Desperate Times call for… Engineering-Part II

I’ve had plenty of setbacks… You don’t know how glad I am to be able to live up to my promise of writing this entry. It really did take forever for me to get this all together without internet. Namely the N-type female chassis mount connector took me a long time to find, as I outlined in the last entry. Tanner’s Electronics thankfully had all the stuff I needed, but before that I had spent days going to different places and trying to find an N-type connector. No one I talked to even knew what it was. The closest I got was an f-type connector used for coaxial connections, which mind you, won’t work for this particular project. Anyway, enough complaining about my mishaps.

Kudos to anyone who can tell me what time it is from that binary clock (the square thing with all the blue lights)

Isn’t it beautiful? If you notice, I even used wall tacks to hold in the N-Connector. Not such a good idea as you’ll see in a second but I was just eager to test this thing. The trickiest part was getting a hole through the can. Never mind butchering the solder a couple of times, as I’ve never soldered anything in my life. Getting the hole through the can proved to be tough without a drill, nail, or anything.

Poor thing never stood a chance

Thank you, Kyle, for showing me how to solder! Once I soldered the #12 copper wire onto the connector, punched holes through the can, and mounted the wire inside, it was time to test it. Here’s a chart of what my Wi-Fi situation looks like without the cantenna.


So I can see 2 access points and both are pretty poor signal. Each have a -91 and -86 RSSI (Received Signal Strength Indication) reading, which would amount to poor bandwidth and probably dropped connections every so often. Apogee is a local service provider, and admittedly we have service now that it’s been 3 weeks since the lightning hit, but given that, my signal strength is pretty poor and I can’t live with poor signal strength. Now let me plug in my cantenna....


Wow! Simply plugging in the can shows me all the world I was missing out on… This image shows a long period of time before I eventually wired everything up. You can see that at 1:10 PM, as soon as I hooked up the cantenna to the wireless USB card, I was inundated with access points. Now, opposed to the 1 or 2 I was receiving signal from earlier, I now have a plethora of options!


If all I have to do is plug in the can to see all these, what happens when I point the can in a certain direction? Afterall, it is a waveguide antenna. Out there you see plenty of campus buildings, a football field, and most importantly, more radio waves! Well you don’t see them per se but believe me, they're there.

My roommate needs to do laundry... I guess I do too though

My wall tacks then proceeded to fall off the can… thus destroying my cantenna. I’m no civil engineer, but I’d say tacks make for a pretty shoddy construction job. The image above is my “improved” can which is bound by soldering the N-connector to the can and duct taping it for reinforcement… I call it the McCormick Cantenna MkII


This is what the can looks like on the inside. There are actually several complex math equations used to determine where you need to puncture the can and how long the #12 copper wire needs to be. To save you the headache, and to avoid admitting I don’t know how to do the math, I used an online calculator to figure out where these need to be. Given the diameter of the can was 3.125 inches across, I needed to puncture the can 2.9 inches up from the bottom. Ideally my can could have been a bit longer to compensate for the length of the wavelength I’m trying to guide since Wi-Fi operates at a frequency of about 2.4 GHz.
To fully test this, I would like to find a big open field, and set up my access point as far away from my can as possible and see what my signal strength can be. Cantennas and waveguide antennas in general can increase the range of your Wi-Fi connectivity by up to a kilometer or in some cases many kilometers. Industrial level antennas can provide wi-fi from the base of a mountain to those users on top of the mountain! Perhaps range testing of my cantenna can be for another entry ;)

Desperate Times Call For… Engineering

As you may remember from my last entry, my dorm was struck by lightning about 3 weeks ago. Although things could be worse, as in my computer could have blown up or the whole housing establishment could have caught fire, instead we merely lost internet. However, this is not to be taken lightly. In fact, for someone like me in an age like this, internet is like a faithful sidekick – it’s always there and no matter how bad the going gets, the trusty steed is still there chuggin' along with you, except without internet, I feel I’ve lost my right hand man.

This is the first of a two part entry I will be putting together this week. I’ll be sharing my experience on coping with internet loss, and my journey to getting it back!

This is no Epic Narrative akin to Lord of the Rings or Star Wars etc, but it’s a story worth telling. The problem: I have no internet. The solution: DIY Wireless Range Extender, AKA, the Cantenna!

A Cantenna, for lack of a better term, is a combination of a Can and an Antenna. Basically, you can use a can and some crafty techniques to build yourself a cheap directional waveguide antenna for long range Wi-Fi.

Here’s what you need:
• A Can
• N Type Female Chassis connector
• 2”+ of #12 copper wire
• Nuts/Bolts
• A Desperate need for internet or otherwise curious as to how antennas work
• Solder/Soldering gun


This list will cost you about $10+, give or take a few bucks. Since I’ve never done this before, I ended up buying a bunch of stuff I didn’t need. Oops!

I actually already had the can of soup, soldering gun, and keyboard

I’ll be taking most of that back within the next week! Construction starts ASAP, as soon as I can finish a couple of other projects I’m working on!

It was harder than you think it would be to find all of this though, especially without internet. I had to use the good ol’ cell phone and call a dozen people before I found all that I needed. There are several stores not worth mentioning that didn’t have anything I needed, but the one store that did have everything was Tanner’s Electronics in Fort Worth… Thank you Tanner!

Despite my endless search for all my materials, there is still a diamond in the rough to be found here. A thin, modest and cute looking cashier with short light hair rang me up at Home Depot. She drew this on my receipt

She said "you have very pretty eyes" :) that made my day! It was pretty obvious I was flustered as I lost my stuff I bought 15 seconds ago and had to ask where I put them. She smiled and laughed as she pointed at them sitting on the checkout counter. In a nervous dash to end my embarrassment, I laughed and admitted to my social ineptitude, and briskly walked out the door, also forgetting where I parked. Nerdyness always gets the best of me in every situation…

End of part I