Radar cross section RCS is the measure of an object's ability to reflect radar signal in the direction of the radar receiver i.e. it is the measure of the ratio of backscatter per steradian (unit solid angle) in the direction of the radar (from the target) to the power density that is intercepted by the target. This application note describes how a modern battery-powered / portable Microwave Vector Network Analyzer with Time Domain Gating can make it easy to do RCS tests on the flight line or in the field.