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Using an Old Satellite Dish as a WLAN Antenna 225

Posted by CowboyNeal from the rolling-your-own dept.
=m8s=Dark Underlord writes "I was browsing for wireless stuff and came across this link that shows how to use an old satellite dish as an 802.11 antenna." The directions tout the range as being 10 miles given line of sight. We've had other stories about building antennas, but I think these are cooler because of their focused nature, but a Primestar dish is a little tougher to locate than a Pringles can or a floppy disk.
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Using an Old Satellite Dish as a WLAN Antenna

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  • Jeez....this is an obvious dupe... (Score:5, Informative)

    by Geraden ( 15689 ) * on Thursday September 18, 2003 @09:28PM (#7000124) Homepage
    The Original Slashdot Article [slashdot.org]

  • Primestar Dish's on eBay (Score:5, Informative)

    by TheMysteriousFuture ( 707972 ) <TheMysteriousFutureNO@SPAMgmail.com> on Thursday September 18, 2003 @09:28PM (#7000127) Journal
    Looks like you can pick up a Primestar dish on eBay for about 50 bucks [ebay.com] (current auctions here [ebay.com]). Shipping looks to be about $20. Anybody know of other sources for acquiring these dishes?

    • Steal one (Score:5, Funny)

      by ArchieBunker ( 132337 ) on Thursday September 18, 2003 @09:31PM (#7000159)
      A few years ago I saw one still attached to a pole near an old trailer foundation along the highway. A few minutes of working it loose and we threw it in the trunk. I had plans to buy a receiver on ebay and get C and Ku band channels but never followed through.

    • Re:Primestar Dish's on eBay (Score:5, Informative)

      by ajlitt ( 19055 ) on Thursday September 18, 2003 @09:34PM (#7000190)
      I've picked one up at Goodwill for $5 (actually a DirecTV dish) and it works great with the cantenna.

    • For $15 more you get the real thing (Score:5, Informative)

      by dcavanaugh ( 248349 ) on Thursday September 18, 2003 @09:36PM (#7000210) Homepage
      Why bother with the Primestar dish for $50 on Ebay when you can get a real 802.11b/g antenna [hyperlinktech.com] with 24dB gain for about $65? If memory serves, every 3dB is double, so 24dB is 2^8 or 256 times the signal strength.

      • Re:For $15 more you get the real thing (Score:5, Insightful)

        by djh101010 ( 656795 ) on Thursday September 18, 2003 @10:22PM (#7000485) Homepage Journal
        Exactly my thoughts - I have several DirectTV dishes lying around that I was going to use for a 1.1 mile 802.11b link, and it just wasn't worth the hassle. The offset feedhorn makes mounting (and the math) inconvenient, and to me it wasn't worth the risk of, ahem, going beyond the 24 dBi of gain that the FCC allows. Better to be able to point to published specs for each piece of gear, and cable losses, and explain how you're not exceeding the legal limits. Yeah it's cool and all that, but what's the gain of these? (I don't know either). is it worth taking a chance?

        For what it's worth, two Linksys WAP11's in bridge mode, and two directional 24dBi gain antennae, and my link is rock solid at 1.1 miles.

        • No kidding. Get the real thing. (Score:4, Informative)

          by Anonymous Coward on Thursday September 18, 2003 @10:58PM (#7000669)
          For what it's worth, two Linksys WAP11's in bridge mode, and two directional 24dBi gain antennae, and my link is rock solid at 1.1 miles.

          I use Linksys WET11 bridges with 24dBi grid antennas made for 2.4GHz (also less than $70 each) and have a rock-solid 11Mbps link a bit over 6 miles away. The trick is to mount your WET11 in a weatherproof box right underneath the antenna, to keep the coax pigtail as short as possible, because signal loss in a long coax is the distance killer. I have only a 3 foot long coax pigtail and run the dc power up the unused pairs of the CAT5 cable to power the WET11. You may have a significant voltage drop at the end of a long CAT5 cable, so you may need to use a +6V or even a +7V DC power supply of adequate amperage to ensure that you still have +5V DC at the end of the CAT5 cable with the WET11 plugged in loading it down. I had to use a +6V, 1.5 amp DC power supply on mine to keep the voltage at +5 volts at the end of my CAT5 cables, or the WET11 wouldn't run.

