How to extend your Wireless Network by building a 2.4 gHz wifi cantenna - How to extend your Wireless Network by building a 2.4 gHz wifi cantenna - P. 5
| Networking - WiFi - Wireless |
In order to test the results of my new wifi cantenna, I used netstumbler. Here is how I measured the gain. I started up my laptop aprox. 50 ft. from my access point. and let netstumbler take some readings. In the image below, these readings are labeled "Wifi Card No Ant.". Then I quickly connected my wifi cantenna, which was pointed at the access point. The resultant rise in signal is the gain of the wifi cantenna.
As best as I can tell from the graph, the readings are as follows:
Wifi Card No Ant. = -74 DBm
Wifi Card with cantenna = -57 DBm
Which gives a gain of 17 DBm. Not bad for about $10 of materials, and perhaps an hour of time!
What I would like to do now is address some common questions people usually have with reguard to my wifi cantenna.
Q: If I build one of these do you think it will reach XYZ distance? (how far will it go)
A. That is a tricky answer, with too many variables. such as, is the other end a "clear line of sight", In other words, can you see it? What about trees and walls and such? All of these things seriously degrade the signal. Unless you have thousands of dollars of test equipment to test your signal path, I suggest you just build one of these and try it.
Q: How do I connect this to my computer?
A. There are a couple of options. First if you have a laptop, you can purchase an Orinoco Gold (not silver..) PCMCIA Wireless card. (This is what I did..) On the edge of the card, there is a tiny antenna adapter (really!) Below is a photo of an antenna connector:
Yeah, I didn't believe it either! Now as far as the type of connector that is. Well its called a "MC connector". You can often times find these wifi cards on Ebay. Unfortunately, there aren't many PCMCIA cards out there with an external antenna connector. I have seen some ambitious folks tear apart their wireless cards to add an external antenna, but I don't recommend this, as it definetly voids the warranty!
Ok Lastly, we still need a cable. Trust me, I don't recommend making one! so when I need a cable, I just order onefrom Cable Experts. They are great guys, and very knowledgeable, and more than willing to answer your questions. The only dowside is that they have a $50 minimum order. But maybe you have a friend that wants to build one too. Also, you can purchase the type N connector you need for the wifi cantenna there.
The second option for connecting to your wifi cantenna:
I have also taken an access point or a router with removeable antennas (like a D-link or Linksys access point, or router) and figure out what kind of connector it is. (Please use google to find out this info, it is easily found there) Then order the appropriate pigtail from our buddies at Cable experts. Once you are hooked up, you are good to go. Now this if for a fixed wifi connection and not necessairly for a portable one.
Q: OK, I've built one of your wifi cantennas, and it just doesn't work! Its worse than with out the wifi cantenna. What gives?
All too often when I get asked this question, after more questions about the installation, I find out that they put the wifi cantenna on the roof of their house, then ran a long piece of coax through their house. The problem is that is that at wifi frequencies, coax / pigtails are very high in RF loss. I recommend a pigtail / coax length between your wifi cantenna and your network device of no more than three feet. What is happening is that you have lost more signal in the coax than what you have gained in the wifi cantenna.
BTW, I have seen people put wireless access points in waterproof boxes and mount the whole assembly on their roof, then run cat-5 cable and power up to it. Like This guy (who is a ham radio operator.. My kind of guy!) who put one on top of his 110 foot tower! Oh yeah!
Q: So only one of my friends can connect to me, what's going on?
This is a highly directional antenna, therefore it only performs very well in one direction. Oh by the way, wifi is at microwave frequencies. Since this antenna concentrates the signal, don't look into the cantenna while it is connected.
I recently received an email from someone who came up with a nice way to mount the WiFi Cantenna. Here is a photo of how he did it:
He used two more 4" Dryer Vent clamps, a sheet of aluminum, a couple of conduit clamps, and PVC pipe for the mast. Thanks Jim! Nice work!
OK, I think that about covers it! I hope I have given you some ideas on how to extend your wifi network. Good luck!
| -- Mike |
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