The OV4-1 (orbiting vehicle 4, experiment 1) dual satellite guided ionospheric propagation experiment has confirmed the existence of long-range, low-loss, earth-detached propagation paths in the bottomside ionosphere with mean path losses smaller than equivalent multihop and, in some instances, smaller than free-space propagation. Satellite-to-satellite signals at 34.3 MHz were received from 56 to 100% of the five-minute samples taken in real time by the ground telemetry network while the orbits of the two satellites were decaying from 300 to 250 km. Measured values of path losses range from between 124 and 159 db. Multipath spread was never found larger than 550 μsec, and there is some evidence that Doppler spread was less than 0.012 Hz. Signals at 20.75 and 46.8 MHz in the satellite-tosatellite link were rarely received beyond the line of sight.