Kun Zhao

Sony Corporation | Sony CSL · Research Center Lund

As reconfigurable intelligent surface (RIS) is expected to be implemented with a large aperture in terms of wavelengths, using a RIS to perform near-field rather than conventional far-field communications might gain some benefits. The electric fields in the near-field region from the near-field focusing and conventional far-field RISs are simulated...

Deployment of the fifth-generation (5G) mobile communications at the millimeter-wave (mmWave) part of the electromagnetic spectrum comes with concerns related to exposure of the human to electromagnetic field (EMF). The irradiation of the human body from phased antenna arrays, integrated into handsets operating at mmWave frequencies, is evaluated i...

This article summarizes the recently discovered opportunities of geodesic lenses for producing high-performing antennas for 5G/6G communications. First, we explain the operation of these lenses based on Geometrical Optics with rays that follow “the shortest optical path” on the geodesic surface. Also, we explain the connection between geodesic lens...

Nowadays, the large number of services provided by mobile phones drives the usage of the millimeter-wave (mm-wave) frequency range for the upcoming fifth generation (5G) mobile communication system, in order to provide wider bandwidths that support high-throughput data transfer. However, the propagation environment becomes hostile at higher frequen...

In this paper, an endfire dual-polarized phased array is introduced for 5G mobile applications, which operates from 26 GHz to 30 GHz with low profile of only 1.1 mm ( ${\bf 0.1\lambda _0}$ at 26 GHz) and small clearance of 3.5 mm. The array consists of interleaved substrate integrated waveguide (SIW) based vertical-polarized elements and notch typ...

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)...

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...

This paper proposes a dual-polarized cavity backed patch antenna for next generation phased arrays for mobile handsets. The antenna exhibits multi-band performance, allowing to cover the 5G bands n257 (26.5 − 29.5 GHz), n258 (24.25 − 27.5 GHz), n261 (27.5 − 28.35 GHz) and a portion of band n260 (37 − 40 GHz). Two orthogonal modes are excited in the...

The exposure to electromagnetic field (EMF) from phased antenna arrays integrated into wireless devices operating at the millimeter-wave (mmWave) part of the spectrum should be evaluated in terms of power density (PD). Two aspects related to test reduction when evaluating the radiation from handset antenna arrays are considered. First, the peak PD...

In this paper, a method to reduce the metal-frame obstruction to the radiation of endfire mm-wave arrays with wideband operation is presented. A 7 mm-wide frame is chosen to emulate the current commercial bezel thickness. Slots of three different sizes are etched on the frame to ensure the wideband endfire behavior. The proposed solution allows the...

This article proposes a compact hybrid beamswitchable phased array, with simple structure, high gain and large coverage in the mm-wave band, for next generation mobile handsets. Four reconfigurable antennas are selected as array elements, consisting of two monopoles, placed on both sides of the short clearance of 3 mm, fed by SIW. Each array elemen...

When placed on the market, mobile handsets are required to comply with relevant electromagnetic field (EMF) exposure limits. In the millimeter-wave (mmWave) frequency band, human exposure to EMF needs to be evaluated in terms of incident power density (PD). In this work, the equivalent currents (EQC) method is applied to assess the PD of a 5G mmWav...

This paper presents a lens antenna concept with multibeam performance in the mm-wave band for the next generation mobile devices. The lens consists of metallic vias, etched in the substrate with different height, to obtain different permittivity. The goal is to correct the phase distribution of the incoming electromagnetic wave, to radiate towards...

In this paper, the propagating characteristics of hard surfaces are employed to reduce the main beam blockage of the handset frame to horizontally polarized endfire millimeter-wave (mm-wave) arrays. To prove the concept, a quad-element Vivaldi array is located at the top part of the handset and the frame with grooves is placed in front of it. The g...

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...

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...

In this paper, a new principle to overcome the blockage of metallic frames in mobile terminals to endfire millimeter-wave (mm-wave) arrays is proposed. The obstruction is solved by etching several slots in the top part of the frame. It is shown that the slots in the handset frame can furthermore enhance the beam-steering gain of a mm-wave bow-tie a...

This paper presents a new SIW horn antenna with high performance in the mm-wave bands for the next generation mobile devices. The proposed antenna is integrated in a double layer of Rogers RO4003C substrate and requires a clearance of only 3 mm. Air vias are etched in the substrate in a specific portion of the horn aperture, in order to correct the...

