GPS is a terminal that uses satellite signals for positioning or navigation. And receiving signals requires the use of antennas. GPS satellite signals are divided into L1 and L2, with frequencies of 1575.42 MHz and 1228 MHz respectively. L1 is an open civilian signal with circular polarization. The signal strength is around 166-DBM, which is a relatively weak signal. These characteristics determine the need to prepare specialized antennas for GPS signal reception.

GPS active antenna

At present, the vast majority of GPS antennas are made of right-handed polarized ceramic media, consisting of ceramic antennas, low-noise signal modules, cables, and connectors. Ceramic antennas, also known as passive antennas or dielectric antennas PCTAH， It is the core technology of GPS antenna. The signal reception capability of a GPS antenna largely depends on the composition and ingredients of its ceramic parts.

The low-noise signal module, also known as LNA, is the part that amplifies and filters signals. The selection of its components is also important, otherwise it will increase the reflection loss of GPS signals and cause excessive noise. The selection of cables should also be based on reducing reflection to ensure impedance matching.

In terms of polarization, GPS antennas are divided into vertical plan and circular polarization. With current technology, the effect of vertical polarization is not as good as that of circular polarization. Therefore, except for special circumstances, GPS antennas generally adopt circular polarization.

In terms of placement, GPS antennas are divided into internal antennas and external antennas. The assembly position of the antenna is also very important. Early GPS handheld devices often used outward facing antennas, which were basically isolated from the interior of the device, and EMI had almost no impact on them, resulting in good satellite reception performance. Nowadays, with the trend of miniaturization, GPS antennas are mostly built-in. At this point, the antenna must be above all metal components, and the casing must be electroplated and well grounded, away from EMI interference sources such as CPU, SDRAM, SD card, crystal oscillator, etc DC/DC。

The application of car GPS will become increasingly common. The exterior of the car, especially the explosion-proof film, can cause serious obstruction to GPS signals. An external antenna with a magnet (which can be attached to the roof of the car) is very necessary for in car GPS.