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Revision 16 as of 2021-06-08 17:57:55
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A smear function to try: A position dither function to try:
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$ D = \lambda/2 $
$ k = 2 \pi / N * L $
||<:-3> $ D = L/2 $ ||<:-3> $ k = 2 \pi / N * L $ ||
|| $ \Delta x = D * ( \sin( k z ) + \cos( k y ) ) $ || ||<-2> $ \Delta y = D * ( \sin( k x ) + \cos( k z ) ) $ || || $ \Delta z = D * ( \sin( k y ) + \cos( k x ) ) $ ||
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$ \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.
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... or some variation of that. This assumes the spacing $ L >> \lambda $, a sparse array, so that the antennas do not couple (much).
We can scale D and k, and also modify 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.
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MORE LATER 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 ==

{{ a4d21.png | | height=768 }}

Annotated version with explanation coming soon.


== 16x16x16 skewed, dithered array ==

{{ a4d21-16.png | | 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

a4d21.png

Annotated version with explanation coming soon.

16x16x16 skewed, dithered array

a4d21-16.png

Annotated version with explanation coming soon.

MoreLater

ArrayPhasing (last edited 2021-06-08 17:57:55 by KeithLofstrom)