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Comment by toomuchtodo | Hacker News Reader

Are you asking if the antenna gets moved to illuminate the target once acquired? I apologize if I misunderstood. If that's the case, the antenna is a solid state phased array; no movement is required. Mobile communications (cellular and satellite) spot beams work under the same principal.

http://www.northropgrumman.com/Capabilities/MESA/Documents/a...

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Of course some radars did physically move their dishes to stay locked on to a target. I'm in the middle of The Invention That Changed the World (spoiler alert: it was radar) and I was stunned to learn how well this worked with analog circuits. An SCR-584, paired with an M9 analog computer, could detect that a plane was moving out of the center of its conical scan, and then convert that into a signal to the motors that drive the dish (and its associated antiaircraft guns).

http://en.wikipedia.org/wiki/Conical_scanning

http://en.wikipedia.org/wiki/SCR-584_radar

Thanks for pointing me to that book - it sounds like something I'd read.

Yeah phased arrays have probably been the rule for decades at that price-no-object level.

Even at the consumer level, there have been phased-array marine -sonars- (e.g. Interphase brand product line) for at least ten years for "only" 4-digit prices. Spatial resolution is of course tied to the number of elements but they do present more information that your typical 1-d "fish finder."

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