[mmaimcal] pointing-introduced phase errors scale with surface rms?

[Harvey Liszt]

Bryan--

I read the JPL memo in cursory fashion.  At first it seemed a showstopper
but now, not.

The phase of a perfect antenna is perfectly uniform over the main beam,
pointing errors introduce no phase error.  It is imperfections in the
antenna which introduce the phase variations which pointing errors take
advantage of, to introduce phase errors.

So there must be a scaling with surface rms; ie the scaling isn't with
antenna diameter and wavelength but with D and lambda/rms or something
like that.  The dsn antennas typically have >= .25-0.5mm = 250-500 micron 
surface  errors, whereas the mma will have something more than an order of 
magnitude smaller rms.  So I think you have to scale the effect down by that 
much, at least.  Perhaps Its probably more like lambda/rms squared.

But, to use your immortal words, "Is this whacked, or what?"  Someone who
really knows antennas should put us out of our misery.

regards, Harvey