Make a solid base for your antenna. This will have to withstand whatever Mother Nature will throw at it. Start by figuring out how tall you want your Yagi antenna to be. Set aside four 1.5-inch-diameter aluminum pipes of that diameter. Use a power drill to make holes every six inches in the pipe. Bolt the pipes together with 6-inch pieces of metal. Bolt these in an "X" formation to give your base the maximum strength.
Bracket a 6-foot aluminum pole to your base. This is where you will eventually attach your Yagi antenna. Be sure not to tighten this too much, as you may want to adjust your array to get different directional reception.
Set aside three long pieces of metal to make the three elements of the Yagi antenna. Here is where you need to do some calculations. First, figure out what wavelength you will be using. The longest of the three elements should be shorter than half of this wavelength. The next two should be progressively shorter (about 5 percent, give or take). These will serve as the reflector, driver and director element, respectively.
Bolt the elements to a length of pipe. Again, you’ll have to do some calculations. The spacing of the elements is very important to the power of the Yagi antenna. The reflector should be affixed one-quarter wavelength from the driver. Similarly, the director should be affixed one-quarter wavelength from the driver.
Connect the length of cable to the top assembly. You’ll probably want to solder the two together to ensure a true connection.
Put everything together by planting the base in the ground. You may want to cement the antenna’s base into the ground, depending on how long you’ll be using the Yagi antenna. Carefully bolt the top assembly to the pipe extending from the base and line it up in the direction you most want to monitor.