The rapid deployment of 5G technology has raised public concern regarding the potential health effects of electromagnetic radiation from mobile devices. This study systematically evaluates the specific absorption rate (SAR) and temperature distribution in a multi-layer spherical head model exposed to near-field radiation from a 5G mobile phone antenna. A planar inverted-F antenna (PIFA) covering the 3.5 GHz band was integrated into a smartphone model, and simulations were performed in COMSOL Multiphysics 6.3 under input powers of 21 dBm and 24 dBm at varying antenna-head distances. The results show that the peak SAR in the brain layer remained at 0.034 W/kg and 0.065 W/kg for the two power levels, both well below the International Commission on Non-Ionizing Radiation Protection (ICNIRP) safety limit of 2 W/kg. The highest SAR occurred in the scalp layer, decreasing gradually through the skull and brain tissues. After 30 min of exposure, the maximum brain temperature reached only 37.223 °C, far lower than the thermal damage threshold. Increasing the antenna-head distance from 5 mm to 30 mm reduced SAR by up to 50.2%, while temperature variations remained negligible (≤0.18%). These findings demonstrate that under typical usage conditions, 5G mobile phone radiation complies with international safety standards and poses no significant thermal risk, thereby contributing to a deeper understanding of bio-electromagnetic interactions and supporting ongoing wireless-communication safety assessments.

A multi-surfaces low-specific absorption rate (SAR) multiple-input-multiple-output (MIMO) antenna for mobile phone is proposed based on collinear reverse currents and multiple hotspots, and implemented by reactance loading. The proposed antenna element mainly consists of a common-mode (CM) dipole, a T-shaped power divider, and a center-loaded inductor. The T-shaped power divider is used to generate multiple peak points of tangential electric field and SAR by exciting the dual-end-fed CM dipole with collinear reverse current. The center-loaded inductor, analyzed by an equivalent circuit, further modifies the current distribution to uniform energy distribution, resulting in a multi-surface low-SAR antenna. Furthermore, by analyzing the position and the phase of the four antennas, the multi-surface low-SAR MIMO antenna is obtained. The fabricated antenna element and MIMO antenna can cover the -6dB bandwidth of 3.4 GHz-3.6 GHz, with the isolation of better than 17.5dB, envelope correlation coefficients (ECCs) of lower than 0.065 and efficiencies ranges from 85% to 95% and from 79.1% to 85.1%, respectively. The normalized measured SARs for the antenna element and MIMO antenna are 0.82 W/kg and 0.42 W/kg, respectively, which not only comply with the standards, but also ensure that SARs of the proposed antenna across multiple surfaces remain consistently low.

This paper introduces a novel Planar Inverted-F Antenna (PIFA) design optimized for biker’s helmets, aimed at enhancing rider safety by facilitating effective communication systems. Road traffic injuries, a significant global health concern, disproportionately affect motorcycle riders, with mobile phone usage while riding increasing this risk. A helmet model, developed in CST software, serves as a testbed for evaluating antenna characteristics. The presented PIFA design, covering a frequency range from 2.36-2.6 GHz, offers a 9.8% impedance bandwidth around the 2.45 GHz ISM band and maintains high efficiency and stability despite variations in helmet materials and placements. Detailed specific absorption rate (SAR) analysis is done to ensure compliance with safety protocols. A link budget analysis examines the communication feasibility between helmet-mounted and mobile phone antennas, as well as between different helmet users. This study contributes significantly to the field of antenna-integrated helmet technology, offering a viable solution to enhance rider safety through improved communication capabilities.

In this paper, we propose a novel dual-band metasurface (MS) designed to enhance 5 G mm-wave antenna performance when integrated with a smartphone glass cover. Unlike prior works that focus on either mm-wave or sub-6 GHz bands, the proposed MS supports both, addressing a key gap in the literature. Through simulations and measurement results, we demonstrate that the MS significantly improves antenna gain and mitigates radiation pattern distortions caused by superstrate loading. A 1× 4 mm-wave patch antenna array operating in the 24–27 GHz band is fabricated and evaluated with and without the MS-loaded glass cover, confirming the performance enhancement. In addition, the integration of a sub-6 GHz antenna on the same substrate verifies multi-band compatibility relevant to practical 5 G smartphones.

