Hmmm, I'm thinking it could be useful as an element for a frequency agile
radar array. Diversity radar?
If current radar detection systems rely on the target detecting an incoming
beam at a given pulse rate and frequency, then by varying the frequency and
pulse rate constantly, detection would be more difficult.
Computer hardware and software is sufficiently powerful to be capable of
processing the target returns at varying frequencies and GPS satellites can
provide a frequency locked source for synchronising the transmitter and
receiver, so you end up with effectively a stealth active radar system.
A wide band electrically tuned antenna would be essential for such an
application. It might even be able to detect stealthy aircraft and ships as
they tend to be optimized to absorb/divert frequencies in the most used
radar bands.
An electrically controlled frequency agile antenna which forms part of an
electrically steerable planar system would also be useful for jamming
multiple frequencies and sources. This could turn out to be a somewhat
expensive project.

Mike G0ULI

"Roger" wrote in message
...
NIST has an article on these antennas and a photo of a prototype.

http://www.nist.gov/public_affairs/techbeat/current.htm