A Uas-Based Ultra-Wideband Radar System For Soil Moisture Measurements

A 2-18 GHz ultra-wideband radar system was designed for soil moisture measurements. We are integrating the system into a small-unmanned helicopter, with a maximum payload capacity of 5 kg. The radar's transmitter generates a highly linear frequency sweep signal based on a fast phase-locked loop and frequency multiplication. The antenna is a four-element array consisting of linearly polarized microstrip monopoles. A custom-designed 1: 4 Wilkinson power divider network feeds the array. In this paper, we present an overview of the radar system and a summary of current development activities, focusing on the antenna structures and initial measurements to show the utility of the system to infer soil moisture characteristics.