[time-nuts] "The GPS navigation is the weakest point,"
jimlux at earthlink.net
Thu Dec 15 20:29:53 EST 2011
On 12/15/11 4:53 PM, Bob Camp wrote:
> Radar bounces off the flat sides very nicely ….
You are right, it does, but it doesn't bounce BACK towards the observer,
which is what you care about. Consider a flat plate at a 45 degree
angle from you. All the radar energy bounces to the side. Turns out
that it's diffraction from the edges of those sides that's the limiting
The first stealth planes (e.g. F-117) were all flat surfaces because you
could actually calculate the reflections and make sure you didn't
inadvertently create a corner reflector.
This is one reason that bistatic radar (transmitter and receiver in
different places) is interesting. You can detect things that have very
low monostatic radar cross section (RCS). (also, radar transmitters are
easy to shoot at, because they're like a big beacon saying "here I
am"... so put out a bunch of transmitters and one receiver and have the
expensive signal processing and operators at the receiver, which is
Even better, you can use something benign as an illuminator... Many of
us have used a TV station as a passive illuminator for a bistatic radar,
using your analog TV set as the detector.
Later, as computational horsepower increased, they could make nice
swoopy surfaces with low RCS, and what's more to the point, low bistatic
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