Huawei MU709 Series Hardware Manual page 50

HUAWEI MU709 Series HSPA+ LGA Module
Hardware Guide
The following antenna efficiency (free space) is recommended for MU709 to ensure
high radio performance of the module:
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In addition, the efficiency should be tested with the transmission line.
S11(VSWR) and S21
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 values are recommended for the antenna of the module:
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In addition, S11 is less important than the efficiency, and S11 has weak correlation to
wireless performance.
S21 indicates the isolation between two antennas.
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 module to minimize
the line length. The diversity antenna needs to be installed perpendicularly to the
primary antenna. The diversity antenna can be placed farther away from the module.
Antenna isolation can be measured with a two-port vector network analyzer.
The following antenna isolation is recommended for the antennas:
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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.
Issue 09 (2017-12-15)
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 (diversity) antenna and the Wi-Fi antenna ≤ –15 dB
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RF Specifications
50