[John S]

On 8/18/2015 12:15 PM, Brian Howie wrote:
In message , George Cornelius
writes
Still, I would be curious as to whether that 50% rule - if it is
accurate at all (does a laser beam hitting a black body have to
reflect back 50%?) - applies to a microwave downlink.

If it's a true black body it's all absorbed , and either conducted away
as heat or re-radiated at the temperature of the black body at
different wavelengths

A better laser analogy is a set of lenses and a focussed fibre-optic
between them. It's possible to arrange this to be nearly 100% efficient.

Brian


It is my understanding that interstellar space (between galaxies) is
about as good a black body as can be obtained. If a source is directed
into that space, I very much doubt a return could be detected by mortals.

[Brian Howie]

In message , John S
writes
On 8/18/2015 12:15 PM, Brian Howie wrote:
In message , George Cornelius
writes
Still, I would be curious as to whether that 50% rule - if it is
accurate at all (does a laser beam hitting a black body have to
reflect back 50%?) - applies to a microwave downlink.

If it's a true black body it's all absorbed , and either conducted away
as heat or re-radiated at the temperature of the black body at
different wavelengths

A better laser analogy is a set of lenses and a focussed fibre-optic
between them. It's possible to arrange this to be nearly 100% efficient.

Brian


It is my understanding that interstellar space (between galaxies) is
about as good a black body as can be obtained. If a source is directed
into that space, I very much doubt a return could be detected by mortals.

Yes it's an infinite heat-sink.

Brian
--
Brian Howie

[Allodoxaphobia[_2_]]

On Fri, 21 Aug 2015 08:52:36 +0100, Brian Howie wrote:
In message , John S writes:

It is my understanding that interstellar space (between galaxies) is
about as good a black body as can be obtained. If a source is directed
into that space, I very much doubt a return could be detected by mortals.

Yes it's an infinite heat-sink.

More properly like an infinitely long piece of coax.

Jonesy
--
Marvin L Jones | W3DHJ | W3DHJ | http://W3DHJ.net/
Pueblo, Colorado | @ | Jonesy | __
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