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When you see a satellite coverage region on the earth, the array antennas form tens of circles (small coverages) in a large coverage. My question is whether all these small circle coverages exist at the same time.

My understanding was the beam forming network delays the signals to all the antenna elements in different amounts. This means one signal of a particular frequency going through all the elements and then radiating into space will have radiation from the elements adding constructively and deconstructively at different points. We can adjust the phases so their add constructively in a desired direction so peak radiation is focused at a particular earth coverage area.

But can multiple signals go through the array and all be simultaneously be focused to different points on the earth? Meaning all those small coverage circles exist at the same time?

Please help, thanks

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  • \$\begingroup\$ Have you got an example of the kind of thing you are talking about? Both the satellite array and the coverage diagrams you mentioned. \$\endgroup\$
    – JRE
    Nov 21, 2019 at 21:56

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Let's only talk about phased array antennas.

YES, it's well possible to have different beams for simultaneous signals. But the delay must be adjusted separately for every antenna element and for every signal. In theory it would be even possible to transmit from one array different signals to different directions at the same carrier frequency. That's because in linear signal processing separate signals do not disturb each other.

I guess making the right phase shift in the baseband separately for every antenna element and for every signal costs money if the array has say 500 elements. But there are institutions who do not ask the price when something essential is needed, so I do not know do such systems exist.

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  • \$\begingroup\$ Such systems most definitely exist, even outside military / intelligence applications. Technically, synthetic aperture radar (SAR) is also a beamforming technique, with the number of virtual antennas easily going into the thousands, especially for spaceborne SAR earth observation satellites. \$\endgroup\$ Dec 16, 2019 at 20:59

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