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
Scissors
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.

PRINTING:

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

Set the print orientation to LANDSCAPE.

VERIFYING SCALE:

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.

Comments

[brian-kn]

Hi, I thank you very much for the reply about the antenna wiring it is more clear now that you have explained, Kind Regards Brian UK

[brian-kn]

Hi can the wires from the yagi antenna be connected with the wires in a a usb connecter and connect directly into my laptop. kind regards brian

[popefelix]

If you mean just soldering a USB connector on to the feedline for this antenna, no, that won't work. You still need something to handle the actual generation and reception of the wireless signal.

However, if you mean connecting the antenna to a USB wireless adaptor, that's possible, provided you connect the feedline from the antenna to the antenna connector on the wireless adaptor. If the adaptro doesn't have one, you'd have to tear it apart and find where the internal antenna was connected.

[popefelix]

If you mean just soldering a USB connector on to the feedline for this antenna, no, that won't work. You still need something to handle the actual generation and reception of the wireless signal.

However, if you mean connecting the antenna to a USB wireless adaptor, that's possible, provided you connect the feedline from the antenna to the antenna connector on the wireless adaptor. If the adaptro doesn't have one, you'd have to tear it apart and find where the internal antenna was connected.

[sololife.sai]

Can i use a wire if so what is the diameter. Thank you

[Biotele]

Of course, it has to be stiff and solid. I don't think it has to be exactly a certain diameter. Maybe someone with antenna theory can enlighten us further.

[Dr.Bill]

I think a larger diameter wire will result in a larger bandwith antenna.
For a router with 2 antennas, why not build 2 yagi's and stack them?
A stacked phased array just like the EME array's for moon bounce.

[iamdarkyoshi]

I have a major problems that needs solving quick: how exactly do i connect the driven element to the antenna? as you can see, the antenna boom is missing the element, because i popped in my original antenna with the usb card, and worked fine, but not the strongest signal. why didnt it work with the copper wire? because i just took the 2 wires coming off my board, and put them on each end of the element, completely skipping the original antenna? how is the wiring diagram? any help would be greatly appreciated, as im bored of trying to get around the schools internet filter, with this i can mooch off of someone elses:D

[estefan2020]

here is a matching using a piece of coax to get the 300ohm down to 50ohm


http://www.k7mem.com/Electronic_Notebook/antennas/yagi_vhf_feed.html

[estefan2020]

@kiranrpatil01 if your phone has an external wifi jack, or you plan on opening ypur phone and soldering some lmr-400 cable to your phone and have a 2ft antenna attached, go for it.

[estefan2020]

here is an online yagi calc for 2.437 ghz, gives more options

http://www.k7mem.com/Electronic_Notebook/antennas/yagi_vhf.html

[chrislarkin]

it did not work because you were completing the circuit at the end of the coaxial cable stopping the signal from traveling through your antena

[estefan2020]

if this was dc theory, yes, but this is ac theory. the driver element acts much like a loop. just like the old circle uhf antenna, this way is called a folded loop, when the folds are the same distance. dc looks like a short, ac does not.

[estefan2020]

http://www.youtube.com/watch?v=BGdwIXMexCY&feature=rellist&playnext=1&list=PLD7A103946CE9C072

here is another yagi folded antenna with aproprate matching cable for 50 ohms.

if you need a wifi with detachable antenna, alfa on fleebay is a good choice

[estefan2020]

I would suggest ether placing glue on your sticks and let it dry, or using plastic wrap around the sticks. this will prevent moisture from the wood interfiering with the antenna.

[kiranrpatil01]

is there any danger by using it ,like licence for WiFi and can it be connected to android mobile to access internet?

[estefan2020]

for cable ebay 'rp-sma lmr 400' 3ft 1mcable $13 this is the only thing you don't want to skimp on, as it is for these frequency's cable signal loss can eat up the gain.

you can get 'RP-SMA male flange' and connect your antenna to your usb antenna adapters jack, and avoid the cable loss. just mount the driver element so it hooks up at the bottom instead of the top.


.

[frankortega]

I found a company and there antenna are not too expensive, I try to build
two type of antenna in (easybuild2.4 GHz), but still lacking some imformation, and its end up lossing my time, need more information,kind ofcable,connector,and how long
the maximum leght of the cable.
thanks

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[jbaker22]

I have a Cisco wrt120n. It has 2 antenna how do I make the yagi antenna?

[Biotele]

I don't understand your question. You build this antenna but you can't connect it to the usn wifi receiver? Can you post a picture of what you build so far? Thanks.

[jbaker22]

This is router what other info. Do you need?

[jbaker22]

It has 2 antena like this shows. The metal parts on the side are the antenna. I would like to attach an alligator clip to 1 antenna which should I clip it to? Then I will attach the other end to the Yagi antenna.

[nzammit]

Hey great instructable! It might be a bit off topic but I have a few old disused TV antennas. Could I somehow change those to receiving WIFI? Thanks.

[dbartley]

Anyone with experience of reflections from the coax itself? I built a 4-element vertically polarized 850-MHz Yagi antenna. With the coax dangling haphazardly from the boom behind, there seemed to be tremendous problems. These problems seem to disappear by looping the coax behind from boom to the mast, forming ROUGHLY another half reflector.

[dbartley]

The ARRL Antenna Book (Chapter 27, 1991) describes this problem of antenna currents on the transmission lines somewhat. The outside of the coax is actually part of the antenna, being directly attached to an active antenna element, though it is perpendicular in this region. But also its metal further back interacts inductively with other antenna elements in its vicinity. Directing the coax back along the boom, with a large loop (about 1.5 wavelengths) behind and down to the wooden mast improves reception consistency somewhat, rather than haphazard arrangement. But the ideal loop seems to be obtained from the tightest possible. Because of the peculiar geometry and the lack of actual measurement rather than qualitative evaluation, it's hard to understand why this is.

[jbaker22]

(removed by author or community request)

[Biotele]

you can use a 2.4 GHZ coax cable with adapter hooked to your router.

[jbaker22]

(removed by author or community request)

[Biotele]

get a solid piece of copper wire that fits into the router's antenna socket, and connect to one side of the dipole. The wire should short.

[jbaker22]

It has no socket. I have to solder and hope I don't ruin the router.

[frisbeechamp1983]

If I added like a reflector to the back to send all waves forward, the put it on a slow rotation like radar, would it still work? It would be attached to a modem in my basement,the wired to the roof of my house.

[andrew101]

actually if you look at yagi antenna theory, the wire just behind the driven wire acts like a reflector If you added a dish behind the antenna, and the spacing was wrong, you would cause undue interference for yourself, and chances are it would work against you.

a possibility would be to add something covering the back that was grounded, it would act as a shield to interference, and not a reflector though.

[Biotele]

Yes that will work. Can you post a picture that sounds like a great idea.

[khan0daulatzai]

guy can any paste a video of this test,,,plzz

[Computothought]

Made your antenna, but have not tested it yet. have to rescue a cable first.

[Biotele]

you don't need a cable a tiny short wire between the active strip on the board and one side of the loop will work. Photo's please. thanks

[andythemac]

Excellent instructable! I've built the antenna but don't know where to solder the co-axial to my DWL-G122 adapter.
Here's some pics of both sides:

[Biotele]

Check out this site:

http://www.sohtell.se/DWL-G122/

this one is better if you want to solder a coax directly:

http://usb-wifi.blogspot.com/2009/12/usb-wifi-dlink-dwl-g122-modification.html

[jzhan]

here's the image

[Biotele]

Excellent. The top one.