An open-source 240-antenna array to bounce signals off the Moon

Posted by Technical-March6780@reddit | hardware | View on Reddit | 13 comments

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diskowmoskow@reddit

I don’t have any use for this but looks absolutely fascinating open source project

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too_tall87@reddit

Can anyone shed some light on how you achieve ~34 dBi of array gain with 72 elements? Are we expected to believe the element pattern gain is ~17 dBi at boresight?

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CallMePyro@reddit

Heh, I have an eng who I work with that behaves exactly like you

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Technical-March6780@reddit (OP)

240 elements, and each element has another \~10dBi element gain

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too_tall87@reddit

Thanks. I was looking at the Starter Phased Array specs with 72 elements.

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unsurejunior@reddit

The unit quad cell looks pretty affordable. If I can remember this exists when it's available, I'd buy one for sure

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Jeep-Eep@reddit

How much bandwidth could you get out of solutions like this?

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Technical-March6780@reddit (OP)

The update https://moonrf.com/updates/
mentions 80 MSPS on each antenna. I think that's I+Q, so 80 MHz of bandwidth. But it looks like their mixer front-end may be more limited to like 60 MHz max.

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Jeep-Eep@reddit

I'm wondering at what scale and sophistication of the array you'd need to use Luna like a giant version of the Echo passive comsats for shit tier internet.

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EME "earth-moon-earth" or "moonbounce" is a thing in amateur radio. People make massive antenna arrays to do this on VHF and UHF frequencies (2m, 70cm and 23cm ham bands). Image search for "VHF EME array" or "UHF EME array" to see what some people have built.

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too_tall87@reddit

Another question I was wondering is how they’ll handle ~307 Gbps data rates (240 elements, 80 MSPS, 8+8 bit I & Q) across the full system. The QuadRF specs mention data rates for each element, and there’s other mentions of MIMO and RF imaging, which makes me think they’re expecting fully elemental data.

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Technical-March6780@reddit (OP)

looks to be daisy chained... so each RF board digitally adds it's 4-antenna contribution (with appropriate phase shifting) to the upstream SERDES and then the result is downstream in the chain

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moschles@reddit

I like everything about this.