RadioGirl

The FCC is not unaware of the use of MMW transmitters in NoS at airports. There's an entire section of the FCC website here:

http://fjallfoss.fcc.gov/ecfs/procee...me=da%2004-373

I've written about this (a lot) before. So don't take my word for it - go to the site above and see what the FCC has to say.

MMW NoS scans from 24.25 - 30 GHz. (With that wide a range there's no real argument about maintaining a central frequency.) One major use of that frequency band is LMDS (Local Multipoint Distribution Service) which is basically a hub station on top of a building in a city, with user stations in nearby buildings. Another is transmission from earth stations to satellites. Military radars also use some of that band. I don't know whether airport radars would be in that band or not.

By comparison, cell phones are between 0.8 GHz and 1.9 GHz. ATC is much lower frequencies (0.1 - 0.2 GHz, from memory). I'm not discounting Barbell's experience of a phone shutting down, but I can't see any way that it's the MMW NoS that's doing it. (Could be the baggage x-ray, could be the NoS attendant's radio system, could be a mobile phone jammer in the checkpoint; I don't know. But the MMW NoS is completely the wrong frequency and power level to be directly interfering with a cell phone.)

Further, the FCC documents indicate that the power levels authorized for the MMW are "Part 15" which means, in layman's terms, very very low. Part 15 is the section that authorizes automobile keyless entry systems, toy remote-controls, things like that. The FCC has given L-3 a waiver (see more below) on the upper limit of the peak value compared to the average value but it's still very very low power. To be absolutely clear, the FCC has imposed a limit, just that it's a higher limit than usual for Part 15.

There's a post I wrote over here: MMW safety basis where I used data from the FCC site to confirm the TSA's claim that the power level is about 1/100,000 of a cell phone power. Really, that's not enough power to interfere with radar even in the same frequency band. It's like saying you're having trouble hearing a conversation because someone three buildings away is whispering.

Also on the FCC website above, a company called FiberTower, which has licensed radio systems in the same frequency band as the NoS, is concerned that the NoS might cause interference to its systems. (It doesn't appear that they have actually experienced interference.) In response, the FCC reinforces that L-3 must keep a list of all installed NoS and their maintenance records, and make them available for the FCC and NTIA to audit. They also reinforce that if the NoS is found to cause harmful interference to licensed radio systems, they have to be modified, screened or turned off to eliminate the interference.

Finally, the FCC L-3 a waiver on the peak value was previously for a limited period of time. In July, the FCC decided (FCC filing 7/21/2011 on the page linked above) to make that waiver indefinite. In doing so, the FCC reiterated several conditions on the use of the NoS:
it has to comply with the Part 15 specs except for the allowed higher peak power value;
the frequency range has to be maintained in 24.25 - 30 GHz;
the NoS has to be used indoors (the building gives additional shielding);
the TSA has to keep a record of where all the MMW NoS are located;
L-3 and TSA aren't allowed to modify the NoS to give higher power, use different antennas, etc;
L-3 and TSA have to report to the FCC if there are any interference complaints.

Note that all of the above is about interference from the NoS to other radio systems. It is not about the health risk (or non-risk) to passengers of the NoS.

Obligatory disclaimer: I absolutely oppose the NoS on 4th amendment grounds, on privacy grounds, on the basis of cost (high) vs benefit (minimal), on the basis of slowing down the checkpoint and on the basis of increasing risk of a passenger's valuables. Probably for other reasons too. I oppose the x-ray backscatter NoS on health grounds. I am not happy that the TSA is continuing to install more NoS devices, nor do I support the FCC's assumption that the NoS is necessary for airport security. But as a radiocommunications engineer, I don't believe that there is a likely radio interference problem from the MMW NoS, and I have good reason to believe that the FCC has a grasp of the technical situation.