Jeff Duntemann's Contrapositive Diary Rotating Header Image

May 27th, 2011:

A Steampunk Aethernet Concentrator


Those who tuned in to my March 18, 2011 entry will recall that I spotted a Star-Rite copper parabolic resistance heater at a consignment store, and brought it home thinking it would make a good Wi-Fi antenna. I put a proof-of-concept lashup together last week and found that it worked very well, even though its diameter is on the low side for 13 cm microwaves. I spent half an hour or so digging through my several bins of odd plastic looking for just the right center insert, and stumbled on a pill bottle that ProbeExposed200Wide.jpgactually pressure-fit into the center hole without any modifation of the bottle or the center hole. (This may seem remarkable if you’ve never seen the quanity of pill bottles and other odd plastic (s)crap I keep out in the garage.)

The Wi-Fi element is a Cisco AE1000 USB 2.0 Wi-Fi adapter, connected to the PC through a 3′ USB extension cable. The female end of the extension cable is glued into a rectangular hole I made in the pill bottle’s white lid with a nibbling tool, and the AE1000 plugs into the adapter cable.

Even with the number of pill bottles I have, finding this particular bottle was a huge break. I still have to figure a way to get the probe fastened into the hole by something better than friction, but that’s just engineering. The bottle works extremely well for another simple but fortuitous reason: It puts the long axis of the AE1000 right where the focus of the copper parabola falls.

I tested for this out in the driveway in an interesting way: I pointed the parabola at the Sun as closely as I could, and then stuck a paper towel tube into the center hole to see where the sunlight would be most intense. The strongest part of the focus is about 3″ from the bottom of the bowl. (I didn’t leave the paper towel tube at the focus for very long, trust me.) This is just about where the AE1000’s antennas sit, if its interior construction is anything like the USB Wi-Fi dongle I sacrified some years back to see how it was done.

FocusTest350Wide.jpgFor as lucky as I got, the position of the adapter isn’t especially critical. We’re not trying to create an image or even intense heat. We’re just trying to concentrate a distant microwave signal on the AE1000, and focus the signal that it emits into a narrower steerable beam. Nor am I going for moonbounce–the real mission of the device is to make sure I can get into the resort Wi-Fi access points when I’m at the Taos Toolbox writers’ workshop this summer. That always depends on where your room is relative to the access points, and in the past, I’ve pulled rooms in dead spots about two throws out of five.

Well, not this time.

Jim Strickland suggested calling it an Aethernet Concentrator, and so it is. (The name of the Wi-Fi adapter is peculiarly appropriate.) I’m not entirely finished yet. I need to paint the pill bottle so that it looks less like a pill bottle, and the copper bowl needs cleaning and polishing generally. But I’ve already tested it, and it increases the strength of my access point downstairs radically. Aiming it up and down the street from here at my desk, it detected nine APs that the naked AE1000 didn’t see plugged into the back of my GX620. (I call this “warsitting.”)

I’m going to do a larger article on the project once I tie the ribbons on it, and I’ll let you know where to find it when I do.