TRANSFORMATION OF POLARIZATION DESCRIPTORS BETWEEN COORDINATE FRAMES

When accounting for polarization effects in radar and communications s ystems, it is often necessary to transform descriptions of the polariz ation state of an antenna or the polarization response of a target bet ween local (or body-centered) and global coordinate frames. Such trans formations correspond to rotation of the polarization basis by a presc ribed angle which is a function of (1) the coordinate transformation m atrix that relates the two coordinate frames and (2) the direction of propagation. Although methods for determining the polarization rotatio n angle have been presented previously in the literature, they can onl y be applied in special cases. Here we solve the problem in the genera l case using methods based on spherical trigonometry and vector algebr a, respectively. In order to apply these techniques, the elements of t he coordinate transformation matrix must be known. Since conventional methods for determining these elements require information which may b e difficult to obtain in practice, we present an alternative method wh ich requires only a pair of directions that have been expressed in ter ms of both coordinate frames.