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The optimization of the directivity of the difference patterns in monopulse array antennas is considered. A subarrayconfiguration is used in order to avoid the need for the implementation of two separate feed networks. An hybrid differential evolution method is applied to contemporarily determinate the weights of the subarrays and the group membership of the elements. Some numerical results are provided together with a validation comparison with data previously published in the literature. 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.

A new approach for the inversion of synthetic and measured scattered data is proposed in this paper. The approach is based on an iterative technique in which the nonlinear equations of the inverse scattering problem are solved within the p-th order Born approximation. A regularization scheme based on an Inexact-Newton method is applied. Several numerical simulations and experimental results are reported. Multiple separated dielectric cylinders are localized and reconstructed in a noisy environment. (c) 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.

A new inverse scattering method is assessed against some of the real input data measured by the Institut Fresnel, Marseille, France. The method is based on the application of an Inexact-Newton method to the Lippmann-Schwinger integral equation of the inverse scattering problem within the second-order Born approximation. The regularization properties of the approach are evaluated by considering the reconstruction of multiple dielectric cylinders.

Phaseless data are used to evaluate the application of an electromagnetic inverse-scattering-based procedure for the detection of cylindrical inhomogeneities, which are schematized as multylayer infinite dielectric cylinders with elliptic cross sections. The electromagnetic inverse problem is recast as a global optimization problem and iteratively solved by an efficient memetic algorithm, which combines deterministic and stochastic concepts. Moreover, a recursive analytical procedure is used for the forward scattering computation. The possibility of localizing and reconstructing the scatterers by using phaseless input data, which would greatly simplify the design of the imaging apparatus, is evaluated both with reference to synthetically produced data and by means of experimental data obtained by a microwave tomograph.

In this paper, the field prediction inside biological bodies exposed to electromagnetic incident waves is addressed by considering inverse scattering techniques. In particular, the aim is to evaluate the possibility of limiting the test area in order to strongly reduce the computational time, ensuring, at the same time, a quite accurate solution. The approach is based on separating the scattering contributions of the region under test and the other part of the biological body. The starting point is represented by the inverse-scattering equations, which are recast as a functional to be minimized. A Green's function approach is then developed in order to include an approximate knowledge (a model) of the biological body. The possible application of the approach for diagnostic purposes is also discussed.

The application of a global optimization procedure to the detection of buried inhomogeneities is studied in the present paper. The object inhomogeneities are schematized as multilayer infinite dielectric cylinders with elliptic cross sections. An efficient recursive analytical procedure is used for the forward scattering computation. A functional is constructed in which the field is expressed in series solution of Mathieu functions. Starting by the input scattered data, the iterative minimization of the functional is performed by a new optimization method called memetic algorithm. (c) 2003 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.

The synthesis of sum and difference patterns of monopulse antennas is considered in this paper. The synthesis problem is recast as an optimization problem by defining a suitable cost function based on the constraints on the side lobe levels. A subarray configuration is considered and the excitations of the difference pattern are approximately determined. The optimization problem is efficently solved by a differential evolution algorithm, wich is able to contemporarly handle real and integer unknowns. Numerical results are reported considering classic array configurations previusly assumed in the literature.

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A novel two-step inverse-scattering technique is proposed for through-the-wall microwave imaging. The approach is based on a regularization scheme developed in the framework of variable-exponent Lebesgue spaces, which enhances the quality of the reconstruction by properly tuning the exponent function that defines the adopted norm. Such a function is built directly from the available data by using a beamforming technique based on a delay-and-sum scheme. After an initial numerical assessment, the approach is validated against experimental measurements in a laboratory environment, with targets placed behind a brick wall. Measured data are collected in time domain by scanning the transmitting and receiving antennas in a multi-illumination and multi-view arrangement. The processing of experimental data is performed in the frequency domain, where data at multiple frequencies are extracted by a Fast Fourier Transform (FFT) and simultaneously processed by the imaging algorithm. The obtained imaging results confirm the good reconstruction capabilities of the developed inverse-scattering scheme in the case of both metallic and low-contrast targets.