They should think about pulling out little regions of spectra normally used for other things and let the market try to do things with them without restriction. They might end up too saturated to be useful, but we might develop smarter receivers and a cornucopia of new products. It's worth a 1% A/B test I think.
That sounds like a disadvantage... but it does let you cram a lot of transmitters into a city. If everyone had a 102Mhz transmitter the resulting network would be like a class room full of five year old boys who each had their own megaphone.
Well, FCC only regulates the U.S., right?
what happens in countries where there's more bands available? i remember a router that allowed me to select twice more wifi channels if i mention i was in japan...
American MacBook Pros (used to?) come locked to 1-11 with no way to change that, which really sucked if you ever traveled anywhere.
ITU states that the ISM (industrial, scientific, medical) bands are nearly-anything-goes free for all in the frequency blocks. 5.8GHz was too expensive at the time wireless caught on, but 2.4GHz was cheap enough.
ITU chose 2.4GHz and 5.8GHz because the microwave emits broad spectrum radiation and harmonics at those frequencies, so they ignored them and made them free to use and abuse.
KC9JEF
Another related tidbit: Microwave ovens getting water molecules so excited at 2.4 GHz ties in with WiFi performance. It's a tidbit the head tech at a local wireless ISP didn't even know... 2.4 GHz WiFi is particularly prone to fading in fog/rain because water absorbs energy so efficiently at that frequency.
If they really want to get into strange frequency trivia, they should explain why Channel 37 has never been used by any over-the-air television station in Canada or the United States. Hint: little green men
The associated absorption graphs do indicate there is a small peak of 2 dB per kilometer around the 2.4 GHz band due to water. (I'd expect to have a larger drop through a wall.)
From: NASA Reference Publication 1108(02) 1987; "Propagation Effects on Satellite Systems at Frequencies Below 10 GHz; A Handbook for Satellite Systems Design; Second Edition" by Warren L Flock.
Does this have safety implications? I mean, if I stay too close to my wifi router can I be damaged?
Your consumer gear runs under Part 15. You cant generate interference, and you accept all interference. It's cut and dry, as in you have no recourse.
Amateur radio, on the other hand, have legal powers to stay on air, and even kick you off. Legally, a ham can command under Part 97 and your Part 15 to turn off your receivers (a good receiver is also a weak transmitter). Now the common courtesy in the ham community is to troubleshoot their problems so everybody benefits. But prior is the law.
As per H2O attenuation, that's way up there in Spark Gap frequencies... around 100GHz. What you're facing is perhaps at most +12dBi from your antenna and -40dB loss due to the good ol inverse square law.
The Water heating in the microwave and associated to 2.4GHz is false. When you have a polar molecule (liquid water) and expose it to alternating EM fields, they gain kinetic energy and warm up. Any polar molecule will exhibit this behavior when exposed to an alternating EM field.
No, no, no, no, no.
http://earth.esa.int/applications/data_util/SARDOCS/_icons/c...
Edit: Preset == Present
I think some of that remote control equipment shared 72 to 76 Mhz for a while. That's a gap, 2/3 the size of a t.v. channel between channels 4 and 5.
I'm wondering if the F.C.C. will take away t.v. channels 2 through 6. Almost everywhere, the stations formerly on those went to U.H.F. with the digital transition. I guess they figure that few people want to buy really big antennas for the lowest frequencies. (UHF and 7-13 use much shorter antenna elements). Anyway, those channels have the best coverage potential of all of them, but they're hardly used now. (see tvfool.com or the FCC database)
