3 ms·

> You'll be expected to never turn on your Pi Zero without an antenna attached again, should your transmitter get fatally confused by the mismatch of hardware-d

> You'll be expected to never turn on your Pi Zero without an antenna attached again, should your transmitter get fatally confused by the mismatch of hardware-defined impedance assumptions. Can the hardware really be damaged by using it without an antenna? I would not have expected that at all.

betamaxthetape 5y ago
Indeed it can - if the impedances are not matched correctly, the transmitted signals can end up being reflected back down the antenna, causing damage to the transmitter. The Wikipedia article on Standing Wave Ratios [1] has more on this topic. [1] https://en.wikipedia.org/wiki/Standing_wave_ratio https://en.wikipedia.org/wiki/Standing_wave_ratio
- buescher 5y ago
  It can, but I’d be a little surprised if the zero w makes enough power to destroy its output without an antenna.
- martin_a 5y ago
  > Indeed it can - if the impedances are not matched correctly, the transmitted signals can end up being reflected back down the antenna, causing damage to the transmitter. I think I've seen this once in a documentary where this blew up a whole ship and then many others, too. I think it was called Independence Day or sth. like that.
  - Crosseye_Jack 5y ago
    Wasn't that a computer virus?
    - martin_a 5y ago
      Nah, I was thinking about this: https://youtu.be/NyOTaHRBTXc?t=110 https://youtu.be/NyOTaHRBTXc?t=110
- tzs 5y ago
  This outstanding 1959 movie from Bell Labs demonstrates standing waves, impedance matching, and more in a very nice way using a couple of Shive wave machines, hosted by Dr. Shive himself [1]. [1] https://www.youtube.com/watch?v=DovunOxlY1k https://www.youtube.com/watch?v=DovunOxlY1k [2] https://en.wikipedia.org/wiki/John_N._Shive https://en.wikipedia.org/wiki/John_N._Shive
Fnoord 5y ago
AFAIK the same is true for any WLAN card with antennas, radio with antennas, HackRF, etc etc.
- londons_explore 5y ago
  I know this is true for big multi-kilowatt power amplifiers. But are there any on-chip silicon amplifiers which can be damaged transmitting into a short or open circuit? Logic to detect that case and power off is trivial and should make the manufacturing process easier too (for one thing, rework of a dry solder joint on an antenna no longer requires the SoC to be replaced).

betamaxthetape 5y ago

Indeed it can - if the impedances are not matched correctly, the transmitted signals can end up being reflected back down the antenna, causing damage to the transmitter. The Wikipedia article on Standing Wave Ratios [1] has more on this topic. [1] https://en.wikipedia.org/wiki/Standing_wave_ratio https://en.wikipedia.org/wiki/Standing_wave_ratio

buescher 5y ago
It can, but I’d be a little surprised if the zero w makes enough power to destroy its output without an antenna.
martin_a 5y ago
> Indeed it can - if the impedances are not matched correctly, the transmitted signals can end up being reflected back down the antenna, causing damage to the transmitter. I think I've seen this once in a documentary where this blew up a whole ship and then many others, too. I think it was called Independence Day or sth. like that.
- Crosseye_Jack 5y ago
  Wasn't that a computer virus?
  - martin_a 5y ago
    Nah, I was thinking about this: https://youtu.be/NyOTaHRBTXc?t=110 https://youtu.be/NyOTaHRBTXc?t=110
tzs 5y ago
This outstanding 1959 movie from Bell Labs demonstrates standing waves, impedance matching, and more in a very nice way using a couple of Shive wave machines, hosted by Dr. Shive himself [1]. [1] https://www.youtube.com/watch?v=DovunOxlY1k https://www.youtube.com/watch?v=DovunOxlY1k [2] https://en.wikipedia.org/wiki/John_N._Shive https://en.wikipedia.org/wiki/John_N._Shive

Fnoord 5y ago

AFAIK the same is true for any WLAN card with antennas, radio with antennas, HackRF, etc etc.

londons_explore 5y ago
I know this is true for big multi-kilowatt power amplifiers. But are there any on-chip silicon amplifiers which can be damaged transmitting into a short or open circuit? Logic to detect that case and power off is trivial and should make the manufacturing process easier too (for one thing, rework of a dry solder joint on an antenna no longer requires the SoC to be replaced).