User's Manual

720 Hardware User Guide

3 RF Interface

Name Pin I/O Function Remarks

ANT_MAIN 76 AI/O 2G/3G/4G main antenna

50 characteristic

impedance

ANT_GPS 92 AI GPS antenna

ANT_AUX 94 AI 4Gdiversity aerial

3.1 2G/3G/4G RF Design and PCB Layout

ANT_MAIN and ANT_AUX is the antenna pin of N720. A 50  antenna is required. VSWR

ranges from 1.1 to 1.5. The antenna should be well matched to achieve best performance. It

should be installed far away from high-speed logic circuits, DC/DC power, or any other strong

disturbing sources.

A 50  antenna is required. VSWR ranges from 1.1 to 1.5. The antenna should be well matched

to achieve best performance.

For multiple-layer PCB, the trace between the antenna pad of module and the antenna connector,

should have a 50  characteristic impedance, and be as short as possible. The trace should be

surrounded by ground copper. Place plenty of via holes to connect this ground copper to main

ground plane, at the copper edge.

For dual-layer PCB, the width of recommended impedance trace is 0.8 mm to 1 mm and the

grounding copper should away from the trace for 1 to 1.5 time of the trace width.

If the trace between the module and connector has to be longer, or built-in antenna is used, a

-type matching circuit is needed, as shown in Figure 3-1.

Figure 3-1 Reference of antenna matching design