ABSTRACTThis paper presents a MIMO antenna specifically designed for 5 G mobile communications. A multi‐branch structure is utilized to enhance the operational frequency bandwidth of the antenna. However, multi‐band antennas tend to increase inter‐band interference, which presents a significant challenge in antenna design. To address this issue, a reverse‐branch configuration is implemented to mitigate mutual coupling between the antenna elements. In contrast to most single‐band mobile phone antennas, the proposed design achieves full coverage in both sub‐6 GHz and millimeter‐wave bands. The antenna can operate simultaneously in the 3.3–3.6, 4.8–5.0, 24.75–27.5, and 37–42.5 GHz bands. The isolation between antenna elements is better than –15 dB, the antenna efficiency ranges from 37% to 75%, the envelope correlation coefficient (ECC) is below 0.1, and the specific absorption rate (SAR) is less than 0.05 W/kg.

The safety of mobile phone antennas concerning electromagnetic exposure to the human body has become a prominent research focus in recent years. Uncertainties in antenna design and manufacturing processes may result in actual electromagnetic radiation levels deviating from design standards, thereby posing a potential risk of electromagnetic exposure. Finite element simulation has emerged as a crucial tool for predicting the specific absorption rate (SAR), owing to its capability to accurately model complex structures. The effective integration of finite element simulation with uncertainty quantification provides valuable scientific insights for optimizing design, shortening research and development cycles, and minimizing commissioning costs. This article proposes an uncertainty quantification method based on Migration-CoKriging (MCK). This method solves the limitations of traditional Co-Kriging that cannot be achieved without a low-precision solver by calculating cross-domain correlations. A more accurate surrogate model is constructed using a smaller training set, which improves the core performance of uncertainty quantification. MCK is combined with Sobol and applied in sensitivity analysis to quantify the influence of each random variable on SAR, thereby establishing a rigorous theoretical foundation for mobile phone antenna design and electromagnetic radiation safety.

There is growing international interest in assessing population exposure to radiofrequency electromagnetic fields, especially those generated by mobile-phone base stations. The work presented here is an experimental study in which we assess exposure to radiofrequency electromagnetic fields in a university environment, where there is a site with mobile-phone antennas and where a large number of people live on a daily basis. The data were collected with a personal exposure meter in two samplings, one walking at ground level and the other using an aerial vehicle at a height higher than the buildings. The geo-referenced electric-field data were subjected to a process in which a theoretical model was adjusted to the experimental variograms, and heat maps were obtained using kriging interpolation. The research carried out is of great relevance, since it provides detailed measurements of the electromagnetic radiation levels both at ground level and at significant heights, using innovative methodologies such as the use of drones. Furthermore, the results obtained allow for contextualizing the exposures in relation to international safety limits, highlighting the importance of rigorous monitoring in everyday environments.

The purpose of research is to develop a computer simulation based mobile phone safety testing scheme that is well suited for testing any mobile phone antenna at different communication frequencies and various realistic scenarios. It has been shown how feasible the study of realistic models is, what difficulties may occur, what effects, moments appear in the modeling process. The aim of the study is also to show the need for changes in the standard of mobile phone safety testing and to investigate the possibilities of implementing these changes. It is preferable for manufacturers to perform testing using human realistic models through numerical calculations and conduct safety compliance testing under realistic conditions to produce more realistic picture. Computer modeling gives the possibility to consider various realistic models, realistic scenarios and different tissue dielectric properties according to the frequency. It was investigated how mobile phone antenna radiation parameters (S11 reflection coefficient) change according to the various positions of the hand and fingers at standard communication 2100 MHz and 3700 MHz frequencies; were estimated Specific Absorption Rate (SAR) values in the human head and their dependence on S11 parameters were studied. Based on the obtained results, it has been shown that the preferred S11 behavior should be one of the indicators in the phone safety standards. For this, manufacturers should carry out mobile phone antenna matching/S11 parameter testing with free space.

