Singular edge behavior: To impose or not impose?that is the question

Ufimtsev, Pyotr Ya.; Khayatian, B.; Rahmat‐Samii, Y.

doi:10.1002/(sici)1098-2760(20000220)24:4<218::aid-mop3>3.0.co;2-i

Cited by 10 publications

(10 citation statements)

References 2 publications

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“…No further mathematical support for this edge behavior is brought here. However, the reader is referred to reference [13] to examine in detail the more accurate representation of edge behavior which is based on geometry as well as the source illuminating the scatterer. This appendix is dedicated to discussing and demonstrating that a large number of sample points in MoM TE analysis is required to characterize cancellation behind an scatterer (deep shadow zone) where incident and scattered field need to nearly cancel each other.…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, we can conclude that antenna pattern is unaffected by edge currents at the gap locations having integrated the current over the scatterer as defined by (13). However, edge currents may become more significant in cross-polarization analysis since the cross-pol level is substantially lower than that of co-pol.…”

Section: Antennamentioning

confidence: 91%

“…This observation is, in fact, very significant since in many studies, edge condition is generally prescribed prior to analytically determining the edge current behavior. In fact, it is shown in [13] that the edge condition is itself a conditional behavior, not only depending on the polarization, but also on the amplitude, and direction of incident field. For a double edge scenario, where one edge shadows another, the "TM edge condition" is different, too.…”

Section: Required Number Of Panelsmentioning

confidence: 99%

“…We try to verify the claim that the edge behavior for TM case near closely spaced double edges may somewhat be different from what is conventionally thought as TM singularity edge condition (also refer to[13]). Three scenario of multiple edges are considered where the currents on the scatterers Downloaded by [York University Libraries] at 17:00 03 January 2015…”

mentioning

confidence: 95%

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Characteristics of Dual Reflector Antennas With Gaps Between the Panels Forming the Subreflector: MOM and PO Analysis

Khayatian

Rahmat‐Samii

2000

Journal of Electromagnetic Waves and Applications

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Beam shaping is primarily performed by shaping the main reflector. An alternative way to shaping the main reflector is to shape the subreflector in a dual reflector system where mechanically movable panels can be deployed. Panels placed on the subreflector can potentially place their own signature on the antenna pattern, a topic which is investigated in this paper. To visualize and categorize generalized panel alignments as a result of panel movements, MoM and PO/PO methods are devised and applied to 2-D geometries based on TM and TE analysis. It should be noted that the panel movements on the subreflector create gaps between the panels which would also increase antenna cross polarization levels which is not addressed here due to 2-D nature of the analysis. Consequently, this study will focus on the antenna pattern characteristics and the required number of panels in conjunction with minimizing grating/sidelobe signature left by the panels displacements with gaps in axial and lateral directions. In addition, antenna gain loss is quantified based on gap sizes between the panels. Current distribution on the reflector antenna is also studied for both TM and TE polarization and several of their key features are examined based on PO/PO and MoM analysis.

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Section: Resultsmentioning

confidence: 99%

Section: Antennamentioning

confidence: 91%

Section: Required Number Of Panelsmentioning

confidence: 99%

mentioning

confidence: 95%

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Characteristics of Dual Reflector Antennas With Gaps Between the Panels Forming the Subreflector: MOM and PO Analysis

Khayatian

Rahmat‐Samii

2000

Journal of Electromagnetic Waves and Applications

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“…(For the -to-case, the Meixner expansion for the current density consists of a constant plus the expansion containing the leading order multiplicative factor.) Note that for certain excitations, any of the terms in (1) or (3) may be weighted by a coefficient of zero and consequently may be an inappropriate choice [19], [31]. As will be demonstrated below, even when the singular term is appropriate the Meixner expansion is usually not sufficient to produce high order behavior.…”

Section: Current Density Near the Tip Of An Infinite Wedgementioning

confidence: 99%

High Order Representations for Singular Currents at Corners

Bibby¹,

Peterson

Coldwell

2008

IEEE Trans. Antennas Propagat.

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In connection with a high order method of moments solution of integral equations for electromagnetic scattering, several approaches are investigated for representing current and charge densities in the vicinity of corners. One approach uses the first terms from the asymptotic solution for an infinite wedge to represent the current density. An alternative approach uses a traditional polynomial type of expansion, but augments it in the vicinity of corners with additional terms from the wedge result. The residual error obtained via the solution of an over-determined system of equations is used to judge the relative accuracy and efficiency of various approaches.Index Terms-Boundary element method, corner singularity, edge condition, high order basis functions, method of moments.

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Electromagnetic modelling of surfaces using method of moments with calculated phase mesh

Sawitzki¹

2015

IET Microwaves, Antennas & Propagation

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An alternative method of moments (MoM) solution for the radiation and scattering of surfaces is presented. One limit of MoM is the high number of basis functions needed, for the segmentation of electrically large surfaces. In this study, a conventional MoM solution is defined with quadrilateral surface patches and at least eight rooftop basis functions per wavelength. Galerkin testing is applied. This conventional MoM is extended with a new approach for the surface segmentation, called the calculated phase mesh (CPM). Efficient basis functions are chosen, and their positions on the surface are calculated with the incident field. In the theory part, the number of unknowns for scatterers with electrically large dimensions is reduced by 50%, compared with conventional MoM meshes with eight functions per wavelength. The incident field on surfaces is calculated numerically. This allows the application of CPM on scattering bodies with a variety of field sources, for example, both the near and the far field of antennas. The valid frequency range for the meshes is described. Three numerical examples are presented. In one example, the number of basis functions was reduced to 69.3%, compared with conventional MoM. The third example shows the application on three‐dimensional scattering bodies.

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Singular edge behavior: To impose or not impose?that is the question

Cited by 10 publications

References 2 publications

Characteristics of Dual Reflector Antennas With Gaps Between the Panels Forming the Subreflector: MOM and PO Analysis

Characteristics of Dual Reflector Antennas With Gaps Between the Panels Forming the Subreflector: MOM and PO Analysis

High Order Representations for Singular Currents at Corners

Electromagnetic modelling of surfaces using method of moments with calculated phase mesh

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