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Precautions For Use Of GPS Antennas
Apr 07, 2017

1, ceramic film: The good or bad of ceramic powder and sintering process directly affect its performance. Ceramic films are mainly 25x25, 18x18, 15x15,

12x12. The larger the ceramic-sided product, the larger the dielectric constant, the higher the resonance frequency, the better the reception effect. Most of the ceramic pieces are square designs for

It ensures that the resonance in the XY direction is basically consistent, so that the effect of uniform star is achieved.

2, Silver layer: Ceramic antenna surface silver layer can affect the antenna resonance frequency. The ideal GPS ceramic chip frequency point accurately falls in 1575.42MHz, but antenna frequency points

Very easy to be affected by the surrounding environment, especially the assembly in the machine, must adjust the appearance of the silver coating, to regulate the frequency point to keep in 1575.42MHz.

3. Feed: The ceramic antenna collects the resonance signal through the feed point and sends it to the back end. Because of the antenna impedance matching, the feed point is not generally in the antenna

It's central, but in the xy direction, minor adjustments. This impedance matching method is simple and does not increase the cost. Move only in single-axis direction called single offset

Antennas, both in the two axes are moved called double bias.

4. Amplifier circuit: PCB shape and area of bearing ceramic antenna. Due to the characteristics of a touchdown rebound in the GPS, when the background is 7cmx7cm uninterrupted Earth,

The efficiency of the patch antenna can be exerted to the utmost. Although the appearance of the structure and other factors, but as far as possible to maintain a considerable area and uniform shape. Amplification Circuit gain

The selection must match the backend LNA gain. SIRF GSC3F requires that the total gain before input can not exceed 29dB, otherwise the signal saturation will generate self-excited.

GPS antennas have four important parameters: Gain (Gain), standing Wave (VSWR), noise coefficient (Noise figure), Axis ratio (Axial ratio).

Especially emphasizing axle ratio, it is an important indicator to measure the difference of signal gain in different directions. Because satellites are randomly distributed in the hemisphere sky,

Therefore, it is very important to ensure that the antenna has similar sensitivity in all directions. The axial ratio is influenced by antenna performance, exterior structure, internal circuit and EMI.