An innovative, simple, low-cost, space-saving, and practical integrated design of a metal-frame-based 5G FR1 microwave (mcw) antenna and a thin-FPC-based 5G FR2 millimeter-wave (mmw) antenna array on a hallow dielectric carrier is proposed for mobile phones. The thin-FPC-based mmw antenna module consists of a 1 × 4 mmw antenna array supporting 5G band n261 with the maximum scan angle to 45°. The mmw antenna module is electrically connected to the metal-frame-based mcw antenna so that the length and impedance of the integrated mcw antenna can be easily optimized to better cover low bands. Based on the –4-dB antenna total efficiency, the integrated mcw antennas can support multiple 5G bands, e.g., n7, n12, n14, n28, n29, n30, n38, n40, n41, n71, and n83, as well as the WLAN 2.4-GHz band. The presented integrated antenna design hence can achieve a compelling antenna total solution for handsets of 5G and beyond. The simulated and measured performance of the proposed design also shows good agreement.

This study introduces RTEEMF (Real-Time Evaluation Electromagnetic Field)-PhoneAnts, a novel Deep Learning (DL) framework for the efficient evaluation of mobile phone antenna performance, addressing the time-consuming nature of traditional full-wave numerical simulations. The DL model, built on convolutional neural networks, uses the Near-field Electromagnetic Field (NEMF) distribution of a mobile phone antenna in free space to predict the Effective Isotropic Radiated Power (EIRP), Total Radiated Power (TRP), and Specific Absorption Rate (SAR) across various configurations. By converting antenna features and internal mobile phone components into near-field EMF distributions within a Huygens’ box, the model simplifies its input. A dataset of 7000 mobile phone models was used for training and evaluation. The model’s accuracy is validated using the Wilcoxon Signed Rank Test (WSR) for SAR and TRP, and the Feature Selection Validation Method (FSV) for EIRP. The proposed model achieves remarkable computational efficiency, approximately 2000-fold faster than full-wave simulations, and demonstrates generalization capabilities for different antenna types, various frequencies, and antenna positions. This makes it a valuable tool for practical research and development (R&D), offering a promising alternative to traditional electromagnetic field simulations. The study is publicly available on GitHub for further development and customization. Engineers can customize the model using their own datasets.

A high head-hand efficiency and low-SAR mobile phone antenna is proposed in this article. The impact of the antenna’s current distribution on its efficiency and spatial-average specific absorption rate (SAR) is analyzed, revealing that unidirectional and uniform current distributions on the antenna can achieve a dual benefit of high head-hand efficiency and low-SAR values. Based on this idea, a double loop antenna consisted of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\lambda $ </tex-math></inline-formula> outer loop with differential feed and a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5\lambda $ </tex-math></inline-formula> inner loop with coupled feed is designed, which can implement unidirectional and uniform current distribution in a wide frequency band. The measured −6 dB impedance bandwidth of the proposed antenna can cover 1710–2690 MHz. Its measured average head-hand efficiency from 1710 to 2690 MHz is −5.3 dB (29.5%). Its simulated normalized peak head and body SAR values are lower than 1.0 W/kg.

Due to limited antenna space, high communication requirements, and strict regulatory constraints, the design of antennas for modern mobile phones has become an exceedingly challenging task. In recent years, numerous studies have been conducted in this area, leading to significant advancements. This review paper comprehensively summarizes recent progress made in antenna design for modern mobile phones. Firstly, the challenges faced in antenna design for modern mobile phones are described, including bandwidth enhancement, integration and decoupling techniques, mm-wave array antennas, satellite communication antennas, as well as interactions between mobile antennas and the human body. Secondly, the basic antenna types (such as inverted-F, slot, loop, and planar inverted-F antennas) commonly used in modern metal-bezel mobile phones along with their key characteristics are briefly summarized. Thirdly, the commonly exployed methods used in practical applications for designing wideband antennas within compact sizes and achieving decoupling among multiple antennas with wide bandwidths are collected. Fourthly, recent advances in the design of compact, wideband, and wide-angle scanning mm-wave arrays for modern mobile phones are summarized. Fifthly, recent progress made in satellite communication antenna designs for modern mobile phones, including broadside and end-fire radiation patterns, is presented. Sixthly, recent studies on the interaction between mobile antennas and the human body are briefly concluded. Finally, the future challenge of antenna design for mobile phones is briefly discussed. It is our hope that this comprehensive review will provide readers with a systematic understanding of antenna design principles applicable to modern mobile phones.

