SATELLINE-3AS and SATELLINE-3ASd
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Especially in portable applications the DTR line (pin 1) of the radio modem should be switched to
position "0" when possible to save power.
7.3
7.3
Antenna Installation
Antenna Installation
7.3.1
Hand portable equipment
•
1/4 wave antenna ( wave length on 450 MHz is about 70 cm)
•
Helix antenna
The antennas are mounted directly on to the antenna connector (TNC) at the top of the radio
modem.
7.3.2
Equipment installed in vehicles
•
1/4-wave antenna
•
1/2 wave antenna
Ideally the antenna should be installed vertically and it should have at least 0.5 m of open space
surrounding it. In a small system 1/4 wave antenna is adequate. There should be a ground plane
below the antenna (truck bonnet or roof). In weak conditions a 1/2 wave antenna is the most
suitable. It can be mounted at the top of a pipe, as this provides it with as much open space as
possible. In places where the antenna cannot be connected directly to the TNC a 50 ohm
coaxial cable must be used to provide the link between the TNC and the antenna.
7.3.3
Master station
•
omnidirectional (1/4, 1/2 or 5/8 wave antenna)
•
directional (yagi or corner reflecting antenna)
The antenna should be installed in an upright position. The exact location of the antenna
depends on a number of factors from system size to physical ground countours. As a general
rule, the antenna for a base station should be located at the highest point in the most central
location of the system.
Alternatively the base station antenna can be situated inside the building, providing that the walls
of the building do not contain metal.
