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Not infrequently, it is desirable to initiate phase coherent communications between terminals mutually unaware of the other's location. A method is proposed which provides automatic synchronization based on strictly geometric considerations, subject to the condition that each terminal is cognizant of its own position in space with respect to a common coordinate system. The method consists of constraining the transmitter to insert time (or phase) delays in each emitted signal as a function of its position and direction of transmission. Similarly, the receiver inserts a delay dependent upon position and look angle. These delays are measured with respect to an imaginary radiation source (usually defined as the origin of the common frame of reference). With proper delays at both terminals the signal arrives at the receiver with an exactly anticipated time (or phase) relationship. Equations are derived expressing the delays to be inserted for communication in two and three dimensions. To implement the automatic synchronization system, either an omnidirectional antenna pattern or a narrow-beam, scanning antenna is prescribed. For the latter case a means is required to aid the transmitter and receiver in establishing expeditiously their common line; an auxiliary synchronization scheme is suggested guaranteeing that any two antennas, one transmitting and one receiving, will confront each other once every scan period. None of the concepts proposed requires an extension of state-of-the-art communication techniques.