Huawei ME909u-523 Hardware Manual page 50

HUAWEI ME909u-523 LTE LGA Module
Hardware Guide
Isolation
For a wireless device with multiple antennas, the power of different antennas is
coupled with each other. Antenna isolation is used to measure the power coupling.
The power radiated by an antenna might be received by an adjacent antenna, which
decreases the antenna radiation efficiency and affects the running of other devices. To
avoid this problem, evaluate the antenna isolation as sufficiently as possible at the
early stage of antenna design.
Antenna isolation depends on the following factors:
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The primary antenna must be placed as near as possible to the ME909u-523 module
to minimize the line length. The secondary antenna needs to be installed
perpendicularly to the primary antenna. The secondary antenna can be placed farther
away from the ME909u-523 module. Antenna isolation can be measured with a
two-port vector network analyzer.
The following S21 values are recommended for the antenna:
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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 primary/secondary antenna of
ME909u-523 module. The RHCP (Right-Hand Circular Polarization) is recommended
for GPS antenna.
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
from the antenna. The power or field strength varies with the angular coordinates (θ
and φ), but is independent of the radial 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. We must notice that GPS signal is
coming from the satellite in the outer space; it means that the incident waves are over
our head.
The following radiation patterns are recommended for the antenna of ME909u-523
module.
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Issue 01 (2014-05-24)
Distance between antennas
Antenna type
Antenna direction
Isolation between the primary and secondary antennas ≤ –12 dB
Isolation between the primary antenna and the GPS antenna ≤ –15 dB
Isolation between the primary (secondary) antenna and the Wi-Fi antenna ≤ –15
dB
Primary/Secondary antenna: omnidirectional.
GPS antenna: directional, point to the Upper Hemisphere.
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RF Specifications
50