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LTE Module Series
EG91 Hardware Design
EG91_Hardware_Design 61 / 93
Figure 30: Reference Circuit of RF Antenna Interface
1. Keep a proper distance between the main antenna and theRx-diversityantenna to improve the
receiving sensitivity.
2. ANT_DIV function is enabledby default.AT+QCFG="diversity",0command can be used to disable
receive diversity.
3. Place the π-type matching components (R1/C1/C2, R2/C3/C4) as close to the antenna as possible.
5.1.4. Reference Design of RF Layout
For user’s PCB, the characteristic impedance of all RF traces should be controlled as 50Ω. The
impedance of the RF traces is usually determined by the trace width (W), the materials’ dielectric constant,
height from the reference ground to the signal layer (H), and the space between the RF trace and the
ground (S). Microstrip and coplanar waveguide are typically used in RF layout to control characteristic
impedance. The following figures are reference designs of microstrip or coplanar waveguide with different
PCB structures.
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NOTES