A COHERENT TRANSMITTING ARRAY USING CONJUGATE PHASING AND BEAM TAGGING.
Interim rept. Jan 65-Mar 66,
OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS ANTENNA LAB
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A system for controlling the phases of the signals radiated by the elements of a transmitting array such that they add coherently at a distant moving target was investigated in terms of the Ohio State University four-element array 30 ft parabolic antennas, 10 KW transmitters, elements located at the corners of a 60 ft square, transmitting and receiving frequencies, approximately 8.33 GHz and 7.73 GHz respectively operating with the Echo 2 satellite nominally 600 mi high orbit and 135 ft diameter. A detailed study of digital and analog methods of implementing phase conjugation showed that a method using digital phase modulators is preferred. When the transmitting and receiving frequencies are unequal, digital phase conjugation can not reduce the phase rate to zero because in most cases the ratio of transmit to receive frequencies is not a convenient rational fraction. Since phase conjugation is an open-loop system, it can not correct for this residual phase rate less than 0.04 Hz or other phase variations caused by propagation time delays, doppler frequency shift, equipment phase instabilities and initial acquisition errors.
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