RCS

Radar Glossary

Radar — RCS

 

 

 

 

 

 

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Information on RCS

The RCS of a target is the projected area that would intercept the transmitted signal and reflect isotropically an amount that produces the returned signal at the receiver. In other words, RCS provides an indication of how well a given target reflects radar energy. With these ideas in mind, it is not surprising that the physical area of a target is normally greater than the RCS because some the incident energy is scattered and absorbed by the target. Use of radar absorbent material (RAM) and specific shapes and angles helps to minimise the RCS. Target aspect also changes the RCS markedly and needs to be allowed for in the design of a radar system. Radar designers normally use extremely pessimistic (low) values for RCS during radar design and performance calculations to ensure their systems meet minimum requirements when introduced into service.
     The RCS of a target is not constant with operating frequency. There are three broad areas of interest with respect to physical target size, operating frequency and resulting RCS. These areas are:
    

  • Raleigh region. If the target is a lot smaller than the wavelength of the radar system, the target is said to be in the Raleigh region. If the target is in the Raleigh region, the radar cross section of the target tends to be smaller than the target's physical size.

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  • Resonance region. If the target is of similar dimension to that of the wavelength, the target is said to be in the resonance region. In the resonance region, the RCS of the target may vary a great deal but tends to be larger than the physical size of the target.

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  • Optical region. The optical region occurs when the target is much larger than the operating wavelength of the radar. This is quite often the case with operational radar systems whose wavelengths are normally in the order of centimetres in length. When operating in this region, the RCS of the target is similar to its physical size.

    •      The implication of these three regions is that the operating wavelength should not be selected in total isolation from target considerations.

    Other topics in our resources on Radar related to RCS include: 
     
  • Radar Range Equation (RRE)
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  • Electronic Warfare (EW)

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