(Download Link: https://vbn.aau.dk/en/publications/dual-polarized-phased-array-with-endfire-radiation-for-5g-handset) This paper proposes a dual-polarized endfire phased array for 5G handset devices at 28 GHz. The proposed 4-element array has low profile of 1.1 mm, small clearance of 2.7 mm, and symmetric patterns in the vertical plane. The array...

The goal of this paper is to propose a new antenna array architecture, that aims to solve the most known limitations of phased antenna arrays, resulting a good candidate for next 5G mobile handsets. The architecture consists of five Quasi-Yagi antennas printed on the short edge of a Roger RO3003 substrate, pointing different directions, and a switc...

This paper presents a new phased array of SIW monopoles, characterized by simple structure, high gain and large coverage, resulting a good candidate for next 5G mobile handsets. The design consists of eight monopoles printed on a Rogers RO4003 substrate. In particular, four antennas are located on top of the PCB to cover the area behind the structu...

In this paper, a 12-element switchable antenna system for handsets is proposed at 28 GHz. The effect of the head and hand in the impedance matching and radiation pattern is assessed. The electromagnetic field (EMF) exposure in the body is analyzed. The evaluation method of exposure for the previous mobile generations is the specific absorption rate...

Human exposure to radio frequency (RF) electromagnetic fields should not exceed the exposure limits set by the relevant regulatory guidelines. In this paper, we provide approaches to determine upper bounds of maximum exposure from multiple antennas. When the total transmitted power is fixed, the maximum exposure can be determined by an eigenvalue d...

In this paper, a novel technique is introduced to reduce the handset metal-frame blockage to the main beam of a millimeter-wave (mm-wave) end-fire antenna array. The metalframe blockage to mm-wave antennas with different polarizations is investigated first. It is found that the blockage is more severe for horizontal polarization than for vertical p...

Above 6 GHz, radio frequency (RF) electromagnetic field (EMF) exposure from mobile communication user equipment (UE) should be assessed in terms of incident power density, rather than specific absorption rate that as below 6 GHz. Such regulatory RF EMF restrictions will constrain the transmit power of the UE and its peak equivalent isotropically ra...

Millimeter-wave (mmWave) frequency bands are promising candidate spectrum for the 5th generation (5G) mobile communication system, but it requires high directional antenna systems to be applied to the base station (BS) and the user equipment (UE) for compensating the high path loss. Due to the randomness of mobile wireless channels, antenna systems...

Radiation from printed millimeter-wave antennas integrated in mobile terminals is affected by surface currents on chassis, guided waves trapped in dielectric layers, superstrates, and the user's hand, making mobile antenna design for 5G communication challenging. In this paper, four canonical types of printed 28 GHz antenna elements are integrated...

The major issues related to antenna system designs in user devices for the next-generation cellular network at millimeter-wave frequencies are addressed. The array topology, packaging, spatial coverage, human body effect and human body exposure are discussed. Keywords-5G, mmWave, user device, antenna array, user body effect, exposure.

The effect of a user’s body on channel characteristics for single user downlink transmission in an urban scenario for the 5th generation (5G) systems is investigated with ray-tracing at 15 GHz and 28 GHz. Three different designs of user equipment (UE) antennas are fabricated and integrated into a mobile phone prototype, and their 3D radiation patte...

Abstract: Above 6 GHz or 10 GHz, the radio frequency (RF) electromagnetic field (EMF) exposure of user equipment (UE) is evaluated in terms of free space power density. The RF EMF exposure compliance of the fifth-generation (5G) UE with an 8 × 1 beam-steering slot array is analyzed in this paper. The maximum exposure (ME) and corresponding maximum...

In this paper, different measurement schemes are studied in order to investigate the possibilities and limitations of scalar- and vector-based measurement systems for radio frequency electromagnetic fields compliance assessments of fifth generation mobile communication user equipment (UE). Two UE antenna array designs, transmitting at 15 GHz and em...

In this paper the user effects on mobile terminal antennas at 28GHz are statistically investigated with the parameters of body loss, coverage efficiency and power in the shadow. The data are obtained from the measurements of 12 users in data and talk modes, with the antenna placed on the top and bottom of the chassis. In the measurements, the users...

