Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror
×
Communications Hardware Hacking Wireless Networking Build

A DIYer's Quick Guide To Cheap Wireless Extension 148

An anonymous reader writes "This piece is described in one of the comments on it as 'a little piece of genius'... and I have to agree! Although Peter Cochrane seems a bit of a crack pot, the ways that he comes up with to get connected when he's out of range in the sticks are pure genius and he makes them appear really simple! Think old satellite dishes, USB dongles and plastic bags and you'd be on the right tracks to upping wi-fi signal by 4 bars." A perfect excuse to link to one of my favorite sites, if you want more details and photos on similar jury-rigged long-distance connections. However, your meterage may vary — I've found USB Wi-Fi devices to be pretty fickle under Linux, with some distros working way better than others.
This discussion has been archived. No new comments can be posted.

A DIYer's Quick Guide To Cheap Wireless Extension

Comments Filter:
  • Citywide Wireless (Score:5, Informative)

    by billy901 ( 1158761 ) on Thursday July 17, 2008 @12:20PM (#24230309) Homepage
    Wouldn't it be nice if this technology was used to make a free citywide wireless internet? We just need a bunch of people with this ambition and it could be done. I once read a book, called When A Strange Comes To Town, in which some people had the same ambition. You can get the book from Project Gutenberg if you look around. It's a newer book that has never been copyrighted.
    • Re: (Score:3, Insightful)

      by Nos. ( 179609 )
      Jury-rigged wifi extenders typically aren't the most reliable things in the world. They also tend to be unidirectional, though omni-direction is possible, you don't get as much gain. You also need to power them, as well as connect them back to the Internet at some point. In the end it all costs money, and someone needs to pay for it.
    • You wouldn't happen to have a link? I searched and all I could find is something by Cory Doctorow.
    • Free... Really? (Score:5, Insightful)

      by gamanimatron ( 1327245 ) on Thursday July 17, 2008 @12:31PM (#24230463) Journal

      I get nervous when folks start talking about "free" services. Seems that more often than not, "free" actually means that I end up paying for power, bandwidth, and the army of bureaucrats that makes sure those bills get paid on time, and that their uncle's brother's company wins next year's bid.

      So, please, count me out. I'll rig my own parabolic signal booster if and when I feel like it.

      • by stranger_to_himself ( 1132241 ) on Thursday July 17, 2008 @12:41PM (#24230607) Journal

        ...I'll rig my own parabolic signal booster if and when I feel like it.

        That's my new sig sorted out then.

      • I get nervous when folks start talking about "free" services.

        Really? Do fire engines make you nervous, then? Or public water fountains? Street lights?

        You must be a nervous wreck in any city.

        As a practical matter, for humans to live in cities (and at this level of population and industry, a lot of us have to - more than half the human race now lives in cities [guardian.co.uk]), a number of public goods and common goods must be provided.

        We can certainly debate whether "free" wi-fi should be one of them, but to get ups

        • Re: (Score:3, Insightful)

          He doesn't get nervous around "free" services, he gets nervous when people talk about "free" services. You see, he understands that all those "free" services you mention are paid for by somebody. I wonder where you live that get the fire engines for free. The last time the fire company near me was talking about getting a new fire truck, the cost was a couple hundred thousand dollars.
          You see the poster you were replying to was a productive member of society and therefore he pays taxes. That means that all
        • Re: (Score:2, Interesting)

          Allow me to clarify, then: Discussion of novel "free" services makes me nervous.

          Every "free" (meaning, of course, tax-supported in one way or another) service I could possibly want, and a great many more I believe should not be "free", are already provided by my current city.

      • by phorm ( 591458 )

        Actually, I'd be fairly happy with "free, as in use" with perhaps some injected google-ads or something of the sort on the http stream (not other ports/procols, of course, since that could break stuff).

        You'd probably have to block or severely limit P2P/torrents as well in many cases, but it would be great for those that need quick access to check some information online.

      • by orasio ( 188021 )

        The cold war has really messed you up. Corporations are not the only way to do things efficiently.

        Cooperation can work easily, in some very particular cases. Public doesn't mean state-run.
        An antenna by itself is useless. If you get together with other people who share your interests, you can build a small network, that allows you to reach other people and for example play low latency games.
        In rural areas, it's better to have a free, fast alternative to whatever there is available, even if it's not up 24/7.

