A day at Chennai Mesh Community – building the Yagi-Uda antenna

In this post I will briefing on the events that happened on Sunday (01/05/2016), were Free Software activists and hardware hackers from the Chennai Mesh Community joined hands together in creating a Yagi-Uda antenna.

First things first, Who we are?

I will keep things short in this section.

We are group of activists from Tamil Nadu, India who have a lot of interest and passion about Free Software and Open Hardware. Recently, we were introduced to Mesh Networks (which we later knew had existed for a long time) and understood that the Internet needs a serious change. We wanted to be a part of this because, Internet was something that was created for people, but now big corporations control one’s access to the internet. So, we created the Chennai Mesh Community with the goal of making Internet the way it should be.

We are a community of the people, by the people and for the people

You can find out more about us from our Facebook page here

Now to the actual post…

Why build it in the first place?

Prior to the having this activity on Sunday, during our regular meetups in person and through messenger, we usually discuss on what had happened in the previous meet and what is the activity for the next meet. So, we thought like why not build an antenna the coming week, because its the basic thing that makes wireless communication possible. If we are going to create a mesh network with routers, we have to bear in mind that the stock antenna isn’t that much powerful to achieve a sufficient range. That being one side of the reason, the other is, if we don’t know what an antenna is and how it operates then we can’t make a rationale decision in choosing a wise router or customizing one to achieve better results.

What we needed to build it?

In order to build the antenna we made use of this instructable as our guide. The reason we chose this guide is that, the materials that were needed in the construction were common household items like Popsicle sticks and paper clips or ones that could be procured easily. The only uncommon household items were coaxial cables and solders (common for Electrical and Electronic students though). So, we spent a fine evening (Saturday) shopping, to procure the parts we needed to build the antenna.

How we built it?

We assembled at 10 A.M in the morning to begin the work. We started out by creating the boom (mechanical support) with Popsicle sticks and gluing them together to form a sturdy base. Then we went on straightening out the paper clips and cutting them to precise length based on the antenna design. The hard part of the construction was interfacing the router’s radio unit with the antenna’s driven element through a coaxial cable. It was hard because, we couldn’t find the perfect cable for the job and improvised with using what we could easily get, which was a cable used for TV’s. Finally, we soldered the leads driven element to that the cable, then to the radio unit.

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Fig (1) – The actual design for the antenna

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Fig (2) – The elements that will form the actual antenna

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Fig(3) – Elements glued to the boom

What were the results?

Initially, we were little skeptical if the antenna would even work, but we had a lot of faith it would. The antenna was working fine despite the hiccups procuring the right materials and doing a perfect build. We had two identical routers in the room, one with a stock antenna and other with the Yagi-Uda antenna. The latter one had a very strong signal than the former. Voila! we created our very first antenna which we have only seen from distance and in text books.

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Fig (4) – Result “The signal was strong with this one”

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Fig (5) – The team

What we learned?

People might think this to be a trivial task and though it might be, we mainly undertook this activity to understand what was happening under the hood of an antenna and how this simple mechanical structure actually transmits a signal over a long range.

Whats up after this?

Now that we built it using Popsicle sticks and paper clips and understood how the antenna works, we are planning on a building an efficient one with copper and taking into account the lesson learned and TODO’s from this activity.

Special mention

Our friends and fellow activists at  PYMeshnet made a Yagi-Uda antenna, which was one of the inspiration for us. The link to the post is here. I would also like to thank the entire Chennai Mesh community members and who were present in the activity which includes myself(Meenakshi Sundaram), Anand, Venkatesh and Ganesh, of whom Ganesh provided with a lots of insights and guidance on the technical part.