On 12/17/14, 4:36 AM, Bob Camp wrote:
HI
On Dec 17, 2014, at 1:07 AM, Chuck Harris <cfhar...@erols.com> wrote:
I would venture that the extent of the magic was to note the physical
center of the array, and call that the phase center.
As long as you always orient the antenna in the same direction, any
errors that might exist in the real phase center will be consistent,
and could be corrected for by noting the offset from a benchmark.
I’m afraid that’s what they do as well. Just spin it and see what a dial
indicator reads sort of thing. I think that I’d want something that actually
did some microwave tests ….
B
The UNAVCO data is an actual RF test.
And from a manufacturing standpoint, I would imagine that typical
tolerances are better than 0.001" (25.4 microns). Changes much bigger
than that would show up as VSWR changes, which *is* something that they
check in manufacturing.
The Leica "artichoke" multiband choke ziggurats (they're not flat, so I
have a hard time calling it a "ring") are cast and then machined.
Casting isn't what I would think is a precision operation, but it
probably is real consistent from unit to unit.
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