Rhotheta RT-300 - Connecting Antenna; Determination of Antenna Position

User Manual Bearing System RT-300
Issue: 2017/06/27 [Rev 1.04.c] Page 69 of 79 12-9-1-0013-9-2-0001-3-1-60
7.1.4 Connecting Antenna
Connect antenna cable (see 7.3) to socket “Antenna Connector“.
7.2 Determination of Antenna Position
The quality of the bearing results is depending largely on the antenna´s position. Therefore, an
antenna position has to be found, where the transmitter´s wave field can reach the bearing
antenna as undisturbed as possible.
The bearing antenna is analysing the incoming wave field and the microprocessor of the
bearing system is determining the direction of incidence of the signal. Reflections of the
incoming signal may interfere with the wave field. The bearing system will determine a direction
of incidence as an average of the incoming and the reflected signal. As a result, there is a
wobbling bearing display, the error will depend on direction of incidence, distance and vertical
angle of incidence of the signal.
Reflections mainly are caused by conducting objects.
- Antennas (especially if working in the same frequency range  GPS-antennas not that
critical)
- Metallic superstructures of vessels
- Metallic masts
- Steel cables
- Wet sail-cloth
- Persons in direct vicinity of the antenna
Therefore, the best position of the antenna is on top of the mast, above other antenna systems
or other obstacles.
In practice, often a compromise has to be found between bearing and other interests.
Therefore we will give you here some guidelines:
- No disturbing objects in the antenna´s horizontal plane if possible
- Disturbing objects as distant as possible
- No metallic objects closer than 30 cm under and above bearing antenna
- No objects in direct antenna range (between antenna beams of antenna, except mast)
In the case of doubt the antenna´s position has to be tested during a practical try-out, prior to
final assembly.
ATTENTION
The antenna´s ground is connected to the DCU. Electrostatic charge may cause
very high voltages. Therefore, it is very important earthing the DCU before
connectin
g
the antenna.