Appendix B – Wireless Antenna
Multi-Tech Systems, Inc. MultiModem Wireless Modem with Ethernet Interface (S000375F)
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Appendix B – Wireless Antenna
The Antenna
The antenna sub-system and integration in the application is a major issue: Choice of antenna (type, length,
performances, thermal resistance, etc.) These elements could affect GSM performances such as sensitivity and
emitted power.
PTCRB Requirements Note:
There cannot be any alteration to the authorized antenna system. The antenna system must be the same
type with similar in-band and out-of-band radiation patterns and maintain the same specifications.
FCC Requirements Note:
The antenna gain, including cable loss, must not exceed 3.0 dBi at 1900 MHz / 1.6 dBi at 850 MHz for
mobile operating configurations and 7.0 dBi at 1900 MHz / 2.3 dBi at 850 MHz for fixed mounted
operations, as defined in 2.1091 and 1.1307 of the rules for satisfying RF exposure compliance.
GSM, EDGE, and CDMA Antenna
The integrated modem antenna connector is a SMA connector.
The SMA connector incorporates a 'Screw-on'
action in order to make the connection easier while providing an excellent RF performance. An additional
advantage is its small physical size, which is 50% of the standard MCX connector.
This type of connector is suitable for the standard ranges of flexible and semi-rigid cables. The characteristic
impedance of the MMCX coaxial connector is 50 ohm. The antenna manufacturer must guarantee that the
antenna will be working according to the radio characteristics presented in the table below.
GSM and E-GSM Radio Characteristics
GSM 850
E-GSM 900
GSM 1800
GSM 1900
Frequency RX
869 to 894 MHz
925 to 960 MHz
1805 to 1880 MHz
1930 to 1990 MHz
Frequency TX
824 to 849 MHz
880 to 915 MHz
1710 to 1785 MHz
1850 to 1910 MHz
RF Power Stand
2W at 12.5% duty cycle 2W at 12.5% duty cycle 1W at 12.5% duty cycle 1W at 12.5% duty cycle
Impedance
50 ohms
VSWR
<2
Typical Radiated Gain
0 dBi on azimuth plane
CDMA Radio Characteristics
CDMA 800
CDMA 1900
Frequency RX
869 to 894 MHz
1930 to 1990 MHz
Frequency TX
824 to 849 MHz
1850 to 1910 MHz
Impedance
50 ohms
VSWR
<2
Typical Radiated Gain
0 dBi in at least one direction
