User's Manual

Bluegiga Technologies Oy
Page 13 of 52
resonant frequency will be tuned upwards. S11 is a measure of how big portion of the transmitted power is
reflected back from the antenna. An adequate performance can be expected if S11 is less than – 7 dB. If
using PCB thickness more than 1.6 mm, or if there is dielectric material around the antenna which is likely to
detune the resonant frequency, the antenna can be tuned in the mother board layout by removing FR4 below
the antenna.
Mother board
BT111
Mother board
BT111
Metal clearance area
Min. 10mm
Figure 7: Recommended layouts for BT111-A
Figure 8: Impedance matching of the antenna of BT111 with two different mother board PCB thickness