          • Re:No kidding. Get the real thing. (Score:5, Interesting)

            by cjsnell ( 5825 ) on Friday September 19, 2003 @12:21AM (#7001099) Journal
            I did a similar setup recently for my father's bicycle stores and here is a photo gallery of the results [chrissnell.com]. I have an aversion to Linksys (their tech support is horrible) and so I became a D-Link convert a few months back. We bought eight DWL-2000AP [dlink.com] access points/bridges (you can select the mode via the web interface) and eight of their DWL-P100 Power-over-Ethernet kits [dlink.com]. We linked our warehouses to our stores via 24dBi grids (from hyperlinktech.com) and, like you, placed our APs on the mast underneath the antennae. For our enclosures, I chose some inexpensive but very well-made Davis Instruments enclosures. They are NEMA-4 rated and are sealed against the elements. We're a dealer [weathertools.com] for Davis so we got them really cheap. Being in South Texas, I was concerned about heat in the boxes so I built custom heat shields [chrissnell.com], which fit around the NEMA enclosures. I built these from R-Matte (which looks like foam plywood) and foil tape. I also used the foil tape to turn cheap-o indoor grade CAT5e into psuedo-outdoor grade cable.

            Chris
      • 3 DB is a change in power by two times. Double the distance is 1/4 the power so the rule of thumb I use is 6 DB doubles the range. In some cases you can actually do better then that because of the spatial selectivity of a directional antenna reducing the effects of other transmitters and noise sources.
      • One Bel (10dB) is a power of ten in intensity. The question I have here is, is that a 22db gain over the stock antenna, or is it a 22db gain over a calibrated 50ohm dipole, as most commercial communications antennas are measured? If the former, what is the gain of the stock antenna?

        Mnem
        "Enough technical gobbledygook. Tell me how we kill this thing."
    • Our junky storage area. They used to provide for us until we jumped ship cause of some service issues. They never got their stuff.

      Time to scheme.

    • Not for long (Score:5, Funny)

      by SuperBanana ( 662181 ) on Thursday September 18, 2003 @09:54PM (#7000344)
      Looks like you can pick up a Primestar dish on eBay for about 50 bucks

      Given the fact this story was just posted on Slashdot..not for long.

      Somewhere, tomorrow morning, some poor satellite dish dealer in East Nowhere is going to be very, very happy and not know why.

    • Yes.

      I'll sell you a 30" new dish without an LNB (not primestar branded) for $75 CDN. Shipping not included. Add LNB for $10 CDN.

      If you're paying $50 US for a heavily used OLD dish, you're being ripped off in a VERY big way.
    • A lot of cable companies will 'buy' your old dish equipment if you switch to digital cable. Call them and ask if they have any old dishes laying around, especially if your a cable customer.
    • if you drive around you can get about 3 primestar dishes for free.

      there are many of them still on their pole's on roofs in rural/ semirural areas.

      Anyone that pay's for a primestar dish is a fool, they are still around for free, and the people that have them are happy to see them go away.
    • I live near Binghamton, NY and have one mounted to a pole (2 feet tall) in concrete. Price is: remove it yourself.

  • You don't own the antenna... (Score:4, Funny)

    by Dancin_Santa ( 265275 ) <DancinSanta@gmail.com> on Thursday September 18, 2003 @09:29PM (#7000137) Journal
    Aren't you supposed to return the antenna at the end of the contract?

  • I've already started on one (Score:4, Interesting)

    by SHEENmaster ( 581283 ) <travis@uUUUtk.edu minus threevowels> on Thursday September 18, 2003 @09:29PM (#7000143) Homepage Journal
    Days ago. And IIRC, it was a /. article that inspired me.

