Ricerc@Sapienza

A closed-form model for the forward scatter radar (FSR) signal is presented with the goal to overcome the far-field (FF) limitation of the commonly used models. The proposed Fresnel closed-form (FCF) model, based on an approximation of the Helmholtz-Kirchhoff electromagnetic theory, correctly represents the received field of rectangular metallic targets crossing the baseline either in the short range or long range of the FSR transmitter and receiver.

In this work, a second-order phase approximation is introduced to provide an improved analytical model of the signal received in forward scatter radar systems. A typical configuration with a rectangular metallic object illuminated while crossing the baseline, in far-or near-field conditions, is considered. An improved second-order model is compared with a simplified one already proposed by the authors and based on a paraxial approximation. A phase error analysis is carried out to investigate benefits and limitations of the second-order modeling.

Recently, the exploitation of polarimetric diversity was considered as a way to improve target detection capability in passive radar systems. Specifically, it was shown that a locally adaptive Polarimetric - Generalized Likelihood Radio Test (PGLRT) detection scheme might represent an effective solution for passive radar exploiting different signals of opportunity. However, depending on the considered application, it could be highly computationally expensive. The present work presents an alternative lower-cost approach, based on a global adaptation of the polarimetric whitening filter.

Suitable strategies to exploit polarimetric diversity have been proved to be able to enhance the target detection capability of passive radar (or passive coherent location - PCL) systems. In this work, the authors describe a novel polarimetric adaptive detection scheme, based on a two-dimensional autoregressive model for the disturbance. The effectiveness of the proposed strategy is shown against experimental data collected by means of a FM radio based multi-channel PCL prototype.