Municipal wifi antenna

Philadelphia's new municipal wifi network kind of sucks, but I'm trying to give it a shot. I'm about 450 feet down the street from a lightpole antenna for the network. There are leafy trees all down the street. When I hang my wireless router out my 2nd floor apartment window (WRT54G with dd-wrt) it can just pick up the signal, but weakly and intermittently. DD-wrt reports signal strength no better than about -72, and it changes constantly. So I'm trying to figure out...

  1. What kind of antenna should I use outside the window, or better yet, through the window? My WRT54G stock omni antennas with handmade reflectors barely pick up the signal. I tried using a prefab "Deluxe Cantenna" and it didn't help. I'm thinking that, because I'm trying to get signal around the trees, a directional antenna isn't the solution. From eBay I got really tall, supposed 9dbi replacement antennas for the WRT54G, and put on the reflectors, but that didn't have much effect either. I'm looking for a cost-effective solution - perhaps one of those Hawking corner antennas, to grab a focused swath of signal?

  1. An alternative is to go on the 3rd-floor roof rather than through the window. I'm not sure yet if I have roof access, but if I do I'm thinking a directional antenna might help because it'd be above the trees. So then there's the cabling issue. To keep the antenna cabling short, I guess I'd have to put my router on the roof as well (in a sealed plastic box?) and then run an ethernet cable down the outside wall and through a window. That would mean leaving a router on the roof, and a window slightly ajar, through an east coast winter. And providing power to the router! (Argh.) I don't think a USB-wifi-stick antenna will work - I want to run my home network (a couple desktop computers and Vonage) off the line, using an ethernet-fed second router. What's the right way to set it all up?

Thanks for your thoughts!

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Just out of curiosity, which version number is your WRT54G and version of DD-WRT? What cantenna did you use? Where was it placed when you tested it? What are the settings on the DD-WRT? Is the municipal wireless a captive portal, does it have client isolation, what are some of the security factors?


This is how I'd do it:

  1. Go into DD-WRT settings under Wirless > Advanced Settings. Check TX Antenna Right and RX Antenna Right Xmit Power 150 - 200 (initially, see how hot it gets under load)

  1. I would get a plastic weather proof box, drill two holes in it, one for the antenna and one for the Ethernet cable. If you don't want to play the power over Ethernet game you may need to get a power extension cord through there so the wall plug can stay inside. Use silicone around the holes to keep it weather proof. Alternatively you can use a solar panel with lead acid battery setup like me.

  2. Once in place, attach the antenna (the cantenna should be fine for
400 meters) TNC RP plug in the, looking from the front of the device (side with lights), on the right side antenna jack. (If you don't get any signal, switch it to the other antenna)

  1. Acquire an antenna grounding adapter (they can be found online or at computer stores), this is in case of lightning. In your DD-WRT configuration Status > Wireless > Site Survey page, you will start seeing signals after adjusting your antenna direction. When you found the municipal wireless access point, click the join button.

  2. Run the long Ethernet cable that should be coming out of your weather proof box down to your desk or computer location. You may attach a switch to it so you can use more computers. Your router is acting as a bridge for that access point.

  1. It is wise to acquire a surge protector. One which supports RJ45 cables. This is also in case of lightning. It will fry the cable, but at least your computer may still be intact.


This is why I wouldn't do it in the first place:

If they don't have client isolation, your security is seriously compromised instead of mildly compromised. VoIP is not secure inherently. Your clear-text passwords will be vulnerable to the rest of the users of that network. E-Mail and chat sessions can be read. Browsing habits can be watched... etc.

Never play that "who's going to do that" card, you never know.


If you can't do it my way, there are workarounds, but most of them are not pretty. Don't think you can run a simple antenna cable a long distance, the Ethernet cable does not endure heavy signal loss at as long lengths as Ethernet cables can. Mounting a large antenna out your window will not be sufficient in most cases if there are a lot of things in the way to scatter the signal. The roof provides a clearer line of sight. If they use an omni directional antenna at the access point location, try to find out where it is. Omni directional antennas work in such a way that being outside its Fresnel ellipsoid, can seriously hinder signal strength on your side. If they provide roof access, you're in good shape.


Answer the top questions, and think about how you can replicate my way (using some creativity on your part). We'll see how far we can get with this endeavor.

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You could more than likely get a usable signal with a directional antenna.

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I thought part of the deal on Philly's WiFi system is that you could call up Earthlink and they would install home equipment for the very purpose you describe at some nominal cost?

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