Illustrations of New Physical Bounds on Linearly Polarized Antennas

Gustafsson, Mats; Sohl, Christian; Kristensson, Gerhard

doi:10.1109/tap.2009.2016683

Cited by 159 publications

(179 citation statements)

References 11 publications

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“…A secondary purpose of the paper is to correct the error, found by Jonsson and Gustafsson [15], that was made in the derivation of one of the main lower-bound formulas in [13] and resulted in that formula applying exactly to only ellipsoidal volumes. (All the comparisons that were made in [13] with the sum-rule lower bounds of Gustafsson, Sohl, and Kristensson [12,16] showed excellent agreement because the comparisons were made for different shaped ellipsoids.) † The Q lower-bound formulas derived in this paper, like those in [13,14], are limited to electrically small antennas with ka 5, where a is the minimum circumscribing radius of the antenna volume V a and k is the free-space wavenumber.…”

Section: Introductionmentioning

confidence: 85%

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: 85%

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

Yaghjian¹,

Gustafsson²,

Jonsson³

2013

PIER

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“…The results in [6,9] are used to derive the physical bounds for antennas whose shapes are limited to rectangular regions 2 . The maximum D/Q ratio is computed with closed form expressions assuming main radiation direction orthogonal to the rectangle.…”

Section: Physical Boundsmentioning

confidence: 99%

“…The performance of the structures considered here has been compared with the physical bounds for rectangular structures [6,9,10], and structures with a rectangular ground plane [8]. This comparison shows that the optimized structures perform close to their physical bounds.…”

Section: Introductionmentioning

confidence: 99%

Antenna Bandwidth Optimization With Single Frequency Simulation

Cismasu

Gustafsson

2014

IEEE Trans. Antennas Propagat.

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A method to compute antenna Q using an electromagnetic simulation at a single frequency is described. This method can easily be integrated into global optimization algorithms. In this way the optimization time of some antenna parameters, e.g., bandwidth, may be signicantly reduced. The method is validated by direct comparison with the physical bound of the analyzed structure. Numerical examples for rectangular antennas and antennas with a rectangular ground plane illustrate the integration of the method into a genetic algorithm. The results predicted by optimization agree very well with those obtained using a commercial electromagnetic solver. These results suggest that the method can be used to yield antennas with Q factors within 20 % of their corresponding physical bound.

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“…Hence, under the assumptions of linearity, continuity, time-translational invariance and passivity, sum rules can be derived from the analytic properties of the forward scattering dyadic, see e.g., [25,26], and have also applications in antenna theory, see e.g., [11,12,24,29,30]. In [23], similar relations are used to determine the ultimate thickness to bandwidth ratio of radar absorbers.…”

Section: Introductionmentioning

confidence: 99%