A symposium preprint presenting a proposed radio spectrum sharing system for navigation, communications, and broadcasting. Satellite-relay down-link bands should be from 450 to 1215 MHz and the up-links from 1400 to 2290, protected from interference by a small adaptive array. Many narrow nonoverlapping beams could be switched retrodirectively by an array-lens antenna system; then less than 10 W power from a small mobile antenna would ensure a top-quality voice circuit. A large concerted effort is needed now to coordinate frequencies, bandwidths, and modulations among many independently developed uses--not forgetting collision avoidance, altimetry, and terminal guidance--in time for consideration at the World Administrative Radio Conference of 1971. 4 pp. Ref.