Differences between revisions 7 and 8
 ⇤ ← Revision 7 as of 2012-11-30 06:38:04 → Size: 907 Editor: KeithLofstrom Comment: ← Revision 8 as of 2012-11-30 06:41:59 → ⇥ Size: 933 Editor: KeithLofstrom Comment: Deletions are marked like this. Additions are marked like this. Line 8: Line 8: || $D = \lambda/2$ || $k = 2 \pi / N * L$ || $\Delta x = D * ( \sin( k z ) + \cos( k y ) )$ || $\Delta y = D * ( \sin( k x ) + \cos( k z ) )$ || $\Delta z = D * ( \sin( k y ) + \cos( k x ) )$ || ||<:-3> $D = \lambda/2$ ||<:-3> $k = 2 \pi / N * L$ |||| $\Delta x = D * ( \sin( k z ) + \cos( k y ) )$ || ||<-2> $\Delta y = D * ( \sin( k x ) + \cos( k z ) )$ || || $\Delta z = D * ( \sin( k y ) + \cos( k x ) )$ || Line 11: Line 12: We can scale D and k, and also modify amplitudes across the array like a Hamming window, and see how that changes the sidelobes. Try scaling D and k, and also modifying amplitudes across the array like a Hamming window, and see how that changes the sidelobes.

# 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 = \lambda/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. 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.

MORE LATER

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