Oki BISM2 - Manual (Page 22)

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10. Application Information
10.1 Antenna Position
The antenna used on the BISM2 Bluetooth module is designed to be largely immune from the effects
of proximity detuning. Normally, antennas operating at 2.4GHz are affected by their surroundings, so
that great care is needed in their placement and orientation.
The BISM2 can be used in most locations and orientations and is only marginally affected by the
presence of a significant ground plane in close proximity.
The antenna distribution is close to isotropic, which means that the orientation of mounting has only a
limited effect on the overall range. However the optimum range is achieved when the two antennae
are directly facing each other
Example of Radiation Characteristics
Horizontal Polarisation Vertical Polarisation
Typical Radiation Characteristics. Measured at 2.5metres from a standard dipole.
The module should not be located in a sealed metal enclosure, as this will act as a Faraday cage and
severely attenuate the radio signal.
The antenna finish may tarnish as a result of environmental effects and handling. This is a cosmetic
effect and does not affect the RF performance.