User Guide

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GM500-U1G_A
Hardware Development Guide
3. Antenna Interface
GM500-U1G_A antenna interface includes a main antenna, an Rx-diversity antenna and a GNSS antenna to improve receiving
performance. The antenna interface has an impedance of 50Ω.
3.1. Pin Definition
The main antenna and Rx-diversity antenna pins definition are shown below.
Table 3-1Pin Definition ofAntenna
Pin Name Pin NO. I/O Description Comment
MAIN_ANT 62 IO Main antenna 50Ω impedance
DIV_ANT 79 AI Diversity antenna 50Ω impedance
GNSS_ANT 10 IO GNSS antenna 50Ω impedance
3.2. Reference Design
The antenna is a sensitive device and its performance is greatly affected by external environments. The radiation performance of
the antenna is affected by the module dimensions, antenna position, occupied space size of the antenna, and the grounding of
surrounding components of the antenna. Besides, the fixed assembly of the antenna, the wiring of RF cables on the antenna, and the
fixed position of the antenna all affect the radiation performance of the antenna too.
The reference design of main antenna and Rx-diversity antenna is shown as below. It should reserve a double-L-type matching
circuit for better RF performance, and place these components as close as possible to the module. The capacitors are not mounted by
default.