        • several people, including myself, in my apartment building broadcast our wifi for the rest of the people. i have never had any bandwidth hogs. never any nefarious activities everyone seems to be so paranoid about. we just consider ourselves good neighbors. i do live in an area where we are all equally poor and those of us that can share - do share. as per the comments here it seems that there are more like minded individuals than i would have thought.
          • Paranoia sounds about right. Even when there is no measurable harm from using a neighbor's wifi when your service is unavailable, you'll still here people indignant about your "stealing". These fearmongers would be happier if it were criminalized to the point where nobody could share, even if they wanted to.

            It only takes a few nutjobs [slashdot.org].

    • Nobody wants it! (Score:5, Informative)

      by drewzhrodague ( 606182 ) <drew&zhrodague,net> on Thursday July 17, 2008 @12:36PM (#24230515) Homepage Journal
      I am one of those long-time WiFi zealots, and it is clear to me that people just don't want free ubiquitous wireless internet -- or they just don't care.

      Here in Pittsburgh, there is occasional talk of some group trying to do this. There have been some people who have received funding, but they waste it, and their project evaporates. Between ten and twenty (or more) companies start off here, and either fade away, or move to some other city. telerama [telerama.com], hobnob [hobnob.com] are the two that stick out (for which I remember URLs to).

      Largest public network here is run by ONE GUY who just went and built it himself, Shadyside WiFi [shadysidewifi.com].

      Otherwise, there is chatter on some of the local lists, but by and large, nobody wants free city-wide wireless Internet. Just me [pghwireless.net].
      • Heh, we just got one neighborhood in our closest local city-like community a neighborhood-wide wifi setup as phase 1 of a municipal wifi project: http://oncee.blogspot.com/2008/06/free-east-end-wireless-up-and-running.html [blogspot.com]

        Of course, I'm referring to it as a city-like community despite being our state capitol since if things don't change it'll be off the most declining cities lists by caveat of being too small to qualify. =)
      • I am one of those long-time WiFi zealots, and it is clear to me that people just don't want free ubiquitous wireless internet -- or they just don't care. Here in Pittsburgh, there is occasional talk of some group trying to do this.

        Oh, I wanted it, I just didn't want it enough to pay the monthly fee for it, and signing up every other day for two free hours to use it for ten minutes was an aggravation. I have internet at work, but needed to get around my corp firewall to support my moonlighting :')

        If I could have got a deal for a pay-as-you-go plan for a reasonable price I'd have taken it. Then I moved to a different building and couldn't get a signal anymore. So I threw up a Linux box at home listening to SSH on port 443, and tunnel

        • So I threw up a Linux box at home listening to SSH on port 443, and tunnel out from work using Putty. I just look like encrypted web traffic to the corp security folks."

          Sometimes a firewall or network monitor will flag that traffic as abnormal. There's often much more upstream traffic on that link than you would expect from https.

      • Are you on crack? Telerama is still all over [telerama.com] (mostly Squirell Hill/Oakland, but many further out from there, too). The reason it's not everywhere-everywhere blanketing the whole city is it COSTS TOO MUCH to do that with WiFi. If you want trully ubiquitous "free" wireless, YOU can pay for it.

        WiFi was never designed for ubiquitous coverage. That doesn't mean other people don't want the coverage, they're just aware of the costs/benefits.

        *googelstalks you* Ahh. Maybe I can have Bryan walk over and bop yo

        • Are you on crack? Telerama is still all over

          Sure, their hotspots are still all over, but their business shut down and went away, dumped their hosting and ISP customers. Aren't you on the WPLUG list?


          blanketing the whole city is it COSTS TOO MUCH to do that with WiFi

          By using DSL to provide the access at each site, then yes -- it is too expensive. I would think that it would be easier to use bridge/repeaters in convenient places -- but then again you get into saturation, and that ends up being expe
      • I am one of those long-time WiFi zealots, and it is clear to me that people just don't want free ubiquitous

        When God was handing out WEP passwords ...
        were you in the line getting both #3 and #4 keys?
    • Heh. We've had people talking this talk since 1998 now, but whoever had tried to walk the walk discovered how hard it is to make work. These guys [funkfeuer.at] actually implemented something along those lines.

    • Re: (Score:1, Informative)

      by Anonymous Coward

      What does "never been copyrighted" mean? It was copyrighted when it was produced. Maybe it was released into the public domain, but unless that actually happened...

    • by Lumpy ( 12016 )

      yes it would be nice.

