Data Hacking

80 Part I — Hardware Hacks
Helix wire: 16-gauge copper wire is ideal for this project. Get several yards of it.
Antenna connector: What you choose here depends on the GPS to which you want to
connect the antenna. You can either use a compression fit or solder it directly.
Building the Antenna
This antenna is based on an design by Walter Gulley, and the original can be seen at www.
ggrweb.com/article/gulley.html.
Here’s how you assemble your antenna:
1. Build the ground plane: This is the base of the antenna, and you make it by cutting a
19-centimeter (7.5 inch) diameter circle out of the middle of the sheet metal (see Figure
4-15). If you are using thin metal, then you can use an old pair of scissors to do this, but a
thicker metal or stainless steel will require shears. Drill a hole in the center of the metal circle
so that the coaxial cable can be passed through. A grommet (or a liberal application or
hot glue or silicone) can be added to protect the cable if you are going to solder the coaxial
outer directly to the ground plate. If you don’t want to do any soldering, then you can
attach the coaxial connector to the ground plate, making an ideal connection. No matter
which method you sue, this connection is required; without it, the antenna won’t work.
FIGURE 4-15: Cutting the hole in the metal sheet that will become the ground plane