Quality factor of general ideal antennas

Fante, Ronald L.

doi:10.1109/tap.1969.1139411

Cited by 219 publications

(139 citation statements)

References 7 publications

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“…Although Collin and Rothschild also limited their method to finding the lower bounds on the Q for spherical and circular cylindrical volumes, their work provides the fundamental understanding for not only the general definitions of quality factor for any antenna [9][10][11] but also for the lower bounds on the Q for antennas confined to an arbitrarily shaped volume [12,13].…”

Section: Introductionmentioning

confidence: 99%

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Yaghjian¹,

Gustafsson²,

Jonsson³

2013

PIER

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Abstract-General expressions for the quality factor (Q) of antennas are minimized to obtain lower-bound formulas for the Q of electrically small, lossy or lossless, combined electric and magnetic dipole antennas confined to an arbitrarily shaped volume. The lowerbound formulas for Q are derived for dipole antennas with specified electric and magnetic dipole moments excited by both electric and magnetic surface currents as well as by electric surface currents alone. With either excitation, separate formulas are found for the dipole antennas containing only lossless or "nondispersive-conductivity" material and for the dipole antennas containing "highly dispersive lossy" material. The formulas involve the quasi-static electric and magnetic polarizabilities of the associated perfectly conducting volume of the antenna, the ratio of the powers radiated by the specified electric and magnetic dipole moments, and the efficiency of the antenna.

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Section: Introductionmentioning

confidence: 99%

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Yaghjian¹,

Gustafsson²,

Jonsson³

2013

PIER

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“…, r ∈ V p (35) Comparing (32) and (34), it may be found that the perturbed fields can be determined by introducing an equivalent electric current source J (r) and an equivalent magnetic current source J m (r) in the region V p , as if the medium parameters had not changed in V p . This is what the compensation theorem implies.…”

Section: Channel Matrix In a Scattering Environmentmentioning

confidence: 99%

“…Considering that V j contains the region V p and the sources producing the differential fields ∆ E = E − E and ∆ H = H − H are given by (35), (39) may be written as…”

Section: Channel Matrix In a Scattering Environmentmentioning

confidence: 99%

“…To this purpose, another antenna quality factor, denoted by Q, is often introduced. This antenna Q is still defined by (52), but withW being replaced by the stored energy outside the circumscribing sphere of the antenna [17][18][19]35]. It can be shown that the ratios of gain G to Q for an arbitrary omni-directional antenna and an arbitrary directional antenna whose maximum size is 2a are bounded respectively by [19] …”

Section: The Best Possible Antenna Performancementioning

confidence: 99%

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Multi-Antenna Information Theory

Geyi¹

2007

PIER

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Abstract-It is well known that the performance of a wireless multiple-input and multiple-output (MIMO) system depends on the propagation channel. The propagation channel models can generally be divided into two different groups, the statistical models based on information theory and the site-specific models based on measurement or ray tracing. In this paper, a general procedure for predicting the MIMO channel model has been presented. Analytical expressions for the channel matrix elements in a general scattering environment have been derived from the statistical theory for a narrow-band electromagnetic field, and have been verified by numerical simulation and experiments. The limitations of information capacity of the MIMO wireless communication system imposed by the antennas have also been discussed, and analytical upper bounds on the information capacity in terms of the antenna parameters for multiple antenna system in free space have been obtained. Once the capacity of a MIMO system is specified, these upper bounds can serve as a criterion for estimating how many antennas are needed or how big the antenna must be to achieve the capacity.

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“…For example, they have been used to derive general properties of linear antennas such as the relations between the field modal amplitudes and the elements of the antenna's equivalent circuit (Chu, 1948), and to derive expressions for the antenna Q and the bandwidth (Fante, 1969;Yaghjian and Best, 2005). Moreover, multipole expansions in spherical, in cylindrical, and in Cartesian coordinates are the basis to calculate the probe-corrected far-field from measured or estimated values of the antenna near field (Hansen, 1988).…”

Section: Introductionmentioning

confidence: 99%

Efficient evaluation of antenna fields by a time-domain multipole analysis

Adam

Klinkenbusch

2009

Adv. Radio Sci.

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Abstract. The contribution describes a systematic method to efficiently determine frequency-domain electromagnetic antenna fields and characteristics for a broad spectrum via a single time-domain (e.g., Finite-Difference Time-Domain, FDTD) calculation. From a time-domain simulation of an antenna driven by a wide-band signal, a single modified Fourier transformation yields the frequency-domain multipole amplitudes. The corresponding multipole expansions are valid for the entire spectrum of the input pulse and at any point outside a minimum sphere enclosing the antenna. This allows a computationally cheap and elegant post-processing of arbitrary antenna characteristics. As an example of use the method is applied to determine high-resolution threedimensional radiation patterns of an antipodal Vivaldi antenna.

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Quality factor of general ideal antennas

Cited by 219 publications

References 7 publications

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Multi-Antenna Information Theory

Efficient evaluation of antenna fields by a time-domain multipole analysis

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