9-2002

    What is all this foolery about? To begin with, this is entirely copied from this guy over at O'reilly. Basically, I printed off his page and used it as a shopping list and construction kit. My only addition is the excessive use of hot glue to hold the thing together. What we have here is an antenna for 802.11b wireless Ethernet. Antenna's and/or dishes for the 2.4GHz spectrum generally run about $150 or so (And that's on the low end, you can get real crazy if you wanted too). Some cool guys out there have been playing with cheap hardware that produces about the same amount of gain as the professional hardware gets. Yes, this is how to build a respectable 2.4GHz antenna for about $4 in parts. The most expensive thing was the pigtail that has Orinoco's funky connector on one end and a nice N-connector on the other end (Which was $25 with S/H). I paid $1.50 for a female N-connector, $1.69 for the Pringles, and like a buck for the all-thread, washers and nuts.

    I really think Afrotech is wearing off on me! I would have built this thing properly, but I had trouble finding all the parts I needed, namely some narrow tubing and 1" washers with 1/8" holes in them. (Or, the first hardware store I went too didn't have everything I needed and I was too lazy to try somewhere else). Anyway, I used hot glue to hold the washers in place as well as holding the N-connector in place. From what I have read about Yagi-Uda style antenna's, the washers don't need to be electrically connected to the rod, so that aspect of this antenna is still ok. It's just that the washers aren't all 100% at the same angle on the all-thread because the center hole in them is too big. I got a solid 5dBm gain; for 45 minutes of work and no tuning it's amazing it works at all! :-)  So here are my pictures of the event, as well as some screen grabs of Netstumbler showing my signal strength levels.

    Oh yea, do this at your own risk- so now you can't say I told you to do it and sue me. You may/might/could/probably/will/defiantly/wont  blow up your wireless card if you do this wrong.

    As far as the actual design, I have read that the foil in the Pringles can is too thin to actually function as a wave guide, so all you are really using is the bottom tin plate to reflect the signal onto the antenna wire, or something like that. I'm certainly not an RF engineer, so this is only speculation and hearsay. Check out the Netstumbler forums for some excellent discussion of antenna design and links to good sites like this.

The starting point. Why the Pot Pie you ask? You shall see very soon... Actually I needed a way to space the washers apart while I was gluing them. The I needed something to fit around the hot glue holding the last washer on at the same time, so some thin card board was the answer. Finally my way of cooking is paying off!

A close-up view of the assembly

A fully glued assembly. Now it just needs some lids to hold it in the center of the can. I used the bottom of a Country Crock mini-tub since I didn't have another can of Pringles on hand.

Assembly and the hole for the N-connector.

Before

After

I used some braided copper wire for the "fuse". I could have left the insulation on it I guess, I just thought this looked cooler :-).

N-connector mounted securely

I ordered my pigtail off the internet as I couldn't find a local source for those funky little Orinoco connectors. My local electronics shop is generally good, but they don't get out much when it comes to new connectors...

Male pigtail connector and female card connector.

Another lovely picture of my card

And how it preformed

I sat outside on a bench and used my AP for reference. This only shows an overall gain of about 5dBm, but you will also notice the signal-to-noise ratio improve by 5dBm as well. I actually plan to make some more antenna's soon that should pull in more signal... We shall see!