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FCC Allows Mix-and-Match Wi-Fi Antennas
Glenn Fleishman writes "We just filed a story at Wi-Fi Networking News about how the FCC recently and quietly approved rules that will allow the legal use of the Pringles can and other antennas. Currently, it's clearly illegal--even though it's incredibly easy--to swap out a manufacturers' antennas from a Wi-Fi access point with an antenna of your choosing. It's legal to sell antennas; not legal to deploy them. Call it the switchblade kit rule: legal to sell, but don't assemble. The FCC's new rule provides a middle ground: a manufacturer can certify their hardware with the highest gain legal antennas of each type (yagi, omni, etc.) and then end-users can swap in antennas of equal or lesser signal characteristics. It's an important move because it removes the potential for community wireless and individual users to be prosecuted for illegal antennas once new certifications are in place."
Does this mean that we can finally get rid of annoying antenna connector types such as RP-SMA and RP-TNC that were originally devised just to make it a pain in the ass to switch out factory antennas? I'd much rather be able to mix and match antennas and cables that can be easily found at local HAM shops.
IIRC, a couple of geeks got in trouble a while back for exceeding FCC regulations. I suppose it would be pretty easy for someone to "know enough to be dangerous."
If you're not sure what dangerous could mean, think microwaves, pacemakers, cell phones, aircraft, etc.
We can use whatever gain antenna we wish so long as standard (60 cm) thick igloo ice can contain the signal.
Trolling is a art,
Channel 1 is in a band that falls in spectrum assigned to amateur radio operators. That means, of course, we can legally transmit up to 2500 watts vs 50 milliwatts if that happens to be the lowest power we need to get the signal through.
It also means we're licensed users of the spectrum, which trumps Part B and means a license holder could, technically, tell a neighbor to move off of channel 1.
I noticed that the article lists a bunch of different antenna types. I didn't know what they all were, so I looked some of them up and thought I'd share:
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The info in quotes is verbatim from http://www.radiolabs.com/Articles/wifi-antenna.ht
Omni: (Omni-Directional)
This is a standard antenna like you'd see on a cordless phone. Broadcasts the signal more or less equally in all directions.
"An Omni-Directional antenna would serve as your main antenna to distribute the signal to other computers or devices"
Yagi Antennas
"Yagi antennas were the design of two Japanese people, Hidetsugu Yagi and Shintaro Uda, and are sometimes referred to as Yagi-Uda antennas...these antennas are typically very directional and are used for point to point."
Yagis look like a ladder with one vertical bar in the center of each step.
Backfire antennas
"The backfire is a small directional antenna with excellent gain. They look similar to a parabolic dish, but the gain isn't as high."
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DrMovieMovie.com:
Witty movie reviews, eating contests, and a guy who once drank a gallon of milk in an hour.
it removes the potential for community wireless and individual users to be prosecuted for illegal antennas once new certifications are in place
No it doesn't. How'd you come to that conclusion?
If a user has an antenna that exceeds the specs that have been certified for that antenna type with that device, it's still illegal to use and the user can still be prosecuted.
And if the manufacturers don't get their devices certified with anything other than their weak default antenna, you still won't be legally allowed to use anything stronger than their default. This will vary by manufacturer -- Linksys might want to sell powerful upgrade antennas to its users, so it will get its equipment certified with a really powerful antenna. Apple, on the other hand, probably has no plans to sell replacement antennas for its Airport devices and will only get certification for its standard antenna.
How is it clearly illegal? I didn't know it was illegal to use your own attenas?
Yes, because license-exempt transmitters ("Part 15" devices) are approved based on a specifc design including the antenna.
Once you modify a Part 15 device, such as by using a non-approved antenna you modify its RF characteristics which change important details such as how much Effective Radiated Power (ERP) which is limited to 4W in the US (many European contries limit WiFi to 1W ERP I believe).
If any one wants to use highpower 802.11 on 2.4gh and use huge wave guide antenas with that high power equipment then all they have to do is get a ham lisense. With the introductory lisense you can use super high power out put transmitters and realy high gain antenas compared to the comercialy avable stuff. How would you like 100 wats PEP on your access point? The only thing is you cant use it for comercial purposes only personal uses. If you get the liscense you also get access to other bands and you can legaly build your own radio equipment. Its not hard to get the lisence either and there are probaly tons of hams in your area to help you get into and promote radio hobbies like packet radio. Check out www.arrl.org, or www.qrz.com if you need some more information.
Faith_Healer -- The antethsis to almost everything, and the worlds worst speller.
Tony Chong, of Cheech'n'Chong, ran a glassblowing shop which made artwork glass tubes. The shop was taken down by the DEA and Chong was charged in court. I didn't keep track of the outcome.
At the end of the day legality is determined by how badly they want to get you.
+++ATHZ 99:5:80
The point of the power limitation is to restrict the signal strength, and thereby reduce interference.
So Tom, Dick and Harry have houses in a row. If each one has nondirectional antennae on his home network, none of them receives network packets coming from another's house. But if Tom and Harry set up directional antennae so they can network together, Dick will receive packets from both Tom and Harry, and his throughput will go down.
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15.204 External radio frequency power amplifiers and antenna modifications (c) Only the antenna with which an intentional radiator is authorized may be used with the intentional radiator.
Now, it says:
15.204 External radio frequency power amplifiers and antenna modifications (c) An intentional radiator may be operated only with the antenna with which it is authorized. If an antenna is marketed with the intentional radiator, it shall be of a type which is authorized with the intentional radiator. An intentional radiator may be authorized with multiple antenna types.
(1) The antenna type, as used in this paragraph, refers to antennas that have similar in-band and out-of-band radiation patterns.
(2) Compliance testing shall be performed using the highest gain antenna for each type of antenna to be certified with the intentional radiator. During this testing, the intentional radiator shall be operated at its maximum available output power level.
(3) Manufacturers shall supply a list of acceptable antenna types with the application for equipment authorization of the intentional radiator.
(4) Any antenna that is of the same type and of equal or less directional gain as an antenna that is authorized with the intentional radiator may be marketed with, and used with, that intentional radiator. No retesting of this system configuration is required. The marketing or use of a system configuration that employs an antenna of a different type, or that operates at a higher gain, than the antenna authorized with the intentional radiator is not permitted unless the procedures specified in Section 2.1043 of this chapter are followed.
A part 13 device can only put out a limited amount of signal. This is why there aren't "ultra-powerful' wifi basestations that can cover super-large distances.
Sure, you can buy or rig any antenna you want, but you're violating part 13, and if someone was catching interference from you and could track you down, they could ( in theory ) take you to court to make you stop flooding the spectrum and overpowering their own part 13 devices. And you could face FCC fines, I guess.
In fact, now that I've read TFA, this ruling doesn't help uncertified antennas at all. In fact, you can expect certified antennas to be more expensive and of more limited types, as uncertified ones are basically now for lawbreakers only, unless maybe they're spec'd to be at *lower* gain than certified ones ( kinda hard to tell from the article, it may be that you're actually only safe with certified antennas ). We'll probably see less variety in antennas now, actually.
What about this rule:
15.247(b)(4) Except as shown in paragraphs (b)(3)(i), (ii) and (iii) of this section, if transmitting antennas of directional gain greater than 6 dBi are used the peak output power from the intentional radiator shall be reduced below the stated values in paragraphs (b)(1) or (b)(2) of this section, as appropriate, by the amount in dB that the directional gain of the antenna exceeds 6 dBi.
Why would the FCC worry about the gain on these antennas?
Because Part 15 for license-free (or license-exempt I can't remember which term they use officially) limited the total effective raditated power (ERP) to 4W, and a limit of 1W transmitter. So you can use a up to a 1W transmitter and a 6db gain antenna and remain within the Part 15 limits, or a lower power transmitter (typically 100-250mW with WiFi) and a higher gain antenna.
Someone please explain why High Gain antennas are/were evil to the FCC?
Because license-free devices have no protection and are suppose not to interefere with licensed "services" (official term) in the same frequency band (2.4 GHz has several users including Industrial, Scientific and Medical usage, and I believe some satellite downlinks are also in 2.4 GHz).
Modified devices may create intereference on harmonics (normally non-approved amplifers are most common cause of harmonics). The limited gain of antennas limits intereference between license-free devices and licensed devices.
The pringles can antennas work really well. I've built two of them. There's plenty of really good guides on how to make the antennas and how they work.