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FIBOCOM SQ806-W Series Hardware Guide
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5 RF PCB Layout Design Guide
For user PCB, the characteristic impedance of all RF signal cables should be within 50Ω. In general, the
impedance of the RF signal cable is determined by the dielectric constant of the material, the cable width
(W), the ground clearance (S) and the height of the reference ground plane (H). PCB characteristic
impedance is usually controlled using both microstrip cable and coplanar waveguide. To illustrate the
design principles, the following figures show the structural designs of microstrip cable and coplanar
waveguide when the impedance cable is at 50Ω.
Microstrip cable complete structure
Figure 5-1 Two-layer PCB microstrip cable structure
Coplanar waveguide complete structure
Figure 5-2 Two-layer PCB coplanar waveguide structure