This paper presents an 8-port MIMO antenna array for use with 5G handsets. The proposed MIMO antenna array comprises eight U-shaped, coupled-fed slot antenna components placed symmetrically on a 0.8 mm thick FR4 substrate. Each antenna has 200 MHz bandwidth and covers 3.4-3.6 GHz. The operational frequency range includes LTE band 48 for 5G cellular applications. Using spatial and polarisation diversity, antenna components are isolated by over 15 dB. The prototype antenna is fabricated and measured, and the experimental results agree with the simulated results. The estimated Envelope Correlation Coefficient (ECC), less than 0.035 based on radiation characteristics, shows that the suggested MIMO antenna array performs well in diversity. These characteristics indicate that the proposed MIMO antenna is a viable solution for 5G smartphone applications.

Polymer materials with a low dielectric constant and low dielectric loss have the potential to be applied to high-frequency signal transmissions, such as mobile phone antennas and millimeter wave radars. Two types of diamines, 4,4'-diamino-p-tetraphenyl (DPT) and crown ether diamine (CED), were prepared for ternary copolymerization with BPDA in this study. Cross-links with molecular chains were formed, increasing molecular chain distance by utilizing rings of CED. The MPI films exhibit a good thermal performance with the increase in CED addition, with Tg > 380 °C and CTE from -4 × 10-6 K-1 to 5 × 10-6 K-1. The Young's modulus can reach 8.6 GPa, and the tensile strength is above 200 MPa when 5% and 7% CED are introduced. These MPI films exhibit good mechanical performances. The dielectric constant of PI-10% film can go as low as 3.17. Meanwhile, the relationship between dielectric properties and molecular structure has been demonstrated by Molecular Simulation (MS). PI molecules are separated by low dielectric groups, resulting in a decrease in the dielectric constant.

The prediction of stochastic processes and the estimation of random fields of different natures is becoming an increasingly common field of research among scientists of various specialties. However, an analysis of papers across different estimating problems shows that a dynamic approach over an iterative and recursive interpolation of random fields on fractal is still an open area of investigation. There are many papers related to the interpolation problems of stationary sequences, estimation of random fields, even on the perforated planes, but all of this still provides a place for an investigation of a more complicated structure like a fractal, which might be more beneficial in appliances of certain industry fields. For example, there has been a development of mobile phone and WiFi fractal antennas based on a first few iterations of the Sierpinski carpet. In this paper, we introduce an estimation for random fields on the Sierpinski carpet, based on the usage of the known spectral density, and calculation of the spectral characteristic that allows an estimation of the optimal linear functional of the omitted points in the field. We give coverage of an idea of stationary sequence estimating that is necessary to provide a basic understanding of the approach of the interpolation of one or a set of omitted values. After that, the expansion to random fields allows us to deduce a dynamic approach on the iteration steps of the Sierpinski carpet. We describe the numerical results of the initial iteration steps and demonstrate a recurring pattern in both the matrix of Fourier series coefficients of the spectral density and the result of the optimal linear functional estimation. So that it provides a dependency between formulas of the different initial sizes of the field as well as a possible generalizing of the solution for N-steps in the Sierpinski carpet. We expect that further evaluation of the mean squared error of this estimation can be used to identify the possible iteration step when further estimation becomes irrelevant, hence allowing us to reduce the cost of calculations and make the process viable.

The performance of mobile phone antennas is strongly dependent on their environment. However, in the literature, there is no standard criterion to judge this environmental sensitivity. In this work, first, an elaborate figure of merit (FOM) is introduced based on the radiation characteristics of antennas. Then, characteristic modes (CMs) are employed to provide another representation of this FOM. This technique is able to deliver an in-depth understanding of the effect of the environment on the radiating modes of an antenna, which are strongly related to the sensitivity. This perception opens the possibility for designers to achieve less-sensitive antennas. To demonstrate the applicability of the proposed FOM, it is applied to a range of mobile phone antennas available in the literature.

