Change search
Refine search result
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Jonsson, B. Lars G.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Shi, Shuai
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Ludvig-Osipov, Andrei
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    On bounds of the Q-factor as a function of array antenna directivity2018In: Proceedings of the 2018 20th International Conference on Electromagnetics in Advanced Applications, ICEAA 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, p. 406-409Conference paper (Refereed)
    Abstract [en]

    In this paper we determine the trade-off between the Q-factor and partial (super) directivity for linear arrays of dipoles. The dipoles are densely spaced in a one or two wavelength long array. We compare the bound for port-feed dipoles with the current optimization approach, with optimal currents on the whole dipole area, and also with an enclosing plate. It is interesting to note that port-feed dipoles are close to the optimal current dipoles in the endfire case, for sufficiently many dipoles in the array, for a wide range of directivities. We also show that the optimization problem for the 'optimal current' and 'the port-feed' cases are very similar and that the Pareto-front (trade-off curve) can be obtained and compared for the different cases.

  • 2.
    Jonsson, B. Lars G.
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Shi, Shuai
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Wang, Lei
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Ferrero, Fabien
    Lizzi, Leonardo
    On Methods to Determine Bounds on the Q-Factor for a Given Directivity2017In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 65, no 11, p. 5686-5696Article in journal (Refereed)
    Abstract [en]

    This paper revisit and extend the interesting case of bounds on the Q-factor for a given directivity for a small antenna of arbitrary shape. A higher directivity in a small antenna is closely connected with a narrow impedance bandwidth. The relation between bandwidth and a desired directivity is still not fully understood, not even for small antennas. Initial investigations in this direction have related the radius of a circumscribing sphere to the directivity, and bounds on the Q-factor have also been derived for a partial directivity in a given direction. In this paper, we derive lower bounds on the Q-factor for a total desired directivity for an arbitrarily shaped antenna in a given direction as a convex problem using semidefinite relaxation (SDR) techniques. We also show that the relaxed solution is also a solution of the original problem of determining the lower Q-factor bound for a total desired directivity. SDR can also be used to relax a class of other interesting nonconvex constraints in antenna optimization, such as tuning, losses, and front-to-back ratio. We compare two different new methods to determine the lowest Q-factor for arbitrary-shaped antennas for a given total directivity. We also compare our results with full electromagnetic simulations of a parasitic element antenna with high directivity.

  • 3.
    Shi, Shuai
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Jonsson, B. Lars G.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Ferrero, Fabien
    Wang, Lei
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    An Investigation of the Bandwidth Optimal Position of an Embedded AntennaManuscript (preprint) (Other academic)
  • 4.
    Shi, Shuai
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Wang, Lei
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Jonsson, B. Lars G.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Antenna Current Optimization and Realizations for Far-Field Pattern ShapingManuscript (preprint) (Other academic)
  • 5.
    Shi, Shuai
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Wang, Lei
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Jonsson, B. Lars G.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    On Q-Factor Bounds for a Given Front-to-Back Ratio2017In: 2017 IEEE Antennas and Propagation Society International Symposium, Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 151-152Conference paper (Refereed)
    Abstract [en]

    In this paper, the goal is to solve an antenna current optimization problem minimizing the stored energy with a desired front-to-back ratio. This minimization problem is non-convex, and we use semidefinite relaxation techniques to find the solution. An initial study on the front-to-back ratio of a dipole shape is presented here.

  • 6.
    Xu, Bo
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Gustafsson, Mats
    Sony Mobile Commun AB, Network Technol Lab Res & Technol, Lund, Sweden..
    Shi, Shuai
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Ying, Zhinong
    Sony Mobile Commun AB, Network Technol Lab Res & Technol, Lund, Sweden..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Upper Bound Study of 5G RF EMF Exposure2018In: 2018 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETING, IEEE , 2018, p. 397-398Conference paper (Refereed)
    Abstract [en]

    Power density emitted by 5G user equipment should not exceed the power density limits set by compliance guidelines. When the amplitude of each port of millimeter-wave array antennas is uniform, the power density maximization problem can be relaxed to a semi-definite program. In this paper, the effect of sampling widths is considered for the maximum power density calculation. The results show that when the sampling distance is less than a half wavelength, the sampling rate should be higher than the Nyquist rate.

  • 7.
    Xu, Bo
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Gustafsson, Mats
    Lund Univ, Dept Elect & Informat Technol, SE-22100 Lund, Sweden..
    Shi, Shuai
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Zhao, Kun
    Sony Mobile Commun AB, Res & Technol, Network Technol Lab, SE-22188 Lund, Sweden..
    Ying, Zhinong
    Sony Mobile Commun AB, Res & Technol, Network Technol Lab, SE-22188 Lund, Sweden..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Radio Frequency Exposure Compliance of Multiple Antennas for Cellular Equipment Based on Semidefinite Relaxation2019In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 61, no 2, p. 327-336Article in journal (Refereed)
    Abstract [en]

    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 decomposition. If an individual antenna has additional power constraint, the exposure maximization problem can be relaxed to a semidefinite program. Two case studies are given to demonstrate the approaches to the maximum exposure of cellular equipment using multiple antennas. The methods and the obtained results provide valuable insights into RF compliance procedures of cellular equipment.

1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf