7.5.1 General
The antenna is the component in the users system that maintains the radio link between the network and the wireless modem. Since the antenna transmits and receives electromagnetic energy, its efficient function will depend on:
•the type of antenna (for example, circular or directional)
•the placement of the antenna
•communication disturbances in the vicinity in which the antenna operates
In the sections below, issues concerning antenna type, antenna placement, antenna cable, and possible communication disturbances are addressed.
In any event, users should contact their local antenna manufacturer for additional information concerning antenna type, cables, connectors, antenna placement, and the surrounding area. Users should also determine whether the antenna needs to be grounded or not. Usually, a local antenna manufacturer should be able to design a special antenna suitable for the integrators application and environment.
7.5.2 Antenna Type
Users should ensure that they choose the right type of antenna for the wireless modem.
The antenna must be designed for the frequency bands deployed in the regions that the wireless modem is being used. For fixed locations this may be dual bands (for example
Other factors in choosing antenna are equally important:
•the impedance of the antenna and antenna cable must be 50 ohms at all frequencies being used
•the antenna
•the antenna VSWR value should be less than 3:1 to avoid damage to the radio device
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