  • Next time on Slashdot... (Score:4, Funny)

    by NakedChick ( 699757 ) <N_a_k_e_d_C_h_i_c_k@hotmail.com> on Thursday September 18, 2003 @09:30PM (#7000149) Journal
    Making a WiFi antenna using a telephone poll. You use the red and green wires to transmit a signal to another WiFi device connected to the red and green wires up to 20 miles away. But what would I know? I'm just a naked chick.

  • Difficult to locate!?!??! (Score:5, Funny)

    by jared_hanson ( 514797 ) on Thursday September 18, 2003 @09:30PM (#7000153) Homepage Journal
    Primestar dish is a little tougher to locate than a Pringles can or a floppy disk.

    Will a DISH Network or DirecTV dish work? I can locate hundreds of these without walking too far. Give me a couple of nights and I can send a bulk shipment you're way for a few thousand dollars.

    Now, where did I put my screwdriver?

  • I once tried this... (Score:4, Informative)

    by KingRobot ( 703860 ) on Thursday September 18, 2003 @09:32PM (#7000174) Homepage
    I tried this a while back, but at the time, even unused sattelite dishes were too expensive. I borrowed a neighbors' dish for the experiment. The hard part was focusing the dish - If you didn't have something sturfy to mount it to, then you would lose the signal pretty easily.

  • Big Dish... (Score:5, Interesting)

    by nitrocloud ( 706140 ) on Thursday September 18, 2003 @09:33PM (#7000184)
    My grandparents have a satelite dish that's about 10 feet in diameter... so should that give access to about 30 miles away? (I know it wouldn't, but it'd be neat to crank the amps)

  • 12 Miles at 5Ghz with Primestar Dish (Score:5, Interesting)

    by ArkiMage ( 578981 ) on Thursday September 18, 2003 @09:33PM (#7000186)
    Where I work our internet connection is via a WISP that uses this "technology". We have a Primestar dish on an elevated pole aimed at a mountaintop 12 miles away. 5Ghz and also a backup 802.11b radio with Yagi antenna that needs an amplifier to go that distance, but does so fairly well. The less-informed employees think the "dish" points to a satellite, not noticing the odd angle it's mounted at :)

    http://www.planetc.com/ is the ISP

    • Re:12 Miles at 5Ghz with Primestar Dish (Score:5, Interesting)

      by MemoryAid ( 675811 ) on Thursday September 18, 2003 @10:00PM (#7000378)
      As I recall, most of the satellite dishes these days have an offset feed, so it is not obvious which way they are pointing. In fact, they usually point a little higher than it appears. That is, a vector normal to the center of the dish points lower than the main lobe of the antenna pattern.

      During a trip to Fairbanks, Alaska last year, it struck me as odd (well, odd looking) that the satellite dishes were pointing at the horizon. The offset-feed dishes looked like they were pointing at the dirt.

      If you want it to appear that your dish is pointing to a satellite, you could mount it with the feed horn on top, giving the appearance of a skyward view.

    • Re:12 Miles at 5Ghz with Primestar Dish (Score:5, Interesting)

      by bill_mcgonigle ( 4333 ) on Thursday September 18, 2003 @10:40PM (#7000580) Homepage Journal
      We have a Primestar dish on an elevated pole aimed at a mountaintop 12 miles away.

      How the heck do you sight something like this in? You have to be accurate within a few seconds, don't you? A search pattern would take forever with that narrow of a beam, wouldn't it?

      Some of the high-end telco gear has a built-in telescope, but those are precision aligned at the factory.
      • Cisco's 21dBi dishes have a 3dB falloff at 12.4 degrees so you don't have to be THAT accurate. For full speed you need to be within about 3-5 degrees, I believe they usually hook up a laptop card and watch a VU like graph to tell when they are at optimal sighting.

      • beamwidth gets wider as you drop in frequency (Score:5, Informative)

        by ChrisCampbell47 ( 181542 ) on Friday September 19, 2003 @12:28AM (#7001128)
        We have a Primestar dish on an elevated pole aimed at a mountaintop 12 miles away.