      Oh wait, I've been helping a group locally do just that for over 6 years now. It used to be possible before the Cable companies and telcos started making it illegal.

    • Welcome to Norwich, home of free WiFi. http://news.bbc.co.uk/1/hi/technology/5297884.stm [bbc.co.uk]
    • by Anonymous Coward on Thursday July 17, 2008 @01:18PM (#24231157)

      It would be much more helpful to protect people from litigation when they open up their wireless networks to strangers. The only thing preventing me from providing free wifi is the tremendous risk of being sued and eventually having to pay for someone else's crimes.

      If you've been wardriving lately, you know that we don't need more access points, we need existing access points to be opened.

      • MOD THIS UP! (Score:5, Interesting)

        by Iron Condor ( 964856 ) on Thursday July 17, 2008 @01:48PM (#24231653)

        I rarely do this, but this AC is making the only point that needs to be made here. My own home router could comfortably serve a block of my neighborhood including the nearby park (I tried) but I'm not going to open it up because under US law I will go to jail if someone uses my open WiFi to download childporn or some such.

        The cost to me would be minimal and I'd set the QOs such that the freeloaders wouldn't interfere with my own activities -- and if everybody did that, we'd already have free ubiquitous wifi in all cities in the US. Because there's always some server around somewhere -- it's been forever since I truly got a "NO networks found". They're just all locked down like crazy because of the absurd US laws that hold a communications provider (me!) responsible for what clients do with the services they provide for free out of the goodness of their hearts...

        • by 1u3hr ( 530656 )
          because under US law I will go to jail if someone uses my open WiFi to download childporn or some such.

          Oh really? And you can cite cases of people this has happened to? Or are you just speculating?

          • Re: (Score:3, Insightful)

            by Firehed ( 942385 )

            If the RIAA is able to successfully sue/prosecute people based off of IP logs, you can be damn sure the CP police can. At least when you're in control of the router, you may be able to trawl through logs and find the MAC associated with the illegal download and hunt down the right person, but don't count on it.

            • "you may be able to trawl through logs and find the MAC associated with the illegal download and hunt down the right person"

              Or trawl through logs to show that the MAC associated with the illegal download does not belong to any user in the household.

              If a murder suspect leaves footprints to your doorstep, it might make you look like a suspect, if upon inspection there is no match to shoe size or brand of shoe in your home, then you are ruled out as a suspect.
              • by Firehed ( 942385 )

                That works a lot better with shoes than it does with MAC addresses. It's a heck of a lot easier to make a computer disappear than change the size of a household member's foot (the shoes themselves are probably easier to get rid of than a computer). I should think that in either situation if the criminal was in the house that he/she would be smart enough to remove the incriminating object, or at least that a jury would assume that this had occurred. That said, we still theoretically have an innocent-until

            • apparently DE:AD:BE:EF:DE:AD:BE:EF is some guy named Peter Shipley [google.com], and he just laughed at me when I called him up and asked him about it.

            • by 1u3hr ( 530656 )
              you can be damn sure the CP police can.

              Or in tehr words, groundless speculation and fear mongering.

        • mod that down (Score:3, Insightful)

          "...under US law I will go to jail if someone uses my open WiFi to download childporn or some such.

          No, you won't go to jail, but you might get investigated and have some equipment confiscated, which is still enough reason for most people not to do it.

      • Re: (Score:3, Insightful)

        by Endo13 ( 1000782 )

        It's nice in sentiment. In reality though, it doesn't work. See, ISPs do need to be profitable to stay in business. The way they do that is by making money on the bandwidth they sell. At the price bandwidth goes for these days, they really cannot stay profitable if every single person were to use every mbit of their bandwidth all the time. People who torrent a lot or keep their bandwidth use maxed otherwise generally cost the ISP more than the monthly payment. It's those other low-use customers who simply d

        • You might be happy having other people subsidising your internet usage, but the other lighter users probably aren't that happy about paying more so you can download whatever it is you download.

          I'm glad you qualified your position with "Personally", but in the scheme of things it seems a bit ridiculous to have pricing that absolutely relies on people not actually using the full service that they're paying for. Put simply: the ISPs are advertising something they cannot possibly deliver, and are relying on peo

          • by Endo13 ( 1000782 )

            You might be happy having other people subsidising your internet usage, but the other lighter users probably aren't that happy about paying more so you can download whatever it is you download.

