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I have had a glance at the references and can see that the adaptation of the phased array for radio astronomy is quite interesting.
The principle of steering a radio beam using a multi-element array of "sensors" and distorting the phase of the feed to each element of the sensor or radiator has been around for a long time. It is used in TV transmitters to tilt the beam so that the signal does not waste power in an unwanted direction.
It was used in the SPS52 radar fitted to the DDG's of the US and RAN to steer the beam electronically in the vertical direction with mechanical scanning in azimuth. The phase of the elements in the vertical direction was computer controlled (1960's computers with racks of equipment and tape drums).
Radio astronomy aerials are massive devices using very large base line pick up areas to get the sensitivity and narrow beam width required. This means that the mechanical steering at high rate is not practical. However electronic steering by phasing can open up real possibilities, particularly involved with interferometry.
Barry
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