Broadband counterwound spiral antenna for subsurface radar applications

Abstract

Subsurface radar, also known as ground-penetrating radar, is increasingly being used for the detection and location of buried objects such as mines and structures that are found within the upper regions of the earth's surface. The thesis gives a review of the work done to date in this area, laying emphasis on the possible antenna designs to match the range of intended applications. An overall design strategy is outlined, together with a more detailed treatment of the ground-penetrating radar subsystems and topics which are relevant to effective subsurface radar operation. These include the dielectric properties of earth materials, the choice of frequency of operation, as well as the design and construction of suitable antennas. Finally, a new antenna structure called the counter-wound spiral antenna, which is suitable for subsurface radar applications, is examined. The counter-wound spiral antenna has a broad bandwidth and a linear polarization with a controllable plane of polarization from a planar geometry. It has an electronically steerable plane of polarization. This unique property offers a reduction in antenna polarization loss and allows the extraction of maximum information from the target scattered echo.