User guide

Multi-Tech Systems, Inc. CallFinder GSM Cellular Gateway 14
Chapter 3 – Wireless Antennas
The Antenna
The antenna sub-system and integration in the application is a major issue. Many parameters of the
antenna are variable (type, length, performances, thermal resistance, etc.). These elements can affect
performance characteristics like sensitivity and emitted power.
GSM Antennas
The CallFinder’s antenna connector is an SMA connector. The SMA connector incorporates a 'Screw-on’
action in order to make the connection easier. It also gives 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 ohms. The antenna manufacturer must
guarantee that the antenna will be working according to the radio characteristics presented in the table
below.
GSM Radio Characteristics
GSM 850 GSM 1800 GSM 1900
Frequency RX
869 to 894 MHz 1805 to 1880 MHz 1930 to 1990 MHz
Frequency TX
824 to 849 MHz 1710 to 1785 MHz 1850 to 1910 MHz
RF Power Stand
2W at 12.5% duty cycle 1W at 12.5% duty cycle 1W at 12.5% duty cycle
Impedance 50 ohms
V
SWR <2
Typical Radiated Gain 0 dBi on azimuth plane
Antenna
An antenna that meets the requirements for use with the wireless product is included with your purchase.