On 4/15/13 8:36 PM, Chris Albertson wrote:
On Mon, Apr 15, 2013 at 8:23 PM, Tom Van Baak <[email protected]> wrote:
I'd be curious what level of improvement is possible. It will depend on the
receiver and the antenna. I believe the NIST project uses fancy antennas
but normal M12 receivers. So there's hope for the amateur.
The M12 is certainly affordable, something like $60. but what is a "fancy
antenna"? How are they different from a normal timing antena?
Probably a choke ring? With small variation in phase center over viewing
angles. The "secret sauce" is in the design of the crossed dipole
elements which are not flat, nor are they constant width.
http://facility.unavco.org/kb/questions/311/Choke+Ring+Antenna+Calibrations
has dimensions
fins are 50-63 mm tall, 25 mm apart, etc.
I suspect that this is not a high precision sort of thing.. (that is, if
your fin spacing isn't exactly 25.1 mm it doesn't make much difference)
L1 is 1575 MHz (approx) or a wavelength of 19 cm. So the fins are 0.315
to 0.26 lambda high and 0.13 lambda apart. If you were making a fancy
corrugated horn, you make the fins range from 1/2 lambda to 1/4 lambda
so you get a nice transition from shorted to open, but that's not what
they're doing here.
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