Easy to Build WIFI 2.4GHz Yagi Antenna





Introduction: Easy to Build WIFI 2.4GHz Yagi Antenna

This antenna will extend the range of your WiFi or 2.4GHz devices (like surveillance cameras) into many miles and kilometers. A yagi antenna is basically a telescope for radio waves. I tired the pringle can antenna and the Yagi beats it hands down in performance.

Step 1: What You Need

This is an absolutely easy project.

You need an ink jet printer/ Computer
Popsicle sticks
White glue
Crazy glue
Big paper clips (you could use any stiff solid metal wire instead)
USB WIFI, preferably with an antenna extension OR a 2.4 GHz device
soldering iron and lead
Sanding papers
Pliers or preferably a nibbler (see photo below, available at radio shack)
a metric ruler with millimeters or a metric caliper.

Step 2: Building Overview

The building steps are simple:

1. Print out the scaled Yagi antenna template* (download from next step).
2. Trim paper clips to size and glue them to the template.
3. Use Popsicle sticks to build the antenna's backbone and hold it together.
4. Connect the USB device to the antenna.

*I used a Yagi modeler java applet to generate the diagram. This modeler applet is found on many websites (google "yagi modeler") and its owner is W9CF.

The modeler gives a diagram and the elements' lengths and position. I carefully scaled the diagram and turned it into a template in order to make the building process easy.

You can visit AB9IL awesome website  to get more details on using the modeler for this 15 element Yagi and other fine antenna projects, such as a 20 element WIFI Yagi .

Step 3: Printing the Yagi Diagram

The most essential point in printing the template is getting the correct scale. In the attached zip file below, are three png picture files.

The antenna is longer than an Letter sized or A4 sized paper. So you have to print the template in two parts (labeled part1 and part2 in the zip file). I have also included the full sized unsplit template if your printer can handle large enough paper.


Make sure to set your printer's properties to ORIGINAL SIZE (not "best fit to page" ect..).

Set the print orientation to LANDSCAPE.


Use a ruler or caliper to measure if the print is of correct scale. You will notice vertical bars crossing the horizontal line. The vertical bars represent the Yagi "elements" which will be made from paperclips. The horizontal line is the backbone of the antenna which will be build out of popsicle sticks.

You will also notice numbers next to the elements. These numbers are in pairs. The first number is the length of the element in millimeters. The second number, is the distance from the start of the diagram to the element, in millimeters.

Measure the size and position of a couple of elements on each prints. If your measurements match the numbers on the diagrams, then your print is to scale and you may proceed. Accuracy need not to be tight for the antenna to perform well.

Now superimpose both prints, until they match at around element 10 or 11, and tack them together with scotch tape or white glue.

Step 4: Cutting the Paper Clips and Fixing Them

You have to trim the paper clips with a nibbler or plier to fit the vertical bars ("elements"). This is fairly straight forward. Lay the paper clip on the template's element and mark the ends with a marker. Snip at the marking.

Make sure that each element fits correctly the length of the bar on the diagram.

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).

Step 5: Building the Backbone

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.

Step 6: Building the Driven Element

The "driven element" in a Yagi antenna, is usually the second one from the start. It is the element that connects to the USB WIFI or 2.4 GHZ electronics.

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 2.4GHz, of course.

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.

Step 7: Connect the Antenna to the Wifi Modem

This is the most difficult part and depends on the electronic hardware you have. please read this step carefully. 

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.

But USB WiFi modems come either with an internal antenna or with an external 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.

Step 8: Performance

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.

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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. but to keep resonant a yagi-uda myst always be tuned for each frequency wanted. 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 ?


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. Overlooked in the connecting the USB dongle to the antenna was the transmission line length, for these frequencies it should be as short as possible and a multiple of 1/2 wavelength I'd suggest as close to 2.41 inches as one could manage (use a small diameter 50 ohm coax). 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. The driven element, #2 in this design: that one I would make from 14awg copper, I'd make a simple dipole rather than a folded dipole, I would take two pieces of wire make 90 degree bends in them cut the bent part to about 1/8 inch and attach my transmission line. Take a piece of heat shrink cut two notches in it about 1/4 inch apart and insert the wires into it and shrink it, maybe reinforce the space in the center (break a tooth from my comb and stick it in the middle before heating the shrink?) cut it down to the correct overall length and insert it last. If you use the folded dipole make sure the folded part is perpendicular to the plane of the rest of the antenna and use 300 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 1080p movies from the other's house during a thunderstorm.

I think you could make an instructable out of all that :D

Can someone please make a video with the instrucions in the comments, because its very difficult to follow.

Can I use a USB Wifi wireless WCDMA router for this? Can you give me a model of something acceptable?

I need to catch the signal on 50 meters sometimes, sometimes longer.

50 meters? That is 6 MHz. Wifi he is describing is 2400 MHz. Take a look at a stepper ir. They tune thru that band and are around $6000. It is a huge antenna but very good. It is a loop like the formed paperclip. In case you are confused, the term meters is the actual physical wavelength in meters of the transmitted signal. The lower the frequency the bigger the antenna has to be. It is factored on 1c, which is the speed if light, 299792458 meters per second. Rounded to 300,000,000 you divide this by the frequency in cycles to get the full wave length. Shorten it by using 300 for length of light / speed and 6 for the MHz instead of cycles and you get 50 meters. A balanced antenna such as a dipole is a 1/2 wavelength, so divide that by 2 for the physical length of a 50 meter dipole, so 25 meter length is correct. For 50 meters you are talking about a huge antenna. You can build an active antenna for just a receiver or use an LC network to tune a shorter wire but it will be compromised in ability. Hint: the antenna is a network, compromising of everything from the board connection point, all the way to the tip of the antenna. Using coax, you will also need a balun. I'm an extra class ham radio operator and an electrical engineer. Look online for antenna calculators will be your best bet. Beverage antennas are great, especially for summer time noise from lightning static crashes but they are even bigger. Sorry for the delay on the post but I just saw this.

By "cat5e" you mean RJ45 cable? I dont know which ones of the wires inside to connect to the antenna? Why do I need a coax if I put an RJ45?

Cat5e is the cable. RJ45 is to connector on the end of the cable, that can go on cat5, cat5e, cat6, etc.

Ok, I built the antenna according to specification, but I am guessing I couldnt make the elements as accurate, I catch a signal from about 1km, but I cant connect to it. I am not an antenna expert. So if I buy a yagi antenna with coax cable it should work allright?

One more thing. If you are mounting this any distance from the wifi, db loss is extreme on higher frequencies like wifi 2400 MHz. Keep the coax short as possible and use cat5e to get to your laptop. LMR400 is a good all around coax but is is nearly 1/2" diameter. The higher the frequency the larger the center conductor has to be because of "skin affect". You can use a short piece of smaller coax and then adapt it to a larger coax. LMR has superior shielding also. Every 3db loss is half of the signal strength. 6db is 75% loss. 9db is 87.5% loss. Every 3db cuts it in half each time in the math. Antenna gain and loss are added to get the ERP...effective radiated power. 5db loss of coax with 8 db gain on the antenna will give you 3db gain so you can double you wifi output power to get the ERP. Just look into a Ubiquity wifi and their antennas. They are nearly 30dbm...1 watt with some very high gain antennas. That can get you 60 km distance if applied correctly...line of sight.

can you please tell me the model number of wifi usb, and how i will sold it to driven element