The quality of the ceramic powder and the sintering process directly affect the performance of the gps antenna. The ceramic patch currently used in the market are mainly 25×25, 18×18, 15×15, and 12×12. The larger the area of the ceramic patch, the greater the dielectric constant, the higher the resonant frequency, and the better the GPS antenna reception effect.
The silver layer on the surface of the ceramic antenna can affect the resonant frequency of the antenna. The ideal GPS ceramic chip frequency is exactly 1575.42MHz, but the antenna frequency is very easily affected by the surrounding environment, especially if it is assembled in the whole machine, the silver surface coating must be adjusted. The frequency of the GPS navigation antenna can be adjusted to maintain the shape of the GPS navigation antenna at 1575.42MHz. Therefore, the GPS complete machine manufacturer must cooperate with the antenna manufacturer when purchasing the antenna, and provide the complete machine sample for testing.
The feed point affects the performance of the gps antenna
The ceramic antenna collects the resonant signal through the feed point and sends it to the back end. Due to the factor of antenna impedance matching, the feed point is generally not in the center of the antenna, but slightly adjusted in the XY direction. This impedance matching method is simple and does not increase Cost, moving only in the direction of one axis is called a single-biased antenna, and moving in both axes is called a double-biased antenna.
Amplifying circuit affects the performance of gps antenna
The shape and area of the PCB carrying the ceramic antenna, due to the nature of the GPS rebound, when the background is 7cm x 7cm uninterrupted ground, the patch antenna’s performance can be maximized. Although it is restricted by the appearance and structure, try to keep it fairly The area and shape of the amplifier are uniform. The selection of the gain of the amplifier circuit must match the gain of the back-end LNA. The GSC 3F of Sirf requires that the total gain before signal input should not exceed 29dB, otherwise the GPS navigation antenna signal will be oversaturated and self-excited. The GPS antenna has four important parameters: Gain, Standing Wave (VSWR), Noise Figure, and Axial Ratio, among which the Axial Ratio is particularly emphasized, which is a measure of the signal gain of the whole machine in different directions. important indicator of difference. Since the satellites are randomly distributed in the hemispherical sky, it is very important to ensure that the antennas have similar sensitivities in all directions. The axial ratio is affected by the performance of the GPS antenna, the appearance and structure, the internal circuit of the whole machine, and EMI.
Post time: Oct-27-2022