Differences between revisions 12 and 15 (spanning 3 versions)
Revision 12 as of 2012-12-05 13:38:01
Size: 1284
Comment:
Revision 15 as of 2013-02-17 05:33:28
Size: 1449
Comment:
Deletions are marked like this. Additions are marked like this.
Line 19: Line 19:
There will probably be stiff competition for spacing functions, perhaps some trolls will take out patents on them, and in the current US patent climate, with == 5x5x5 skewed, dithered array ==

<<EmbedObject(a4d21.swf,play=true,loop=true,width=1024,height=768)>>

Annotated version with explanation coming soon.
Line 22: Line 26:
MORE LATER == 16x16x16 skewed, dithered array ==

<<EmbedObject(a4d21-16.swf,play=true,loop=true,width=1024,height=768)>>

Annotated version with explanation coming soon.

MoreLater

Array Phasing

When we randomly dither the position of the emitters in a 3 dimensional phased array, it smears out the grating lobes. I am looking for a better function.

A position dither function to try:

D = L/2

k = 2 \pi / N * L

\Delta x = D * ( \sin( k z ) + \cos( k y ) )

\Delta y = D * ( \sin( k x ) + \cos( k z ) )

\Delta z = D * ( \sin( k y ) + \cos( k x ) )

... or some variation of that ( I originally tried D = \lambda/2 , with little effect). This assumes the spacing L >> \lambda , a sparse array, so that the antennas do not couple (much). Try scaling D and k, and also modifying amplitudes across the array like a Hamming window, and see how that changes the sidelobes.

This happens on top of the array of perhaps hundreds of emitters on the thinsat itself, which beamforms to a few degrees of angle, reducing power splattered far from the target.

The signal is broadband, so there is not a well defined \lambda . We may end up making k a function of x, y, and z as well.

5x5x5 skewed, dithered array

Embedded application/x-shockwave-flash

Annotated version with explanation coming soon.

16x16x16 skewed, dithered array

Embedded application/x-shockwave-flash

Annotated version with explanation coming soon.

MoreLater

ArrayPhasing (last edited 2022-03-15 01:37:15 by KeithLofstrom)