Data Hacking

70 Part I — Hardware Hacks
Antenna Placement
Where you place an external antenna is just as important as how you hold a GPS receiver.
When using a fixed or semi-fixed antenna, you need to carefully consider where you place it in
order to get the best coverage.
On a car, place the antenna as high as possible. The roof is the best place for it, while the hood
and near the flat glass panels are worse. The area around the hood has high electromagnetic
interference, while glass and flat metal surfaces cause signal reflections and signal loss (see
Figure 4-10).
FIGURE 4-10: Good and bad placements for antenna on a car
Another possible area for placement is inside the front or rear plastic bumper, although bear in
mind that small impacts can damage the antenna.
The problem with in-car use of GPS is that most people think that because they can get a
satellite lock on their GPS when it is in their shirt pocket, in the car, they don’t need to worry
about antenna placement. The truth is that poor antenna placement in a car, especially using a
GPS signal from inside the vehicle that has traveled through the metal skin of the vehicle, is
likely to result in a very inaccurate signal. If your vehicle has tinted metalized windows, this can
severly degrade the GPS signal you receive, and an external antenna becomes a must.