Before You Start

Before you start this journey, you should understand one thing: You don’t end up with a powerful, durable antenna for long-term use. For that you want to build, or buy, a more rugged, commercial- grade unit. In Chapter 3, we will show you how to make the famous coffee can waveguide antenna, which can be made quite a bit more powerful and sturdy than this lightweight paperclip model.

But, with that cautionary note, this paperclip antenna will work. It will extend the range of the antenna built into your wireless Network Interface Cards (NICs), and can produce a gain of up to 9 dBi. And you will be able to point to it with pride as your entry in that unofficial scavenger contest to push more and more bits for less and less cost.

There are more efficient and probably more effective ways to build a Wi-Fi antenna than using a paperclip. But are there any more fun? What could be better than using the humble paper clip as the central ingredient for your next antenna? For many reasons, the paperclip appears over and over as the ultimate MacGyver tool. It is dirt

cheap, found anywhere and easily hidden in the palm of the hero’s hand even while his captors pat him down. How many times have you seen the paperclip open handcuffs and locks in the movies?

As with many of the projects in this book, local laws may regulate the usage of such an antenna. You should familiarize yourself with the local rules and regulations before you dive in.

What You Need

Use the following list to collect and prepare the items you’ll need to build your antenna. I’ve listed dimensions in both metric and foot/inches units where possible. I’ve included eye protection in the list of items you need to have before you start. Don’t skip this, or other safety precautions—please!

Here’s what you need:

Four large paperclips (the largest has to be at least 11.49 cm (4.52 inches) when straightened)

A flat wooden spoon, the kind that comes with ice cream cups—or some other suitable

platform for supporting your antenna prongs (perhaps a floppy disk)

Wi-Fi pigtail cable connected to your laptop NIC (wireless PCMCIA card with an external connector).

Solder iron and solder. An iron in the 15 W to 30 W range will work fine. Thin rosin core solder (0.75 mm is a good size) is preferred for electronic work because acid core solder will corrode components.

Small bottle or tube of craft glue (virtually any kind will do)

Small wire cutters

Needle-nosed pliers

A ruler that marks tenths of an inch (such as a drafting ruler from a craft store) or a metricruler with markings for millimeters

A pen for marking hole locations

Eye protection for cutting wires and soldering

A pair of vise grips or (even better) a small tabletop vise (the kind used for making fishing flies) for holding your antenna securely while working on it

A drill with a bit slightly smaller than the diameter of the paperclips or else a thin wire brad and a light hammer for tapping it through the wood.

You can get more background information on this antenna design at the following Web sites:

www.xaviervl.com/Antenne/Frisko/

www.seattlewireless.net/index.cgi/MicroTVAerial

www.wifi-montauban.net/communaute/index.php/DisquettAntenna

The pioneers of the paperclip antenna speak French, and their Web sites are in the French language, but they include translation links for English (and other) readers.

Some popular Web search engines provide translation tools for dozens of languages. Visit the language section at www.altavista.com or www.google.com and use the Language Translation links to view the sites in other languages. Sometimes the translated text is a little choppy, but the meaning comes through.

Choosing a Wireless Card

You will have more success in your paperclip antenna project if you are working with a good wireless card.Wireless cards can come with or without built-in external connectors. The cheaper cards without such connectors are mainly bought by corporations that assume their employees will only be connecting to the nearby access points in the workplace environment.

It is possible to access the internal connectors of wireless cards (NICs) that don’t have such external jacks—but doing that is its own separate bit of technical wizardry that involves “cracking the case” of the NIC to get at its connectors. Close-up photos of this feat are online at www.ivor.it/wireless/pigtail.htm.

However, 802.11b cards are now much cheaper than they were in the past, and it generally just makes more sense to buy a new card that comes with built-in external connectors you can attach the coaxial pigtail to (see Figure 2-12). These come in several varieties (“MC-Card,”  

“MMCX,” and others) so make sure that your pigtail connector matches the kind you have on your wireless card. Increasingly, the cards seem to have standardized on using female MMCX connectors—for which the pigtail then needs a male MMCX connector.

Choosing Platform Materials

This antenna was first made using a wooden spoon from a French ice cream cup called “Frisko” (hence its name). It is just large enough to accommodate the four prongs, and just thick enough to allow them to stand up well.

However, the mind boggles at all the many possible materials that can be used. These antennas have been made with medical tongue depressors, floppy diskettes, and small cardboard tubes. We used a jumbo-sized craft stick, also known as a popsicle stick. Credit cards don’t work well, because they are too thin. They don’t support the prongs well (without mounds of glue) and so the prongs tend to flop over and even touch.

You can glue a wooden clothespin to the platform you select, so that the antenna can be easily clipped on a stable mount, like the side of your laptop screen.