Ultra-wideband ground penetrating radar with orbital angular momentum control

Abstract

Ultra-wideband (UWB) ground penetrating radar (GPR) is an effective, widely used tool for detection and mapping of buried targets. However, traditional ground penetrating radar systems struggle to resolve and identify congested target configurations and irregularly shaped targets. This is a significant limitation for many municipalities who seek to use GPR to locate and image underground utility pipes. This research investigates the implementation of orbital angular momentum (OAM) control in an UWB GPR, with the goal of addressing these limitations. Control of OAM is a novel technique which leverages an additional degree of freedom offered by spatially structured helical waveforms. This paper examines several free-space and buried target configurations to determine the ability of helical OAM waveforms to improve detectability and distinguishability of buried objects including those with symmetric, asymmetric, and chiral geometries. Microwave OAM can be generated using a uniform circular array (UCA) of antennas with phase delays applied according to azimuth angle. Here, a four-channel network analyzer transceiver is connected to a UCA to enable UWB capability. The characteristic phase delays of OAM waveforms are implemented synthetically via signal processing. The viability demonstrated with the method opens design and analysis degrees of freedom for penetrating radar that may help with discerning challenging targets, such as buried landmines and wires.