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Hi all,

An aspiring celestial  navigator decloaking to throw in his two cents to
the conversation.

I have been following this thread with some interest, as in a distant
previous life I designed and built antennae, including those for use in
radar systems.  If I may be so bold, I will try to summarize the general
effects at work with respect to passive radar reflectors, assuming ideal
conditions (reality is more complicated).

Your typical passive reflector consists of three mutually orthogonal
sheets of metallic material.  That is fancy-speak for three pieces of
metal or metallic material that form right angles to one another and are
known as corner reflectors.  Visualize a cube with three sides missing.
The basic principle is the angle of incidence equals the angle of
reflection.  (Billiard players utilize this principle for bank shots.)
In this case of three sided corner reflectors, this means any energy
impinging upon the reflector is directed back to the source.  Most of
the energy is sent back to the source - hence a vessel utilizing a
reflector appears 'brighter' on the radar screen of the vessel who is
the source of the radar signal.

There is an everyday example of such a reflecting device - the
'reflectors' found on bicycles.  If you place your bicycle in a dark
room and shine a flashlight/torch on the reflector from various angles,
you will get a pretty good idea of the principle at work with respect to
passive radar reflectors.

Those familiar with the current generation of stealth aircraft in the US
arsenal will note that there are no surfaces at right angles to one
another on those planes.  By keeping the surface angles obtuse, the
impinging radar energy is reflected away from the source and reduces
what is known as their radar cross section.  In very simple terms, they
look a lot smaller (less threatening) than they really are.  In the
recreational boating world, stealth is anathema to the desired effect.

A previous post mentioned the use of a crinkled ball of aluminum foil.
Theoretically this might improve the radar return because of the random
nature of the ball's surfaces and, arguably, is better than nothing.

I hope this has been helpful.

V/R,

Tim B.

PS: Thanks for all of the informative discussions.

   

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