My Wi-Fi Cantenna project - building a Wi-Fi antenna out of a Pringless can.
10.8.2011 - Figuring out the last details and buying some parts
Part list
All-thread, 3mm diam., 15cm long
5 washers, inner diam. 3mm
2 nuts, inner diam. 3mm
Aluminum tubing, diam. 6mm
12 gauge solid copper wire (2mm diam.)
Antenna connectors
    (N-type on antenna,
    Reverse SMA on Wi-Fi card)
USB Wi-Fi card
Pringless can + two lids
The webpage I took my instructions from promised it would take about 1 hour to build the antenna. Today I slowly start to realize that this project will take a bit longer to finish.

Yesterday I spent several hours figuring out what parts to buy and where to buy it. Especially hard was finding a way to hook the antenna into my computer. I decided to buy a USB Wi-Fi card (without an external antenna connection) and try to mount an antenna connection to it later.

After looking up the parts needed on the internet I realized the antenna connectors would cost 15€ themselves. The USB Wi-Fi card was a bit cheaper, only 10€ and still with quite good specs.
I went to three different shops just to get my hands on the all-thread, washers, nuts and Pringless can for about 7 Euros. Another two shops will need to be visited to get the antenna connectors and Wi-Fi USB card. But I decided to get those parts later because I didn't knew whether the project would succeed or not. That because of:
  • I could not find any aluminum tubing, I need to find something else
  • The all-thread was too short and two of them need to be joined together
Instead, I decided to try connecting the antenna without any connections, just a cable. Instead of buying a USB Wi-Fi card I will try to connect it directly to the built-in Wi-Fi card of my laptop, just to make sure it is working before buying anything else.

Why did I choose reverse SMA connectors to connect the cable with the Wi-Fi card?
Because my router also uses Reverse SMA for its antennas, and that would make it possible to easily connect the antenna to my wireless router. But more about that when/if I buy those 15€ connectors.
Investigating the possibility of connecting the Cantenna to my computer's internal Wi-Fi card
Internal Wi-Fi card in bottom right corner

As the Acer Aspire One 8" is known for having a weak Wi-Fi signal it would not be an ultimate setup to use the Cantenna together with that Wi-Fi card. It can however be used for testing whether the Cantenna is working and how much increase in signal it can deliver.
11.8.2011 - Start building the Cantenna
The internal part of the Cantenna is almost done with the two all-threads joined together, the washers, nuts and 1 of 2 Pringless lids in place.

As I could not find any aluminum tubing, I instead used some plastic wall straps (right image) by drilling a hole in the middle of them. Whether it is a working replacement or not, at least this page states that the tubing is just for holding the washers in position. Another question mark is how my too thick all-thread is going to affect antenna performance. I should also mention that the solid copper wire I have got my hands on is just 0.7mm when it should be 2mm.
15.8.2011 - Finishing the Cantenna
After having a break in the antenna building, today I finished the Cantenna. When testing with my laptop's builtin Wi-Fi card the results weren't as good as expected.
Test results when connecting Cantenna to my laptop's internal Wi-Fi card: (higher is better)
  • SNR 30 using Cantenna
  • SNR 40 using laptop's builtin antenna

Why is the Cantenna (which should provide a 13dB gain), performing worse than my laptops builtin antenna?
  • The all-thread is too thick (8mm when it should be under 3mm).
  • The laptop's builtin card (which I connected the Cantenna to), have 2 or 4 inputs (don't know, upper right image), but I only connected my Cantenna to one of them.
  • The Pringless can is taller than the instructions were written for. The all-thread is a few centimeters away from the copper wire inside the can. The instructions only says it should be just forward of it.
  • My washers were a little thicker than the ones in the instructions, making the all-thread about 3mm longer than in the instructions.
  • I didn't check that the solid copper wire inside the can was pointing straight, it could have been angled when testing (as you see on the bottom right image).