Algorithm for the Computation of the Generalized Fresnel Integral

3The generalized Fresnel Integral appears as a canonical function in the uniform ray field representation of several high-frequency diffraction mechanisms, such as double wedge or vertex diffraction. Here we propose an algorithm for its calculation which is valid both for real and imaginary arguments as required for treating the general case in the uniform geometrical theory of diffraction framework.reservedmixedG. CARLUCCIO; F. PUGGELLI; M. ALBANIG., Carluccio; F., Puggelli; Albani, Matte

Time-Domain UTD Vertex Diffraction Coefficient for the Scattering by Perfectly Conducting Faceted Structures

4reservedmixedFederico Puggelli; Giorgio Carluccio; Matteo Albani; Filippo CapolinoPuggelli, Federico; Carluccio, Giorgio; Albani, Matteo; Filippo, Capolin

A Stochastic Extension of the Uniform Theory of Diffraction accounting for Geometrical Uncertainty or Surface and Edge Roughness

Abstract We present a stochastic extension of the Uniform Theory of Diffraction (UTD) which is capable to account for some uncertainty in the objects position or geometry, including roughness of surfaces or edges. Namely, we derive a solution for the electromagnetic field scattered by a perfectly conducting wedge whose faces are described as a statistical perturbation of a standard flat wedge. We give a uniform closed form expressions for the evaluation of the main statistical moments of the total electric field. The proposed statistical UTD formulation is suitable for engineering applications which involve UTD ray based codes. Some numerical examples highlight the accuracy and the effectiveness of the proposed ray description

An Open-Resonator Sensor for Measuring the Dielectric Properties of Antarctic Ice

In this paper, the theory behind the design of a microwave sensor for the accurate measurement of firn complex permittivity is presented. This class of microwave sensors, based on the open-coaxial re-entrant cavity method, is specifically designed to measure, by means of a simple and quick procedure, the complex permittivity profile of low loss materials. A calibration procedure is introduced to derive the complex permittivity of the material under measurement (MUM). Two specimens of this class of microwave sensors have been realized to sample the complex permittivity profile of a 106-m long ice core drilled from the Antarctic plateau at Concordia Station. The preliminary results of the on site measurement campaign are reported, showing very good agreement with theoretical models available in the literature

A hybrid numerical-composite UTD ray analysis of the radiation by large locally convex conformal arrays on large platforms

A new efficient hybrid numerical-composite UTD ray solution is presented to describe the radiation from an aperture formed by a large phased array antenna mounted conformally on a locally convex, but otherwise relatively arbitrary large platform. The aperture distribution is first obtained from a numerical solution for the array fields, which takes into account only the local array portion of the platform geometry, via the finite element-boundary integral (FE-BI) or the finite element method (FEM) based approaches. The electromagnetic (EM) equivalence theorem can be used to obtain the equivalent sources over the array aperture; the latter equivalent sources then radiate the array fields via a new composite uniform geometrical theory of diffraction (UTD) for arrays. This composite UTD describes the fields radiated by the entire array in terms of just a few rays arising from a point in the interior of the array aperture, and from specific points on the edges and corners of the array aperture boundary. These rays once launched from the array aperture then interact with the rest of the platform via the conventional UTD. Such an approach is far more efficient than solving the whole large complex array and its even larger platform simultaneously in some numerical fashion. Furthermore, it provides a physical insight into the array radiation mechanisms