Low-frequency computational electromagnetics for antenna analysis

Burke, G.J.

doi:10.1109/5.119565

Cited by 16 publications

(3 citation statements)

References 71 publications

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“…Some difficulties with NEC modelling of the interconnected [16] and complicated tower lattice elements have been reported in earlier works [3]. In view of the same, a previous work employed experimental approach with electromagnetically reduced scale model of 120 m tall towers.…”

Section: Models Employed In the Literaturementioning

confidence: 95%

Investigation on the Potential Rise and Currents in Insulated Mast Scheme with Single Tower During Stroke Interception

Kumar¹

2010

JLR

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Abstract:The insulated mast scheme for the lightning protection system can be found in a few practical designs. Many advantages over conventional protection system are some times envisaged. However, the technical literature on the analysis of such schemes and further quantification of their protection efficacy is rather scarce. As a first step to address this problem, the present work is taken up and the potential rise at the top and ground end currents in insulating mast scheme with single tower is investigated for several tower heights and pertinent values of other parameters. The quantities that are investigated are the potential difference across the insulation and ground end currents for both tower and the ground wires. Quantifications are carried out for the relevant range of stroke current front times. The influence of number of ground wires, their earthing location and to a limited extent, the length of the insulating support have been ascertained. Some relevant discussion on insulation strength is made. These findings are quite novel and aid in quantification of the practical efficacy of the insulated mast scheme. The level of induction to the support tower and possible flashover to the same are not in favour of this scheme.

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Section: Models Employed In the Literaturementioning

confidence: 95%

Investigation on the Potential Rise and Currents in Insulated Mast Scheme with Single Tower During Stroke Interception

Kumar¹

2010

JLR

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“…This approximation on the element shapes is made possible by the very low frequency range of interest for which elements can be represented with a good accuracy by equivalent resistances and inductances. However, such a wired model has been also used for lightning and antenna problems [3].…”

Section: B Modelisation Of a Cfrp Structurementioning

confidence: 99%

Modeling strategy for functional current return in large CFRP structures for aircraft applications

Revel¹,

Piche²,

Peres³

et al. 2008

2008 International Symposium on Electromagnetic Compatibility - EMC Europe

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The strong increase of utilization of CFRP materials in industry has deeply modified the methods of analysis and challenged the numerical tools. In electromagnetism, many issues arise from the replacement of metallic elements by CFRP ones, the main being the protection against direct and indirect effects of lightning. An other important issue is the sizing and optimization of functional current return path on a large structure as an aircraft fuselage. The object of this paper is to present an original approach for studying the current return in a partially metallic fuselage structure covered with CFRP panels in a frequency range comprised between the continuous current up to few tens of kHz. (Abstract) I. PRESENTATION OF THE PROBLEMIn aeronautic industry, metallic structure and fuselage handle the following important roles or functions : signal and fault current return, voltage reference for all electrical equipments, personal protection against electrical shocks, lightning and High Intensity Radiated Fields (HIRF) protection and antenna ground plane reference for the main electrical ones. The use of CFRP materials for fuselage and internal structural elements of an aircraft imposes to assess the correct handling of these functions when all were more easily achieved due to the high electrical conductivity of Aluminum and Titanium alloys. For the functional current (corresponding to the current of functioning equipments that returns through the structure), this results in two main issues. First, poor conducting structure may induce a voltage drop that will be lacking for equipments. Second, depending on the frequency, a certain critical amount of current will flow through CFRP assemblies, or junctions, resulting in local temperature increases with possible mechanical damages. The management of current return distribution over different elements of a large aeronautical structure (fuselage, frames, tracks, cross beams,…) should be tackled with care especially for the aircraft weight optimization. The numerical modeling appears to be an helpful way for current distribution prediction, with the objective to size and optimize the so called Electrical Structure Network (ESN).The critical point in the numerical modeling of such a system is the frequency range of interest. In the case of an aircraft, this range of frequency includes the DC (28V) and goes from 360 to 800 for the 115V AC power supply. This has leaded to analyze different methods available and adapted for such a problematic. II. MODELING STRATEGY A. Numerical methods reviewAfter an evaluation of several methods (FDTD, PEEC,…), our choice has been oriented towards BEM/MOM methods [1,2] for which a specific module has been developed to address the very low frequency range of concern. This choice has been done according to the method capability to model :• CFRP skin covered by metallic mesh• Internal metallic elements• Internal CFRP elements• Several sources with their amplitude and phase• Non-perfect connections (junctions) between internal, interface elements...

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“…A substantial amount of research has been conducted on MoM and the technique has matured into a very flexible full-wave simulation tool [6]. The Rao et al basis functions [7] and thin-wire approximations [8], [9] allow considerable freedom in modeling planar conductors and wire structures.…”

Section: A Mommentioning

confidence: 99%

Human proximity effects on circular polarized handset antennas in personal satellite communications

Colburn

Rahmat‐Samii

1998

IEEE Trans. Antennas Propagat.

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Satellite-based systems are the next step in mobile communications. Recently, several low and medium earth orbit mobile communication satellite systems have been proposed and are currently being deployed. For all these systems, high-performance circularly polarized antennas for the mobile terminals are of importance. Although considerable material is available on circularly polarized antennas, there is an absence of information on how the human's close proximity to the antenna affects the circular polarization purity of the radiated field. This paper presents an analysis of representative circularly polarized helical handset antennas. Although other physically less obtrusive circular polarized antennas are available for the handset, the helix is used because of its wide bandwidth properties and capability to provide both circular and linear polarization. Thus, this element could be used for handsets that are planned to work with both the terrestrial-based communications systems of today and the satellite-based communication systems of tomorrow. The intent is to characterize the effects the close proximity of a human head model has on the computed performance of the circular polarized antenna. The method of moments (MoM) and finitedifference time-domain (FDTD) numerical techniques are used to study various helix structures on top of a small box representing a handset. In order to be able to effectively apply FDTD, a novel square helix structure is introduced. Results computed with these two techniques are compared to illustrate the accuracy of each implementation. The results indicate significant polarization purity degradation caused by the presence of a human head. For the particular geometry simulated, the presence of a head model degraded the average axial ratio within a verticle 50 cone from 2.9 to 9.1 dB. This significant increase in axial ratio can have profound effects on link budgets.

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Low-frequency computational electromagnetics for antenna analysis

Cited by 16 publications

References 71 publications

Investigation on the Potential Rise and Currents in Insulated Mast Scheme with Single Tower During Stroke Interception

Investigation on the Potential Rise and Currents in Insulated Mast Scheme with Single Tower During Stroke Interception

Modeling strategy for functional current return in large CFRP structures for aircraft applications

Human proximity effects on circular polarized handset antennas in personal satellite communications

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