OT: According to wikipedia, the PAVE PAWS phased array operates in the 420-450 MHz UHF range, with a corresponding wavelength of 66cm; if the error margin is really 0.1*lambda, the system is built to a precision of 6cm, significantly easier to meet than 0.1mm.
Also, it would be easy to compensate any error by controlling the phase of the fed signals.
I was thinking of that very link when I wrote this. Dunno know why I didn't look more carefully for it.
The number L = lambda/10 is actually part of the standard definition for a microwave system. Any circuit that has a physical dimension greater than L is too "big" to use standard circuit analysis, because the voltage and current values you measure at different points will be different due to propagation delays, even when those points are connected by a wire with no reactance and negligible resistance at lower frequencies.
The world's biggest microwave system (biggest machine period, actually) is the US power grid, even though it oscillates at a measley 60 Hz. Lambda is about (.6c / 60 Hz) = 1800 miles.
This is proof that, electrically as in so many other things, the Midwest is 180 degrees out of phase with the rest of the country.
Also, it would be easy to compensate any error by controlling the phase of the fed signals.
See http://en.wikipedia.org/wiki/Ballistic_Missile_Early_Warning...