Passive vs. Active GPS Antennas

The difference between passive, active, internal, and external antennas.

GPS (Global Positioning System) systems work by receiving signals from satellites. That isn't possible without an antenna. While most GPS units, including phones and portable navigation units, have built-in hidden antennas, some include the option to add an external antenna. While it usually isn't necessary to install an external GPS antenna, there are cases where it can help.

Passive vs. Active GPS Antenna

Overall Findings

Passive GPS Antenna
  • Unpowered: Idly picks up GPS signals in the air to locate a navigation device.

Active GPS Antenna
  • Powered: Amplifies the antenna signal to increase the reception range of a GPS device.

Passive vs. Active GPS Antennas

Whether installed in a phone or to the rear of a vehicle, there are two types of GPS antennas: passive and active. Passive antennas idly receive GPS signals and pass those signals to a GPS navigation device. Active units include a powered amplifier that allows the antenna to pull signals from larger distances. Amplified antennas nearly double the signal reception range of a GPS device.

Active antennas are typically more expensive and more challenging to install than passive antennas. Still, these antennas can be installed farther away from a GPS tracker. For this reason, these are better suited for large vehicles or situations where a signal must be maintained.

GPS Reception Interference

GPS devices work by receiving signals from a network of satellites. By accounting for the direction and signal strength of satellites in the network, a GPS device can precisely locate its physical position on Earth, usually in the form of a dot on a digital map.

When an obstruction blocks a GPS device's view of the sky, it may be unable to identify satellite signals. The result is either a failure to locate a device or degraded location accuracy. Tall buildings are a common source of signal degradation, as are the metal roofs of cars and trucks.

The risk of signal obstruction can be mitigated by placing a GPS device on or next to a vehicle window, but not always. Thicker roofs, for example, are more difficult for signals to penetrate than thinner ones, and tinted windows can have tiny metal particles that block GPS signals.

Who Needs a GPS Antenna?

Most GPS navigation devices come with internal antennas that work fine in most cases. In some instances, an external antenna is used to feed information to the GPS device remotely. This is used when there is too much interference or an obstructed line of sight between the GPS unit and the sky. External antennas are also useful in place of older GPS units with dated internal antennas.

If you find that your GPS unit sometimes fails to obtain a signal or it seems inaccurate at times, an external antenna may fix the problem. It's cheaper and easier to move the unit around in the car first, since that may alleviate obstruction and interference issues. Still, you may find that the only viable solution is to install an amplified external antenna.

If you've been using a GPS unit for a while and never noticed any signal loss or accuracy issues, you probably don't need an external antenna. If your GPS unit often fails to obtain a signal or it seems inaccurate, an external antenna may fix the problem. Another situation where an external antenna could help is when you're traveling off the grid or into a remote region, where GPS reception is uncertain.

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