Quality factor of an electrically small antenna radiating close to a conducting plane

Johan Sten, Arto Hujanen, Päivi Koivisto

    Research output: Contribution to journalArticleScientificpeer-review

    49 Citations (Scopus)

    Abstract

    Expressions are derived for the smallest achievable radiation quality factor (Q) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. The contribution of non-propagating energy in the near field is obtained explicitly using a spherical harmonics decomposition. The radiation Q is found to depend on the radius (relative to wavelength) of the smallest sphere that encloses the antenna and its image, the ratio of the vertical and horizontal dipole moments, as well as the positions of the dipoles relative to each other and to the plane. A number of simple wire structures are analysed with NEC (based on the method of moments), and the approximate Q obtained from their fractional bandwidth are compared to the corresponding theoretical minima.
    Original languageEnglish
    Pages (from-to)829-837
    Number of pages9
    JournalIEEE Transactions on Antennas and Propagation
    Volume49
    Issue number5
    DOIs
    Publication statusPublished - 2001
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Antennas
    Radiation
    Dipole moment
    Method of moments
    Wire
    Decomposition
    Bandwidth
    Wavelength

    Cite this

    @article{d394674c80494e549142e042c446efd9,
    title = "Quality factor of an electrically small antenna radiating close to a conducting plane",
    abstract = "Expressions are derived for the smallest achievable radiation quality factor (Q) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. The contribution of non-propagating energy in the near field is obtained explicitly using a spherical harmonics decomposition. The radiation Q is found to depend on the radius (relative to wavelength) of the smallest sphere that encloses the antenna and its image, the ratio of the vertical and horizontal dipole moments, as well as the positions of the dipoles relative to each other and to the plane. A number of simple wire structures are analysed with NEC (based on the method of moments), and the approximate Q obtained from their fractional bandwidth are compared to the corresponding theoretical minima.",
    author = "Johan Sten and Arto Hujanen and P{\"a}ivi Koivisto",
    year = "2001",
    doi = "10.1109/8.929637",
    language = "English",
    volume = "49",
    pages = "829--837",
    journal = "IEEE Transactions on Antennas and Propagation",
    issn = "0018-926X",
    publisher = "IEEE Institute of Electrical and Electronic Engineers",
    number = "5",

    }

    Quality factor of an electrically small antenna radiating close to a conducting plane. / Sten, Johan; Hujanen, Arto; Koivisto, Päivi.

    In: IEEE Transactions on Antennas and Propagation, Vol. 49, No. 5, 2001, p. 829-837.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Quality factor of an electrically small antenna radiating close to a conducting plane

    AU - Sten, Johan

    AU - Hujanen, Arto

    AU - Koivisto, Päivi

    PY - 2001

    Y1 - 2001

    N2 - Expressions are derived for the smallest achievable radiation quality factor (Q) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. The contribution of non-propagating energy in the near field is obtained explicitly using a spherical harmonics decomposition. The radiation Q is found to depend on the radius (relative to wavelength) of the smallest sphere that encloses the antenna and its image, the ratio of the vertical and horizontal dipole moments, as well as the positions of the dipoles relative to each other and to the plane. A number of simple wire structures are analysed with NEC (based on the method of moments), and the approximate Q obtained from their fractional bandwidth are compared to the corresponding theoretical minima.

    AB - Expressions are derived for the smallest achievable radiation quality factor (Q) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. The contribution of non-propagating energy in the near field is obtained explicitly using a spherical harmonics decomposition. The radiation Q is found to depend on the radius (relative to wavelength) of the smallest sphere that encloses the antenna and its image, the ratio of the vertical and horizontal dipole moments, as well as the positions of the dipoles relative to each other and to the plane. A number of simple wire structures are analysed with NEC (based on the method of moments), and the approximate Q obtained from their fractional bandwidth are compared to the corresponding theoretical minima.

    U2 - 10.1109/8.929637

    DO - 10.1109/8.929637

    M3 - Article

    VL - 49

    SP - 829

    EP - 837

    JO - IEEE Transactions on Antennas and Propagation

    JF - IEEE Transactions on Antennas and Propagation

    SN - 0018-926X

    IS - 5

    ER -