In free space, a folded dipole has a ohm impedance at resonance, but the impedance drops drastically when parasitic elements are brought into close proximity. Print and use this plan view when building the 15 element yagi wifi antenna. Print and use this plan view when building the 20 element yagi wifi antenna. This high gain wifi antenna can be constructed in a couple of hours and requires some measuring, cutting, bending, and bolting of metal. Use caution around the sharp edges.
When finished, put it up and enjoy a very durable antenna that provides outstanding wifi performance. Assemble the yagi wifi antenna following the steps below, starting with preparation of the boom, followed by mounting the elements. After the elements are mounted, a suitable connector is added, and the antenna is tested over-the-air. Keep in mind that it can be connected to most usb wireless adapters by cutting the circuit board antenna trace and patching in a pigtail feeding the antenna.
After all of the elements are measured, cut, and mounted, the antenna should resemble the finished yagi pictured below. Connect the pigtail or connector to the driven element. Then connect the wi-fi adapter or wireless router to the antenna and start checking over-the-air signal strengths.
Note that the antenna may be sensitive to polarization: when the antenna seems to bring in the best signal, rotate it to find the best polarization. Mounting the antenna is possible using commonly available hardware, such as 90 degree angle brackets, U bolts, or even velcro.
Closeup of the wifi yagi feedpoint. Keep the leads short! The completed wifi yagi antenna. For the most practical method of signal checking, consider using a wifi auditing utility such as Kismet or Slitaz Aircrack-ng. Either of these will produce a rapidly updated received signal strength indication that is useful for comparing or aiming wifi directional antennas.
Make a set of measurements for any desired wi fi access points on the original antenna, then make a new set for the yagi wifi antenna. The antenna should exhibit high forward gain and front-to-back ratio. A prototype in fact performed as well as the wi-fi 12 turn helical antenna shown elsewhere in these pages. Again, for ultimate performance over long distance wifi links, use a short version of the yagi to feed a parabolic reflector as well as a high powered wifi adapter.
Watch a video the wi fi yagi antenna construction on Youtube:. Someone made a very well constructed wifi yagi with a plexiglass boom! Their video adds some hip hop music and slick graphics to showcase this design. It retains attributions and links to this page, so the webmaster is happy to see it!
There are others too! One person, in China, built one and created a smart-phone access point covering a long section of street. Disclosure: AB9IL. If you make a qualifying purchase after clicking a link on this website, the associate affiliated with this site may earn a comission at no cost to you.
Wireless bridges work like a long run of ethernet without cable Providing internet connectivity from one building to users in a remote house or office. Providing internet connectivity from one highrise building to another across town. Providing internet connectivity from an onshore location to users on an island.
Sharing connectivity between two locations which can't be linked by cable. Element data for the 15 Element Yagi Wifi Antenna. Element Length mm Position mm 1 Reflector Element data for the 20 Element Yagi Wifi Antenna. Fix the elements in place with crazy glue. Leave element 2 for later. This is the element that connects to the electronics and is called "the driven element" as in being driven by electronics.
The backbone holds the shape of the antenna. I just cut pieces of popsicle sticks and fit them between the gaps of the elements. I used white glue to fix them in place. Start from element 15 backward. When you arrive to element 2 move on to the next step. The "driven element" in a Yagi antenna, is usually the second one from the start.
It is a broken loop and not a straight wire. A loop of wire resonates at a specific radio frequency depending on its dimensions. The dimensions of the driven element in this antenna is set at 2. It just happens that its about the size of a common big paper clip. You need to clip the paperclip so that it loops around and meet in the center but the end not touching, leaving a gap see photo. Fix it in place with crazy glue and build the back bone around it. When all the elements and sticks are in place, reinforce the antenna with another layer of popsicle sticks.
Glue full lengthed popsicle sticks on top of the antenna. The antenna should become mechanically stiff. Then rip the paper template of the antenna. This is the most difficult part and depends on the electronic hardware you have. The basic idea is that you need to solder a wire between the WiFi board's RF output and the driven element of the yagi antenna. Those with external antennae, like mine, are easier to connect because you are just replacing the external whip antenna with the Yagi. Those with internal antenna may need to have their on-board strip antenna modified as illustrated in the pictures here.
