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HUAWEI ME909 Series Mini PCIe Module
Hardware Guide
RF Specifications
Issue 0.1 (2013-06-09)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
31
Antenna direction
The antenna correlation coefficient differs from the antenna isolation. Sufficient
antenna isolation does not represent a satisfactory correlation coefficient. For this
reason, the two indicators need to be evaluated separately.
For the antennas on laptops, the recommended envelope correlation coefficient
between the primary antenna and the diversity antenna is smaller than 0.5.
Gain and Directivity
The radiation pattern of an antenna represents the field strength of the radiated
electromagnetic waves in all directions, but not the power density that the antenna
radiates in the specific direction. The directivity of an antenna, however, measures the
power density that the antenna radiates.
Gain, as another important parameter of antennas, correlates closely to the directivity.
The gain of an antenna takes both the directivity and the efficiency of the antenna into
account. The appropriate antenna gain prolongs the service life of relevant batteries.
The following antenna gain is recommended for ME909 module. Gain of the
primary/diversity antenna ≤ 2.5 dBi
The antenna consists of the antenna body and the relevant RF transmission cable. Take the
RF transmission cable into account when measuring any of the preceding antenna
indicators.
Huawei cooperates with various famous antenna suppliers who are able to make
suggestions on antenna design, for example, Amphenol, Skycross, etc.
4.5.2 Interference
Besides the antenna performance, the interference on the user board also affects the
radio performance (especially the TIS) of the module. To guarantee high performance
of the module, the interference sources on the user board must be properly controlled.
On the user board, there are various interference sources, such as the LCD, CPU,
audio circuits, and power supply. All the interference sources emit interference signals
that affect the normal operation of the module. For example, the module sensitivity
can be decreased due to interference signals. Therefore, during the design, you need
to consider how to reduce the effects of interference sources on the module. You can
take the following measures: Use an LCD with optimized performance; shield the LCD
interference signals; shield the signal cable of the board; or design filter circuits.
Huawei is able to make technical suggestions on radio performance improvement of
the module.
4.5.3 GSM/WCDMA/GPS Antenna Requirements
The antenna for ME909 module must fulfill the following requirements: