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Mobile Antenna Systems for 4G and 5G Applications with User Body Interaction
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the thesis, the user body effect on antennas in a mobile terminal is discussed. In order to overcome the degradation of Multiple-Input Multiple-Output (MIMO) performance due to the user body effect, a quad-elements MIMO antenna array which can mitigate the body effect through an adaptive antenna switching method is introduced for 4G mobile terminals. In addition, various bezel MIMO antennas that are robust to the impedance mismatching caused by the user effect have also been presented.

The study of user body effect is later extended to frequency bands at 15 GHz and 28 GHz for future 5G communication systems. The results reveal that a human body will cause a significant shadowing loss, which will be a critical loss in 5G cellular networks.

The electromagnetic field (EMF) exposure of a mobile terminal is also studied in this thesis. Below 6 GHz, the simultaneous transmission specific absorption rate (SAR) for MIMO antennas is the primary concern due to its complicated assessment procedures. Above 6 GHz, the free space power density is adopted as the basic parameter of exposure limits globally, and preliminary studies have been presented to address major challenges in EMF exposure assessment for 5G mobile terminals. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. , p. 65
Series
TRITA-EE, ISSN 1653-5146 ; 2017:137
Keywords [en]
Antenna, MIMO, mmWave, Mobile communication, SAR, Power density, User body effect, Channel modeling, Multiplex efficiency
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-215266ISBN: 978-91-7729-550-1 (print)OAI: oai:DiVA.org:kth-215266DiVA, id: diva2:1147366
Public defence
2017-10-27, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20171005

Available from: 2017-10-05 Created: 2017-10-05 Last updated: 2017-11-08Bibliographically approved
List of papers
1. Body-Insensitive Multimode MIMO Terminal Antenna of Double-Ring Structure
Open this publication in new window or tab >>Body-Insensitive Multimode MIMO Terminal Antenna of Double-Ring Structure
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2015 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 63, no 5, p. 1925-1936Article in journal (Refereed) Published
Abstract [en]

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, the MIMO cellular antenna can operate at 830-900 MHz, 1700-2200 MHz, and 2400-2700 MHz, for 2G, 3G, and LTE bands, respectively. The MIMO Wi-Fi antenna can cover two Wi-Fi bands from 2.4 to 2.5 GHz and from 5.2 to 5.8 GHz. The effect of a user's body on the MIMO cellular antenna is investigated on CTIA standard phantoms and a real user. Since our antenna mainly operates in the loop mode, it has a much lower efficiency loss than conventional mobile antennas in both talking and data modes. Our theoretical analysis and experiments have shown that our design has low body loss and an attractive industrial design.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-171167 (URN)10.1109/TAP.2015.2408617 (DOI)000356513700005 ()
Note

QC 20150720

Available from: 2015-07-20 Created: 2015-07-20 Last updated: 2017-12-04Bibliographically approved
2. User Body Effect on Phased Array in User Equipment for the 5G mmWave Communication System
Open this publication in new window or tab >>User Body Effect on Phased Array in User Equipment for the 5G mmWave Communication System
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2017 (English)In: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 16, p. 864-867Article in journal (Refereed) Published
Abstract [en]

The millimeter-wave 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 3-D measurement data, and its impact on some key parameters for phased array in the UE, such as the total scan pattern, the coverage efficiency, and the probability of detection, are analyzed.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
Coverage efficiency, fifth-generation mobile system, human body effects, millimeter wave (mmWave), phased array, user equipment (UE) antenna
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-208282 (URN)10.1109/LAWP.2016.2611674 (DOI)000399319100039 ()2-s2.0-85018949860 (Scopus ID)
Note

QC 20170609

Available from: 2017-06-09 Created: 2017-06-09 Last updated: 2017-10-05Bibliographically approved
3. Channel Characteristics and User Body Effects in an Outdoor Urban Scenario at 15 and 28 GHz
Open this publication in new window or tab >>Channel Characteristics and User Body Effects in an Outdoor Urban Scenario at 15 and 28 GHz
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2017 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 65, no 12, p. 6534-6548Article in journal (Refereed) Published
Abstract [en]

The effect of a user's body on channel characteristics for single user downlink transmission in an urban scenario for the fifth generation (5G) systems is investigated with ray-tracing at 15 and 28 GHz. Three different designs of user equipment (UE) antennas are fabricated and integrated into a mobile phone prototype, and their 3-D radiation patterns are measured both with and without a user. The user remains in Cellular Telephone Industries Association (CTIA) standard data mode and talk mode during measurements. The results show that the user's body will cause a strong shadowing loss and generate a large fluctuation on the received signal strength of the UE at both 15 and 28 GHz, which is crucial to channel modeling studies at frequencies above 6 GHz. In addition, the user's body effect on a linear array system in an UE is presented, and the main challenges for the future work are also addressed.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
5G, array, body effect, channel, millimeter wave (mmWave), mobile phone, user equipment (UE)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-215256 (URN)10.1109/TAP.2017.2740959 (DOI)000417885000031 ()2-s2.0-85028501647 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20171005

Available from: 2017-10-05 Created: 2017-10-05 Last updated: 2018-01-12Bibliographically approved
4. SAR study of different MIMO antenna designs for LTE application in smart mobile handsets
Open this publication in new window or tab >>SAR study of different MIMO antenna designs for LTE application in smart mobile handsets
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2013 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 61, no 6, p. 3270-3279Article in journal (Refereed) Published
Abstract [en]

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 typical LTE frequency points (0.75, 0.85, 1.9, and 2.1/2.6 GHz) when the ground plane length varies from 90 to 150 mm. The SAR, when dual elements operate simultaneously, is also studied through the SAR to PEAK location spacing ratio (SPLSR) according to the FCC standard. The simulations are carried out on both an SAM head phantom and a flat phantom by CST 2011, and measurements on the flat phantom are made with iSAR and DASY4 to verify the accuracy of our simulations.

Keywords
LTE, MIMO, mobile handset, specific absorption rate
National Category
Telecommunications Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-134252 (URN)10.1109/TAP.2013.2250239 (DOI)000319871400043 ()2-s2.0-84878719556 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20131121

Available from: 2013-11-21 Created: 2013-11-20 Last updated: 2017-12-06Bibliographically approved
5. EMF Exposure Study Concerning mmWave Phased Array in Mobile Devices for 5G Communication
Open this publication in new window or tab >>EMF Exposure Study Concerning mmWave Phased Array in Mobile Devices for 5G Communication
2016 (English)In: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 15, p. 1132-1135Article in journal (Refereed) Published
Abstract [en]

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 have not been well defined for the mobile device application. In this letter, we present the power density property of phased arrays in mobile devices at 15 and 28 GHz. Uniform linear patch arrays are used, and different array configurations are compared. Suggestions for the power density evaluation are also provided.

Place, publisher, year, edition, pages
IEEE, 2016
Keywords
5G, device output power, electromagnetic field (EMF) exposure limit, mobile device, phased array, power density
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-187339 (URN)10.1109/LAWP.2015.2496229 (DOI)000374301400006 ()2-s2.0-84963959771 (Scopus ID)
Note

QC20160520

Available from: 2016-05-20 Created: 2016-05-20 Last updated: 2017-11-30Bibliographically approved

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