Re: How many satellites are in geosynchronous orbit by now?

> The strength of a radar transmission tends to drop as the inverse of
> distance squared. This transmission bounces off an object and the
> strength of that echo tends to drop as the inverse of distance squared.
> It is the round trip taken together, and not the echo itself, that
> will have a power drop off that tends to decay as the inverse of
> distance to the fourth power.

For anyone who would like further explanation of the inverse square
law, it is a simple artifact of geometry for expansion in 3-dimensional
space from a point source. The classic diagram shows a candle
radiating out to a square at one unit of distance, and extended to four
squares at two units of distance, etc.

Here's a more elaborate version:
http://homepage.smc.edu/balm_simon/IMAGES/astro%201a/star_properties/inverse_square.jpg

For our radar situation, such a diagram could be expanded upon to show
how a radar echo acts as a source in itself that emanates from the
target and expands according to the inverse square law as it travels
back to the receiver, yielding the round trip power attenuation
governed by distance to the fourth power.


~ CT

.

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