Long range WiFi antenna from Illy coffee can

http://blog.jgc.org/2012/02/long-range-wifi-antenna-from-

illy.html

I have a stack of half finished projects that I'm trying to complete.

Happily, the first one was finished late last night: a long range WiFi

antenna made using an empty coffee can. Working from the ideas

here I made an antenna from the following:

1. An empty 250g Illy Espresso ground coffee can

2. A Type N bulkhead socket and a Type N plug

3. A piece of WiFi antenna extension cable with a reverse SMA

connector on the end.

4. A short piece of coat hanger for the active element of the antenna

Here's a shot inside the can showing the antenna element and the

Type H bulkhead socket screwed into place. I simply drilled five holes

in the can using a HSS drill.

And from the outside:

The active part of the antenna is made by soldering a piece of coat

hanger into the Type N bulkhead connector.

For testing I'm using a USB WiFi adapter that has a reverse SMA

connector on the side:

The cable was pretty simple to make, all that was needed was

connecting the Type N connector on one end:

And the coffee can lid proves handy because the adapter and cable

can all be stored inside the can when not in use. I made a little cover

for the bulkhead socket using the neck of a balloon that I tied and

turned inside out:

Testing using a combination of iwlist and Kismet showed that the

antenna was both directional (as would be expected from its design)

and more sensitive than the little whip antenna.

From the top room in my house I could see 58 networks using the

standard antenna and 97 using the can pointing in one direction. The

received power was on average between 3 and 9 dB better with the

antenna for distant networks and had much greater range (that's

between 2x and 8x better).

About 1/4 mile from my house (actually 423m or 0.26 mile or 1386

feet) is a business hotel that offers its guests free WiFi. Pointing the

antenna in its direction I was able to connect to the hotel WiFi (which

doesn't have a WEP or WPA password) and then reach a screen

where I had to agree to the hotel's terms and conditions for use of

their network.

Looks like I've got a backup connection if my home broadband goes

down.

PS There are lots of details missing from this blog post because I

linked above to a very detailed explanation of the whys and

wherefores of building a can antenna. Look there for critical details

on picking a can size (the Illy can is a good size for the frequency of

WiFi), the length of the active element, and the position within the can.

The other thing that's worth noting is that I shortened the cable going

to the antenna as it was too long: the longer the cable the worse the

loss.

For more information:

http://www.turnpoint.net/wireless/cantennahowto.html