AXIAL RATIO OF THE PROJECTED POLARIZATION ELLIPSE,

The axial ratio of the polarization ellipse of a radio wave is often evaluated using a crossed-dipole antenna system placed in a horizontal plane. The axial ratio of the ellipse as deduced from the responses of the two antennas should correspond to the axial ratio of the ellipse in the wave-front as projected onto the horizontal plane. When one of the two dipoles is situated in the plane of incidence of the radio wave, the axial ratio of the projected polarization ellipse is a function of the angle of incidence and the orientation of the polarization ellipse in the wave-front. A convenient parameter with which to relate axial ratio and orientation is the angle made by the major axis with the line of intersection of the wavefront with the horizontal plane. This line would actually correspond to the direction of one of the dipoles when the other is situated in the incident plane. In his paper Polarization measurements of Jupiter radio bursts at 10.1 Mcs, Dowden Aust. J. Phys. 16 398-410. 1963 investigated the extent of variation of the axial ratio of the projected ellipse with the angle of incidence and with orientation. In the equations presented by him for evaluating the projected axial ratio, there appears to be an omission the curves shown could not be reproduced by using the equations he gives. The purpose of this communication is to present a set of equations from which these curves can be reproduced. A set of curves, drawn by using equations, is shown.