I wrote a three-part series of articles entitled "How to Build a Long-Range Wi-Fi System" that is still available with Part #1 starting at http://goo.gl/VpO8F. In that article, I described how I installed an external antenna on the back of my motor home that allows me to connect to wi-fi networks a quarter-mile away and sometimes even further.
In Part #3 of the article (available at http://goo.gl/IgkvI), I described the masts that I used. My first experiment was with a military surplus set of ten four-foot long fiberglass poles. That didn't work very well. The poles were big, heavy, awkward to install, and looked ugly. It got stares in the campground. I later discovered a telescoping aluminum flagpole mount made for recreational vehicles. Although it is described as a flag pole, this mast is perfect for use with a small to medium sized antenna on top! I use it for both my wi-fi antenna and for a television antenna that works a lot better than the one installed at the factory on the motor home's roof.