TRANSIENT PLANE-WAVE SCATTERING FROM AN ANNULAR RING ABOVE A LOSSY HALF-SPACE

The transient backscattered field response of a ring above a lossy hal f space is investigated to gain a better understanding of the time-dom ain behavior of a radar target above the ocean or the earth's surface. The transition point from early to late time is determined for the th ree cases of the isolated ring, the ring above a lossless half space, and the ring above a lossy half space, using frequency inversion and S EM techniques. It is shown that when placed above a half space, the re sponse of a target is a complicated succession of excitations, followe d ultimately by a pure series of system natural modes. If the half spa ce is lossy, the approximate effect on the late time is through the ad dition of two exponential signals with damping coefficients dependent on the incidence angle and the properties of the half space.