If only one point target P(x0,y0,0) on the earth is to be looked at, Image 3.1 SAR geometry represents a simple SAR geometry, which considers neither the earth’s curvature nor the curved flight path of the satellite. If we follow the flight path of the satellite in Image 3.1 in τ-direction and watch the behaviour of the slant range R(τ), we will realize that the slant range of the satellite’s motion towards the object P(x0,y0,0) is decreasing. Putting some distance between the SAR carrier and the illuminated object increases the distance R(τ) (see Image 3.11). So the slant range is a function of the azimuth time and reaches its minimum at point τ0. With the aid of the length of the antenna array respectively the synthetic aperture which is a result of vres · τ, the slant range R(τ) between the antenna and a point target on the ground during the fly-by can be calculated by means of a geometric addition, demonstrated as follows:
KeywordsRange Resolution Chirp Signal Azimuth Direction Slant Range Range Direction
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