Experimental evaluation of modular antenna arrays at 28 GHz under the presence of human body

The goal of this thesis is to develop and test an experimental method for characterising antenna arrays for mobile phones at 28 GHz under the presence of the user. Previous studies were based merely on computer simulations, or on measurements with actual humans, where repeatability is an unsolved issue. Antenna measurements with a human phantom have now been carried out and analysed for the first time. For their validation, simulation methods for characterising mm-wave mobile phone antennas under the presence of a human body, and the detailed evaluation process are presented here, including spherical coverage and total array gain. Utilising the presented simulation methods, a simplified human phantom is designed, validated, and manufactured. The electrical properties of human tissues are well known, and different material recipes to mimic human skin were reported in previous studies. Based on these, we created a polyethylene-based skin-like material with electrical properties similar as in human skin. This material was used as a surface for the final human phantom. This phantom was then used in radiation-pattern measurements at 28 GHz. Two planar 2x2 dual-polarised antenna arrays were designed and manufactured. As expected, the design of the microstrip-feed line network was crucial in the design of the antenna arrays, especially the mutual coupling needs to be low to ensure the designed operation of the arrays. Antenna radiation pattern measurements, both in free space and with the human phantom, were carried out in an anechoic chamber. The losses of feed cables and connectors were de-embedded by calculating suitable amplitude correction terms that normalize differences between measured and simulated free-space element patterns. The phantom measurements were performed with both antenna arrays, and after mathematical beam-forming with a suitable amount of element-phasing cases, the spherical coverage of each array was calculated. Element radiation patterns and spherical coverage of both antenna arrays under the presence of the human phantom were compared to the simulations. In the spherical coverage CDFs of both arrays, the difference between measured and simulated peak gain is 1 - 2 dB, and the difference between measured and simulated median gain level is 0.6 - 2 dB. This comparison shows that the proposed experimental method for characterising mm-wave mobile antenna arrays in the presence of the user is feasible. One test array also was measured twice with the phantom and the maximum difference between spherical coverage CDFs was 1 dB proving good repeatability of the proposed experimental method

Interaction of antenna systems with human body

The research investigates the influence on the human body on a communication system. To understand this, the effect of hands free kit (HFK) on energy absorption in the body was investigated when operating a smart phone at 2G. Findings on the research are given in the thesis report. Also, the influence of the way in which a phone is held on a phone s received power was investigated. The result was compared to that obtained using a hand phantom acquired from SPEAG. This was to check if the hand phantom best represents the human hand when using it in experiments. The setup for the experiment was in an anechoic chamber at Loughborough University. The mobile phone transmitted in the 2G system. In further experiments carried out on the body, two antennas were attached to the body in six different orientations to receive power from a source creating a Single Input Multiple Output (SIMO) system. The antennas used were monopoles mounted on a circular ground plane. These antennas were designed and constructed with the influence of the body taken into consideration. The use of diversity techniques to improve transmission to an on-body system is investigated with the antennas on the body. For each alignment, the transmission to the on-body was compared with the transmission to the corresponding off-body (free space). Experiments for this work were carried out in three environments

User Effects on Mobile Phone Antennas: Review and Potential Future Solutions

This paper explores the significant impact of human proximity on antenna design evolutionin mobile communication from GSM to LTE and future 5G technologies. It offers a comprehensive viewof the challenges posed by human interactions in current antenna designs, alongside modern solutions tomitigate these issues. Central to our study is the crucial role of extensive data acquisition in enabling AI-driven 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 upto 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 thehistorical trajectory of user-induced antenna challenges and their current implications, illustrating a coherentprogression. 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 toaddress user effects using cutting-edge machine learning algorithms. (PDF) User Effects on Mobile Phone Antennas: Review and Potential Future Solutions. Available from: https://www.researchgate.net/publication/375926643_User_Effects_on_Mobile_Phone_Antennas_Review_and_Potential_Future_Solutions [accessed Nov 28 2023].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 AI-driven 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.</p

Measurement evaluation of EMF effect by mobile phone on human head phantom

Interaction of electromagnetic field (EMF) with environment and with tissue of human beings is still under discussion and many research teams are investigating it. One of electromagnetic devices is mobile phone. There are many simulations and measurements on models or phantoms of human body to biological effect of EMF acquirement. This paper deals with laboratory measurement evaluation of EMF effect by mobile phone on human head phantom

MEMS Tunable Frame Antennas Enabling Carrier Aggregation at 600 MHz

The goal of this paper is to propose a tunable antenna system, that aims to cover the LTE low band (699&#x2013;960 MHz), medium band (1710&#x2013;2100 MHz) and high band (2100&#x2013;2690 MHz), as well as the 600 MHz bands by tuning. The architecture consists of four multiband antennas, made up of different radiators, placed in the frame of the mobile handset at the optimized distance of 0.5 mm from each other. Simulations including MEMS tunable capacitors prove that, it is possible to reconfigure the dual resonance in low band, without deteriorating the antennas performance. The tuning ability of the fabricated structure is tested with the PNA and measurements of the total efficiency are performed in the MVG SG24. The results of the measurements are in accordance with the simulations and confirm that the operating frequency of the proposed frame antenna array in low band can be tuned down to the starting point of band 71, with a &#x2212;6 dB impedance bandwidth of 32 MHz, without altering the antennas behaviour in medium and high band. The resulting peak value of the total efficiency of &#x2212;5.3 dB at 615 MHz is acceptable, considering the mobile phones in the market. Moreover, the analysis of the user effects, carried out via simulations both in data and in talk mode, reveals a reduced total efficiency of 4 and 8 dB on average, due to the user hand and the user hand-head respectively, compared with the performance in free space