In addition to the complicated external environment in practical applications, the car navigation system mainly affects the antenna receiving ability mainly in the following aspects:

1. Ceramic chip: The quality of ceramic powder and the sintering process directly affect its performance. The ceramic sheets currently used in the market are mainly 25×25, 18×18, 15×15, 12×12. The larger the area of the ceramic sheet, the larger the dielectric constant, the higher the resonance frequency, and the better the receiving effect. The ceramic sheets are mostly square in design to ensure that the resonances in the XY direction are basically the same, so as to achieve the effect of uniform star collection.

2. Silver layer: The silver layer on the surface of the ceramic antenna can affect the antenna resonance frequency. The ideal GPS ceramic chip frequency point accurately falls at 1575.42MHz, but the antenna frequency point is very easily affected by the surrounding environment, especially when assembled in the whole machine, the frequency point must be adjusted to maintain the frequency point at 1575.42MHz by adjusting the shape of the silver coating. .

3. Feed point: The ceramic antenna collects the resonance signal through the feed point and sends it to the back end. Due to 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 the cost. Moving only in the direction of a single axis is called a single-biased antenna, and moving both axes is called a double-biased antenna.

4. Amplifier: The shape and area of the PCB carrying the ceramic antenna. Due to the ground-bounce characteristics of GPS receiving signals, when the background is a 7cm×7cm uninterrupted ground, the antenna's effectiveness can be brought into full play. Although restricted by factors such as appearance and structure, try to keep a considerable area and uniform shape. The choice of amplifier gain must match the back-end LNA gain. Sirf's GSC3F requires that the total gain before signal input should not exceed 29dB, otherwise the signal will be oversaturated and will cause self-excitation.

The 5g base station antenna manufacturer tells you that the receiving environment as a car navigator antenna is more complicated. The metal shell and glass explosion-proof film of the vehicle, especially the metal powder-containing car film, and the in-car audio, will interfere or even hinder the signal received by the built-in GPS antenna. Especially if the front windshield of the vehicle is covered with a metal film, the satellite signal reception strength of the car navigation system will drop by 25%-50%. Therefore, it is necessary to have an external antenna for the stability of GPS satellite signal reception.