ATGGBL54138M-SMA-3 System: GPS L1 / L5 GLONASS G1 BeiDou B1 Galileo E1 Mount: Magnetic Connector(Optional): SMA or other Cable Length(Optional): Optional Dimension: 41 x 38 mm An external GPS antenna is a type of antenna that is mounted outside of a device, such as a vehicle or a GPS receiver. It is commonly used in applications that require a stronger and more reliable GPS signal, such as in marine navigation or aircraft navigation. Unlike internal antennas that are built directly into a device, external antennas are connected to the device via a cable and require separate installation. External GPS antennas come in a variety of shapes and sizes, including patch antennas and helix antennas, and can be either passive or active. Active antennas contain an amplifier that boosts the GPS signal, increasing its sensitivity and range. In addition to improving GPS signal quality, an external GPS antenna can also help to reduce interference from surrounding objects. Choosing the right external GPS antenna for your application depends on a variety of factors, including signal strength, range, and installation requirements.