            For the most part, I'm pretty sure those people don't mind. Most of those kinds of people prefer to pay extra for extra capacity they won't use 99% of the time, just so they have it available in that rare situation where they do want it. Not that I'm saying I think it's right or fair that other people help subsidize my own bandwidth usage. But it seems to me, most users like the current situation.

            but in the scheme of things it seems a bit ridiculous to have pricing that absolutely relies on people not actually using the full service that they're paying for. Put simply: the ISPs are advertising something they cannot possibly deliver, and are relying on people simply not being able to find enough to do on the internet so they don't have to provide the service they sold their customers.

            It does *seem* ridiculous, and you'll get no argument from me on that count. But any alternative system will mea

    • Re: (Score:3, Interesting)

      Saskatoon Saskatchewan Canada has free citywide internet. It's slow as a dog during the day but quite usable at night for basic browsing/emailing etc. Great for us touring musicians!

      Here is another smaller scale hack using a metal strainer/steamer [instructables.com] as a collector.

      But a satellite dish will only help the reception, not the access point on a city-wide basis, so it's benefits are limited. However, it might give hope to cottagers where wifi is close but not quite.

      What the article describes as going from zero b

    • The technology discussed in this article wouldn't help much for that. What would help are the $50 open-mesh mini routers [open-mesh.com].
  • Coral Cache link... (Score:1, Informative)

    by Anonymous Coward
  • Rhombic Antennas (Score:5, Interesting)

    by hardburn ( 141468 ) <hardburn@wumpu s - c a v e.net> on Thursday July 17, 2008 @12:26PM (#24230391)

    Does anyone know of any attempts to use Rhombic Antennas [tpub.com] with WiFi? They're very simple and provide huge gain. Their typical downside is that the length of one leg needs to be 8-12 wavelengths, which means they're the size of a football field when you're dealing with most radio frequencies, but 2 GHz has a 0.15m wavelength. A point-to-point rhombic should easily fit on the roof of a house.

    • Re:Rhombic Antennas (Score:4, Informative)

      by elgatozorbas ( 783538 ) on Thursday July 17, 2008 @01:42PM (#24231573)
      I suspect these antennas are typically aimed at much lower frequencies (say HF/VHF), and require a ground plane. The reason why I think so is that for (super) high frequencies, antennas are mostly self-contained (one piece you can attach to a pole) and don't require a large garden and poles and the like.This is not the kind of structure you use for pleasure, but because you have to (at low frequencies).
      • Re: (Score:2, Informative)

        by Born2bwire ( 977760 )

        I suspect these antennas are typically aimed at much lower frequencies (say HF/VHF), and require a ground plane. The reason why I think so is that for (super) high frequencies, antennas are mostly self-contained (one piece you can attach to a pole) and don't require a large garden and poles and the like.This is not the kind of structure you use for pleasure, but because you have to (at low frequencies).

        There wouldn't be any reason why this would be worse at high frequencies than low frequencies. I could envision making a printed version of this on a very thick PCB and using the bottom copper cladding as your ground plane. Heck, a sheet of aluminum foil could probably do it in a pinch. The ground plane size at Wifi frequencies is not very large. I would guess the main reason that people haven't done this is why bother? The short wavelength of 2.4 GHz compared to everyday length scales means that it is

  • !news (Score:4, Insightful)

    by Thelasko ( 1196535 ) on Thursday July 17, 2008 @12:27PM (#24230407) Journal
    everybody knows that old satellite dishes and Asian parabolic cookware can be used to boost wifi signals.
  • by dickens ( 31040 ) on Thursday July 17, 2008 @12:29PM (#24230427) Homepage

    Check out. [gnswireless.com]

    • by dickens ( 31040 )

      Did I mention I haven't gotten used to the new editor yet ? Duh. I meant to check "these guys" at gnswireless.com out.

    • There are plenty of used satellite dishes on Craigslist and such for $20-50. Just pick up one of those and do as in TFA. Sure, you may not get a whole mile out of the deal, but if you can direct that at a nice neighbor's house...?

  • by i_want_you_to_throw_ ( 559379 ) on Thursday July 17, 2008 @12:33PM (#24230471) Journal
    I found this great instruction on Instructables [instructables.com] (pops new) on how to create a usb wifi out of a 2.00 strainer from WalMart. Works like a champ!

    My friend lives across the Ohio River and we're able to send the signal across the river that way.
  • The simplicity and brilliance of this idea is astounding.

