DETEWE varix 14, Описание, Установка, Пусконаладка

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2 - 30 Description varix 200/varix 14 (DECT)
2 Planning a cordless communications network
Circular polarisation
The electrical field vector retains the same absolute value, but its direction rotates, its end-
point thus describing a circle. With respect to the propagation direction, it may rotate either
in a clockwise or in an anti-clockwise direction. The spatial diagram of such a field would be
a clockwise or anti-clockwise corkscrew-shaped curve.
polarisation used in
varix 200 systems
with integrated DECT
network
The antennae used by DeTeWe are circularly polarised in a clockwise direction, i.e. the field
oscillation plane rotates in a clockwise direction. The transmission and reception antennae
must be aligned accordingly (i.e. have the same polarisation). It is important to understand
that only an antenna which is aligned to the polarity of the wavefront at the antenna location
will achieve maximum reception signal power.
Rule to remember:
The reception and transmission antennae must always have the same
polarisation and must be aligned to one another.
Down-tilt
The electrical down-tilt is a measurement that describes the angle by which an antenna ”looks
downward” when it is mounted vertically. An antenna with a positive down-tilt thus does not
radiate its power in a horizontal direction, but obliquely downwards. The same result can be
achieved by mounting an antenna which has no down-tilt at an angle causing it to point
downwards (see figure 2.19). Down-tilt is required in this case in order to ensure that the
maximum field strength is achieved at a height where the PPs are most frequently operated
(approx. 1.80 m).
Fig. 2.19 Antenna characteristic with down-tilt
Down-
tilt