Measurement of Coordinates for a Cylindrical Target Using Times of Flight from a 1-Transmitter and 4-Receiver UWB Antenna System

This paper presents a new UWB impulse radar system consisting of a central radiating antenna (1.9 GHz center frequency, 2 GHz bandwidth) and four receiving antennas designed for the detection and location of dielectrically large objects with dimensions comparable to the spatial dimensions of the probe pulse. Together with the radar system, a solution method for determining the coordinates for detected targets is developed based on the time of flight of the probing pulse along raypaths from the radiating antenna to the object, and then reflected to each of the receiving antennas. An algorithm based on Pearson’s correlation coefficient is used to accurately determine time of flight of the signals scattered by the object. The antenna geometry makes it possible to use simple trigonometry and Heron’s formula, to calculate the coordinates of the reflecting bright spot on a target. The algorithm has been tested by numerical simulations, and by experiments with a cylindrical metallic object (diameter 10 cm), and a plastic-cased PMN-2 landmine buried in natural clay soil. For the experiment, GPR signals were acquired on a 4 x 4 square grid at 10-cm step from a height of about 30 cm above the ground. The system detected the test object in all positions and the positioning error in majority is equivalent to the object size.