Reduction of a Radar Cross Section Using Active Antenna Elements

The traditional approaches to reducing an object's radar cross section are passive in nature, such as changing the shape of an object or coating the object with a non-reflecting material. Examples of passive applications of traditional approaches to RCS reduction are the Lockheed-Martin F-117 fighter aircraft, the Boeing B-2 nuclear bomber and the USS Zumwalt (DDG-1000). Here a new approach to solving this problem is explored, which is based on the principal of destructive interface between the reflected (returned) radar signal from the object and a radiated signal that emanates from an antenna mounted on the structure. A canonical system model consisting of a sensor, feed network, and radiating element is analyzed, and results that show that under limited conditions an effective radar cross section reduction is possible. That is, by sensing the signal on the object due to the incident field and then radiating a canceling (nullifying) wave from a surface-mounted antenna, it is possible to partially cancel out the total returned signal.