35,725 research outputs found
Wave scattering from slit coupled cylindrical cavities with interior loading. II. Resonant mode expansion
No full textHigh-Frequency Green’s function for an infinite periodic line array of phased electric dipoles on an infinite stratified grounded dielectric slab
No full textThis paper deals with the spatial domain parametrization and physical interpretation of the asymptotic high-frequency solution pertaining to the asymptotic Green's function for an infinite periodic line array of phased parallel dipoles on an infinite stratified grounded dielectric slab. This Green's function is the basic constituent for deriving the array Green's function (AGF) for a semi-infinite array of dipoles, which is treated elsewhere. The linear array is synthesized as a superposition of smoothly phased periodicity-matched line sources. Each smoothly phased line source excites surface and leaky conical waves and associated coupled space wave contributions, which exhibit a transitional behavior at their appropriate shadow boundaries. The spectral integral which represents this space wave contribution is treated asymptotically by the use of an appropriate transition function
Wave scattering from slit coupled cylindrical cavities with interior loading. I. Formulation by ray-mode parametrization
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The Truncated Floquet Wave Diffraction Theory for Planar Phased Arrays: an Overview
No full textThis paper summarizes the research activities conducted at the University of Siena during the past six years on the truncated Floquet wave diffraction theory under the continuous guidance of Professor Felsen. During that period, we have analyzed and validated the diffraction phenomena in both the frequency and time domains pertaining to large planar phased arrays of different topologies and with quite general excitation profiles. The associated canonical dipole array Green's functions (AGFs) have been expressed in terms of constituents in a generalized high frequency asymptotic, periodicity-adapted, Floquet wave (FW)-modulated uniform geometrical theory of diffraction (UTD), which highlights the relevant wave physics. The present paper summarizes the essentials of these AGFs for large planar rectangular phased dipole arrays in free space, escalating sequentially from free-space geometries to multilayered media, with the eventual utilization of the Method of Moments (MoM) for practical applications. Particular emphasis is given to those aspects which are in progress, and have not yet appeared in print
Asymptotic high-frequency Green's function for a planar phased sectoral array of dipoles
No full textThis paper deals with the derivation and physical interpretation of a uniform high-frequency Green's function for a planar right-angle sectoral phased array of dipoles. This high-frequency Green's function represents the basic constituent for the full-wave description of electromagnetic radiation from rectangular periodic arrays and scattering from rectangular periodic structures. The field obtained by direct summation over the contributions from the individual radiators is restructured into a double spectral integral whose high-frequency asymptotic reduction yields a series of propagating and evanescent Floquet waves (FWs) together with corresponding FW-modulated diffracted fields, which arise from FW scattering at the array edges and vertex. Emphasis is given to the analysis and physical interpretation of the vertex diffracted rays. The locally uniform asymptotics governing this phenomenology is physically appealing, numerically accurate, and efficient, owing to the rapid convergence of both the FW series and the series of corresponding FW-modulated diffracted fields away from the array plane. A sample calculation is included to demonstrate the accuracy of the asymptotic algorithm
Three-dimensional Green’s function for planar rectangular phased dipole arrays
No full textThis paper deals with the construction, physical interpretation and application of a uniform high-frequency representation of array Green’s functions (AGFs) for planar rectangular phased arrays of dipoles. An AGF is the basic constituent for the full-wave description of electromagnetic radiation from large periodic structures. For efficient treatment of high-frequency phenomena, the AGF obtained by direct summation over the contributions from the individual radiators is globally restructured via the Poisson sum formula into a series of propagating and evanescent Floquet waves (FWs) together with corresponding FW-modulated diffracted waves, which arise from FW scattering at the array edges and vertexes. These results are obtained by high-frequency uniform asymptotics applied to the wave integrals generated by Poisson summation in the spatial or spectral domains. The final algorithm is physically appealing, numerically accurate, and efficient, owing to the rapid convergence of both the FW series and the series of corresponding FW-modulated diffracted fields away from the array plane. The use of the asymptotic AGF in the full-wave analysis of large slot arrays is discussed, with the inclusion of numerical results
High-frequency green's function for a semi-infinite array of electric dipoles on an infinite grounded stratified dielectric slab: Part III - Phase-matched wave interactions and numerical results
No full textThe particular effects of phase matching in interactions between different wave species and interaction mechanisms pertaining to the asymptotic Green's function for a semi-infinite phased array of parallel dipoles on an infinite grounded stratified dielectric slab are addressed. The two previous parts have lead to a grouping of certain asymptotic terms, which provides physically appealing interpretations of interacting wave processes that involve slab-modulated propagating (radiating) Floquet waves (FW), slab-guided leaky waves (LW), evanescent (nonradiating) FWs and surface waves (SW), together with their associated conical edge-coupled wave constituents. Special attention is now given to the role, in these wave interaction functions,of the difference between the propagating wave numbers (i.e., the degree of phase matching) that characterizes any pair of propagating FWs and LWs, and evanescent FWs and SWs. Cutoff transitions of FWs from the evanescent to the propagating regime are described also in terms of a second wave interaction function, structured similarly to the first. In connection with applications, the interaction between SWs and evanescent FWs, as well as FW transitions from evanescent to propagating, are discussed from the perspective of scan blindness in actual arrays. Various numerical studies highlight the role of phase matching in different proble
High-Frequency Green’s Function for a Semi-Infinite Array of Electric Dipoles on an Infinite Grounded Stratified Dielectric Slab. Part II: Spatial Domain Parameterization
No full textThis second part of a three-paper sequence deals with the spatial domain parametrization and physical interpretation of the relevant asymptotic high-frequency Green's function for a semi-infinite phased array of parallel dipoles on an infinite stratified grounded dielectric slab. This array Green's function (AGF) has been previously derived using a spectral domain formulation; the relevant asymptotic solution contains contributions associated with Floquet waves (Ms), and corresponding surface, leaky and diffracted waves excited at the array edge. Both the truncated-FW series and the series of corresponding diffracted field contributions exhibit excellent convergence properties. In the present paper, through application of the Poisson summation, the AGF for a plane-stratified grounded dielectric slab is developed in terms of space domain FW-dependent Kirchhoff radiation integrals which are synthesized by superposition of periodicity-modulated phased line sources oriented parallel to the edge. The asymptotic evaluation of each Kirchhoff radiation integral leads to a grouping of various asymptotic terms, which provide physically appealing interpretations of a variety of wave processes, encompassing slab-modulated propagating (radiating) and evanescent (non-radiating) FWs, slab-guided surface waves (SWs) or leaky waves (LWs), and their edge-coupled phenomenologies. The present space domain parametrization leads to the same asymptotics as that from the spectral domain parametrization, but allows a clear description of the spatial wave interaction processes. Index Terms-Diffraction, high frequency, patch array antennas
“Toward a full-Wave-Based Electromagnetics Approach to Chaotic Footprints in a Complex Deterministic Environment: A Test Model with Coupled Floquet-type and Ducted-type Mode Characteristics”
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