Easy to Build WIFI 2.4GHz Yagi 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.

Comments

[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.

[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.


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[Geomod]

The problem with the coax could the impedance match, your cable could be of a different impedance of the ones reporting that the conection worked.
Also I recommend using a balun for a better match, if the impedance of your device is 75 Ohm you could try with a TV balun, I'm not sure if that will work because there is a lot of diferent of the frenquency of their design.

[keriksen1]

A balun is a good idea. I'v build sevral yagis (thou not for 2.4GHz) using a small program called YagiDesigner (google for it). It also calculates and explains the balun for you.

[tjl115]

Please be more specific an the coax connection at the antenna. you make no reference as to where the coax center conductor and shield connections. Your description only mentions a jumper between the active and driven elements. Also which is the active element? I understand that the loop is the driven element.
Thanx, if you can clarify those connections it should be a good build.

[Biotele]

You are correct, there is a very good reason why I didn't get a picture. I didn't have a decent macro camera to take pictures close up before I potted it and heat shrunk the circuitry to secure it. When I got it to work, I was too excited playing with it that I did not wait to get another camera.
I will try to draw a picture.

[5Volt]

I totally agree: better and close-up pictures are necessary to understand this point.
Great project.