3 ms·

So it wasn't obvious to me why they needed a $250,000 network analyser, given that there's no network and no signal to analyse. Apparently they used it as a sig

So it wasn't obvious to me why they needed a $250,000 network analyser, given that there's no network and no signal to analyse. Apparently they used it as a signal generator, and to plot the attenuation. I can imagine a less-costly experimental setup. The amplification result is rather puzzling; I wonder if the antenna was in contact with the helmet, transforming the helmet into an extension of the antenna? Also, the receiving antenna, presumably located between the helmet and the cranium, is stated to be a directional antenna. What kind? Was it a yagi array, or some kind of dish? I'd like to know how they fitted a directional antenna under the helmet, without it showing. I thought a crisp packet was supposed to be effective as a radio shield, and there's a lot more metal in tinfoil. Someone should try to replicate this.

yodon 4y ago
>it wasn't obvious to me why they needed a $250,000 network analyser, given that there's no network and no signal to analyse Radio frequency (RF) network analyzers are test and measurement instruments used to characterize the performance of RF and microwave components and systems. >The amplification result is rather puzzling; I wonder if the antenna was in contact with the helmet The helmet is functioning as a roughly spherical resonant cavity. Any such resonant cavity will have resonant frequencies and the signal strength inside the cavity will be stronger at certain locations and frequencies than outside the cavity. >I'd like to know how they fitted a directional antenna under the helmet, without it showing. They placed a helmet around an antenna, with the antenna inside a mannequin head, so as to measure the signal strength that would be present in the locations that would be inside the head if the helmet were to be worn by the wearer.
- denton-scratch 4y ago
  Thanks! That stuff isn't in the article. I took a "network analyser" to be the kind of thing I used to use to debug wire protocols, but more expensive.

yodon 4y ago

>it wasn't obvious to me why they needed a $250,000 network analyser, given that there's no network and no signal to analyse Radio frequency (RF) network analyzers are test and measurement instruments used to characterize the performance of RF and microwave components and systems. >The amplification result is rather puzzling; I wonder if the antenna was in contact with the helmet The helmet is functioning as a roughly spherical resonant cavity. Any such resonant cavity will have resonant frequencies and the signal strength inside the cavity will be stronger at certain locations and frequencies than outside the cavity. >I'd like to know how they fitted a directional antenna under the helmet, without it showing. They placed a helmet around an antenna, with the antenna inside a mannequin head, so as to measure the signal strength that would be present in the locations that would be inside the head if the helmet were to be worn by the wearer.

denton-scratch 4y ago
Thanks! That stuff isn't in the article. I took a "network analyser" to be the kind of thing I used to use to debug wire protocols, but more expensive.