Polymers/polymer matrix composites possessing low dielectric constants (low-k polymer dielectrics) contribute to the advance of electronics, for instance, microprocessor chips, mobile phone antennas, and data communication terminals. However, the intrinsic long-chain structural characteristic results in poor thermal conductivities, which draw heat accumulation and undermine the outstanding low-k performance of polymers. Herein, multisource free-volume effects that combine two novel kinds of extra free volume with the known in-cage free volume of polyhedral oligomeric silsesquioxanes (POSSs) are discussed to reduce the capacity for dielectric constant reduction. The multisource free-volume effects of POSSs are associated with the thermal conductive network formed by the hexagonal boron nitride (BN) in the polymer matrix. The results show a decent balance between low-k performance (dielectric constant is 2.08 at 1 MHz and 1.98 at 10 GHz) and thermal conductivity (0.555 W m-1 K-1, 4.91 times the matrix). The results provide a new idea to maximize the free-volume effects of POSSs to optimize dielectric properties together with other desired performances for the dielectrics.

This paper explores the significant impact of human proximity on antenna design evolution in mobile communication from GSM to LTE and future 5G technologies. It offers a comprehensive view of the challenges posed by human interactions in current antenna designs, alongside modern solutions to mitigate these issues. Central to our study is the crucial role of extensive data acquisition in enabling AIdriven methodologies. We emphasize the need for diverse and comprehensive datasets to refine AI models. Our research demonstrates notable achievements, with our deep neural network-based models reaching up to 90% accuracy in radiation pattern classification and 87.5% in angular delay profile categorization. These results underscore our proficiency in incorporating AI into antenna engineering. We trace the historical trajectory of user-induced antenna challenges and their current implications, illustrating a coherent progression. This narrative underscores the parallel evolution of antenna designs and user interactions, enhanced by our advanced model classification techniques. Our work presents an efficient method to address user effects using cutting-edge machine learning algorithms.

This article describes the computational analysis of Radio Frequency - Electromagnetic Field (RF-EMF) exposure of Uterus-Fetus Units (UFUs) embedded inside the body of a 26 year old human female. Realistic UFU models are obtained from ultrasound images acquired for different fetuses and at specific development stages (7 weeks, 9 weeks and 11 weeks old), for which a deep-learning based segmentation method is developed. Each UFU model is then inserted into a computational electromagnetic model of a 26 year old female. The Specific Absorption Rate (SAR) of the fetus at commonly used wireless communication frequencies is estimated using a commercially available numerical electromagnetic solver. The Inverted F antenna (IFA), which is a commonly used mobile phone antenna was used as the excitation source. Fetus SAR values are reported for different combinations of excitation frequencies, phone positions and UFU ages. It was found that the fetus SAR for all the cases is well below the maximum allowable exposure limit of 80 mW/kg, as prescribed by ICNIRP. Furthermore, we replaced the embryo with uterus tissues and calculated the SAR in the uterus tissues (i.e. uterus tissues with same volume and shape, and at the same location as that of UFU). The uterus SAR values were found to be only marginally different from that of fetus SAR.

This paper proposes an eight-element dual-band multiple-input multiple-output (MIMO) antenna that operates in the fifth generation (5G), n78 (3400-3600 MHz), and WLAN (5275-5850 MHz) bands to accommodate the usage scenarios of 5G mobile phones. The eight antenna elements are printed on two long frames, which significantly reduce the usage of the internal space of the mobile phone. Each antenna element is printed on both surfaces of one frame, which consists of a radiator on the internal surface and a defected ground plane on the outer surface. The radiator is a rectangular ring fed by a 50 Ω microstrip line which is printed on the top surface of the system board. A parasitic unit is printed on the outer surface of each frame, which is composed of an inverted H-shaped and four L-shaped patches. Each parasitic unit is connected to the internal surface of the frames through a via, and then it is connected to a 1.5 mm wide microstrip line on the top surface of the system board, which is connected to the ground plane on the bottom surface of the system board by a via. Four L-shaped slots, four rectangular slots, and four U-shaped slots are etched onto the system board, which provides good isolation between the antenna elements. Two merged rectangular rings are printed on the center of each frame, which improves the isolation further. The return loss is better than 6 dB, and the isolation between the units is better than 15 dB in the required working frequency bands. In addition, the use of a defected ground structure not only makes the antenna element obtain better isolation but also improves the overall working efficiency. The measurement results show that the proposed MIMO antenna structure can be an ideal solution for 5G and WLAN applications.