  • Old news anyone? (Score:5, Insightful)

    by b96miata ( 620163 ) on Thursday July 17, 2008 @12:34PM (#24230497)

    I'm too lazy to search for how many times the satellite dish wifi setup has been posted on slashdot, but suffice to say I had one on my roof 5 years ago after getting the idea from a web page that was itself a couple of years old. (even the actual useful link added on by the editor is from 2004)

    It's not even a good writeup of the concept. Here's a summary of the "Genius":
    -Stick it on the end of the arm.
    -Electronics don't like water.
    -The sun is hot.

    There's nothing genius about this. It's a rehash of something people have done for years, sans details.

  • by Gordonjcp ( 186804 ) on Thursday July 17, 2008 @12:36PM (#24230519) Homepage

    ... my own comment, yesterday? [slashdot.org]

  • Not new (Score:3, Interesting)

    by drewzhrodague ( 606182 ) <drew&zhrodague,net> on Thursday July 17, 2008 @12:37PM (#24230539) Homepage Journal
    This isn't really new, there have been people doing this kind of thing for years. Check Seattle Wireless dot net [seattlewireless.net] for their experiences. I'm sure there are others.
  • by Anonymous Coward

    I always hear about projects like these. Could this be used to connect my brother and my houses if we don't have LOS? We're in seperate apartments, obfuscated by light trees, about 15 feet of elevation difference, and perhaps 4 brick walls.

  • by viking80 ( 697716 ) on Thursday July 17, 2008 @12:42PM (#24230621) Journal

    10 years ago you might have had to improvise, but today you can get cheap high quality antennas and amplifiers that is a lot better than a USB dongle in an old satellite dish.

    My favorite source is http://www.hyperlinktech.com/ [hyperlinktech.com]
    and you can do your link analysis here:
    http://cgi.gbppr.org/wireless.main.cgi [gbppr.org]

    If you really need big distances, you can use an old 12' sattelite dish, but otherwise stick to the formula above. It will save you a lot of time and trouble.

    I have reliable links over 10km with 10mW running at 50Mb/s

  • It's not that easy (Score:5, Informative)

    by Puls4r ( 724907 ) on Thursday July 17, 2008 @12:48PM (#24230697)
    It's not that easy - and you might be better off just buying a cheap unidirectional antennae I live in a rural community and a 3G USB dongle several months ago. The low signal strength meant I was on the slow end of the speed for 3G. I tried the exact thing he did, but tried some other options as well. First, I purchased a $50 unidirectional antennae. That improved my signal strength by 10db. That was enough to get me to the range of 1300 down and 400 up consistently, with full "bars". So then I unplugged the antennae, added a couple of active USB cables, and put the dongle on the roof (1 story up). That improved my signal 5 db without the antennae, and 3 db with the antennae. So now I had improved about 13db. Finally, I grabbed my old dish, and aimed it at the cell tower. Then I put the dongle in place of the amp unit. Please note that most dishes have offset amp units, so you dish looks like it's aimed "below" the tower. It helped several decibles. I replaced the unidirection antennae and put in the dishes sweet spot, and it got me nothing more. Short version - I was better off elevating the dongle and attaching a cheap unidirectional antenna than I was playing with the dish. I suspect that will be true of most who play around with this. Final note - I have experience making other antennas - AM, FM, etc. I can assure you it wasn't lack of knowledge that prevented any huge increase in signal when using the dish.
    • Re: (Score:2, Interesting)

      by Anonymous Coward

      Why use a unidirectional antenna with a dish? The dish focuses a wide beam (eg 45 deg) at the amp to a narrow beam (eg 1 deg) at a distance. The unidirectional antenna is already radiating at a narrow beam, so the dish will basically be a flat mirror for the signal, which will not help at all (as you noticed).

      You should try with one or the other, not both.

  • by Bombula ( 670389 ) on Thursday July 17, 2008 @12:50PM (#24230727)
    Every year or so I hunt for a simple utility to allow me to connect to more than one wifi network simultaneously and boost bandwidth that way. Never had any luck. Anyone know if this is feasible or not? The apartment complex where I currently live has multiple secure wifi networks set up specifically for residents, plus a bunch of folks have unsecured ones based on local cable broadband they don't mind sharing. If there was a way to connect to all of them at once ... awesome.
    • > connect to more than one wifi network simultaneously
      That's easy - just get a NIC/Wifi AP for each network you want to use.

