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  • Easy to Build WIFI 2.4GHz Yagi Antenna

    The average person is not going to be able to make this because it leaves out the most important step; so I'll try to explain without going into the math : Matching the impudence of the feed line (the wire that connects to the folded over paper clip). RF signals at this high frequency is VERY sensitive to length. It is critcal to cut the lengths perfectly, also the lengths are for copper wire not steel. So the best material would be solid copper wire that you can buy at the hardware store. I used 18ga and kept the lengths within a millimeter of the size. 1. For the connecting wire you MUST use 50 Ohm coax cable. It comes in 75 or 50 Ohms and its usually printed on the side. If you use a plain old wire this becomes part of the antenna and you lose the "quarter wavelength" that ...

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    The average person is not going to be able to make this because it leaves out the most important step; so I'll try to explain without going into the math : Matching the impudence of the feed line (the wire that connects to the folded over paper clip). RF signals at this high frequency is VERY sensitive to length. It is critcal to cut the lengths perfectly, also the lengths are for copper wire not steel. So the best material would be solid copper wire that you can buy at the hardware store. I used 18ga and kept the lengths within a millimeter of the size. 1. For the connecting wire you MUST use 50 Ohm coax cable. It comes in 75 or 50 Ohms and its usually printed on the side. If you use a plain old wire this becomes part of the antenna and you lose the "quarter wavelength" that tunes this antenna to 2.4Ghz. Bigger is NOT better with antennas. The best reception comes from keeping the antenna element EXACTLY at this length. Skipping this will give you worse reception and there is no point in making at that point. 2. Solder, dont tape the center conductor of the coax to the center paper clip at the very edge of one end. Don't form a loop, keep the ends electrically separated and keep the paper clip at a 90' angle to the other paper clips, don't lay it flat, that messes up the length between the 1st and 3rd paper clip which are the most critical lengths. 3. Keep the coax as short as possible. Anything over 3" is going to turn the coax into part of the antenna and this can burn out the wifi transmitter. When you solder it to the trace make sure you connect it the beginning point if the antenna if its a "squiggle" shaped antenna on the circuit board. If you solder to the end you have screwed up the length. You will also have to scrape away part of the trace that forms the rest of the antenna, this is permanent so it your not sure be cautious. if there is a connector it will be very tiny and the best way id to cut the cable coming out and connect that. The inside of the cable goes to the inside of your coax and the out must also connect. Some coax cables have aluminum and solder wont stick to it; while still useable it may not be the best choice if you are not experienced with building electronics. 4. Better way to make the driven element: The outside conductor of the coax must be connected to the ground of the wifi device. This will be outer ring of the connector in your device, this will connect to the shield of your coax. Take the folded over paper clip like in the tutorial but instead of making a loop, make it the length in the print out as a straight piece. Cut the piece in half. This now becomes a dipole antenna, and will work better because it used the ground in your wifi device. Solder the center conductor of the coax to one half and the shield to the other half and glue them onto the popsicle stick with a very small gap between like in my picture. 5. Finding the ground: this is probably the hardest part. For this to work you need to hook the outside of the coax to the ground. If there is a connector in your wifi device it the outside conductor of the connector. If you just have a squiggle you are going to have to find the ground plane on the circuit board. This is usually a very thick trace that "floods" the circuit board where one side of most of the parts connects to. There is really no easy way to spot this without some knowledge of electronics. If you don't do this step it may still work but wont work well if it does defeating the purpose of this DIY. If you want to learn more look up wavelength and 1/4 wave length. Its a complicated subject with lots of math. Unfortunately this project just wont work if you skip steps or mess anything up. Seems simple but really everything has to be done right for it to work. Hope this helps.

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