Okay, you got me curious to see if I could give you some definitive information. It turns out that Francis Peak is a JSS - joint site for the FAA as well as military surveillance of our borders. Regarding the radar itself, Francis Peak has a ARSR-1E radar system that operates in the L Band between 1.2 and 1.4 Ghz (dual frequencies separated by 80Mhz). The magnetron peak output power is 400,000 watts, feet into an amplitron to effectively double the effective radiated power output (10 dB gain). And while I didn't see any specs on the antenna gain and beam width, I'd guess the antenna output power would be up in the megawatts.
While your Phantom operates at 2.4 Ghz (and maybe 5.8 Ghz for FPV, etc), the concern is whether the radar sidelobe harmonics would interfere with your copter. At this link, they say the FAA does have a bandpass filter at "many" sites to help alleviate out of band interference.
http://the-puzzle-palace.com/files/sect5.pdf
Of course, at close distances even the smallest out of band leakage could overpower our puny Phantom transmitters that only put out microwave energy a hundred thousand times smaller the energy of the Francis Peak system. And while the radar antenna is continuously spinning around, if the signal jams the Phantom's receiver for an instant, it would take more time to re-acquire a lock from our Tx than another radar pulse coming around to possibly continually jam the receiver. And the worse case scenario is you flew within 50-100 feet of the radome and the energy actually fried the electronics in your Phantom's integrated circuits or changed the magnetic calibration - how very exciting!
Also, be aware the Francis Peak site has numerous line of sight terrestrial microwave antennas the retransmit radar signatures as well as communications, telemetry tracking and control, etc.
Okay, so the bottom line is, "Do you feel lucky?" Personally, I stay clear by a fair distance. Certainly 1 mile away should be okay with your frequency spectrum, unless you are using a FPV operating at 1.3 Ghz.
Finally, checking out the Francis Peak site, during construction the workers wore knee-high thick rubber boots to avoid getting bit by rattlesnakes who forgot they were not supposed to be found at 9,700 feet!
Happy flying and keep us posted...
Enjoy, Michael
http://www.fas.org/nuke/guide/usa/airdef/arsr-4.htm
http://en.wikipedia.org/wiki/Joint_Surveillance_System
http://en.wikipedia.org/wiki/Air_Route_ ... ance_Radar
http://the-puzzle-palace.com/files/sect5.pdf
http://the-puzzle-palace.com/files/sect5.pdf
ARSR-1E (Fig. 7a). The ARSR-lE is an FAA two dimensional L-band (1215-1400 MHz) air-route-surveillance radar (ARSR) with a conventional magnetron feeding 400 kW peak power into an amplitron (crossed-field amplifier) to provide an additional 10 dB gain. The amplitron may be switched in or out as required by the operator. Amplitrons are characterized by a very wide noise floor only 40-60 dB below the fundamental. In many ARSR’S, including this one, a bandpass filter has been used to reduce the spurious sidebands outside the 1220-1380 MHz range