How to Build Your Yagi Antennaby Andrew Copley
Yagi antennas differ from most antennas. The reason is that each Yagi antenna is designed to receive a tight band of frequencies according to its size. The sizes range from 1 foot to several yards, so it is important to know the frequencies you wish to receive before building your antenna.
Yagi antennas have four main parts. The boom, reflector, driven element and a series of directors. Each wire or rod is slightly larger than the one before it. This means the antenna is directional and with each wire directs and focuses the signal. The end result is you get a strong signal hitting the driven element.
Find out the frequency you wish your antenna to receive. Use an online Yagi antenna design program to find the size of all the antenna parts. Each program starts with the frequency you wish to receive. From there, follow instructions to find the sizes you need. Print out the page with the spacing and sizes for each part for reference.
Draw a line on one side of the piece of wood running down the exact center. The line should run along the full length. The wood must be straight with the line centered perfectly.
Place a mark at the center line 5 cm from the end of the piece of wood. Label that first mark "1." This will be your starting point for the rest of your measurements.
Starting at the mark labeled 1 (reflector position), measure and mark the distance along the center line to the driven element. Continue down the line, marking in the spacing for each of the director elements. Make sure the director elements go in order of largest to smallest heading away from the driven element. Continue numbering the holes from your starting mark of 1.
Drill a hole through the wood at each of the marks you made. Make sure to drill straight through so the drill comes out of the wood centered on the other side.
Mark the numbers you used running down a sheet of paper. This is where you are going to place your cut pieces of copper wire once they are cut. The lengths are slightly different, and if mixed up the antenna's efficiency will be compromised.
Cut one piece of copper wire at a time using your wire cutters. Cut each piece a little longer than the measurement you need. File the rough edge off, giving you the correct measurement needed. Place the cut piece of copper wire beside the number on the piece of paper to avoid confusion. The reflector is number 1. The driven element is number 2 and the directors start at number 3 going from longest to shortest.
Working with one piece at a time, press the copper wires through the corresponding numbered hole on the piece of wood. Center it using your ruler to make both sides even. Do this for all the copper wires, except for wire number 2. Number 2 is the driven element and needs to be formed first.
The number 2 copper wire is the heart of the antenna (dipole), so take your time with this part. Feed the wire through the hole and center it. The goal is to make the shape of a paper clip. Using your pliers, bend one end 180 degrees so that the end is approximately over the middle of the piece of wood. Do the same with the other end of the wire. There should be a 5mm gap between the two ends. Make any adjustments to fit those measurements. This piece is now called a folded dipole.
Attach the appropriate connector for the unit you are using to the open ends of your folded dipole. Check with the manufacturer of your unit to find out which adapter will work best. TVs, radios and routers all have different connectors.
Mount your antenna onto any type of stand to suit your decor. Try it out. You may need to turn your antenna for the best signal.
- Keep your antenna away from strong electric fields, such as monitors etc.
- Be as accurate as possible with your measurements.
- Use a drill press for the holes if possible.
- antenna 2 image by Vita Vanaga from Fotolia.com