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Some knowledge about GPS antennas
Apr 07, 2017

Overview of GPS Antennas


GPS is the terminal that locates or navigates by accepting satellite signals. And the reception of the signal must be used to the antenna. GPS satellite signals are divided into L1 and L2, the frequency of 1575.42MHZ and 1228MHZ respectively, which L1 for the open civilian signal, the signal is circular polarization. The signal strength is 166-DBM or so, belonging to the weaker signal. These characteristics determine the need to prepare special antennas for the reception of GPS signals.


Classification of GPS Antennas


1, the GPS antenna from the polarization mode is divided into vertical plan and circular polarization. With the current technology, the effect of vertical polarization is not comparable to circular polarization. Therefore, in addition to the special case, the general GPS antenna will adopt circular polarization.


2, from the placement of the GPS antenna into the built-in antenna and external antenna.


The assembling position of the antenna is also very important. The early GPS hand-held machine adopts the valgus antenna, at this time the antenna and the whole internal basic isolation, EMI is almost not the impact of the star, the effect is very good. Now with the miniaturization of the trend, the GPS antenna more built-in. At this point the antenna must be in all metal devices, the shell must be electroplating and good grounding, away from EMI interference sources, such as CPU, SDRAM, SD card, crystal oscillator, DC/C.


The application of on-board GPs will become more and more common. The car's enclosure, especially the automobile explosion-proof membrane will be the GPS signal to have serious obstruction. An external antenna with magnets (which can absorb the roof) is very necessary for on-board GPS.


Construction of GPS antenna


At present, most GPS antennas are right-polarized ceramic media, the components are: ceramic antenna, low noise signal module, cable, connector. The ceramic antenna is also called passive antenna, dielectric antenna, PCTAH, it is the core of GPS antenna technology. The signal acceptance ability of a GPS antenna depends largely on the ingredients of its ceramics.


The low noise signal module is also called LNA, which is the part of amplifying and filtering signals. The selection of components is also important, otherwise it will increase the reflection loss of GPS signals, and causing excessive noise. The selection of cables should also be used to reduce reflection as the standard, to ensure the matching impedance.