Compact FMCW radar for a UAS Sense and Avoid system

U.S. Federal Avionics Administration (FAA) regulations limit the use of unmanned air systems (UAS) in commercial and private industry because of the potential danger that they pose to other aircraft. The development of an onboard Sense and Avoid (SAA) system is necessary for UAS to share the same airspace as other aircraft. This paper presents the design and fabrication of a radar sensor designed for use as part of a reactive path planning system. The radar is a Frequency Modulated Continuous Wave (FMCW) type with two receive channels. This enables monopulse processing to provide both range and bearing information of detected targets. Without connectors or antennas, it weighs 46 g, is 7.6 × 5 × 3.8 cm in size, and costs less than $100 when built in quantities of 100 or more. The radar has been tested using outdoor targets and is currently being integrated with a UAS autopilot and collision avoidance algorithm for airborne testing.