The middle example shows the amplitude of the reflections from a vertical cylinder. The example on the left illustrates mirror-like reflection or specular reflection, here the reflection is proportional to 1/ 2. Radar cross-section is dominated by shape, because it's the shape that governs how much of the incident power is intercepted and sent back, as illustrated in the three examples below, where the objects are assumed to be large compared to the incident wavelength. To drop the detection range by a factor of two, the required return loss off of the object can be calculated:Īn absorber with a 12 dB return loss allows the scatterer to get twice as close to the radar before being detected, compared to an object with 0 dB return loss. Here A R is the receiving area of the antenna. We define as the area of an ideal "mirror" that reflects that amount of power back to the source. The power returned (P R) is measured by the radar cross-section (RCS), denoted. The incident wave excites currents on the scatterer (the target you are trying to illuminate) which then becomes an antenna re-radiating with its own antenna pattern. Where G T is the gain of the antenna and P T is the power radiated by the antenna. The power density (S) reaching a target is equal to : In directional antenna systems, most of the radiated power is sent into a forward cone: Here is the index to this page (part two):Ĭlick here to go to our main page on absorbing materials.Ĭlick here for examples of radar cross-sections at microwave frequencies (new for May 2012!) Introductionīefore we can discuss radar cross-section reduction, we first must examine the physics behind radar cross-section.
Part three is on radar absorbers and absorption mechanisms.
Part two is on radar cross-section physics You are here! Part one is on fundamentals of electromagnetic waves. This web page is part of a three-part tutorial on radar absorbing materials used for radar cross-section reduction.
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