>Maybe its snake oil, or maybe they didn't buy ads in the magazine.
Traveling
>wave tubes are non-trivial devices. I'd just as soon try cooking a
>semiconductor, cuz its black art. But as far as a plasma intermodulating,
>any plasma heated with RF should intermodulate AFAIK. I remember a fox hunt
>I was on, where I used a switched dipole antenna. Just a diode (1N914/4148)
>switching between a couple 2 meter 1/2 wave dipoles. As a guy using it
moved
>near the receiver, we could hear the switching frequency in a different
>receiver as the antenna's intermodulated signals . So re-radiating a signal
>(repeat-back jamming) isn't tough to spoof a dumb digital toy, but
designing
>a negative resistance electron or plasma TWT is rocket science. I heard a
>can of rusty nails (iron oxide semiconductor) could cause a cell site to
>drop calls. But there your transmitting hundreds of watts, recieveing
>microwatts, and dropping calls if the SAT tone is messed up. That's the
idea
>behind passive RFID transponders. Put a diode on a tuned circuit, the diode
>switched with a very low current micropower PIC, and interrogate it with a
>radar beam.

I have always thought that the ideal police radar jammer would be a length
of microwave plumbing with PIN diodes across it at a critical point,
probably several spaced at 1/4 wave intervals, and then driving the diodes
from a current source so they switch off and on at a suitable audio
frequency to represent a car at about 30mph. If the plumbing was long enough
the radar unit may think there was two cars in the beam because of the time
between echoes. I had even considered the possibility of having a U shaped
piece of plumbing with a horn at each end running around the roof of the car
to get the length! Totally passive device - if you can hear it officer you
must be transmitting :)

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