Hacker News Reader

Comment by lima | Hacker News Reader

> Like, they'd cook you if they leaked out.

Nope, they wouldn't. The standing wave would break down as soon as it left the enclosure. It would still be a potentially harmful amount of radiation, but not like that.

And no, 24 GHz is not in common use. It's used for special applications, mostly highly directional tower-to-tower links (I have one sitting on my roof for a high-bandwidth HAM radio link). With 5G, it will be ubiquitous in an unprecedented way. We've already seen plenty of interference with 5 GHz.

Of course, there's a lot of fearmongering whenever RF radiation is involved, but there are genuine safety concerns.

Source: HAM radio operator

View on HN

In school, we used to learn about the RF service technicians returning with stories of dead birds and other such phantasmagoria in and around the sweet spots of the feedhorn, antenna, transmission line, transmitter or other such sensitive areas of high power microwave operations.

Professor also admonished us that such technicians must always be infinitely certain that the transmitter is not operational at the time of service.

> Professor also admonished us that such technicians must always be infinitely certain that the transmitter is not operational at the time of service.

It's a good thing your professor is not a tower technician. No self respecting technician climbs up a tower without knowing his potential exposure.

There is a reason both the US FCC and EU ICNIRP have guidelines for human exposure, and if you are a tower technician you wear a personal RF densitometer to ensure you are not exposed above these levels.

https://en.wikipedia.org/wiki/Personal_RF_safety_monitor

"Electromagnetic field densitometers, as used in the cellular phone industry, are referred as "personal RF safety monitors", personal protection monitors (PPM) or RF exposimeters.[1] They form part of the personal protective equipment worn by a person working in areas exposed to radio spectrum radiation."

And even with a densitometer, when working on high-powered live equipment, you also wear a protective suit:

https://upload.wikimedia.org/wikipedia/commons/c/c7/Nardaler...

I hope you forward this information to your professor. Industrial RF radiation is not something you want to play around with.

I saw a video recently where a guy took a densitometer to a street with 5g in my country, and lets just say that there was plenty of sweet spots where it was well over 500uw/m2. Im no expert or anything, but seems like allowing 4 different vendors to put up 5g infrastructure all over the place might not be such a great idea.

I lived in a place where they had many co-located LTE base stations and power density about 1/4 mi away from these exceeded 75 mW/m^2. Now, I get it that a typical wifi base station transmits up to 500mW, but that's a point source and the inverse square law works to your advantage - the total dose in any one direction is minimal.

Not so when it's a huge multi-tier tower - that's your whole body facing the tower getting that dose.

I'm a software engineer, a technologist, by trade and I was in complete denial about this until I started getting serious eczema that only went away when I stopped using wireless gadgets and avoided staying too long in areas with cellular base stations.

I denied and denied and denied but repeated experiments on myself only revealed how my body reacts to this stuff. My ideal power density is less than 1mW/m^2 to not break out. And there seems to be a relationship to what LTE bands the tower is transmitting on - outside the US I seem to do better. It could be the frequency, or could be the modulation.

hmm your comment makes it sound as if I had said that my professor recommended reckless abandon such that we should climb the tower in swimwear during a heavy rain after cranking the tranmitter to maximum?

Yes it's true. Unfortunately I cannot edit my comment any more. I do apologize, as it seems I actually misinterpreted your comment.

You can erase all references to your professor and swimwear tower climbing from the text. Hats off to him! And again, sorry for the mistake.

No worries, I reckoned that a misunderstanding must have occurred!

Still, I couldn't resist a vision not unlike the penultimate and electrifying golf scene with Bill Murray & the bishop in Caddyshack.

I believe these "sweet spots" are technically referred to as "modes". Think of them as "balls" of RF located in a specific area.

>Nope, they wouldn't. The standing wave would break down as soon as it left the enclosure. It would still be a potentially harmful amount of radiation, but not like that.

Yeah that's a good point

>And no, 24 GHz is not in common use. It's used for special applications, mostly highly directional tower-to-tower links (I have one sitting on my roof for a high-bandwidth HAM radio link).

That's what I mean by common use. Omnidirectional antennas aren't in common use.

Reply on news.ycombinator.com