Timeline for Why don't cellphones use unidirectional antennas?
Current License: CC BY-SA 3.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 1, 2023 at 22:14 | vote | accept | Geremia | ||
| Oct 1, 2023 at 22:14 | answer | added | Geremia | timeline score: 1 | |
| Sep 30, 2023 at 2:10 | answer | added | Kyle | timeline score: 1 | |
| Aug 1, 2016 at 20:11 | comment | added | Geremia | @DaveTweed Yes, it's set by the wavelength, but it seems a directional array doesn't need to use full wavelength separation between the elements. For a cellphone, they might have to be something like, e.g., 1/64th of a wave. | |
| Aug 1, 2016 at 14:56 | comment | added | Dave Tweed | It isn't that there's a tradeoff between electronics and physical size. The physical size is set by the wavelength of the radio wave in question -- this is basic physics, and there's no way around it. And no, I'm not interested enough in the topic to work out the numbers. | |
| Aug 1, 2016 at 14:05 | comment | added | Geremia | @DaveTweed Your comment could be turned into an answer if you quantify it, explaining how such a small unidirectional array would require electronics with too small of a time resolution for producing the phase delays that it isn't practical with current electronic technology. | |
| Jul 31, 2016 at 15:43 | comment | added | Dave Tweed | Do you understand how physically large such an array would have to be in order to be able to provide useful gain (directionality) in any arbitrary direction? I don't think you'd want to put such a thing in your pocket! And there would be no power savings -- the circuits needed to provide electronically-variable delays to such a large number of elements would consume far more power than the "excess" transmit power used with omni antennas. | |
| Jul 31, 2016 at 1:46 | comment | added | Geremia | how does a cell phone "know" where the "best" tower is located? How they normally determine this. One dipole alone of the array suffices for that. Once connected to the tower, it could switch into unidirectional mode (i.e., use all the dipoles of the array). | |
| Jul 31, 2016 at 1:28 | comment | added | hazzey♦ | And how does a cell phone "know" where the "best" tower is located? Is it going to save power to have a cell phone have a massive database of all tower locations, powers, and gain patterns and to combine that with an always on GPS for specific location? At any given time a cell phone could be in range of multiple towers. | |
| Jul 30, 2016 at 21:32 | history | edited | Geremia | CC BY-SA 3.0 |
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| Jul 30, 2016 at 20:06 | comment | added | Geremia | @fibonatic Many cellphones can already tell what direction they're oriented. They have built-in compasses and accelerometers. Changing direction would simply change the relative phases of the antennas such that the maximum power is always directed toward the cell tower. | |
| Jul 30, 2016 at 19:17 | comment | added | fibonatic | What if you be making a call and you suddenly turn around? | |
| Jul 30, 2016 at 17:37 | history | asked | Geremia | CC BY-SA 3.0 |