        How the heck do you sight something like this in? You have to be accurate within a few seconds, don't you? A search pattern would take forever with that narrow of a beam, wouldn't it?

        The beam isn't that narrow. Let's do a quick mental calculation. A typical direct-to-home Ku-band dish is going to have a beamwidth of about 1 degree (2 degrees, whatever) in order to be able to isolate the right satellite on the arc. That's at Ku-down, which is about 11 GHz. A given antenna will get "wider" as you go down in frequency, so the beam width at 2.4 GHz for this same antenna is much wider. I believe the beam width and frequency scale inversely, so if you go down in frequency by about a factor of 5 (11/2.4) then your beamwidth (however you want to measure it) goes up by the same factor.

        So your beamwidth at 2.4 GHz is going to be something like 5-10 degrees. And it's not a super sharp rolloff, so you'll find that signal easy.

        Another way of expressing all of the above is to say that an antenna with a certain gain at a high frequency (like Ku band) is going to have a lower gain at a lower frequency, and the corollary of that gain reduction is lobe spreading.

        Hey, maybe someone here can point us to a visualization tool for this -- looking at an antenna pattern for a given antenna, crank down the frequency and watch the lobes spread out and drop.

        • Thanks for the info, you know your stuff - maybe you can clear up a point I'm confused on for me:

          A typical direct-to-home Ku-band dish is going to have a beamwidth of about 1 degree (2 degrees, whatever) in order to be able to isolate the right satellite on the arc. That's at Ku-down, which is about 11 GHz. A given antenna will get "wider" as you go down in frequency, so the beam width at 2.4 GHz for this same antenna is much wider.

          It was my impression that a DSS satellite bathed a large section of the

  • it may have 10 mile range... (Score:5, Funny)

    by deathcloset ( 626704 ) on Thursday September 18, 2003 @09:34PM (#7000192) Journal
    but it is powerless against slashdotting!

  • Hard to locate? (Score:5, Funny)

    by christopherfinke ( 608750 ) <chris@efinke.com> on Thursday September 18, 2003 @09:34PM (#7000195) Homepage Journal
    Satellite dishes aren't hard to find; just visit any trailer park or upper-lower/lower-middle class neighborhood, and I guarantee you, there'll be a dish stuck on the corner of every other house. The kids'll be running around half-naked, there'll be a car or two on the lawn, but getting satellite tv still seems to be first priority.
    • Interesting. I commented several days ago about how the mom in public housing that is paying for broadband internet (the one with the daughter that's being sued by the RIAA) should re-prioritize.

      I was quickly flamed, parent gets "Funny." Can anyone say double standard?

      • I really wasn't trying to be funny, just commenting on the sad situation of a large percentage of low-income families: broadband, satellite, manicures, and pricey clothes all seem to come before vaccinations, sanitation, and education.
      • A 12 year old kid will NOT be able to compete in tomorrow's marketplace or the global community if she doesn't grow up Internet-connected today. If that mother disconnects the cablemodem, one more kid from the next generation will be lost.

        But satellite tv has no redeeming educational value, and kids running around half naked eating dirt is just funny as hell.

  • Bah! (Score:3, Funny)

    by Kedisar ( 705040 ) on Thursday September 18, 2003 @09:37PM (#7000212) Journal
    I STILL say my dish [space.com] is better than anything you can get. Damn, I can WiFi to my brother's computer all the way in Zeta-Twelve!

  • slashdot strikes again! (Score:3, Funny)

    by focitrixilous P ( 690813 ) on Thursday September 18, 2003 @09:37PM (#7000213) Journal
    wwc.edu better set up a bunch of these things and stream the site to someone with more bandwith...

  • Re: (Score:2, Informative)

    by account_deleted ( 4530225 )
    Comment removed based on user account deletion

  • FCC rules (Score:5, Informative)

    by Anonymous Coward on Thursday September 18, 2003 @09:43PM (#7000276)
    Hey, guys, this would violate FCC part 15 and other applicable rules. Specifically, we are referring to ERP (effective radiated power).

