|Networking - WiFi - Wireless|
(they were pretty ideal conditions, but more on that later..) And I probably could have gone farther, but I wasn't too keen on hiking through the woods with tall weeds, and uneven terrain balancing my laptop with one hand, and pointing one of these cantenna with the other hand. (yes, the neighbors are used to me doing strange things, and they just smile and nod.. Yes people, he really is harmless!)
Here is a photo of the finished wifi cantenna:
|Typically my approach to projects is that they need to be inexpensive, but they also need to use readily available materials. this project is no different. Please excuse me while I slip into "geek mode" for a minute. This type of antenna is what is called a waveguide. There are several parameters. The two most significant ones are called the cut off frequency of the TM 01 mode and the cutoff frequency of the TE 11 mode. Basically these two parameters define the highest and lowest frequency that the cantenna can operate.|
My problem was that I was having a hard time finding some sort of tube that was readily available. The closest thing I could find was a 4 inch aluminum dryer vent tube. This, according to waveguide calculations, was too big in diameter, and causes the upper cut off frequency to be too low. However, in messing around with many antennas through the years, I have realized that although antenna theories help us design antennas, sometimes it is an inexact science. So basically knowing that the diameter of a 4" dryer vent is too big for "optimum", I thought I should at least give it a try, and see how it works anyway. OK, I'm done with "geek mode" for now.
Let's get down to business, Here is a cross section diagram of the wifi cantenna:
Location of the female type-N connector, and length of the antenna are critical. Below is a closeup with dimensions: