RF collectors??
I know enough to know that I don’t know if the following is even feasible.
When I was a kid we would go from time to time to the Detroit Science Center where they had this pair of 2-3m diameter parabolic dishes facing each other across the room. Sit on the bench in front of one, and you could hear whispers from the corresponding person, even though the museum din was nearly intolerable.
I have various RF devices (wifi, bluetooth, etc.) I understand that the point of these devices is to use radio frequencies that penetrate many things. However, I also know that reflections and bouncing RF waves can cause interference, and that MIMO technology takes advantage of the reflections to improve the signal. (At least I think so, 6.003 was a long time ago.)
If I want to put a directional antenna on my device, I have to first of all have been prescient enough to buy a device with an antenna jack, and second pay a fortune for the antenna. The idea is that you hook the antenna directly into the receiving hardware.
What about directional reflectors like those parabolic sound mirrors? Why not have a dish that is permanently pointed at a tower, and any cellphone placed in the sweet spot would get a great signal? Seems like a way to deal for instance with campgrounds in national parks; there’s a safety advantage to having cellphone access, but nobody would be able to justify the cost of blanketing a park with towers. But if there were emergency parabolic reflectors, you could hike to the nearest one, put your phone in the focal point, and call for help. Of course this assumes you’re not worsening all the issues with echoes and distortion. Again, I don’t know enough to know if this is even feasible. But the idea of creating RF sweetspots for public (or private) use is kind of cool, especially if they don’t require connection into your equipment and are passive.
Another potential use might be to create deliberate dead spots, like blocking cellphone reception in a building in order to have ‘quiet’ meeting rooms. The US Federal Communications Commission strictly prohibits active interference or jamming devices, but it’s not clear to me if they can regulate passive interfering devices.