    Have fun if you get nailed!
    • Have fun 'getting nailed'. Uh, yeah. All the FCC will do is knock on your door and tell you to take the antenna off.

    • Re:FCC rules (Score:2, Informative)

      by Anonymous Coward
      The Part 15 rules are not nearly as strengient as you might think. For example, the rules only allow for a maximum input power of 30 dbm (1 watt) at the intended radiator (input to the antenna), but on a point-to-point link you can have a Shit Load(tm) of gain as long as your antenna radiation pattern falls within a few degrees beamwidth. When I mean a Shit Load(tm) of gain, I'm talking about in the several hunderd watts range. The rule is that for each 3db of antenna gain over 6db, you have to reduce yo
      • "Be careful of the middle rail, it is pushing 600 volts."
        "It's not the volts that kills you, it's the amps."
        "Well how many amps are we talking?"
        "Enough to push a train ..."

        800 Watts? Jesus man, my microwave only does 700 watts and that is enough to cook a chicken. I can only envision 800 watts of microwave energy on a focused beam, on the end of a pointy stick. Look like something out of Ghostbusters.
    • Not using your typical 17dBm card and any real length of connecting cable. Point to point limits for ERP are pretty high. Cisco sells a bundle with a 20dBm bridge and a 21dBi antenna. I believe the limit is either 42 or 45 dB ERP.

  • Canteena for $19.95, shinier and FCC legal ! (Score:5, Informative)

    by Proudrooster ( 580120 ) on Thursday September 18, 2003 @09:51PM (#7000317) Homepage
    If you are interested in this, check out the Canteena solution [cantenna.com] which has a 12 db gain. You can get a *new* shiny antenna for much less than the cost of a used Primestar dish on EBAY. I know the dish in the article boasts 22 db gain with a 10 mile range but, keep in mind that setting up communication that is line of site 10 miles apart is nearly impossible. (Just try using a camera with an 8x telephoto lens to take a non blurry picture, you'll start to get the idea. ) Have fun!

    • Re:Canteena for $19.95, shinier and FCC legal ! (Score:5, Informative)

      by v1 ( 525388 ) on Thursday September 18, 2003 @10:07PM (#7000419) Homepage Journal

      I shopped around a month ago for wifi antennas too, and found there's a lot of rip-offs and a few hiddeen gems. Cantenna doesn't come with the pigtail, which doubles the price. Add a "mounting bracket" (it's a camera tripod) and the price is now triple.

      For about the same money, check out the real thing by Pacific Wireless: http://www.rangeextender.com/224pagransy.html

      24db gain, versus the cantenna's 12. Adding 12 more db of gain amounts to 16 times more signal than the Cantenna, and it even comes with a weatherproofing kit and is meant to mount to a pole outside where it belongs. I don't think a Cantenna would last one season outside where I live, and it certainly won't mount on my roof using that camera tripod.

      I think the Cantenna is meant for people that want to just experiment, war-drive, look for waps near their house, etc. If you really want to establish a long-distance or "shooting through trees" link, the Pacific Wireless looks to be the real deal.
    • What is an 8x telephoto lens? The 2x,3x,4x specs are mearly the ratio of of the shortest to longest focal length on a lens. I can HANDHOLD a 24mm 8x telephoto lens rock solid. The short end of that lens is 3mm.

      I can also support a 400mm lens rock solid, exposures at 1/2000th of a second will be as sharp and free from blur as any photo you care to take (given we both use the same film format, no fair if one of us uses 35mm and the other brings out the 8x10 studio camera.)

      You need a better analogy, it's eas
  • You can get one of the big dishes and an echostar box from a pawn shop and try to pick up analog C and KU band channels. Some semi-premium channels are still unscrambled. AFAIK you can still subscribe to big dish services. Apparently a cleaner signal and no mpeg artifacts.

