TechSpot

Wireless Network 300m away

By BlueSky
Jan 28, 2005
  1. Hi folks,
    Well, i need guidance in the worst way here,lol. Here's what i am trying to accomplish:

    I would like to set up a wireless network from 1 building...... to other buildings across an open field approx 300metres away. Now what i was thinking was to buy a D-Link 800Access Point and put a high-gain directional antenna onto it , and place this antenna in the window facing the open field. So far so good?

    ok, now on the receiving computers, what kind of equipment will i need here? Will i also need high gain antennas capable of reaching back? If so, how would i hook up a laptop for wireless? (since the internal laptop antenna would not be sufficient, and there is no way of putting an external antenna on usb wireless cards, right)?

    I am sure open to any and all suggestions here since the only wireless network i have done so far is within the same building.

    Thanks.
     
  2. StormBringer

    StormBringer TS Rookie Posts: 2,871

  3. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    Thanks,
    Actually the Cantenna was in my shopping basket already, lol. Now the Cantenna/AP would deliver signal to the buildings..... but would i need another Cantenna to deliver signal BACK?

    Also, i did some further reading and found out that Hawking makes a "plug 'n play" 6DB directional antenna with built-in usb wls adapter that would work excellent for a laptop to boost signal. I wonder though, would 6db be enough to cover 300metres back?
     
  4. Rick

    Rick TechSpot Staff Posts: 6,305   +52 Staff Member

    You should not need a second antenna to broadcast with, unless your signal is still weak after you install the first antenna.

    If your goal is share the main building's Internet with another building, then the directional antenna should do the job to get the signal from point A to B.

    Your next struggle will be to share the wireless throughout the whole building (Point B). If your repeater / access point isn't powerful enough to broadcast across the 2nd building entirely, then you will probably want to also invest in a more powerful omni-directional antenna. You would attatch this antenna to your wireless repeater in the second building and this should increase the radius of range.

    I'm unsure about the 6Db antenna - Db ratings can be misleading. It also may be fine or not enough.. The only to find out is try. :) Another alternative might be to invest in a more powerful wireless card for the laptop(s). While most "everyday" wireless cards put out about 20-30mw, there are some higher end PCMCIA cards that do about 200mw. This translates into much better reception. The cards theirselves run about $80+. I haven't shopped around for one of those in awhile though, so it may be cheaper or even more. :)
     
  5. nein

    nein Banned Posts: 226

    There is no PCMCIA cards that can do about 200mW, at least not in the United States. None of them are allowed to put out more than 30mW = 15dBm of power which is regulated by the FCC.

    The 200mW ones you mentioned are the 30mW models which came included with 8 dBi antennas.
     
  6. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    Ok, so can someone please clarify how an AP works in repeater mode? Does this mean i would have AP#1 with high gain antenna in building 1, and then have AP#2 placed in a good central location in building 2 along with a good omni antenna, but instead this second AP is in repeater mode instead of AP mode?..... and that means AP#2 has no CAT5 wires going to it (it's truly wireless except for the power cord?)

    I suppose this would work a lot better (and cheaper) (and simpler) than trying to have each client "beam back" using their own high gain directional antennas, right?
     
  7. StormBringer

    StormBringer TS Rookie Posts: 2,871

    You seem to have the basics of it down. I think the best thing would b3e to use an LoS antenna (something like the cantenna) to go between the buildings then the second AP can distribute through the building.
     
  8. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    What about using a AP with Cantenna for Location A....... and then at Location B use another AP in repeater mode with an 8db omni antenna mounted on the roof. The 8db omni mounted to the roof of a central building should allow signal for the diff small buildings clustered in Loc B, and also have enough power to transmit back nicely to Loc A right?

    Also, in order to obtain a clear line of sight at Loc A with the AP/Antenna, i would need to run a 200ft CAT5 cable from the router...... is this ok to do?
     
  9. MrDJ009

    MrDJ009 TS Rookie Posts: 78

    Sounds like a workable plan.

    I think you have the right picture. I'm also using a D-Link and considering their DWL-G800AP ( http://www.dlink.com/products/?pid=267# ) to solve a similar problem. Check out their "product diagram" and "quick install guide" links on their product page. This product can be configured in one of two modes--AP or repeater. You are obviously interested in the latter.

