Stored energy in general antenna system: A new approach

Alzahed, Abdelelah M.; Mikki, Said; Antar, Yahia M. M.

doi:10.1109/eucap.2016.7481171

Cited by 10 publications

(12 citation statements)

References 5 publications

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“…where P is the principal Cauchy value operator and δ the Dirac delta function, the relations (39) and (41) when summed over all radiation modes jointly imply the existence of the following antihermitian component…”

Section: The Nonlocal Antenna System Radiation Pattern In Momentum Spacementioning

confidence: 99%

Nonlocal Antenna Theory - Part I: Foundations

Mikki¹

2020

Preprint

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Section: The Nonlocal Antenna System Radiation Pattern In Momentum Spacementioning

confidence: 99%

Nonlocal Antenna Theory - Part I: Foundations

Mikki¹

2020

Preprint

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Section: Localized Energy: Motivations and General Considerationsmentioning

confidence: 99%

“…Consequently, it was suggested in [30,31] that stored energy and reactive energy should be distinguished from each other. A more useful definition of stored energy briefly proposed in [30] and further developed in [25][26][27] was to define stored energy as recoverable energy, i.e., the energy that can be retrieved from the antenna system after switching off its steady-state source. In this paper, we focus on the second energy type listed above, localized energy, which we consider an independent energy form distinct from both reactive and stored energy.…”

Section: Motivation and Backgroundmentioning

confidence: 99%

“…It is well known that the total radiation energy in an unbounded exterior region is infinite. That is, if the exterior domain is denoted by V R , where R is the maximum dimension of V R , then the following divergence holds for any radiating antenna [11,31,25,26] lim…”

Section: Poynting Localized Energy: the Fundamental Theorymentioning

confidence: 99%

“…Also in traditional RF and microwave antenna engineering, localized energy has been singled out as one of the main principles behind ultrawide band (UWB) performance [20,21]. Therefore, it has become essential to look into the near-fields of the antennas more comprehensively and focus on aspects like localized energy, moving beyond the standard notions of reactive-energy and antenna-Q factors [22][23][24][25][26][27].The subject of localized energy was recently treated from a more general perspective, that of the Weyl (plane-wave) expansion [28,29], which was used to propose a spacetime spectral theory of localized energy in [30,31]. Localized energy in the near-field interaction zone was also analyzed and estimated in [32] for strongly-coupled wire antennas.…”

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confidence: 99%

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On Localized Antenna Energy in Electromagnetic Radiation

Mikki¹,

Sarkar²,

Antar³

2019

PIER M

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We provide a general and rigorous formulation of antenna localized electromagnetic radiation energy in generic antenna systems based on Poynting flow instead of the spectral approach proposed earlier. The main theory is first developed using the principles of energy-momentum conservation and the center-of-energy theorem, culminating in the derivation of a direct localized energy expression. It is rigorously established that this expression satisfies the main features expected of physical energy, mainly positive definiteness and regularity. The obtained formula involves only the radiated fields (no current or charge) source and is easier to compute using specialized direct time-domain EM solvers. The proposed approach is expected to play a role in understanding energy localization in coupled antennas and shed light on gain enhancement methods. LOCALIZED ENERGY: MOTIVATIONS AND GENERAL CONSIDERATIONSThe subject of localized energy has emerged in recent years as one of the potential critical domains projected to play increasingly important roles in various applications. For example, we mention 5G and mmWave technologies, which are accompanied by interactions and energy exchange at multiple physical scales, often in dense and complex electromagnetic environments; indeed, systems like Ultra-Dense Networks (UDN) and massive MIMO involve interactions in the near-zone and hence increased localization [1,2]. Also, it is now established that near-field nano-optics, subwavelength imaging, plasmonics, and optical antennas all involve highly nontrivial processes of local energy enhancement [3,4]. Electromagnetic energy localization has also been studied in depth within the context of condensed matter physics [5] and is a familiar subject in periodic structures like photonic crystals. Energy localization is now seen as a fundamental factor in electromagnetic therapy in general [6] and microwave hyperthermia in particular [7]. However, while looking into the electromagnetic energy in the near-field of antennas, the applied electromagnetics community mostly focuses the attention towards the "reactive energy" for antennas [8][9][10][11][12][13][14][15]. It should be noted here that near-field focusing is another classical antenna application where energy localization is essential [16][17][18], and the same is true for the closely related subject of wireless power transfer [19]. Also in traditional RF and microwave antenna engineering, localized energy has been singled out as one of the main principles behind ultrawide band (UWB) performance [20,21]. Therefore, it has become essential to look into the near-fields of the antennas more comprehensively and focus on aspects like localized energy, moving beyond the standard notions of reactive-energy and antenna-Q factors [22][23][24][25][26][27].The subject of localized energy was recently treated from a more general perspective, that of the Weyl (plane-wave) expansion [28,29], which was used to propose a spacetime spectral theory of localized energy in [30,31]. Localized energy in th...

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Space‐time analysis of energy localization: A Poynting flow perspective with applications to pattern reconfigurable dipoles

Sarkar

Mikki

Antar

2019

Int J RF Microw Comput Aided Eng

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In this paper, we explore the dynamics of electromagnetic energy, especially in the near‐field region of radiating antennas, from a fundamental perspective (ie, no limitations on antenna shape and nature of excitation signal) and identify some key future research directions. First, we provide a comprehensive critique of the frequency‐domain reactive energy and circuit‐theoretic Q‐factor based approach, which is predominantly adopted in literature. In this way, we emphasize on the importance of adopting a general time‐domain approach to characterize the near‐field electromagnetic energy of arbitrary antennas. Next, we revisit the inherent ambiguities associated with the Poynting power‐flux term in the context of electromagnetic energy, and point out the nonuniqueness of the reactive energy, conventionally obtained by subtracting the far‐field radiation density from the total electromagnetic energy density around antennas. Furthermore, we discuss the concept of Poynting localized energy and its potential integration with FDTD techniques, and investigate its space‐time behavior for a Yagi‐Uda principle based pattern reconfigurable dipole system.

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Stored energy in general antenna system: A new approach

Cited by 10 publications

References 5 publications

Nonlocal Antenna Theory - Part I: Foundations

Nonlocal Antenna Theory - Part I: Foundations

On Localized Antenna Energy in Electromagnetic Radiation

Space‐time analysis of energy localization: A Poynting flow perspective with applications to pattern reconfigurable dipoles

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