The microwave properties of Saturn's rings

Radio interferometer observations at 1420, 2695, and 8085 MHz show that the ring particles are nearly lossless at microwave frequencies. The microwave brightness temperature of the rings is less than 20 K. The ability of the rings to obscure part of Saturn's disk indicates that most of the particles must be larger than 5 cm in diameter. A model assuming particles of water ice is consistent with the radio interferometer, radar, and millimeter wave observations. Subject headings: radio radiation, planetary - Saturn