Abstract :
In April 1961 radar contact with Venus was established in the Soviet Union. A transmitter and receiver at about 700 Mc/s were used in conjunction with an analysing and integrating system which enabled both the range of the planet and the Doppler spread in the returned signals to be determined. From the range data a new value of the astronomical unit is found; from the Doppler spread it is deduced that the maximum rotation period of the planet is eleven days. Venus is found to re-radiate about 10% of the radio energy intercepted by the disc.
