sentences:  The illuminated patch has a width in azimuth of
  
  The length measured along the surface is
  
  The area illuminated by the radar is then given by
  
  For 'small' beamwidths this approximates to
  
  The clutter return is then
  
  Substituting for the illuminated area formula_28
  
  where formula_30 is the back scatter coefficient of the clutter.Converting formula_31 to degrees and putting in the numerical values gives
  
  The expression for the target return remains unchanged thus the signal to clutter ratio is
  
  This simplifies to
  
  In the case of surface clutter the signal to clutter now varies inversely with R. Halving the distance only causes a doubling of the ratio (a factor of two improvement).There are a number of problems in calculating the signal to clutter ratio.