  • Wardrving aerodynamics will take a hit (Score:4, Funny)

    by kaamos ( 647337 ) on Thursday September 18, 2003 @09:59PM (#7000363)
    *rolls down window*

    "- Sir, you are aware that you have a huge TV antenna duct-taped to the roof of your mini-van?

    - Hun, yeah, I do

    - And that there seems to be 2 sets of eyes in the back of the mini-van that look like they belong on ghouls

    - I think you mean geek sir. And don't mind the flashing leds too, we are having a lan party.

    - In a mini-van ?

    - Mmh, yeah.

    - Ok, drive safe"

    *rolls up window and keeps on following the signal*

    • Hehe, reminds me of the dialogue at the beginning of a Butthole Surfers song....

      (Kids in car, singing "I don't give a fuck about the fbi, I don't give a fuck about the cia..."...cop siren goes off, car pulls over and cop starts talking:

      - Whatch'a doing?

      - Chewing chocolate.

      - Where's you find it?

      - Mmh, doggy dropped it?

      - (pause)...move along.

  • winegard.com (Score:3, Interesting)

    by kjh ( 7459 ) on Thursday September 18, 2003 @10:00PM (#7000375)
    In a past life, I used to provide ISP services to a company in Iowa that manufactures dishes used by many of the top names, including DirecTV. I checked their website, www.winegard.com, and it doesn't appear they yet have a consumer distribution channel. But if you want a bunch of dishes, these folks can probably provide them.

    FWIW- I toured the plant, and saw sheet metal stamped into dishes. It was impressive.
    • Wow! You mean you found something actually made in the USA?!

    • Re:winegard.com (Score:3, Interesting)

      by shepd ( 155729 )
      Most manufacturers of commodity items don't sell to end users. Heck, they don't even like selling directly to dealers (but most will, if they don't sell in your country [Yes, winegard has not a single official wholesaler in Canada]).

      You need to find a satellite dealer. They shouldn't have *ANY* trouble getting you a vast selection of dishes, including those made by Winegard (which, surprisingly for an american part, are well priced, and are well built).

  • LAN away (Score:2, Funny)

    by super_ogg ( 620337 )
    Imagine the long distance LAN parties.. whoa yah.

    Call your buddies up around the neighborhood and your ready.
    ogg
  • "I sacrificed a db of gain here by not turning it over, mostly because I'm mounting it on a vent pipe, and didn't want to put that kind of wind load on it. As mentioned above I don't really need the extra signal either."

    Wonder if he realizes what that vent pipe is for? Are there any studies on the interference factor from 'methane gas' emmisions on WI-FI?

    Maybe it's just the bathtub/sink vent.

  • Why use a mini-dish? (Score:3, Funny)

    by theycallmeB ( 606963 ) on Thursday September 18, 2003 @10:38PM (#7000571)
    Unless you are actually worried about taking up too much space (and why should we let that get in the way?), why use one of those little mini-dishes? Go all out and find an old 8-ft diameter big dish system. Not only will get a much larger reflector area, but if the control arm and box are still in working order, you can remotely slew over an arc of about 50-60 degrees without modification. This could let you change focus to different nodes from your computer.

    Plus it is far more conspicuous, and therefore infinitely more cool.

  • Making your own dish might be fun but.. (Score:3, Informative)

    by anethema ( 99553 ) on Thursday September 18, 2003 @10:45PM (#7000606) Homepage
    There are much better solutions. While a pringles can and cantenna might work, assumng you put it right in the focal point, build the cantenna right, and can find the dish, this might be a better way to go:

    Try this. [pacwireless.com]

    Its a 24dB gain antenna (Thats 256 times power folks), its guaranteed to work, it HAS a feedhorn, and all the calculations have been done for you. Not only that, its a grid antenna so there is almost no wind loading. You might pay 50bux or more for a primestar dish on ebay, plus trying to get the can into the focal point, etc. There is certainly a certain apeal in doing it yourself, but sometimes work for the sake of work is no fun at all.

    The best thing? Its only 70 bux, WITH the feedhorn and pigtail.