In the millimeter-wave (mmW) frequency band, radio frequency electromagnetic field (RF EMF) exposure is evaluated in terms of free space power density rather than the localized specific absorption rate (SAR) used in current cellular communications. In this study, we investigated RF EMF exposure of user equipment (UE) mock-ups employing a patch arra...

The millimeter wave (mmWave) phased array in the user equipment (UE) for 5G communication is studied in this letter. In particular, the body effect on the phased array in the UE at 15 GHz is investigated with the 3D measurement data, and its impact on some key parameters for phased array in the UE, such as the total scan pattern, the coverage effic...

Recently, multiple-input multiple-output (MIMO) technology and diversity have attracted much attention both in industry and academia due to high data rate and high spectrum efficiency. By increasing the number of antennas at the transmitter and/or the receiver side of the wireless link, the diversity/MIMO techniques can increase wireless channel ca...

The challenge of surface wave excitation and propagation to millimeter-wave (mm-wave) antennas of future fifth-generation (5G) cellular system is addressed in this paper. This paper presents three different schemes by simulation, including mushroom-like electromagnetic band-gap (EBG) structures, cross-shaped resonant structures and T-shaped wave tr...

The multiplexing efficiency of 4×4 higher order MIMO with different MIMO topologies under different propagation scenarios in a mobile terminal is presented in this study. The mean effective gain, correlation coefficient and multiplexing efficiency of different MIMO topologies are compared and the impact from the angular spread of the incoming wave...

The application of using the capacitively coupled body area network (BAN) to build up the communication between a mobile phone and a wearable device is presented in this letter. The proposed system operates at 26 MHz, the capacitively coupled BAN channel is discussed, and electrode designs for wearable devices and smartphones are proposed. The tran...

Recently, multiple-input multiple-output (MIMO) technology and diversity have attracted much attention both in industry and academia due to high data rate and high spectrum efficiency. By increasing the number of antennas at the transmitter and/or the receiver side of the wireless link, the diversity/MIMO techniques can increase wireless channel ca...

In this paper, the latest study of the millimeter wave (mmWave) phased array in mobile terminals for the 5G communication is presented. New parameters for evaluating the mmWave phased array in mobile terminals are introduced. Furthermore, the hand effect on the phased array in mobile terminal at 15 GHz is also investigated. Keywords—mmWave, 5 th Ge...

In this paper, the latest study of the millimeter wave (mmWave) phased array in mobile terminals for the 5G communication is presented. New parameters for evaluating the mmWave phased array in mobile terminals are introduced. Furthermore, the hand effect on the phased array in mobile terminal at 15 GHz is also investigated. Keywords—mmWave, 5 th Ge...

In this paper, results of the latest study regarding human exposure to the mmWave phase array in mobile terminal for 5G mobile communication are presented. FCC guideline has been reviewed and power density is used to evaluate the human exposure in the mmWave band. The purpose of the paper is to present the basic power density property of the mmWave...

In this paper, we propose a novel multimode multi-input multi-output (MIMO) antenna system composed of a dual-element MIMO cellular antenna and dual-element MIMO Wi-Fi antenna for mobile terminal applications. The antenna system has a double-ring structure and can be integrated with the metal frame of mobile terminals. With the multimode excitation...

In this paper, we present three cellular antenna designs for the smart watch application by using the metal watch belt. Our proposed antennas can cover cellular bands down to 700 MHz and up to 2.7GHz. Their performance in the free space and user cases are measured and discussed. The SAR evaluation guideline from FCC is also introduced and SAR measu...

In this paper, we present three cellular antenna designs for the smart watch application by using the metal watch belt. Our proposed antennas can cover cellular bands down to 700 MHz and up to 2.7GHz. Their performance in the free space and user cases are measured and discussed. The SAR evaluation guideline from FCC is also introduced and SAR measu...

In this abstract, we present a MIMO bezel antenna design composed by double metal ring structure. The MIMO antenna mainly operates in the loop mode and can cover the majority fraction of cellular bands globally. Good efficiency (>-4dB) and low envelope correlation coefficient (<0.5) can be achieved, which make sure our antenna has good MIMO perform...

