3 ms·

It is unconnected, so it will not dissipate anything (shield). Depending on whether or not it is positioned on a wave node, it will either be a passive reflecto

It is unconnected, so it will not dissipate anything (shield). Depending on whether or not it is positioned on a wave node, it will either be a passive reflector or director. It won't be a satellite dish as the comment thread on the page mentions, though, which is both a passive reflector and a focusing device, whose curvature requires at least some level of precision to be of any help. For something much more helpful, see http://ham-radio.com/k6sti/wifiyagi.htm http://ham-radio.com/k6sti/wifiyagi.htm

Aloha 9y ago
It need not be grounded to be an semi-effective shield, we're talking about frequencies that drywall will attenuate here. Think about it this way, if it can reflect TX, it can also reflect other cochannel signals from that direction. It may very well be working in more than one mode - but I strongly suspect its a far better shield, than it is a forward power reflector. It also may strongly effect the VSWR of the existing dipoles used here.
- arghwhat 9y ago
  A signal from the "correct" direction will have ~half its energy reflected towards the antenna, resulting in gain. A signal from the "wrong" direction will have ~half its energy reflected away from the antenna, resulting in attenuation. It won't shield, though. That requires that you dissipate the signal somewhere. But to be fair, it's a wild guess. It's a semi-flat piece of foil placed at an angle, at a random distance from 3 individual antennas. That's why I linked to the nice and simple, easy-to-calculate yagi-uda for if you want to hack with antenna gain.
  - Aloha 9y ago
    You'd effectively creating a multipath generator with this setup, which means you have the primary signal, then a couple microseconds later, a reflection that is probably 20db under the main signal. No disagreement that the yagi thing you pointed out would work better. That said, this is a MIMO router, so that may change the modulus on the multipath problem.
    - arghwhat 9y ago
      A reflection with just 1 microsecond delay would require a 300 meter reflection path (e.g. 150 meter to/from the reflector). I think you might be thinking of multi-path propagation within the context of long-distance communication (e.g., a HAM QSO). A regular home Wi-Fi network is already a complex multi-path system, as the primary propagation mode is reflections from walls and ceilings, leading to plenty of self-interference with many hot- and cold-spots from constructive and destructive inteference. We are at most introducing a few stronger reflections in an already extremely reflection-heavy environment. The big question is whether it does any good, either through attenuation or gain. As for MIMO, I must admit to not knowing much about it—I know it utilizes spacial separation to increase bandwidth, but I do not know much of its actual implementation, and thereby weaknesses.

Aloha 9y ago

It need not be grounded to be an semi-effective shield, we're talking about frequencies that drywall will attenuate here. Think about it this way, if it can reflect TX, it can also reflect other cochannel signals from that direction. It may very well be working in more than one mode - but I strongly suspect its a far better shield, than it is a forward power reflector. It also may strongly effect the VSWR of the existing dipoles used here.

arghwhat 9y ago
A signal from the "correct" direction will have ~half its energy reflected towards the antenna, resulting in gain. A signal from the "wrong" direction will have ~half its energy reflected away from the antenna, resulting in attenuation. It won't shield, though. That requires that you dissipate the signal somewhere. But to be fair, it's a wild guess. It's a semi-flat piece of foil placed at an angle, at a random distance from 3 individual antennas. That's why I linked to the nice and simple, easy-to-calculate yagi-uda for if you want to hack with antenna gain.
- Aloha 9y ago
  You'd effectively creating a multipath generator with this setup, which means you have the primary signal, then a couple microseconds later, a reflection that is probably 20db under the main signal. No disagreement that the yagi thing you pointed out would work better. That said, this is a MIMO router, so that may change the modulus on the multipath problem.
  - arghwhat 9y ago
    A reflection with just 1 microsecond delay would require a 300 meter reflection path (e.g. 150 meter to/from the reflector). I think you might be thinking of multi-path propagation within the context of long-distance communication (e.g., a HAM QSO). A regular home Wi-Fi network is already a complex multi-path system, as the primary propagation mode is reflections from walls and ceilings, leading to plenty of self-interference with many hot- and cold-spots from constructive and destructive inteference. We are at most introducing a few stronger reflections in an already extremely reflection-heavy environment. The big question is whether it does any good, either through attenuation or gain. As for MIMO, I must admit to not knowing much about it—I know it utilizes spacial separation to increase bandwidth, but I do not know much of its actual implementation, and thereby weaknesses.