    Right now im using one of those, and two 10 foot C-band dishes to make a big triangle network connection. The C-band to C-band dish connection is over 30km long. (Yea I'm in Canada: 30 kilometers = 18.6411358 miles)
    • DON'T buy these if you live in an area that gets frequent icestorms. Aironet looked into them before they were bought by Cisco and up here in fridged Ohio they did not last through too many winters due to icing issues. I'm suprised you've had good luck with them in Canada (guess it depends on where you live, but 90% of the population lives within 100 miles of the southern border right?)
      • Not sure about the border thing. Sounds somewhat right, tho i can name a good few really big cities farther than that.

        Either way, there is a wired dish, and a non wire mesh dish, with the same gain. Are the icing issures you're talking about affecting the feed horn? temp. cycle warping?
      • -1, wrong.

        I live in Minnesota, and have had one hanging on my roof for the last 16 years. I just took it off two weeks ago when I repainted (it was for an old "wireless cable" system that folded ten years back. Somewhere around the 900 MHz range, as I recall.) It was in fine shape right up until the time I threw it the 25 feet to the ground, unlike the crappy Radio Shack TV yagi mounted on the same mast. I didn't examine its condition when I chucked it in the neighbor's dumpster, but the dumpster is s

  • I have an old one in my back porch, DISH sent me a new upgrade and I have no use for the old. Well until now.

  • That would make a great WiFi antenna (which is, of course, the 21st Century's version of "that would make a great bong.") Cory Doctorow [boingboing.net]

    Charles Miller

  • Obligatory Legal Reminder (for US residents)... (Score:4, Informative)

    by Anonymous Coward on Thursday September 18, 2003 @11:32PM (#7000886)
    Changing the antenna on wifi devices is prohibited by FCC regulations. 47CFR15 [fcc.gov]
    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.

    Only the party obtaining the FCC certification is allowed to specify another antenna. You, the user, cannot alter the device even if it meets the requirements of 15.247. Modifying approved transmitters is generally not allowed, with the notable exception of the Amateur Radio Service. A new configuration with higher antenna gain requires a new certification. 47CFR2 [fcc.gov]:

    2.932 Modification of equipment.

    (a) A new application for an equipment authorization shall be filed whenever there is a change in the design, circuitry or construction of an equipment or device for which an equipment authorization has been issued, except as provided in paragraphs (b) through (d) of this section.

    (b) Permissive changes may be made in certificated equipment, and equipment that was authorized under the former type acceptance rocedure, pursuant to 2.1043.

    2.1043 Changes in certificated equipment.

    (a) Changes to the basic frequency determining and stabilizing circuitry (including clock or data rates), frequency multiplication stages, basic modulator circuit or maximum power or field strength ratings shall not be performed without application for and authorization of a new grant of certification.

    [emphasis added]

    So unless you have the money to spend on a complete recertification (it's neither cheap nor easy), leave your wifi alone!

    • Years ago the FCC's enforcement unit would send out white vans crammed with signal equipment in order to discover unauthorized transmitters and other violations of the regs. Those vans are pretty much gone now.

      These days, they wait for complaints of interference before they send out the vans, and there are far fewer of them than there used to be. The mentality has changed from being the airwaves police to transferring the responsibility of discovering violations to operators, and the public. The only t

  • I was looking at the slightly elliptical curve of the dish and it occured to me, the Star Choice dishes (Canadian) are designed to pick up two satellites at once. It could maybe give a wider line of sight if someone modified something like this. I think the feed can would have to be modified for something like this to work. Think something like this might work? or would I be wasting my time?
    • Its not really wider, its just has two diffrent focal points. Down by the cable tv head end there must be 20-30 sitting next to the dumpster.

      The real jems are the old 39 inch starchoice dish's. Over 30 dB of gain! which may be illegal but industry canada isn't going to bother you unless your causing problems with someone eles' communtications.

