HUAWEI EM820W HSPA+ PC Embedded Module
Hardware Guide
RF Specifications
Issue 01 (2010-12-09)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
19
4.3.2 Conducted Transmit Power
The conducted transmit power is another indicator that measures the performance of
EM820W. The conducted transmit power means the maximum power that the module
tested at the antenna port can transmit. According to the 3GPP protocol, the required
transmit power varies with the power class.
Table 4-3 lists the required ranges of the conducted transmit power of EM820W. The
tested values listed in the
Test Value
column must be within the range from the
minimum power to the maximum power.
Table 4-3
EM820W conducted Tx power (unit: dBm)
Test Value
Item
Minimum Power
Required in the
3GPP Protocol
Maximum Power
Required in the
3GPP Protocol
EM820W
GSM850 31
35
32
GSM900 31
35
32
GSM1800 28
32
29.5
GSM1900 28
32
29.5
W2100 21
25
23
W1900 21
25
23
900 21 25 23
W850 21
25
23
4.4 Antenna Design Requirements
4.4.1 Antenna Design Indicators
Antenna Efficiency
Antenna efficiency is the ratio of the input power to the radiated or received power of
an antenna. The radiated power of an antenna is always lower than the input power
due to the following losses: return loss, material loss, and coupling loss. The
efficiency of an antenna relates to its electrical dimensions. To be specific, the
antenna efficiency increases with the electrical dimensions. In addition, the
transmission cable from the antenna port of the EM820W to the antenna is also part
of the antenna. The cable loss increases with the cable length and the frequency. It is
recommended that the cable loss should be as low as possible, for example, U.FL-
LP-088 made by HRS.
The following antenna efficiency (free space) is recommended for the EM820W on a
laptop to ensure high radio performance of the EM820W:
z
Efficiency of the master antenna > 40% (–4 dB)