Mobile Phone Chassis Research Articles

Side-edge dual-band MIMO antenna system for 5G cellular devices

An eight-element multiple-input multiple-output (MIMO) antenna system is presented for two distinct 5G allocated bands, i.e., 3.5 and 5.2 GHz. The MIMO radiating elements are printed on each side of the mobile phone chassis, having dimensions of 150 × 7 mm2, while the microstrip feeding lines fed through a coaxial connector are printed on the main board, having dimensions of 150 × 75 mm2. The single element of the MIMO antenna system consists of a modified slotted rectangular patch radiator. One slot is composed of a hybrid shape (which consists of both T- and L-shaped patterns), and the second one is a typical inverted L-shaped slot. The placement of slots generated two different current paths, which led to dual-band response at 3.5 and 5.2 GHz. In the MIMO configuration, the arrangement of radiating elements ensures pattern diversity characteristics, which are useful for MIMO systems. Furthermore, the MIMO antenna system offers a minimum isolation of 13.5 and 21.5 dB at 3.5 and 5.2 GHz, respectively. From the results, it is also observed that the radiating elements offer a radiation efficiency of ≥70% at 3.5 GHz, while at 5.2 GHz, the radiation efficiency is noted to be >55% with acceptable gain. A comprehensive analysis of key performance parameters, e.g., envelope correlation coefficient (ECC), mean effective gain (MEG), and channel capacity (CC), was conducted, and it is noted that the proposed MIMO antenna system exhibits an ECC of less than 0.015, MEG of < −3 dB, and CC of 39.5 bps/Hz. In addition, the specific absorption rate (SAR) analysis of the proposed MIMO antenna was conducted and observed a value of 1.35 and 1.05 W/Kg at 3.5 and 5.2 GHz, respectively. To verify the computed results, a prototype of the proposed MIMO antenna was fabricated and subjected to thorough measurements. It was observed that the measured results satisfied the simulated data and aligned excellently with the measured data. Based on the performance of the proposed MIMO antenna, it became evident that the MIMO antenna structure can be used as a potential candidate for future fifth-generation (5G)-enabled smart phones.

Empirical Evaluation of a 28 GHz Antenna Array on a 5G Mobile Phone Using a Body Phantom

Implementation of an antenna array on a 5G mobile phone chassis is crucial in ensuring the radio link quality especially at millimeter-waves. However, we generally lack the ability to design antennas under practical operational conditions involving body effects of a mobile user in a repeatable manner. We developed numerical and physical phantoms of a human body for evaluation of mobile handset antennas at 28 GHz. While the numerical phantom retains a realistic and accurate body shape, our physical phantom has much simpler hexagonal cross-section to represent a body. Gains of the phased antenna array configuration on a mobile phone chassis, called co-located array is numerically and experimentally evaluated. The array is formed by placing two sets of 4-element dual-polarized patch antenna arrays, called two modules, at two locations of a mobile phone chassis. Modules are intended to collect the maximum amount of energy to the single transceiver chain. Spherical coverage of the realized gain by the array shows that the experimental statistics of the realized gains across entire solid angles agree with numerical simulations. We thereby demonstrate that our antenna evaluation method reproduces the reality and our phantom serves repeatable tests of antenna array prototypes at 28 GHz.

Characteristic Mode Analysis applied to antennas

Abstract This paper introduces the Characteristic Mode Analysis in the computation of electromagnetic resonant modes in conducting bodies. Canonical cases (thin wire and a rectangular plate) are analyzed, along with real-world complex structures, a mobile phone chassis and an unmanned aerial vehicle. Given the analogy to other areas, such as modal analysis in Differential Equations, this method can be another tool when teaching Electromagnetic Radiation and antenna related topics.

Skin Temperature Distribution over Human Head Due to Handheld Mobile Phone Call using Thermal Imaging Camera

The possible biological hazards due to the mobile phone electromagnetic (EM) field exposure are caused mainly by a temperature rise in tissue. Hence, the calculation of temperature in tissue may be more realistic than the calculation of specific absorption rate (SAR) due to the more direct relationship between temperature and safety. The heat transfer to human tissue due to a phone call is caused by a combined effect of conductive heat transfer caused by the basic non-microwave-related activity of the mobile phone and the absorption of the microwave. This paper investigates the role of heat transfer in living tissue due to thermal conduction. This is achieved using a thermal imaging camera to measure and map the skin temperature distribution over human head due to mobile phone EM emission. Two commercial mobile phone brands, that is, Apple iPhone 7 Plus and Huawei P20 Pro, are used at 1800 MHz cellular connection and approximate radiated power of 0.125 W to measure the skin temperature over human head at both, cheek and tilt position for 6 and 30 min calls. The results show that in spite of the direct proportion between the deposited SAR and temperature increase in human tissues, the heat transfer due to thermal conduction may not directly proportional to the SAR, where other factors may play important roles, for example, mobile phone chassis material, heated battery, antenna location inside the mobile phone, and mobile phone position in close proximity to head.

A Lumped-Element Decoupling and Matching Network for a Four-Element Mobile Handset MIMO Antenna

This paper presents the first realization of a lumped-element decoupling and matching network (DMN) for more than two-element mobile MIMO arrays. The realization of the DMN is based on an existing method, which is improved in terms of bandwidth and the number of network elements. The array is designed to operate in the 2.6–2.7 GHz LTE band. The DMN is applied to a four-element MIMO antenna array located on one side of the mobile phone chassis. The array initially has a strong coupling of −3 dB, which is improved to −7 dB with the DMN. In other words, this denotes a reduction of 30 percentage points in coupled power. The DMN also improves the total efficiency by 21 percentage points at best.

A Capacitive Coupled Patch Antenna Array With High Gain and Wide Coverage for 5G Smartphone Applications

In this paper, a novel capacitive coupled patch antenna array capable of providing high gain and 360° coverage in the elevation plane is proposed. The proposed antenna element is studied in detail using the theory of characteristic modes to enhance the bandwidth. It exhibits a uniform radiation pattern with a stable gain when integrated with the mobile phone chassis. These elements are positioned in the mobile phone chassis as a set of four sub-arrays each with 12 antenna elements to provide high realized gain around 16.5 dBi with each sub-array providing 90° coverage. The antenna array is fabricated, and the beam steering performance of the array is evaluated using a beam-steering test bed. The results show that it covers the frequency range of 24–28 GHz, which is a promising band for future 5G-based smartphone services as predicted and could be a strong candidate for 5G applications.