Pave PAWS and 420-450 MHz in Sacramento Valley
Pave PAWS & the 50 W PEP Maximum Power Limit on 70 cm
A little recognized portion of FCC Part 97 regulations applies to 420-450 MHz operations in most counties in our Sacramento Valley section: 47 CFR §97.313 (f) No station may transmit with a transmitter power exceeding 50 W PEP on the UHF 70 cm band from an area specified in footnote US270 to §2.106 of part 2. The indicated affected areas are specified in http://www.arrl.org/us270, in the State of California within a 240-kilometer (150 mile) radius around locations at Beale Air Force Base, California (latitude 39°08' North, longitude 121°21' West). More information on the additional impact on 70 cm repeater stations is at http://www.narcc.org/NARCC-ARRL-PAVE-PAWS-Update-2014a.pdf
The Amateur Radio Service shares the 70 cm band on a secondary basis with the US Government which has priority. The US Department of Defense routinely monitors and locates signal sources on these frequencies. Our voluntary cooperation is mandatory to avoid interference with the Pave PAWS (Phased Array Warning System) radar at Beale AFB and thus to assure our continued access to these frequencies.
The 70 cm Pave PAWS Radar at Beale AFB
Posted December 8, 2018
The Sacramento Valley has the distinction of being home to Beale AFB—one of the Pave PAWS (Precision Acquisition Vehicle Entry Phased Array Warning System) 420-450 MHz radar installations in the continental US. Since 1979, Pave PAWS continues to be a key component of the US Department of Defense missile defense and satellite surveillance mission.
The Beale AFB AN/FPS-132 Pave PAWS radar is housed in a 105 foot high five story triangular building with two 20° tilted faces that each contain a phased array of 2,677 circular polarized crossed dipole antennas with a gain of 38.6 dB and beam width of 2.2°. Computers electronically control the phase of the antenna elements to steer the radar beam rapidly within microseconds. The facility can scan from 3° to 85° elevation over a 240° arc of azimuth with a range of 3000 nautical miles for objects of 10 m2 size. Each array face transmits 600 kW peak power output (145 kW average) with a normal 18% duty cycle. In search mode, the Pave PAWS radar emits random pulses of about 300 kHz bandwidth that are centered every 1 MHz throughout the 420-450 MHz band. In tracking mode the pulse bandwidth can increase to 30 MHz.
The US Department of Defense (DoD) is the primary user of the 70 cm band shared with the Amateur Radio Service as the secondary user. FCC Part §97.313 (f) limits our amateur radio transmitter power to 50 watts PEP within a distance of 150 miles radius from the Beale AFB Pave PAWS in Yuba County. Since its 2007 system upgrade, the Beale AFB Pave PAWS radar has required additional power restrictions on some 440 MHz repeaters in this area. Radio amateurs may continue to operate on 70 cm thanks to our voluntary cooperation with limits coordinated among the ARRL, NARCC, the DoD and FCC. A status report is posted at http://www.narcc.org/NARCC-ARRL-PAVE-PAWS-Update-2014a.pdf