HUAWEI EM820W HSPA+ PC Embedded Module
Hardware Guide
RF Specifications
Issue 01 (2010-12-09)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
21
Frequency
Band
Transmit
Frequency
Conducted
Transmit
Power (dBm)
Ant
Isolator
(dB)
Wi-Fi Front End
Filter Attenuation
(dB)
GSM850 824–849
MHz 33
18
36
GSM900 880–915
MHz 33
18
36
DCS 1710–1785
MHz
30
17 34
PCS 1850–1910
MHz
30
17 34
S11 or VSWR
S11 (return loss) indicates the degree to which the input impedance of an antenna
matches the reference impedance (50 ohm). 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 antennas on laptops:
z
S11 of the master antenna < –6 dB
z
S11 of the slave antenna < –6 dB
z
S11 of the GSP antenna < –10 dB
z
S11 of the Wi-Fi antenna < –10 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 antennas on laptops.
Envelope Correlation Coefficient
The envelope correlation coefficient indicates the correlation between different
antennas in a multi-antenna system (master 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 master antenna and the slave antenna indicates a
high diversity gain. The envelope correlation coefficient depends on the following
factors:
z
Distance between antennas
z
Antenna type
z
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.