Simplified Analytical Approach for an Airborne Bent Wire Ground Penetrating RADAR Antenna System

Abstract

In this paper, modified analytical equations for the total electric field intensity in the far field region of a 10 MHz bent wire antenna have been proposed. The antenna system is meant for the airborne ground penetrating RADAR application for bedrock survey. This bent antenna is having vertical, slant and horizontal segments joined together along with the parasitic element. The current in the antenna wire is assumed to be a sinusoidal distribution which drops to zero at the ends. Current in both the energized and parasitic elements contribute to the fields in the far field region of the antenna system. Separate field equations for the various segments of the antenna system have been derived and finally summed to obtain the required equation for the electric field intensity at the far field region of the antenna. The MATLAB R2017b© simulation results of the far field antenna analytical equations show good agreement with the HFSS© simulation results of the 10 MHz antenna system. Direct measurements of these radiation characteristics in a typical GPR environment present a lot of practical difficulties. In this work, the influence of the helicopter on the 10 MHz GPR antenna during the airborne survey, is simulated using EMPro© and analyzed. This placement analysis resuls from the simulation gives us the appropriate range of distance values that can be maintained between the helicopter and antenna during the glaciological survey before performing the real time survey. A tradeoff between scattering parameter (S11) and directivity is considered to propose the optimum distance. The overall antenna structure seems to be a promising candidate for low frequency airborne GPR glacier explorations.