I stand corrected; if the gbppr.org site is accurate, all it takes is a powerful sweep across the band.

I really like the one that takes the nearby handset's transmit power and upconverts it to the receive frequency; it should be almost impossible to trace.

Another nice device is the reverse biased small-signal diode. Reverse biasing a 1N4148 at 150V or so (current limited) is awfully noisy. A low-q resonance to reduce out of band power....