Method for measuring the direction and wave mode of the radio echoes that are detected by a satellite radio sounder in the Earth's magnetosphere

A method based on measuring the electric polarization of a wave has been de vised to measure the direction and wave mode of the echoes that are detecte d by a satellite radio sounder in the Earth's magnetosphere. Except for dir ections that are almost exactly perpendicular to the magnetic held, this me thod is found to work at frequencies above about 20 kHz with an angular err or of less than about 1 degrees. A second method that is based on measuring the Faraday rotation of the axis of polarization has also been devised to measure the echo direction when the ordinary and extraordinary echoes that are produced by a radio sounder overlap to produce an elliptically or linea rly polarized wave. These two methods will then be used to analyze the meas urements of the Image radio sounder that is scheduled to be launched in the year 2000, as described in the feasibility analysis for the Image sounder that was published in 1995.