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Power Density Measurements at 15 GHz for RF EMF Compliance Assessments of 5G User Equipment
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang University, China.ORCID iD: 0000-0003-4381-6889
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
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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. 6584-6595Article in journal (Refereed) Published
Abstract [en]

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 employing patch and notch antenna elements, are considered for different phase excitations. Using free space power density as the exposure metric, the maximum permissible transmitted power of UE, compliant with the maximum permissible exposure limits specified by the U.S. Federal Communications Commission (FCC) and the basic restrictions of the International Commission on Non-Ionizing Radiation Protection, is determined. The accuracy of different measurement schemes is assessed using numerical simulation. Verifying measurements is carried out in a semiane-choic chamber. The results indicate that, for UE employing array antennas and intended to be used in immediate vicinity of the human body, scalar measurement systems used in combination with straightforward field combination techniques will lead to overly conservative results. A more accurate and less conservative approach for these products is to conduct separate measurements for different excitations in order to span the space of possible excitations. This will result in a more complicated measurement setup and increase the measurement time, which points to a need for very fast measurement systems.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2017. Vol. 65, no 12, p. 6584-6595
Keywords [en]
Antenna array, assessment method, fifth generation (5G) mobile communication systems, maximum permissible transmitted power (MPTP), power density, radio frequency (RF) electromagnetic field (EMF) exposure, user equipment (UE)
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-221024DOI: 10.1109/TAP.2017.2712792ISI: 000417885000035Scopus ID: 2-s2.0-85038858525OAI: oai:DiVA.org:kth-221024DiVA, id: diva2:1173363
Funder
Swedish Research Council
Note

QC 20180112

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2023-03-08Bibliographically approved
In thesis
1. EMF Exposure and Radiation Performance of Millimeter-Wave Antennas in 5G Mobile Terminals
Open this publication in new window or tab >>EMF Exposure and Radiation Performance of Millimeter-Wave Antennas in 5G Mobile Terminals
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Since 2019, 5G has been rolled out in many countries. To support the demand of increasing traffic capacity, for the first time, the millimeter-wave (mmWave) frequency spectrum is exploited for the mobile wireless telecommunication technologies. For the telecommunication industry,  many questions are raised with the advent of 5G mmWave, including what would impact the performance of mmWave antennas in a mobile terminal and how to evaluate the impacts/effects. This thesis focuses on two topics about 5G mmWave mobile antenna performance. One is the radiation performance for mmWave antennas integrated in the mobile terminal. The other is electromagnetic field (EMF) exposure from mmWave mobile antennas. 

When integrated into a mobile terminal, the radiation performance of mmWave antennas can be affected by the housing conditions, for example, phone casing and display, etc. By detailed step-by-step simulation analyses, different types of housing effects, as well as the effects of the user's hand, are investigated. The effects of realistic housing conditions are also examined with far-field measurements and near-field antenna diagnose based on the solution to the inverse problem. The analyses provide useful insights into mmWave mobile antenna design and measurements in realistic housing environments. 

The mobile terminal needs to comply with regulations on EMF exposure before putting them on the market. By carrying out multi-physics simulation hybridizing the electromagnetic problem and the thermal problem, the correlation between tissue temperature rise and incident power density generated by the mmWave antennas is studied. Various field combination methods for EMF exposure from array antenna elements are investigated with simulations and measurements, and methods for calculating the upper bound of EMF exposure from the mmWave antenna array are developed. 

Recently, the international EMF exposure guidelines have been revised, including the changes of the EMF exposure limits in the mmWave frequencies. The implications of the revised limits are investigated by assessing the maximum power and maximum equivalent isotropically radiated power (EIRP) that are allowed to be transmitted from mmWave mobile antennas in the ideal as well as realistic scenarios. The obtained results provide valuable input to the device manufacturer, network operators, and standardization bodies.

Abstract [sv]

Sedan 2019 har 5G rullats ut i många länder. För att hantera den ökade efterfrågan på datakapacitet så utnyttjas för första gången frekvensspektrum inom millimetervågsområdet (mmW) för mobil kommunikationsteknik. Med tillkomsten av 5G uppkommer många frågor för telekommunikationsindustrin, såsom vad påverkar prestanda för mmW-antenner i mobila terminaler och hur utvärderar man effekterna av denna påverkan. Denna avhandling fokuserar på två aspekter kring prestanda för mmW-antenner. Den ena är strålningsprestandan för mmW-antenner integrerade i mobila terminaler, och den andra är exponering för elektromagnetiska fält (EMF) från dessa antenner. 

När en mmW-antenn är integrerad i en mobil terminal så kan strålningsprestandan påverkas av installationsförhållandena, exempelvis telefonhöljet och bildskärmen. Genom detaljerade simuleringsanalyser, steg för steg, undersöks olika typer av effekter av installationsmiljön samt effekten av användarens hand. Vidare undersöks också effekter av realistiska installationsförhållanden med hjälp av fjärrfältsmätningar och närfältsanalyser baserade på lösningar till det inversa problemet. Analyserna ger viktiga insikter om design och mätning av mmW-antenner i realistiska installationsmiljöer.

Mobila terminaler måste uppfylla krav och riktlinjer för EMF-exponering innan de sätts på marknaden. Genom att utföra multifysiksimuleringar som hybridiserar de elektromagnetiska och termiska problemen så studeras korrelationen mellan temperaturökningen i kroppsvävnad och den infallande effekttätheten från mmW-antenner. Olika fältkombinationsmetoder för EMF-exponering från gruppantennelement undersöks genom simuleringar och mätningar, och metoder för att beräkna den övre gränsen för EMF-exponering från gruppantenner i mmW-området utvecklas.

De internationella riktlinjerna för EMF-exponering, inkluderande gränsvärdena i mmW-området, har nyligen reviderats. Konsekvenserna av de reviderade gränsvärdena undersöks genom att bedöma vilken maximal uteffekt och vilken maximal ekvivalent isotropiskt utstrålad effekt (EIRP) som kan tillåtas för mobilantenner i mmW-området för både ideala och realistiska scenarier. De erhållna resultaten ger värdefull information för mobilterminaltillverkare, nätoperatörer och standardiseringsorgan.

Place, publisher, year, edition, pages
Stockholm, Sweden: Universitetsservice US-AB, 2021. p. 65
Series
TRITA-EECS-AVL ; 2021:14
National Category
Telecommunications
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-290657 (URN)978-91-7873-785-7 (ISBN)
Public defence
2021-03-18, Zoom, Stockholm, 09:00 (English)
Opponent
Supervisors
Note

QC 20210225

Available from: 2021-02-25 Created: 2021-02-23 Last updated: 2022-06-25Bibliographically approved

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