Dual frequency use technique that uses both 12- or 20-GHz and 40-GHz satellite downlinks is proposed to share resources mutually for achievement of higher communication capacity with restricted use of the satellite transmission power during rainfall attenuation. Communication capacity of the satellite downlink is estimated from the satellite availability by applying frequency diversity and dual frequency use techniques. Dual frequency use technique achieves superior communication capacity for 40-GHz attenuation range from 5 to 10 dB during rainfall when the satellite power is shared between 12- or 20-GHz and 40-GHz downlinks.