Huawei MU709s-2 Hardware Manual page 24

HUAWEI MU709s-2 HSPA+ Mini PCIe Module
Hardware Guide
The following antenna efficiency (free space) is recommended for MU709s-2 Mini
PCIe module to ensure high radio performance of the module:
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In addition, the efficiency should be tested with the transmission cable.
S11 or VSWR
S11 indicates the degree to which the input impedance of an antenna matches the
reference impedance (50 Ω). S11 shows the resonance feature and impedance
bandwidth of an antenna. Voltage standing wave ratio (VSWR) is another expression
of S11. S11 relates to the antenna efficiency. S11 can be measured with a vector
analyzer.
The following S11 value is recommended for the antenna of MU709s-2 module:
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In addition, S11 is less important than the efficiency, and S11 has weak correlation to
wireless performance.
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 MU709s-2 Mini PCIe
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 MU709s-2 Mini PCIe module. Antenna isolation can be measured with
a two-port vector network analyzer.
The following antenna isolation is recommended for the antennas on laptops:


Polarization
The polarization of an antenna is the orientation of the electric field vector that rotates
with time in the direction of maximum radiation.
Issue 02 (2014-09-18)
Efficiency of the primary antenna: ≥ 40% (below 960 MHz); ≥ 50% (over 1710
MHz)
Efficiency of the diversity antenna: ≥ half of the efficiency of the primary
antenna in receiving band
S11 of the primary antenna: ≤ –6 dB
S11 of the diversity antenna: ≤ –6 dB
Distance between antennas
Antenna type
Antenna direction
Isolation between the primary and diversity antennas: ≤ –12 dB
Isolation between the primary antenna and the Wi-Fi antenna: ≤ –15 dB
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RF Specifications
24