Are sat dishes too small?
 

Ah! So you managed to solve it! Well done!

Care to reproduce it here, and, if I agree with the solutions, allow
me to reproduce it on my site?

Alternatively, feel free to PM me using the contact address on the JJ
home page below.

On Fri, 08 Jun 2012 14:47:20 +0100, John Legon
wrote:

Since then, I have realized that the calculation can be done without
making any assumptions at all, since it is possible to use the three
dimensions to work out where the axis intersects the dish. For the
dishes I measured this proved to be about 15 mm from the lower edge.
It was all a bit theoretical, and in practice the placing of the LNB at
the exact (geometrical) focal point doesn't seem to make an enormous
difference to the efficiency of the average sized dish.
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Are sat dishes too small?
 

Java Jive wrote:
Ah! So you managed to solve it! Well done!

Care to reproduce it here, and, if I agree with the solutions, allow
me to reproduce it on my site?

OK, I'll try to put it together. It won't be a complete formal proof -
that would be too tedious - but will sketch out the logic, which rests
on some quite interesting properties of the parabola...




Alternatively, feel free to PM me using the contact address on the JJ
home page below.

On Fri, 08 Jun 2012 14:47:20 +0100, John Legon
wrote:
Since then, I have realized that the calculation can be done without
making any assumptions at all, since it is possible to use the three
dimensions to work out where the axis intersects the dish. For the
dishes I measured this proved to be about 15 mm from the lower edge.
It was all a bit theoretical, and in practice the placing of the LNB at
the exact (geometrical) focal point doesn't seem to make an enormous
difference to the efficiency of the average sized dish.

Are sat dishes too small?
 

"Jim Lesurf" wrote in message
...
In article , 2BSur2Bsur
wrote:
On 07/06/12 23:51, Bill Wright wrote:
Richard Tobin wrote:

Other aspects of optics, such as diffraction, and the correct
explanation of refraction, depend on light being a wave.

It seems reasonable to label these two aspects geometric and wave
optics.

This being the well known conundrum of wave/particle duality.


Where's my tea. And my infinite improbability drive.

A more recent duality which may have an impact here is that what we used
to
call 'fairy cake' might now be called 'cup cake'. Can the drive tell the
difference?...

That's just rampant Merkinisation.

--
Max Demian