Antenna system of the NASA Wind spacecraft measured with the Russian radar facility "Sura"

Joint experiments between the Russian radar facility "Sura" and the NASA Wind spacecrafthave permitted the authors to measure the antenna patterns of two orthogonal dipoles mounted on the spacecraftand to determine the polarization state of the radar array. Both findings were produced by direct measurements. The Wind antenna operating frequency range is 1.075 to 13.825 MHz. The spacecraftis spinning around its Z axis and a dipole "Z" is oriented along this axis and another dipole "Y" is in the plane normal to Z which coincides with the eclipticplane. Three modes of Wind antenna operation were used: the Y signal added with the Z signal, the Y signal phased shifted by 90/spl deg/ added with the Z signal, as well as the Z signal itself. These three Wind antenna modes permit the measurement of the Stokes parametersof the radiation.