A side-edge frame dual-band eight-element MIMO antenna array for 5G handset

In this paper, a dual-band 8 × 8 multi-input multi-output (MIMO) array antenna operating in 3.5 GHz band (3400–3600 MHz) and 5.5 GHz band (5150–5925 MHz) for 5G mobile handset is presented. The proposed hybrid antenna includes a comb-shaped monopole and an L-shaped open slot antenna which are symmetrically located on the inner surface of the side-edge frame of smartphone. Pattern diversity is achieved that can mitigate envelope correlation coefficients (ECCs) and improve the MIMO system performances. The prototype of proposed dual-band eight-element MIMO antenna is fabricated and experimentally measured. The results show that isolation <−10 and <−15 dB, respectively in the lower band and high band without any additional decoupling element are achieved and the desired bands are satisfied under the condition of −6 dB impedance matching. Moreover, the essential parameters for evaluation of the MIMO system performance such as the ECC, mean effective gain (MEG), and ergodic channel capacity are calculated. Furthermore, the influence of user's hand on the radiation characteristics of proposed MIMO antenna are also investigated and discussed. Based on the result, the proposed MIMO antenna is a good candidate for use in future 5G applications.

Ultra-Compact mm-Wave Monolithic IC Doherty Power Amplifier for Mobile Handsets

This work develops a novel dynamic load modulation Power Amplifier (PA) circuity that can provide an optimum compromise between linearity and efficiency while covering multiple cellular frequency bands. Exploiting monolithic microwave integrated circuits (MMIC) technology, a fully integrated 1W Doherty PA architecture is proposed based on 0.1 μm AlGaAs/InGaAs Depletion-Mode (D-Mode) technology provided by the WIN Semiconductors foundry. The proposed wideband DPA incorporates the harmonic tuning Class-J mode of operation, which aims to engineer the voltage waveform via second harmonic capacitive load termination. Moreover, the applied post-matching technique not only reduces the impedance transformation ratio of the conventional DPA, but also restores its proper load modulation. The simulation results indicate that the monolithic drive load modulation PA at 4 V operation voltage delivers 44% PAE at the maximum output power of 30 dBm at the 1 dB compression point, and 34% power-added efficiency (PAE) at 6 dB power back-off (PBO). A power gain flatness of around 14 ± 0.5 dB was achieved over the frequency band of 23 GHz to 27 GHz. The compact MMIC load modulation technique developed for the 5G mobile handset occupies the die area of 3.2 mm2.

Consumers Decision Making Process and Buying Behaviour towards Mobile Handsets

– The purpose of this paper is to investigate the decision making process adopted by consumers while buying the mobile handsets and to study the consumer buying behaviour towards mobile handsets. Design/methodology/approach –Consumer behaviour is observed and analyzed with the help of descriptive analysis. The effect of internal factors has been seen on this decision making process. For this purpose MANOVA analysis has been put to use. Wilk’s lambda has been considered as an analysis factor. Findings – Consumers’ buying behaviour depends upon their purpose behind buying a mobile phone. Choice of their phones differs on the basis of various functions they performed on phone; they focus on buying the phone they are familiar with and which fulfills their purpose. Research limitations/implications – Even though the world as a whole is rapidly adopting smart phones, there is a high degree of variation in how they have been adopted in different parts of the world. Practical implications – In the present competitive world, growth of smart phones is a truly global story; there are lots of important factors which create differences in how technology has evolved in different countries. Originality/value – This paper contributes to the knowledge of the marketers about mobile handsets in several ways. It would also be helpful for the marketers to know the actual decision making process followed by them while buying a new mobile handset, which will help them in formulating their strategies to attract the customers.

Copper recovery by slurry electrolysis using ionic liquids from waste printed circuit boards

<p>The regulatory framework of heavy metal pollution associated with electronic waste is prevalent all over the world. As a result of technological advancement and change in consumer patterns, the life span of electrical and electronic products has been shortened. This has contributed to the emergence of massive amounts of electronic waste that needs to be handled. With the exponential growth of the telecommunications sector, the recycling of useful resources from electronic waste devices, especially mobile phones, is of great significance. Besides, the presence of valuable metals enables the recycling of electronic waste potentially appealing. In this research, numerous types of ionic liquids like Butyl methylimidazolium hexafluorophosphate [Bmim][PF6], Butyl methylimidazolium chloride [Bmim][Cl], Ethyl methylimidazolium chloride [Emim][Cl] and Butyl methylimidazolium tetrafluoroborate [Bmim][BF4] were used to analyze the copper leaching behavior of electronic mobile handset devices. Several influential aspects on the leaching efficiency of copper including different types of ionic liquid, temperature and leaching time have been examined. The findings showed [Bmim][PF6] and [Emim][Cl] were better ionic liquids in appropriate conditions for high copper leaching rates.</p>

Fast Power Density Assessment of 5G Mobile Handset Using Equivalent Currents Method

<div>As the fifth-generation (5G) mobile communication is utilizing millimeter-wave (mmWave) frequency bands, electromagnetic field (EMF) exposure emitted from a 5G mmWave mobile handset should be evaluated and compliant with the relevant EMF exposure limits in terms of peak spatial-average incident power density. In this work, a fast power density (PD) assessment method for a 5G mmWave mobile handset using the equivalent currents (EQC) method is proposed. The EQC method utilizes the intermediate-field (IF) data collected by a spherical measurement system to reconstruct the EQCs over a reconstruction surface, and then computes the PD in close proximity of the mobile handset with acceptable accuracy. The performance of the proposed method is evaluated using a mmWave mobile handset mock-up equipped with four quasi-Yagi antennas. The assessed PD results are compared with those computed using full-wave simulations and also those measured with a planar near-field (NF) scanning system. In addition, three influencing factors related to the accuracy of the EQC method, namely, the angular resolution, the phase error, and the handset position in the IF measurements, are also analyzed. The proposed method is a good candidate for fast PD assessment of EMF exposure compliance testing in the mmWave frequency range.</div>

Dual Band and Dual Diversity Four-Element MIMO Dipole for 5G Handsets

The increasing popularity of using wireless devices to handle routine tasks has increased the demand for incorporating multiple-input-multiple-output (MIMO) technology to utilize limited bandwidth efficiently. The presence of comparatively large space at the base station (BS) makes it straightforward to exploit the MIMO technology’s useful properties. From a mobile handset point of view, and limited space at the mobile handset, complex procedures are required to increase the number of active antenna elements. In this paper, to address such type of issues, a four-element MIMO dual band, dual diversity, dipole antenna has been proposed for 5G-enabled handsets. The proposed antenna design relies on space diversity as well as pattern diversity to provide an acceptable MIMO performance. The proposed dipole antenna simultaneously operates at 3.6 and 4.7 sub-6 GHz bands. The usefulness of the proposed 4×4 MIMO dipole antenna has been verified by comparing the simulated and measured results using a fabricated version of the proposed antenna. A specific absorption rate (SAR) analysis has been carried out using CST Voxel (a heterogeneous biological human head) model, which shows maximum SAR value for 10 g of head tissue is well below the permitted value of 2.0 W/kg. The total efficiency of each antenna element in this structure is −2.88, −3.12, −1.92 and −2.45 dB at 3.6 GHz, while at 4.7 GHz are −1.61, −2.19, −1.72 and −1.18 dB respectively. The isolation, envelope correlation coefficient (ECC) between the adjacent ports and the loss in capacity is below the standard margin, making the structure appropriate for MIMO applications. The effect of handgrip and the housing box on the total antenna efficiency is analyzed, and only 5% variation is observed, which results from careful placement of antenna elements.