Evaluation of antenna Q

Collin, Robert; Rothschild, S.

doi:10.1109/tap.1964.1138151

Cited by 388 publications

(325 citation statements)

References 7 publications

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“…However, it is noted that hypothetical materials with conductivities (σ e ≥ 0, σ m ≥ 0) independent of frequency such that i (ω) = ei (ω) + σ e /ω and µ i (ω) = µ mi (ω) + σ m /ω, where ei (ω) and µ mi (ω) are equal to or greater than zero for all frequencies as well as equal to zero in a frequency window (band) about the ω of interest, should not be included in the exceptions because these nondispersive conductivities do not affect the internal energy [23]. They merely change the efficiency η in (8) to maintain the high accuracy of the inverse relationship in (8) between bandwidth and Q. This is further corroborated in the improved formulas (11) where a frequency independent σ e or σ m does not contribute to the Q-energy because (ω i ) = σ e = 0 and (ωµ i ) = σ m = 0.…”

Section: General Expressions For Quality Factormentioning

confidence: 99%

“…In 1964, Robert E. Collin, to whom this issue of PIER is dedicated, and S. Rothschild evaluated the Q of antennas by judiciously subtracting the infinite energy of the radiation field from the infinite energy of the total field of antennas to obtain a finite "reactive energy" of the antenna [8]. 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%

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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: General Expressions For Quality Factormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Yaghjian¹,

Gustafsson²,

Jonsson³

2013

PIER

View full text Add to dashboard Cite

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“…approaches the admittance of L L C R tank resonator and therefore C g has less influence on the propagation characteristics [18]. By applying Taylor series approximation, (1) becomes…”

Section: Theorymentioning

confidence: 99%

“…Here the structure acts as an open ended transmission line, so the zeroth mode frequency is determined by shunt circuit [18].…”

Section: Theorymentioning

confidence: 99%

“…The proposed antenna with dimension 0.0186λ 0 ×0.020λ 0 ×0.003λ 0 mm 3 has a zeroth order resonance at 503 MHz, which makes it electrically very small [18], where λ 0 is the free space wavelength corresponding to the resonant frequency. In addition the high gain wide band of the original bowtie antenna at higher frequencies [15] is retained.…”

Section: Introductionmentioning

confidence: 99%

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Modified Bowtie Antenna for Zeroth Order Resonance

Roshna¹,

Deepak²,

Sajitha³

et al. 2014

PIER C

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Abstract-A novel extremely compact Zeroth Order Resonator (ZOR) antenna with a chip inductor, for Digital Video Broadcasting-Handheld (DVB-H) application, is presented. The proposed antenna has a bowtie structure with an overall dimension of 0.0186λ 0 × 0.020λ 0 × 0.003λ 0 mm 3 at 503 MHz. The zeroth resonance property makes the resonant frequency to be independent of the antenna dimension. The 3 : 1 VSWR bandwidth of the antenna is 39 MHz and offers an omnidirectional radiation pattern. A 99.1% reduction in the overall area of the structure is achieved compared to a conventional circular patch antenna operating at the same frequency.

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Comparison of time and frequency domain numerical modelling of outbound and local power from two perpendicularly oriented, electrically small TM dipoles

Liu

Ong

Grimes

et al. 1999

Int. J. Numer. Model.

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Earlier work using the time dependent Poynting theorem has shown that the complete description of power in a multimodal radiation field requires the use of three numbers; two are sufficient only with a single modal field. Where three numbers are required it is not possible to correctly represent power as a complex number. In the common notation the third number is a suppressed phase angle; when multiple power fields are combined to form a single one it is essential to account for the suppressed phase angles. The differences in power calculations using the time and frequency domain power theorems are manifest in determination of the energy flow that remains local to the source, oscillating between the near field and source, which does not form part of the far field power. In this paper we numerically model, using commonly accepted frequency and time domain techniques, the simplest antenna design that clearly illustrates the differences between time and frequency domain representations of reactive power. We calculate and contrast the instantaneous and the steady‐state far field and local powers emitted from two identical, perpendicularly oriented electrically small TM dipoles as a function of relative phase between the two dipoles. Copyright © 1999 John Wiley & Sons, Ltd.

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Evaluation of antenna Q

Cited by 388 publications

References 7 publications

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Modified Bowtie Antenna for Zeroth Order Resonance

Comparison of time and frequency domain numerical modelling of outbound and local power from two perpendicularly oriented, electrically small TM dipoles

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