GPS antenna refers to the antenna used for positioning or navigation by receiving satellite signals. What factors affect GPS antenna?

1.Ceramics: The quality of the ceramic powder and the sintering process directly affect its performance. The ceramics used in the market are mainly 25 × 25, 18 × 18, 15 × 15, 12 × 12. The larger the area of the ceramics, the more The larger the electric constant, the higher the resonance frequency and the better the acceptance effect. Most of the ceramic plates are square in design, to ensure that the resonance in the XY direction is basically consistent, so as to achieve the effect of uniform star reception.

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 accurately falls at 1575.42MHz, but the antenna frequency point is very easy to be affected by the surrounding environment, especially when assembled in the whole machine, it must pass Adjust the shape of the silver surface coating to adjust the frequency to stay at 1575.42MHz. Therefore, GPS manufacturers must cooperate with the antenna manufacturers when purchasing antennas, and provide samples of the entire machine for testing.

3. Feed point: The ceramic antenna collects the resonance signal through the feed point and sends it to the back end. Due to the impedance matching of the antenna, the feed point is generally not in the center of the antenna, but is adjusted slightly in the XY direction. Such an impedance matching method is simple and does not increase cost. Moving only in the single-axis direction is called a single-biased antenna, and moving in both axes is called double-biasing.

 4. Amplifying circuit: The shape and area of the PCB that carries the ceramic antenna. Due to the characteristic of GPS ground bounce, when the background is 7cm × 7cm uninterrupted ground, the efficiency of the PATCH antenna can be maximized. Although constrained by factors such as appearance and structure, try to keep a considerable area and uniform shape. The selection of the gain of the amplifier circuit must match the back-end LNA gain. Sirf's GSC3F requires that the total gain before signal input must not exceed 29dB, otherwise signal oversaturation will occur Excited.