Comment by kube-system
9 hours ago
> So they don’t effectively block communication to and from the device?
That is impossible to know without knowing the characteristics of the signal, noise, attenuation performance, sensitivity of the receiver, and other environmental conditions.
> Or they don’t block all RF?
They definitely don’t.
If you want to attenuate an RF signal, you need to do RF engineering. There are products to help people do this (eg RF test enclosure), but they aren’t marketed as “blocking RF” because that is nonsensical. The products that advertise as “blocking RF” without any real specifications are unsuitable for serious RF engineering, they are primarily sold to conspiracy theorists, hypochondriacs, etc.
>> So they don’t effectively block communication to and from the device?
> That is impossible to know without knowing the characteristics of the signal
Do you dispute that de facto these products work?
Yes I have spent thousands of dollars and months testing them.
You can cut off GPS and high frequency cell spectrum pretty easily. Most cell spectrum is effectively attenuated by good quality professional RF enclosures designed for those frequencies. 2.4 ghz signals like wifi (with good quality radios) are hard to attenuate to the point where they can’t connect to other radios nearby, even with very expensive RF test enclosures.
If you’re trying to block against an unknown threat you are fucked. If someone wanted to back door a baseband they’d probably make it transmit at low speeds and low frequencies to be resistant to attenuation.
What kind of RF can travel through a few mm of metal?
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Jesus. That sucks. Thanks for sharing, fascinating stuff.
I will, I've got two and neither one can shut off a longwave FM radio.