[time-nuts] Re. DIY atomic "resonator"
David I. Emery
die at dieconsulting.com
Wed Apr 12 16:12:18 EDT 2017
On Wed, Apr 12, 2017 at 11:18:00AM -0700, jimlux wrote:
> Yep. There's been a fair amount of work over the past decades on using
> modulated reflectors for measuring antenna patterns (e.g. on phased
> arrays). You can have a diode/dipole suspended by resistive leads (with
> an impedance of 377 ohms/square that are invisible) and turn it on and off.
> Bolomey (I think) had an array of modulated reflectors, so you could
> measure multiple points in the near field at the same time, and only
> need to scan in one dimension. I can't remember if the reflectors were
> modulated at different rates or with PN codes - either would work to
> separate the responses.
In case some of you have not followed the Snowden (and related)
revelations about CSS/NSA/CIA snooping technology, apparently modulated
reflectors (corner reflectors with diode switches) are a standard trick
for ex-filtrating digital data streams from PCs and displays and the like
and have been used upwards into the Gigabit per second area...
Interesting to hear about using them for probing antenna
Dave Emery N1PRE/AE, die at dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."
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