Proposed design of search radar for thin wire detection

Abstract

In this paper we look at the scattering of electromagnetic waves from thin wires. We propose a vehicle mounted search radar system that rotates 360° about the vertical axis. Our wire of interest is lying on a lossy ground plane. It is generally flat but has many bends, which gives it a vertical extent. The system is designed using a wire scattering simulator to predict the response of a test wire to various illuminations. The simulator makes use of the Method of Moments technique to predict the scattering of E&M waves in 3D. Several approximations make the tool fast and versatile. Among these is the general assumption of the wire as a metal filament (with infinitesimal radius). To include a lossy ground plane we suggest the use of the NEC2 simulator. In the development of this problem, we first look at scattering from a 3D thin wire. The conclusion of the simulation phase of this work is that the cardinal flash or glint response of the wire must be observed for the wire to be detectable. This response occurs when the wire is illuminated directly from the side. Because this scenario occurs at an unknown location as the vehicle passes by the wire, our design suggests the use of a spinning search radar. A brief experiment is performed using a search radar as a validation of concept. The observed glint response is shown and suggestions are made for how a practical system could reduce false alarms. We conclude the paper with a preferential configuration for a search radar suggested by simulation for this given application.