    You are also correct about the Ethernet port, which is only needed for product configuration. However, there should be no harm in connecting it to a network switch at site B, for easy access if you want to reconfigure. Take note D-Link only represents that this unit will repeat the wireless signal of a specific D-link router, one AP or another DWL-G800AP. So double check before buying if you plan to repeat another model AP in building A.

    The only caution I see is that these units have very low transmit power (32mW) with an advertised indoor/outdoor range of 100m/400m using the stock 1 dB antenna. Thus the higher gain antennas will be a must. I've been disappointed with my D-Link router which gets nowhere near their advertised outdoor range even after adding an 8.5 dB antenna.
     
  10. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    Thanks for the confirmation that i am approaching this the right way.

    I was wondering if anyone has tried wireless usb adapters such as this:
    http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=168277&CatId=369

    They would be super easy to plug into a laptop or desktop usb port, and it looks like this model has some sort of built in flip-up antenna so thay may help with pointing at the omni antenna. Would these type be a good idea, or stick with pci wireless cards for desktops and get a separate antenna to go with them?
     
  11. Rick

    Rick TechSpot Staff Posts: 6,305   +52 Staff Member

    I never mentioned I was shopping in the U.S, now did I? :D

    Just kidding.. I've seen 200mw PCMCIA cards for sale by online stores that ship in the U.S, but I suppose that doesn't make it kosher with FCC, now does it? ;) The only one I've seen for sale though is a 200mw card by Senao, but it is indeed 200mw.
     
     
  12. MrDJ009

    MrDJ009 TS Rookie Posts: 78

    Antenna and wiring issues.

    Are you suggesting that at location A you would have an AP/antenna connected to a router, which you will mount 200ft. from the AP? If so this sounds workable since Ethernet is OK for at least 300 ft.

    However, while I'm no engineer, everything I've been reading would say: Keep the distance between the antenna and the radio (a/k/a AP) as short as possible. External antennas, and the cabling that go with them, result in unavoidable signal loss. The greater the distance between the antenna and the radio the greater the signal loss. In other words you must give back some of the gain you're expecting from a higher powered antenna the farther it's mounted from the AP. You may want to go for a 15 dB (especially at the B site) to allow for this loss if you must mount the antenna any distance from the AP. There is some really good Q&A related to this on the Seattle wireless web site ( http://seattlewireless.net/index.cgi/PigTail ). If the Seattle dialogue is on the money you lose about 0.4dB for each foot of cable plus about .1dB for each N type connector. They also indicate that the quality of the cable is “a big deal”, so don’t skimp here.

    If Ethernet cabling is a challenge you might want to consider connecting you location A router and A/P by using HomePlug. I picked up this idea from JrWire.com ( http://www.jiwire.com/wi-fi-home-setup-extend-range.htm ). The HomePlug spec allows for Ethernet via your electrical wiring. From reviews I’ve read it works quite well. I’m actually using this and I’ve had no problems and it seems to work well. I choose the D-Link DHP-100 connectors which are reasonably priced but there are other available. The one compromise is that the HomePlug spec is limited to 14 Mbps. This should be OK for sharing your routers low speed broadband signals from a cable or DSL line. However, HomePlug wouldn’t be a good substitute for networking computers whenever Fast or Gigabit Ethernet is practical.
     
  13. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    Yes, at Location A i would need to run a 200ft CAT5 from the router to the AP. This will allow me to place the antenna directly onto the AP using just the pigtails so as to avoid signal loss.

    At Location B, if i decide to mount the 8db omni on the roof, i have a 30ft D-Link Heavy Duty Cable for this purpose. It was designed for work with their 18db outdoor antenna. However, i will look into the specs on the cable to see how much signal quality i will lose. If the loss is too great, i may have to consider a higher db as you mentioned, or perhaps a different mounting situation.

    Thanks for bringing this to my attention.
     
  14. StormBringer

    StormBringer TS Rookie Posts: 2,871

    you shouldn't need a second antenna at location B. Since the Cantenna is a directional antenna, it will shoot the signal directly to location B and should be picked up fine by the second AP unless there is a lot of interference and/or it is not Line-of-sight.
     
  15. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    Wouldn't the computers at Location B need the benefit of an omni antenna in order to get a quality signal? And wouldn't Location B need an fairly powerful antenna in order to beam back to Location A?
     
