[Elecraft] Undetectable Radar

[Stuart Rohre]

Mike, in radar as in QRP, there is no free lunch.

Rest assured any broad spectrum signal can be found.  For one thing it 
inevitably brings up the noise floor and that can be detected.  Good 
receivers like the K2, could be helpful in noting such effects from new 
radars or BPL use in an area.

Spreading your signal out over many frequencies with a noise like character, 
your radar then suffers from lack of coherency, and thus your range will be 
affected, and perhaps its discrimination of the size of objects.

However, there are systems being studied that look at the effect on the 
spectrum of objects moving thru.

(like the flutter on your TV signal when a plane flies over)

That passive sort of radar has much to offer.  There is no emanation from 
the site of the radar receiver, and thus the target generates the only 
signal.  A couple of receivers provide the ranging by comparing delays in 
signals effects.  Again range suffers, and you have to have a super quiet 
receiver to extend range.  No free lunch, but the trade offs are attractive 
from the stealth angle.

Stuart
K5KVH