??????A diagonal antenna??€“chassis mode is investigated in long-term evolution multiple-input??€“multiple-output (LTE MIMO) antennas. The MIMO bandwidth is defined in this paper as the overlap range of the low-envelope correlation coefficient, high total efficiency, and -6-dB impedance matching bandwidths. Utilizing the diagonal mode analysis, the...

This letter discusses the usage of high-gain steerable antenna arrays operating at millimeter-wave (mmWave) frequencies for future cellular networks (5G). Based on the probable outline of the 5G networks, a method for characterizing phased array antennas in cellular handsets has been introduced. For analyzing the performance, the total scan pattern...

The electromagnetic field (EMF) exposure to millimeter-wave (mmWave) phased arrays in mobile devices for 5G communication is analyzed in this letter. Unlike the current cellular band, the EMF exposure in the mmWave band (10-200 GHz) is evaluated by the free-space power density instead of the specific absorption rate. However, current regulations ha...

In this paper, we investigate the SAR performance of an IFA antenna for the smart watch application. The SAR performance is evaluated by both body shape phantoms and FCC standard flat phantoms. Differences of the SAR performance in different phantoms are compared and discussed.

MIMO reference antennas are proposed for over the air (OTA) measurement applications. The reference antennas could get rid of feeding cable interference and control envelope correlation coefficients (ECC) continuously by only changing the length of an etched slot on a dual-feed PIFA. If only the ECC is investigated, the MIMO reference antenna is op...

An LTE MIMO antenna array, which is adaptive to the effects of the user's body, is presented for mobile terminals. The bands of 750-960 MHz and 1700-2700 MHz are covered with a good efficiency in free space. Three kinds of user effects are studied, namely, “SAM head and PDA hand,” “PDA hand,” and “dual hands.” The array is formed by selecting the b...

In this paper, MIMO reference antennas with different correlation coefficients are proposed for Over-The-Air (OTA) applications. The correlation can be simply controlled through a slot etched on a dual-feed PIFA with the similar total efficiency. Three kinds of situations are investigated with the proposed method: high correlation (HC), mid correla...

This paper mainly focuses on the specific absorption rate (SAR) of the dual-element LTE MIMO antenna in mobile phones. Four designs of dual-element MIMO antenna (namely, dual semi-ground-free planar inverted-F antenna (PIFA), co-located antenna, dual OG PIFA in parallel position, and dual OG PIFA in orthogonal position) are studied under four typic...

In this paper, the diagonal antenna-chassis mode is introduced to reduce the correlation between MIMO antenna elements. With this mode a wideband LTE MIMO antenna array is proposed, which can cover an impedance bandwidth of 747-960 MHz with an envelope correlation coefficient (ECC) less than 0.5 and an total efficiency better than -3 dB.

This paper reports a study of body loss for LTE MIMO antennas in mobile phones with the effects of different mobile phone lengths. Two designs of dual elements MIMO antenna (dual Semi PIFA and co-located antenna) are studied under two typical LTE and mobile phone frequency points (0.85GHz and 1.9 GHz) with three mobile phone lengths (110mm, 130mm a...

The reduction in the radiation efficiency of an antenna in a mobile handset due to user's hand effects in the talking and data modes is studied. A parameter called "body loss" is defined to evaluate the degradation of the radiation efficiency. A C-fed on-ground (OG) PIFA antenna, which can cover two typical LTE bands of 0.75 GHz-0.96 GHz and 1.7 GH...

A body-effect-adaptive compact wideband LTE MIMO antenna array with quad elements for mobile terminals is proposed in this paper. It can cover the bands of 750-960 and 1700-2700MHz with a low envelope correlation coefficient. Through different combinations two of the four elements can be utilized as dual element LTE MIMO antenna array to reduce thr...

The bandwidth of a printed antenna with a rotated rhombus slot is enhanced further by introducing 7 parasitic stripes, one of which is embedded on an edge of the rhombus slot downside while the others are on the upside. The mechanism of the wideband antenna is explained. The measured results indicate a large impedance bandwidth of 122.6% (1.59 GHz–...

A closely-located MIMO antennas of tri-band with an inter-PIFA (Planner Inverted-F Antenna) spacing of only 20 mm is proposed for WLAN mobile terminal applications. Two L-shaped slots etched on each PIFA are introduced appropriately to achieve high isolation at higher frequencies and tri-band property. The MIMO antenna can operate in the bands of 2...