Radar cross sections( RCS ) of conducting objects are measured at X-band using HP8510-A network analyzer. Bronze spheres are used as reference targets, where backscattring RCS is measured to determine the relation between RCS and scattering parameter $S_{21}$. Measured RCS of the rectangular conducting plate with varying aspect angle is compared with those calculated from the geometrical theory of diffraction( GTD ) and the physical optics( P.O. ). It is shown that measured data are very close to those of GTD. Distribution of 900 samples of measured RCS of a model airplane is compared with log-normal probability distribution model. With this measurement system, the RCS of any complex target that satisfies the far-field criterion may be measured upto the accuracy of the maximum reflection of the anechoic chamber walls, i.e., $S_{21}$ $\cong$ -50dB which corresponds to 5 ㎠ in the backscattering RCS, at X-band."
