User's Guide

BL28EU-RD1 OEM Manual and User Guide
8
Figure 6-5
Due to the nature of the weave chosen for each PCB, the dielectric constant of the NAD board is 4.1 while
the main board is 4.3. A dielectric constant of 4.2 was chosen in the stripline calculation, while 4.3 was
used for the microstrip calculation.
Main board stack up may vary so these line widths may need to be recalculated. IT IS HIGHLY
RECOMMENDED TO USE A SIMILAR STACKUP AS SHOWN IN FIGURE 39 WITH MICROSTRIP
ROUTING AND GND CUTS ON LAYER 2 WITH GND REFERENCE ON LAYER 3. THERE
SHOULD BE NO ROUTING ON L2 AND SOLID GND ON L3 UNDERNEATH THESE ANTENNA
LINE MICROSTRIP TRACES.
The antenna traces need to routed STRAIGHT OUT OF THE NAD TO THE NEAREST NAD EDGE.
The lines need to be tapered from 433micron to the 967micron width gradually but quickly.
Figure 6-6
These line widths may vary depending on the stackup selected for the main board.