Notes on the quality factor and bandwidth of radiating systems

Johan Sten, Arto Hujanen

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)

Abstract

This article attempts to clarify the concept of quality factor (Q) in connection with ideal radiating systems. Three different aspects are covered: Q (i) as a relation between the stored energy and radiated power in the modes corresponding to a given radiation field outside a spherical source volume, (ii) as a function of the measurable impedance or admittance and (iii) as a function of the bandwidth of a resonated system. The first approach yields a theoretical lower limit: the larger the sphere, the more inconceivable in practice. The second approach approximates the observable stored energy and incorporates the minimum energy necessary for the transport of energy from the feed point to the region outside the circumscribing sphere. The third method yields the antenna Q on condition that the input impedance corresponds to a single resonance phenomena.
Original languageEnglish
Pages (from-to)189-195
JournalElectrical Engineering
Volume84
Issue number4
DOIs
Publication statusPublished - 2002
MoE publication typeA1 Journal article-refereed

Fingerprint

Quality Factor
Bandwidth
Energy
Impedance
Antennas
Radiation
Antenna
Necessary

Keywords

  • quality factor
  • antennas
  • stored energy
  • bandwidth
  • input inpedance

Cite this

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title = "Notes on the quality factor and bandwidth of radiating systems",
abstract = "This article attempts to clarify the concept of quality factor (Q) in connection with ideal radiating systems. Three different aspects are covered: Q (i) as a relation between the stored energy and radiated power in the modes corresponding to a given radiation field outside a spherical source volume, (ii) as a function of the measurable impedance or admittance and (iii) as a function of the bandwidth of a resonated system. The first approach yields a theoretical lower limit: the larger the sphere, the more inconceivable in practice. The second approach approximates the observable stored energy and incorporates the minimum energy necessary for the transport of energy from the feed point to the region outside the circumscribing sphere. The third method yields the antenna Q on condition that the input impedance corresponds to a single resonance phenomena.",
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Notes on the quality factor and bandwidth of radiating systems. / Sten, Johan; Hujanen, Arto.

In: Electrical Engineering, Vol. 84, No. 4, 2002, p. 189-195.

Research output: Contribution to journalArticleScientificpeer-review

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AU - Sten, Johan

AU - Hujanen, Arto

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AB - This article attempts to clarify the concept of quality factor (Q) in connection with ideal radiating systems. Three different aspects are covered: Q (i) as a relation between the stored energy and radiated power in the modes corresponding to a given radiation field outside a spherical source volume, (ii) as a function of the measurable impedance or admittance and (iii) as a function of the bandwidth of a resonated system. The first approach yields a theoretical lower limit: the larger the sphere, the more inconceivable in practice. The second approach approximates the observable stored energy and incorporates the minimum energy necessary for the transport of energy from the feed point to the region outside the circumscribing sphere. The third method yields the antenna Q on condition that the input impedance corresponds to a single resonance phenomena.

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