Finding the Wavelength of Any Frequency Making cantennas to work with any wireless signalĢ.4GHz is a common frequency for Wi-Fi and its wavelength makes the canntenna an ideal size–not too big, but not too small. While this may not seem like much, if you have ever changed your wireless routers channel to get a better signal, you know that it does make a difference. Basically, just know that the 2.4GHz spectrum isn’t just 2.4GHz, it is actually 2.401 to 2.483. Or if you are feeling very bold, examine the Radio Frequency Allocation chart, which gives a very broad but complex overview of all the available radio frequencies. If you are confused about using 2.437 instead of just 2.4, take a look at the chart below to see how each channel has its own frequency. Now that we know the wavelength for our radio frequency, we can begin calculating the dimensions of the can based on the guidelines mentioned previously. For channel 6 in the 2.4GHz spectrum, we need to plug in 2.437. You could just use 2.4, but in order to be a little more accurate, we will use two more decimal places. For f, we need to plug in the Wi-Fi frequency. We know v will be 300 (rounded up based on the speed of light mentioned above). Wavelength (mm) ≈ Velocity of wave (Mm/sec) / Frequency (GHz) For the purposes of an easy-to-remember formula, I rounded up and converted meters to Mega meters. Formula for Calculating the Wavelengthįirst, it is important to know that radio waves travel at the speed of light, which is about 300 Mega meters (Mm) per second (the exact speed is 299,792,458 meters/sec).
There is an online calculator, which will help you determine the dimensions of your cantenna.
The copper element should be x millimeters away from the back of the can (rear standoff)–this is based off the overall diameter of the can. The copper element should be approximately 1/4 of the wavelength. The diameter of the can should be longer than 1/2 of the wavelength. The length of the can should be longer than 3/4 of the wavelength. This will also help conceptualize what to do when making it or if you are modifying the can for a different frequency. There are a few basic guidelines to follow when making a cantenna. In order to find out the right size of the can, we need to do some math. The only difference is that radio waves are invisible. If you can perfectly match the size of your waves to fit inside the can, you will get capture the most water, or in our case, a wireless signal. If you make really large waves in the water but have a really small can, you won’t catch many or they will just break up. Now imagine you want to catch some of those waves in an aluminum can. The wavelength will be the distance between each wave you produce. The frequency is how many waves you can make in x amount of time. The velocity is the rate at which the wave changes position. If you can, imagine you can create waves in a small pool. The wavelength of a signal is the velocity of the wave divided by the frequency. Dimensions of the Can MatterĮach radio frequency has a different wavelength. Radio waves will be “guided” into the can and interact with the wire element, which sends a signal down the pigtail cable and then to your computer or router. 
The aluminum can acts as a medium for the radio waves to be guided through, hence the term waveguide cantenna.
Basic understanding of wireless networking concepts (radios, wavelengths, frequencies, etc.). DOUBLE BIQUAD WIFI ANTENNA NEC FILES INSTALL
Ability to install components with screws. Fine-tip Sharpie or other utensil to mark the location of the screws. Can opener (or something to remove the lid with). Digital (preferred) or analog calipers or just a tape measure. Soldering iron (a fine-tip with lower heat works best). 12-gauge copper (if you have scrap cables, you could also unsheath them and see if the copper wire is thick enough to fit into the N connector). Screws (sometimes they come with the chassis-mount N connector). 
pigtail) or an N-male to RP-SMA-male cable for connecting to USB adapters
RP-TNC-to-N-male cable for connecting to most routers (a.k.a. Empty 1qt baby formula can or other similarly-sized aluminum can. A wireless router with external, removable antennas, preferably with custom firmware or a wireless USB dongle with a removable antennta. Requirements For This Walkthrough Materials Create a cantenna to drastically extend your Wi-Fi signal! Works great with a router that has external antennas, like the old-school classic WRT54G.
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