Radar envelope is a critical Measure of Performance (MOP) identified in the Test and Evaluation Master Plan (TEMP). This is the volume of space where a radar system is required to reliably detect an object with a specific size and speed. This is one of the requirements that must be evaluated as part of the acceptance testing process. Radar systems have natural deficiencies because the laws of physics create performance constraints that cannot be altered. The ambiguity function associated with pulse compression and scalloping associated with moving target indication are two examples. Complete coverage requires radar at multiple locations and multiple different kinds of radar. Definition Radar system specifications require a specific level of performance within a specific radar envelope. This performance includes the following characteristics. Cross section Blind range Radial velocity Instrumented range Scan time Altitude Elevation angle Bearing coverage Sidelobe performance Data is extracted and recorded from the radar system while aircraft, balloons, ships, drones, missiles or other objects are moved within the radar envelope. The recorded data is compared to distance, altitude, and speed of the objects to evaluate the pass-fail criteria. These are the typical shapes of the physical radar envelope. Flattened donut Cylinder with spherical void near the center Disk with spherical void near the center Pie with a missing slice and spherical void near the center Cross-section The cross-section is the minimum apparent surface area observed in the direction of the radar that must be detectable. Cross section for anything except a perfect sphere depends upon the aspect angle, which how far the reflector is rotated with respect to the radar pulse. Blind range The blind range for a radar system is the distance occupied by the transmit pulse and the setup time for the receiver. Non-Doppler radar are blind for the duration of the transmit pulse. Setup time is associated with two devices. Branch-duplexer receiver protection Antenna beamforming The branch-duplexer often includes a gas-filled tube that has high attenuation for high power microwaves but no attenuation for low power microwaves. This produces microwave noise during the setup-time at the end of the transmit pulse. Phased-array antennas use phase shifters that require adjustment after the end of the transmit pulse, and these phase shifters create modulation and high sidelobes that corrupts receive signals until after the setup time. Active phased-array radar may not have this limitation. Nap-of-the-earth flying techniques can be used to avoid