Enhanced Class 1 Bluetooth v2.1 Module
Hardware Integration Guide
Americas: +1-800-492-2320 Option 2
Europe: +44-1628-858-940
Hong Kong: +852-2923-0610
www.lairdtech.com/bluetooth
17
CONN-HIG-BT740
Note: Copper cut-away on all layers in “antenna keep-out” area under BT740-SA module on host PCB.
Refer to “antenna keep-out” defined in
7.4 PCB Land Pattern and Antenna Keep-out for BT740-SA
6.3.2
Antenna Keep-out and Proximity to Metal or Plastic
Checklist (for metal /plastic enclosure):
Figure 12A and 12B shows recommended and not recommended locations for metal with respect to a
BT740-SA module on-board antenna.
Minimum safe distance for metals without seriously compromising the antenna (tuning) is 40 mm
top/bottom and 30 mm left or right.
Metal close to the BT740-SA chip monopole antenna (bottom, top, left, right, any direction) will have
degradation on the antenna performance. The amount of degradation is entirely system dependent
which means some testing by customer is required (in their host application).
Anything metal closer than 20 mm starts to significantly degrade performance (S11, gain, radiation
efficiency).
It is best that the customer tests the range with a mock-up (or actual prototype) of the product to
assess effects of enclosure height (and material, whether metal or plastic).
Figure 6-3: Recommended BT740-SA placement on host PCB and proximity to metal cover
Figure 6-4: Not recommended BT740-SA placement on host PCB and proximity to metal cover
6.4
External Antenna Integration with BT740-SC
Refer to the regulatory sections for
FCC
,
IC
, and
CE
, for details of use of BT740-SC with external antennas in
each regulatory region.
The BT740-SC family has been designed to operate with the antennas listed below with a maximum gain of 2
dBi. The required antenna impedance is 50 ohms. External antennas improve radiation efficiency.
Item
Part Number
Mfg.
Type
Gain (dBi) Connector Type
1
MAF94045
Laird
Internal
2
UFL
2
WRR2400- IP04-B(MAF94019)
Laird
Dipole
1.5
UFL
3
WTC2450-IP04-K(MAF94006)
Laird
Dipole
2
UFL
4
S181FL-L-RMM-2450S
Nearson (Laird) Dipole
2
UFL
