Apr 7, 2011, 09:23 PM
I have a relative in a hospital, He is going to be a long time recovering so he brought in a notebook computer and can (almost) access the hospital WiFi. He can't reposition their access point, can't get a wired connection. He does get WiFi but it drops out frequently because the signal is weak. Apparently their system is designed to only cover common areas and hallways and he is about 40 feet away from a reliable signal.
So I'm thinking of a hardware fix. Perhaps a WiFi to Ethernet bridge that can use an external antenna and then we aim the antenna at the access point? I think we need to improve reception to make it reliable
What to get?
Apr 8, 2011, 12:58 AM
Here's the perfect can for a coffee can antenna. The proportions are nearly perfect:
Damn good coffee, too. I highly recommend the Calabria Blend.
I've built a couple of these.
Get a USB wifi adapter that has an antenna connector - the Alfa brand is excellent and inexpensive. The wifi adapter is small enough to just plug directly into the connector on the coffee can. This avoids a coax cable and resultant cable loss. You can use a reasonably long USB cable and it will work fine, without the signal loss from a long coax cable.
Forget about Pringles cans - they are bunk - the inside of the Pringles can is NOT metalic.
Use the basic "Yuban" design, but use an online calculator to determine the feed-point for the Cafe Calabria can (or similar-sized can.) The longer, skinner can will work better than a fat Yuban can.
I epoxied a nut to the side of the can, so that it can be mounted on a mini camera tripod.
I drilled a hole in the can for the female N connector that you solder the feed wire to. I picked up a metal SMA to N adapter (NOT a cable, but a solid adapter.) That way, the wifi adapter just hangs off the side of the can.
Here's the wifi adapter. Actually, it will probably do a pretty good job without the cantenna. I took my cantenna out on the balcony and can pick up 200+ signals from around the neighborhood and as far away as across San Diego Bay, a couple of miles. They have a number of models, ranging up to 2W power. I haven't heard good things about the 2W model, though. Stick with 1W or the 500mW model that I used.
And a couple of articles on antenna construction: