Product Info

LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design
5-62
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Figure 32: Reference Circuit of RF Antenna Interface
1. Keep a proper distance between the main antenna and the Rx-diversity antenna to improve the
receiving sensitivity.
2. ANT_DIV function is enabled by default.
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,
the distance between signal layer and reference ground (H), and the clearance between RF trace and
ground (S). Microstrip line or coplanar waveguide line is typically used in RF layout for characteristic
impedance control. The following are reference designs of microstrip line or coplanar waveguide line with
different PCB structures
.
Figure 33: Microstrip Line Design on a 2-layer PCB
NOTES