    • by GameboyRMH ( 1153867 ) <gameboyrmh@@@gmail...com> on Thursday July 17, 2008 @01:17PM (#24231123) Journal

      I've been looking into a similar setup. You need multiple wireless adapters and a load-balancing utility.

      http://forums.remote-exploit.org/archive/index.php/t-7419.html [remote-exploit.org]

      A quick and dirty way to do it with Linux iptables:

      http://tetro.net/misc/multilink.html [tetro.net]

      My goal is to create a monster wardriving setup for constant on-the-road connectivity.

    • I could be wrong on this and probably am, but isn't wireless-N just 2 wireless-G channels bonded together? If this is accurate then the tech exists. It just may not exist in an easily digestible capsule. Although the bonded G channels would be through the same device so maybe using 2 different devices would be the problem......

      You might read this article. [techworld.com]

      This [google.com] might help too....
    • Mesh networks [wikipedia.org] basically do what your require, so it is feasible. Using a mesh network you will connect all of your neighbors in a big seamless network (i.e. your neighbor to the West will be able to see your neighbor to the East). You would need some sort of firewall to prevent that from happening.

      I'm sure it's possible, I'm also sure you will need two wifi adapters (or one device that has two built in) since your neighbors are likely on different channels. I don't know of any software specifically int
  • Humm so how you you send when your 500 M out of range. That's fine to receive any signals but screwed if you want to send. good idea but FAIL
    • by Ferzerp ( 83619 )

      Because as we all know, parabolic dishes only work to receive and will not allow you to direct your emitted RF...

      Oh wait... bouncy bouncy works both ways.

      • Re: (Score:2, Informative)

        by Anonymous Coward

        There are EIRP limits. Basically you can't legally use a directional antenna to improve the signal on the sender side if you're already at the EIRP limit. The only benefit of the directional antenna in that case is that you can lower the emitter power and don't pollute the unused directions with your signal. To establish long-haul wifi connections legally, you need directional antennas on both sides to boost signal reception, not emission.

    • There's a nice symmetry here. Antenna gain/direction works equally for reception and transmission. A good receiver will also be a good radiator.
  • It's jerry-rigged, not "jury-rigged," dammit!
  • by aharth ( 412459 )

    Just tried on my balcony: WiMax box in front of old sat dish = ~ 30% higher transfer rate!

  • It's getting easier to use USB WiFi adapter with linux lately. Linuxwireless.org has done some great work with the re-written modules, which are included in the recent kernel version. And some companies are paying attention. I've been using the Wi-Fire for long range wifi for a while, and hField Technologies just released a Linux Version [hfield.com], which I've had no problem with on my Suse or Fedora machines.
  • Not news... (Score:4, Interesting)

    by jemenake ( 595948 ) on Thursday July 17, 2008 @04:24PM (#24234151)
    Sorry, but this really isn't news. Hell... even *I* have done this, which means that it can't be anywhere near the cutting edge. :P The concept of putting a cantenna or bi-quad at the focal point of the dish has been out there on web pages for years. I fitted *my* dish so that I could interchange a cantenna or a USB dongle as the need arose.

    The advantage of the USB dongle is that you don't incur the line losses of the antenna cable if your laptop/PC is a long way from the dish. You can get around the problem of USB cable-length limitations by using some nifty USB "extension cords" which are basically a long USB cable with a 1-port hub at the end.

    I will add one thing that I haven't seen on any pages, however. Most satellite dishes have the arm positioned away from the centerline axis of the dish... usually below it, which must be accounted for when aiming. For example, if the arm holding your dongle/cantenna is 10 degrees below the centerline of the dish, then you'll be receiving signals from whatever is 10 degrees above the centerline. It's the same concept as flat mirrors... angle of reflection equals angle of incidence.

    Why does this matter? Well, if you are trying to communicate with a station that's at relatively the same elevation as you, then you're going to have to point the dish down toward the ground a bit. This can be very conspicuous... especially if, ahem, the other station's owner doesn't know you're communicating with them (cough, cough). The best solution that I've come across is to turn the dish upside-down so that the arm holding the dongle is on top, which allows you to point the centerline of the dish skyward again, so that it looks more like the other dishes in the neighborhood. Almost nobody will notice that the arm is affixed to the top of the dish rather than the bottom... and even fewer will grasp the ramifications of it.

You know you've landed gear-up when it takes full power to taxi.

Working...