Basics Of GPS Antennas

By Gerald J.K. Moernaut And Daniel Orban, Orban Microwave Inc.

In order to select or specify the right GPS (Global Positioning System) antenna, it is important to have a basic understanding of how GPS antennas work and what level of performance is required. This article will provide an overview of the general properties of GPS antennas and briefly compare three common types.

Throughout this article, when we refer to GPS antennas, we should really say Global Navigation Satellite System (GNSS) antennas.

The term GPS literally refers to the U.S. Department of Defense's NAVSTAR GPS constellation of satellites; however, it is commonly used to describe any of a number of navigation systems that have been and are currently being developed, including the European Galileo and the Russian GLONASS systems.

We will first consider the functionality and performance needed in a GPS antenna.

Properties to consider when selecting GPS Antennas include:

• Frequency coverage
• Radiation pattern
• Circular polarization
• Multipath suppression
• Phase center
• Impact on receiver system sensitivity
• Interferers handling