First Results of Polarimetric Passive SAR Imaging

This paper describes the application of passive radar polarimetry from an airborne platform. In particular, it focuses on the exploitation of signals received with different polarized antenna elements. The signals are used to create Synthetic Aperture Radar images. We present an approach to combine the images in order to extract more information from the observed scene. The suppression of the direct signal interference, being a critical disturbance in passive radar, is also addressed in this paper. We show a simple method, which is able to remove the interference, thus improving the resulting image.

I. Introduction

One focus of passive radar research is on the development of systems onboard of moving (typically airborne) platforms [1]–[7]. The goal is to replicate in a passive radar context typical active airborne radar applications, such as Synthetic Aperture Radar (SAR) and Ground-Moving Target Indication (GMTI). A passive radar system (also called Passive Coherent Location (PCL)) typically consists of a communication or broadcast Transmitter (TX) (the so-called Illuminator of Opportunity (IO)) and a Receiver (RX) mounted on a stationary or moving platform. The RX receives the direct signal from the IO and signal echoes reflected from targets and clutter. Typical IOs are broadcast TXs, e.g. Digital-Video-Broadcast-Terrestrial (DVB-T), Frequency Modulated (FM), or Digital-Video-Broadcast-Satellite (DVB-S) [8], [9], and communication transmitters, e.g. WiFi or Long Term Evolution (LTE), 5G, etc. [10], [11].