You need to slightly experiment in this case. I have tried soldering a coax to my board's antenna connectors and the two ends of the yagi's active element loop but it did not work in my case. I have no explanations why that did not work, but other DIYers that have built Yagi antennae connected their antenna in this manner. In my case, I just connected a single thin strand of copper wire between the active element of the strip antenna and one end of the loop of the driven element.
Please read the annotations of the pictures for more details. The performance was pretty spectacular for this easy to build antenna. I was able to see the WiFi of a hotel that was 2 miles away from my home.
The most difficult part was connecting the antenna to the USB modem. Okay well I read through the entire post and I saw many things that made a lot of sense, also saw a lot of unnecessary flaming, but I do have a few comments to make.
Right off the bat the one individual that asked about having his modem in the basement with a rotating antenna on the roof needs a reality check. Take the dongle apart and connect a USB extension cable to it and mount it directly on the antenna assembly.
Paper clips vs copper, at this frequency it's not going to make much difference, however the specific model was generated using 14awg copper. Someone said glue it all to cardboard then cover it with more cardboard actually a strong and stable design, original author said build around popsicle sticks wooden , both are subject to absorbing moisture from the air and either can have a poor dielectric constant, I would suggest some kind of plastic they make popsicles with plastic sticks.
The lengths of the elements, the spacing between them, and keeping them all in the same plane and parallel to each other is the most important consideration. If you use the folded dipole make sure the folded part is perpendicular to the plane of the rest of the antenna and use ohm twin lead to connect to the dongle, but your SWR will probably be much higher, reducing your effective gain and possibly resulting in early failure of the dongle.
Horizontal vs vertical, after you have your antenna connected and have connected to some network you can try rotating it about its horizontal axis to see if you can get a better aspect on the other antenna more bars. All in all though good job to Biotele, it's cheap, it's easy, and if done right will provide excellent results. I did not build this antenna, but I built 2 antennae very similar before reading this post, My son and I live almost 2 miles apart and either of us can stream p movies from the other's house during a thunderstorm.
Reply 1 year ago. Was the setup with your son line of sight, or was there any foliage between you? Was this able to extend the original wifi network to the second location? Reply 6 years ago on Introduction. Reply 7 years ago on Introduction. Thanks upon this project. For my recommendation, I would advise you to use a usb to Ethernet adapter then feed your router with Ethernet as usual. I'm a ham radio operator and have build many yagi antennas and am going to build this one.
Here's a suggestion. Then you do not need to print out the guide. Also realize there are factors outside your control so getting accuracy to about 1 mm is good enough for element spacing and length. If you aren't that accurate, it will just decrease the gain some, but the antenna will still work much better than an omnidirectional one. Question 1 year ago. I still dont get where to put the wires on the natena I have USB wifi with external port for antena, I have the coaxial cable Bit did not see ani diagram where to solder them on the antena..
May be I miss something because of poor english, so please someone to help with a simple diagram on Paint. PS This looks exactly like an oldschool external TV antena. If I use one wouldnt be better?! Question 1 year ago on Step 4. Question 2 years ago on Step 2.
As others have pointed out, the impedance matching is done poorly and not even explained properly. I have added a picture of a matched element that also acts as an impedance transformer.
The 2. That means you use a 2in wire, solder the center of the coax to its center, then fold one leg in half and solder it to the shielding. See image. This is why those internal laptop antennas out of stamped metal have that shape.
It's the quarter-wave hoof. Reply 2 years ago. Assuming your laptop is less than 20 years old, it will have USB ports which means you can follow the instructions as stated. Question 3 years ago. How the heck do you make precise cuts? I have a dial caliper that measures up to 6 inches, and gets down to the thousandth 0.
I can convert your mm to inches, but I still can't seem to find a non-tedious way to cut a 14 guage piece of steel wire to precise measurements.
I want to know how non-precise you can be with these, because not even a million dollar company with the greatest factory can give accuracy to a theoretical set amount of millimeter cut.
Question 3 years ago on Step 3. I understand that skin effect is paramount to impedences and that if you increase the diameter of the driven element you can also increase the bandwidth and decrease the impedance to like 50 ohms and that a good measuring stick is your best friend in building these things as long as the math formula is good. A tube within a tube allows you to adjust such lengths. Skin effect means tubes are better than wires which are heavier.
BUT, where are the formulas for the driven lengths vs diameters and velocity factors of whatever cables? Can someone please make a video with the instrucions in the comments, because its very difficult to follow. Can you give me a model of something acceptable?
Reply 4 years ago.
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