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Wave scattering from slit coupled cylindrical cavities with interior loading. II. Resonant mode expansion
No full textWave scattering from slit coupled cylindrical cavities with interior loading. I. Formulation by ray-mode parametrization
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Three-dimensional Green’s function for planar rectangular phased dipole arrays
Full text linkThis 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
Asymptotic high-frequency Green's function for a planar phased sectoral array of dipoles
Full text linkThis 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
Frequency domain Green's function for a planar periodic semi-infinite phased array. Part I: truncated Floquet wave formulation
Full text linkThis two-part sequence deals with the derivation and physical interpretation of a uniform high-frequency solution for the field radiated at finite distance by a planar semi-infinite phased array of parallel elementary electric dipoles. The field obtained by direct summation over the contributions from the individual radiators is restructured into a double series of wavenumber spectral integrals whose asymptotic reduction yields a series encompassing propagating and evanescent Floquet waves (FW's) together with corresponding diffracted rays, which arise from scattering of the FW at the edge of the array. The formal aspects of the solution are treated in the present paper (Part I). They involve a sequence of manipulations in the complex spectral wavenumber planes that prepare the integrands for subsequent efficient and physically incisive asymptotics based on the method of steepest descent. Different species of spectral poles define the various species of propagating and evanescent FW. Their interception by the steepest descent path (SDP) determines the variety of shadow boundaries for the edge truncated FW. The uniform asymptotic reduction of the SDP integrals, performed by the Van der Waerden procedure and yielding a variety of edge-diffracted fields, completes the formal treatment. The companion paper (Part II [1]) deals with the phenomenology of these local diffracted waves based on the present formal solution. The phenomenology encompasses all possible contributions of propagating and evanescent edge diffractions excited by propagating and evanescent FW's. The outcome is a physically appealing and accurate high-frequency algorithm, which is numerically efficient due to the rapid convergence of both the FW series and the series of relevant diffracted fields. This is demonstrated by numerical examples for radiation from a strip array in Part II. ©2000 IEEE
Frequency domain Green's function for a planar periodic semi-infinite phased array. Part II: diffracted wave phenomenology
Full text linkThis second part of a two-paper sequence deals with the physical interpretation of the rigorously derived high-frequency asymptotic wave-field solution in Part I, pertaining to a semi-infinite phased array of parallel dipole radiators. The asymptotic solution contains two parts that represent contributions due to truncated Floquet waves (FW's) and to the corresponding edge diffractions, respectively. The phenomenology of the FW-excited diffracted fields is discussed in detail. All possible combinations of propagating (radiating) and evanescent (nonradiating) FW and diffracted contributions are considered. The format is a generalization of the conventional geometrical theory of diffraction (GTD) for smooth truncated aperture distributions to the truncated periodicity-induced FW distributions with their corresponding FW-modulated edge diffractions, Ray paths for propagating diffracted waves are defined according to a generalized Fermat principle, which is also valid by analytic continuation for evanescent diffracted ray fields. The mechanism of uniform compensation for the FW-field discontinuities (across their truncation shadow boundaries) by the diffracted waves is explored for propagating and evanescent FW's, including the cutoff transition from the propagating to the evanescent regime for both the PW and diffracted constituents. Illustrative examples demonstrate: 1) the accuracy and efficiency of the high-frequency algorithm under conditions that involve the various wave processes outlined above and 2) the cogent interpretation of the results in terms of the uniform FW-modulated GTD
Radiation Properties of Planar Antennas Array Based on Certain Categories of Aperiodic Tilings
No full textTwo-dimensional aperiodic tilings are collections
of polygons, devoid of any translational symmetries, capable of
covering a plane without gaps and overlaps. Although aperiodic,
these structures can exhibit order and symmetry in an extended
sense. In this paper, we study the radiation properties of planar
antenna arrays based on certain categories of two-dimensional
aperiodic tilings that illustrate diverse aspects of aperiodic order.
Background material on aperiodic tilings and their known elec-
tromagnetic properties is reviewed. Results are illustrated to
highlight the effects of aperiodic order in the antenna array
radiation properties. Potential applications are also envisage
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