Envelope (radar)

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.

[1] Radar systems have natural deficiencies because the laws of physics create performance constraints that cannot be altered.

The recorded data is compared to distance, altitude, and speed of the objects to evaluate the pass-fail criteria.

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.

The blind range for a radar system is the distance occupied by the transmit pulse and the setup time for the receiver.

Nap-of-the-earth flying techniques can be used to avoid detection when the blind range exceeds the radar horizon.

Excessive scan time allows high-speed objects to travel a large distance toward the radar without being detected.

The radiation pattern of a rotating truncated parabolic antenna for radar fixed pedestal has a fan shaped beam with a vertical gap in coverage.

This reduces radar sensitivity at certain radial velocities, but MTI allows the main lobe of the antenna beam to be aimed closer to the ground.

Wind speed above about 5 mile/hour moves debris fast enough to create excessive clutter load, which eliminates most of the MTI improvement.

Reflections from large objects and stray electronic emissions may enter the radar antenna from a sidelobe.