Enabling Detect and Avoid (DAA) operations for small Unmanned Aircraft Systems (sUAS) requires the use of multiple sensors working together, both onboard the aircraft and on the ground. A ground based radar system provides several unique capabilities to this mission and complements the onboard vehicle sensors, including cooperative transponders. These benefits include longer detection ranges (for early warning) based on available size and power, reduced cost for dense environments, and more efficient RF spectrum usage. This paper discusses these benefits and suggests testing that can be done to develop and prove out sUAS DAA requirements for BVLOS operations.