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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.
30
Distance between antennas
Antenna type
Antenna direction
The primary antenna must be placed as near as possible to the ME909 module to
minimize the cable length. The diversity antenna needs to be installed
perpendicularly to the primary antenna. The diversity antenna can be placed farther
away from the ME909 module. Antenna isolation can be measured with a two-port
vector network analyzer.
The following antenna isolation is recommended for the antennas on laptops:
Isolation between the primary and diversity antennas: ≤ –12 dB
Isolation between the primary(diversity) antenna and the GPS antenna: ≤
–15 dB
Isolation between the primary antenna and the Wi-Fi antenna: ≤ –15 dB
Polarization
The polarization of an antenna is the orientation of the electric field vector that rotates
with time in the direction of maximum radiation.
The linear polarization is recommended for the antenna of ME909 module.
Radiation Pattern
The radiation pattern of an antenna reflects the radiation features of the antenna in the
remote field region. The radiation pattern of an antenna commonly describes the
power or field strength of the radiated electromagnetic waves in various directions
fromtheantenna.Thepowerorfieldstrengthvarieswiththeangularcoordinates(θ
andφ),butisindependentoftheradial coordinates.
The radiation pattern of half wave dipole antennas is omnidirectional in the horizontal
plane, and the incident waves of base stations are often in the horizontal plane. For
this reason, the receiving performance is optimal.
The following radiation patterns are recommended for the antenna of ME909 module.
Primary/Diversity/GPS antenna: omnidirectional
In addition, the diversityantenna’s pattern should be complementary with the
primary’s.
Envelope Correlation Coefficient
The envelope correlation coefficient indicates the correlation between different
antennas in a multi-antenna system (primary antenna, diversity antenna, and MIMO
antenna). The correlation coefficient shows the similarity of radiation patterns, that is,
amplitude and phase, of the antennas. The ideal correlation coefficient of a diversity
antenna system or a MIMO antenna system is 0. A small value of the envelope
correlation coefficient between the primary antenna and the diversity antenna
indicates a high diversity gain. The envelope correlation coefficient depends on the
following factors:
Distance between antennas
Antenna type