      I've been thinking about setting up a relay system here in western newfoundland, moutain top to moutain top to give high speed internet and maybe telephone services

  • FCC doesn't care (Score:5, Informative)

    by PureFiction ( 10256 ) on Friday September 19, 2003 @01:58AM (#7001484)
    The FCC doesn't seem to care much about power levels and antennas in the ISM band. Remember, it's kind of a throwback "freebie" given to appease the anarchist crypto parasites and cheap low end consumer equipment for those unable to afford the "protected and scarce" high dollar bands that go up for auction. :-)

    The only exception might be certain commercial product vendors who try and sell out of spec equipment to the masses. That is actually worth their time, but some guy with a primestar dish? no way. [ Like linksys getting pressured to take their 2.4Ghz amps off the market because they could interoperate with too many other "unapproved" equipment configurations. Supposedly they can sell them again [smallnetbuilder.com] after making them harder to use with anything but linksys/cisco. arg. ]

    There are a number of smaller WISP's that I've come across in the northwest that run 1/2W and 1W amps on their directional point-to-point and point-to-multipoint configurations, but until someone complains that they are interfering, there is no way the FCC is going to proactively come out and bitch.

    Wireless users groups across the nation post plans and site configurations using all sorts of unapproved antennas, radios, amplifiers, etc. There is no widespread FCC CRACKDOWN going on. In fact, I challenge anyone to name an incident where a WiFi user (not company) was pressured or forced by the FCC to alter their equipment back into spec. It doesn't happen.

    Personally I think this is a good thing. The FCC has done more harm in the 802.11 space than good. Like antenna connectors. Do you know why there is a proliferation of SMA, RP-SMA, N-type, BNC, RP-BNC, MMCX, and any number of other bastardized formats for antennas and equipment? The FCC requires vendors to make their radio's use proprietary connectors to prevent people from easily and usefully extending the range of their equipment with generic antennas. Not that the vendors mind. Nothing like vendor only parts with the associated 400% markup to pad the profit line.

    Let the FCC play with the Big Co's and handle licensed spectrum. The ISM bands are where its at.
  • I've got a reasonably fool proof way of making use of these offset dishes, unless of course you're the more talented fool. The Australian Fox TV dishes are similar, but lend themselves to this technique. Aquire some mirrored perspex or something similar. Cut it into small squares, or just steal a mirrorball. Randomly cover the surface of the dish with these using double sided tape. The thinnner the tape, the better. When you reckon you've got enough, point your dish at the sun so that the focal point, your

  • I wonder? (Score:2, Interesting)

    by Grandmasta ( 612724 )
    I used to live in a relatively old area of town, and seem to recall seeing gigantic dishes (which, I assume, were used to pick up broadcast signals, or some archaic form of satellite TV...this is all speculation on my part, of course) ... firstly, does anybody else know what I'm talking about, and secondly, would you be able to use one of those? :) what sort of signal would you get, do you think?

  • DIY (Score:2, Informative)

    by Koos Baster ( 625091 )
    Some links:

    KI7cx [qsl.net] dish
    Primestar [wwc.edu] dish
    Bi-Quad feed for primestar [trevormarshall.com] DIY
    10 Euro dish with biquad feed [weijand.nl]
    Modifying Confier Antennas for Wireless Networking [martybugs.net]

    More info: Wireless Leiden [wirelessleiden.nl]
  • Luckily primestar dishes aren't that hard to find considering that when dish network bought them out, they installed new dishes for everyone often times leaving the old one installed or in the yard of the house where they did the installation.

  • Dish Network dishes, free (Score:3, Interesting)

    by jridley ( 9305 ) on Friday September 19, 2003 @08:01AM (#7002534)
    I know they're not as desirable as Primestar dishes, but Dish Network and DirecTV dishes work also. I got a couple for free just by asking. Go to the place that you bought your satellite system from (What, you're on cable? Well, get with it!), and ask. My source said that they occasionally would have a spare dish from an installation, and after a few years in business they had a heap of them in the basement, still in the box. They were more than happy to let me walk out with a couple.

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