Due to the shape and area of the PCB carrying the ceramic antenna, due to the characteristics of GPS rebound, when the background is 7cm × 7cm uninterrupted ground, the performance of the patch antenna can be maximized.
Although it is restricted by factors such as appearance and structure, try to keep a considerable area and a uniform shape.
The selection of the gain of the amplifier circuit must match the gain of the back-end LNA. Sirf’s GSC 3F requires that the total gain before signal input must 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 them, the axial ratio is particularly emphasized, which is an important indicator to measure the difference of the signal gain of the whole machine in different directions.
Since the satellites are randomly distributed in the hemisphere sky, it is very important to ensure that the antenna has similar sensitivity 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.