5 ms·

Blocking radio waves and electromagnetic interference with the flip of a switch

48 points by sriram_malhar 4y ago

superkuh 4y ago
This article is oddly-specific about the possible use cases for an electrically switchable conductive film. Somehow I doubt that S21 attenuation in the non-conductive mode is going to be low enough that anyone is going to want to put this around their radio antennas. Unfortunately I can't tell because sci-hub hasn't added new articles to their database since the case against it in India started in 2020 and this is locked behind a paywall.
- Oxidation 4y ago
  My immediate (i.e. unconsidered) thought is a solid state zone plate (like a radio version of a Fresnel lens) which can be used for adjustable focusing or steering of incident radio waves.
  - 310260 4y ago
    MU-MIMO does what you describe and is implemented in WiFi and 3GPP (LTE/5G) standards. Leads to significant gains in spectral efficiency too.
- greenbit 4y ago
  You wouldn't put shielding around an antenna, that kind of defeats the purpose of being an antenna. The thing about circuits that work at GHz frequencies, is that the wavelengths are small enough that practically any part of your circuit can absorb EM, so it would be handy if the enclosure had this shielding effect.
  - superkuh 4y ago
    A copper foil (or tin shield box) would be far better.
    - superkuh 4y ago
      A kind soul emailed me the full text paper. Apparently the transition from conductive to non-conductive via oxidation is irreversible. So this would be a special coating applied to products to protect them from EMI during supplychain/shipping but not afterwards? Seems niche. But it is cool.
- deleted 4y ago
  [deleted]
- thrilled2behere 4y ago
  It does seem a little weird, yeah. I mean, the researchers are from Drexel University. I would've figured that the applications that they would be most interested in would be fast optical switching and MEMS devices - whereas in this press release it seems like they're trying to "sex" up the findings by suggesting that they can be used to make a Romulan cloaking device for macroscopic antennas. This article might have suffered at the hands of an overenthusiastic PR team.
deleted 4y ago
[deleted]
EricE 4y ago
I need to figure out how to turn this into a 5G shield. Will make millions.
notadev 4y ago
47 U.S. Code § 333 - Willful or malicious interference No person shall willfully or maliciously interfere with or cause interference to any radio communications of any station licensed or authorized by or under this chapter or operated by the United States Government. [1] https://www.law.cornell.edu/uscode/text/47/333 https://www.law.cornell.edu/uscode/text/47/333
- egberts1 4y ago
  bounced radio waves are fair game. IANAL.

48 points by sriram_malhar 4y ago

This article is oddly-specific about the possible use cases for an electrically switchable conductive film. Somehow I doubt that S21 attenuation in the non-conductive mode is going to be low enough that anyone is going to want to put this around their radio antennas. Unfortunately I can't tell because sci-hub hasn't added new articles to their database since the case against it in India started in 2020 and this is locked behind a paywall.

Oxidation 4y ago
My immediate (i.e. unconsidered) thought is a solid state zone plate (like a radio version of a Fresnel lens) which can be used for adjustable focusing or steering of incident radio waves.
- 310260 4y ago
  MU-MIMO does what you describe and is implemented in WiFi and 3GPP (LTE/5G) standards. Leads to significant gains in spectral efficiency too.
greenbit 4y ago
You wouldn't put shielding around an antenna, that kind of defeats the purpose of being an antenna. The thing about circuits that work at GHz frequencies, is that the wavelengths are small enough that practically any part of your circuit can absorb EM, so it would be handy if the enclosure had this shielding effect.
- superkuh 4y ago
  A copper foil (or tin shield box) would be far better.
  - superkuh 4y ago
    A kind soul emailed me the full text paper. Apparently the transition from conductive to non-conductive via oxidation is irreversible. So this would be a special coating applied to products to protect them from EMI during supplychain/shipping but not afterwards? Seems niche. But it is cool.
deleted 4y ago
[deleted]
thrilled2behere 4y ago
It does seem a little weird, yeah. I mean, the researchers are from Drexel University. I would've figured that the applications that they would be most interested in would be fast optical switching and MEMS devices - whereas in this press release it seems like they're trying to "sex" up the findings by suggesting that they can be used to make a Romulan cloaking device for macroscopic antennas. This article might have suffered at the hands of an overenthusiastic PR team.

deleted 4y ago

[deleted]

EricE 4y ago

I need to figure out how to turn this into a 5G shield. Will make millions.

notadev 4y ago

47 U.S. Code § 333 - Willful or malicious interference No person shall willfully or maliciously interfere with or cause interference to any radio communications of any station licensed or authorized by or under this chapter or operated by the United States Government. [1] https://www.law.cornell.edu/uscode/text/47/333 https://www.law.cornell.edu/uscode/text/47/333

egberts1 4y ago
bounced radio waves are fair game. IANAL.