  16. Rick

    Rick TechSpot Staff Posts: 6,305   +52 Staff Member

    Benefit? For sure. What wireless network would not benefit from a more powerful omni-directional antenna? :)

    Unless Building B is small, you probably will need a good omni-directional antenna. Investing in a more powerful omni antenna may also help your signal from Point A to Point B, slightly. But the purpose of this antenna would be soley for rebroadcasting the signal and giving Building B better coverage.

    Sure, there's beaming back, but the directional antenna is not just one way. It outputs and recieves signals. So, as long as the signal can reach Point B, then it can also recieve signals from Point B as well.

    Also, MrDJ009 had a really suggestion about the possibility of setting up a power network. Although I've never actually used one, I've heard positive things about them. You should check out his link.
     
  17. nein

    nein Banned Posts: 226

    Actually United States of America is one of the most permissive place in the world, it often had the most permissive power output requirements better than other places such as Japan.

    Currently US of A is top most permissive at 30mW output. Any other hardware with more than 30mW are illegal.

    This is why Dlink sells hardware with typical 2dBi antennas included, 2dBi antennas compensated for the expected 2dB insertion loss from actual 15dBm output.
     
  18. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    Does it make a lot of difference (in terms of signal range) if the omni was mounted on the roof, or mounted indoors? My goal for the omni at Location B is to share the internet with up to 8 different computers among the buildings in the "horseshoe" pattern, who would use smaller desktop directional antennas to point to the omni. If i were able to mount the omni indoors i could eliminate the extra cable and connect direct to the AP which would prevent signal loss. However, I am not sure if the signal would be adequate to all of the buildings. Would a 12db omni be a gigantic signal range boost as opposed to the 8db omnis?


    I am almost there.... but still am unsure regarding the omni.
     
  19. nein

    nein Banned Posts: 226

    Everything made a difference depending upon varying parameters considered, for example both statements below are correct.

    I get better TV/radio reception when it rains.
    I get worst TV/radio reception when it rains.

    It would in open space such as on a boat in open water.

    In most normal wireless access-point/router configurations, 12dBi omnis are less "omni" than 8dBi omnis, and both of them are much less omni than 2dBi omnis.
     
  20. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    Are you trying to say that the supplied 2db omni that comes with the access point has better range than a 12db omni used on that same AP? Please explain.
     
  21. nein

    nein Banned Posts: 226

    "Omni" didn't stand for omni-power nor omni-range, it's omni-directional with 30mW of maximum transmit power.

    8dBi omnis transmited that same max 30mW, distributing out 8dB more in particular intended direction and less in others, while true omnis are isotropic and transmited evenly in all direction. There's no free lunch.

    Typical 12dBi omni's RF field maps tended toward toroidal shapes, but if you actually get a toric mapping, it is more romboidal.
     
  22. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    ok, my plan was for the 2nd AP at site B to be able to service the entire set of buildings in this horseshoe pattern. The AP would be located at the "top" of the horseshoe. If i were to place the AP in the window of this central building, and seeing that each other building has line of sight view to that window..... can i get away with desktop directional antennas for computers wishing to connect to the AP.... and not bother with a bigger omni antenna for the AP?

    Anyone, anyone?.... this is the last item I need to be clear on before doing the ordering.
     
  23. BlueSky

    BlueSky TS Rookie Topic Starter Posts: 35

    ok guys, still working on this.......
    I seem to be having very poor luck with signal range while attempting to place the AP hooked to the Cantenna indoors in a window covered by large grid metal grating (yes i know its bad)...... according to my wifi finder the signal drops alltogether after about 30ft from the window..... yikes. I've also tried it with a panel antenna, and with the regular omni..... seems to be poor range regardless. I'll have to take the setup fully outdoors to see what happens i guess. Hopefully its the metal thats knocking the heck out of the signal....if not, i am going to be very disappointed in the DWL-800AP's.

    Are signal amplifiers worth the money? What would they do on the D-Link that has an output of 32mW? There is one by Hawking (HSB1) http://www.hawkingtech.com/prodSpec.php?ProdID=224 that gets mixed reviews, and although it says it can boost output 100-500mW, i think it just gives higher quality within the same range, and not necessarily greater distance.

    This is proving to be much tougher than i first anticipated............
     
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