[mastax]

2.4GHz was used for microwave ovens and thus the spectrum was reserved for their interference. Or rather, the spectrum was made free for low power uses because Serious Business couldn’t be done on those frequencies due to the microwave ovens.

[davisr]

While that provides a plausible origin story, it doesn't stand to reason why the 2.4 GHz carrier frequency has been sustained for so long. For toy or prototype purposes, sure, the FCC could say "put them next to the microwave ovens." But Wi-Fi is, at this point, a critical national security utility, or even as you put it yourself, "serious business."

I'm not a radio engineer, but it doesn't take that many brain cells to beg the question: for a handheld/laptop device, why choose a carrier wave frequency absorbed by the body holding it, and by the metallic electronics sitting beside it? Logically, that's one of the most energy-inefficient frequencies one could choose, and a terrible design choice for personal wireless communication technology. I think a good engineer would want to conserve power and not be blocked by the very body holding it.

However, as the future unfolded, we now have nearly every household with a bright radiant point light casting human-shaped shadows, trivially reconstructed, to detect not only the body's silhouette but it's heartbeat and respiration, too.

And with everything we know, with leaks going back decades about the abuses of government power, surveilling their own citizenry, recording, analyzing, and manipulating the population in subtle ways, resulting in the financial benefactor of a handful of billionaires and the power benefactor of media-savvy pawns, why are these basic technological choices not being questioned more?

(mastax, I'm replying to you because you're top reply, but felt it important to continue my original point.)

[mastax]

> While that provides a plausible origin story, it doesn't stand to reason why the 2.4 GHz carrier frequency has been sustained for so long. For toy or prototype purposes, sure, the FCC could say "put them next to the microwave ovens." But Wi-Fi is, at this point, a critical national security utility, or even as you put it yourself, "serious business."

Yes, but it started out as a little experiment using the scraps of free spectrum available while wireless carriers were paying billions for spectrum licenses. As WiFi has gotten more and more critical, the FCC and industry have worked to overcome many different technical and regulatory challenges to make more and more spectrum available to WiFi notably the 5GHz, 6GHz, 45GHz, and 60GHz bands. The FCC has a financial incentive to not make more unlicensed spectrum available (when they could charge license fees for it instead) and under your theory they'd have national security incentives to keep everything on 2.4GHz as well. Yet they keep making more and more spectrum available unlicensed to WiFi anyway because it's just that important now.

> Logically, that's one of the most energy-inefficient frequencies one could choose, and a terrible design choice for personal wireless communication technology.

That is just not true. 2.4GHz works great for WiFi, that's why it's still being used. It penetrates walls pretty well while still being able to handle a decent data rate. Furthermore, all radio frequencies are absorbed by the body, and 2.4 GHz does not have any special higher absorption rate from what I can see. The actual resonance is at about 80MHz: http://niremf.ifac.cnr.it/docs/HANDBOOK/chp3-3-1.htm#336

I don't find it hard to believe that the government has an interest in using radios for through wall imaging/surveillance purposes but the idea that that had some influence on the decision to use 2.4GHz radio for wifi in 2025 doesn't fit the evidence. Additionally, they'd need to have receivers spread around to be able to capture this surveillance data so they could also spread transmitters around at whatever frequency suits their fancy. They don't need to use WiFi for that.