandwidth, low SAR, good telemetry range, and high gain.

This paper proposes a compact dielectric resonator-based high gain dual-band hybrid antenna. The antenna is proposed to work in a dual ISM (industrial, scientific, and medical) band, i.e., at 2.40 - 2.48 GHz and 5.725 - 5.875 GHz. The designed antenna can work as a radiator in the lower band (2.37 - 2.49 GHz) and as a sensor in the upper band (5.34 - 6.00 GHz). The non-invasive blood glucose sensing application is chosen at a higher frequency band, and a lower band is chosen for wireless communication. From a single transmission feed line, both frequency bands are generated by the fundamental mode T M 10 of radiating slot and H E M 11 mode inside cylindrical DRA, respectively. The designed antenna is optimized and simulated to get the best possible results in terms of S-parameter, bandwidth, gain, radiation pattern, efficiency in a lower band, and sensitivity toward blood permittivity in a higher band. This work performs regression analysis and fasting experiments for blood glucose sensing. The link budget analysis is also done at different data rates for wireless communication. The Specific absorption rate (SAR) value is calculated in finger tissue to ensure safety. The simulated and measured results of the designed antenna suggest that it can be used for non-invasive blood glucose sensing and wireless communication applications. To the author's knowledge, no antenna was reported prior for radiating as well as sensing applications. [ABSTRACT FROM AUTHOR]

BACKGROUND: In wireless communication standard 4G and 5G, the body centric network plays an important role for the wireless communication between various devices. OBJECTIVE: This research relates to a wide-band conformal co-planar waveguide (CPW) antenna for wearable applications. METHODS: The proposed CPW antenna is printed on 0.1 mm thick bio-compatible polymide substrate whose dielectric constant and permittivity are 3.5 and 0.02 respectively. The total area of the antenna is around 17.5 × 15 mm 2 which is significantly smaller than the wearable antennas proposed in literature. The proposed antenna is designed to operate in new ISM band 5.8 GHz with the bandwidth of 5.3–6.3 GHz with 2:1 Voltage Standing Wave Ratio (VSWR). The antenna is printed on the flexible substrate and hence robustness of device is evaluated by bending analysis. It reveals the superior performance of the designed CPW antenna over the desired spectrum of operation. RESULTS: Specific Absorption Rate (SAR) is calculated after placing the antenna at various places of human phantom model and showed that SAR values are below 1.6 W/Kg which is the maximum margin recommended by Federal Communication Commission (FCC), i.e when tested with 1 g and 10 g of human tissue of phantom model, for the test frequency range of 5.5–6.1 GHz, SAR value falls between 0.9987 and 0.921 W/Kg respectively. The antenna also shows the radiation efficiency around 92% with overall realized gain 5.2 dBi which are substantial values for wearable applications. CONCLUSION: The outcomes of this research revealed the feasibility of the recommended antenna becoming a major contender of future Internet of Things (IoT) applications. [ABSTRACT FROM AUTHOR]

In this paper, a slotted pentagon ringtone patch antenna is proposed for the hyperthermia application. The proposed antenna operates in the ISM of 434 MHz and the size of the proposed antenna is 120 × 120 × 1.6 mm3, making it a more suitable applicator for hyperthermia treatment. The antenna structure is considered in the combined single-layer human tissue model and simulated in Ansys HFSS 2020R1 software. The gain obtained for the proposed antenna is − 9.1 dBi. The specific absorption rate is achieved for the x-axis variation inside the phantom at different penetration depths, and these are all within the limits of the IEEE standards. [ABSTRACT FROM AUTHOR]