Model-based Optimization of Compressive Antennas for High-Sensing-Capacity Applications

This paper presents a novel, model-based compressive antenna design method for high sensing capacity imaging applications. Given a set of design constraints, the method maximizes the sensing capacity of the compressive antenna by varying the constitutive properties of scatterers distributed along the antenna. Preliminary 2D design results demonstrate the new method's ability to produce antenna configurations with enhanced imaging capabilities

Multi-Resolution Subspace-Based Optimization Method for the Retrieval of 2D Perfect Electric Conductors

Perfect Electric Conductors (PECs) are imaged integrating the subspace-based optimizationmethod (SOM) within the iterative multi-scaling scheme (IMSA). Without a-priori information on the number or/and the locations of the scatterers and modelling their EM scattering interactions with a (known) probing source in terms of surface electric field integral equations, a segment-based representation of PECs is retrieved from the scattered field samples. The proposed IMSA-SOM inversion method is validated against both synthetic and experimental data by assessing the reconstruction accuracy, the robustness to the noise, and the computational efficiency with some comparisons, as well

A Novel Approach for Qualitative Imaging of Buried PEC Scatterers

A new linear approach for support reconstruction of impenetrable objects is described and tested in case of scattered field data collected in Ground Penetrating Radar measurement configuration. Starting from the considerations that in high conductivity scatterers the currents induced inside the scatterers are only localized on its boundary and that they take up only few pixels of the entire investigation domain, a sparsity promoting inversion technique is formulated. The flexibility of the approach allows to counteract the specific difficulty to work under “aspect limited” measurement configurations, as the one at hand. Examples with numerical noisy data are given to demonstrate and validate the effectiveness of the method in localizing and in retrieving the shape of the unknown objects buried in lossy soil

A Simple Quantitative Inversion Approach for Microwave Imaging in Embedded Systems

In many applications of microwave imaging, there is the need of confining the device in order to shield it from environmental noise as well as to host the targets and the medium used for impedance matching purposes. For instance, in MWI for biomedical diagnostics a coupling medium is typically adopted to improve the penetration of the probing wave into the tissues. From the point of view of quantitative imaging procedures, that is aimed at retrieving the values of the complex permittivity in the domain under test, the presence of a confining structure entails an increase of complexity of the underlying modelling. This entails a further difficulty in achieving real-time imaging results, which are obviously of interest in practice. To address this challenge, we propose the application of a recently proposed inversion method that, making use of a suitable preprocessing of the data and a scenario-oriented field approximation, allows obtaining quantitative imaging results by means of quasi-real-time linear inversion, in a range of cases which is much broader than usual linearized approximations. The assessment of the method is carried out in the scalar 2D configuration and taking into account enclosures of different shapes and, to show the method’s flexibility different shapes, embedding nonweak targets

Electromagnetic Scattering From Two-Scatterers Using the Extended Propagation-Inside-Layer Expansion Method

In this paper, the electromagnetic scattering from two scatterers is analyzed from a rigorous integral formulation solved by the method of moments (MoM). G. Kubick´e has recently developed the E-PILE (Extended Propagation-Inside-Layer Expansion) method to calculate the scattering from an object above a rough surface for a two-dimensional problem. This method allows us to calculate separately and exactly the interactions between the object and the rough surface. The purpose of this paper is to extend the E-PILE method to a three-dimensional problem

Application of the CBF Method to the Scattering by Combinations of Bodies of Revolution and Arbitrarily Shaped Structures

In this paper, an algorithm is described which enables efficient analysis of electromagnetic scattering by configurations consisting of arbitrarily shaped conducting bodies and conducting bodies of revolution (BoR). The well-known problem resulting from the loss of azimuthal mode decoupling, when in addition to BoR geometry there exists a body that does not belong to the rotational symmetry of the BoR, is circumvented by the use of characteristic basis function (CBF) method. This however requires careful implementation of the method in order to obtain stable and efficient procedure

Harmonic Detection and Selectively Focusing Electromagnetic Waves onto Nonlinear Targets using Time-Reversal

Ultra-wide band radar is a growing interest for the enhanced capability of ranging, imaging, and multipath propagation. An ultra-wide band pulse imposed on a system provides a near impulse like response and is, therefore, more descriptive than a conventional monotonic pulse. Combining pulse inversion with ultra-wide band DORT (a French acronym for the decomposition of the time reversal operator) is a technique which could be used to for greater visibility of nonlinear targets via harmonic detection in the presence of larger linear scatterers. Energy can be selectively focused onto nonlinear scatterers in complex, inhomogeneous environments. This thesis1, will expand upon previous work, and demonstrate nonlinear detection and selective focusing with pulse inversion combined with DORT