Microwave antennas
Antennas are of particular importance for microwave
transmission. It is only as a result of the high antenna gain that it is
possible at all to transport low transmit power of microwave equipment
over large distances with an adequate signal level for the receiver. On
the other hand, it is only possible through extremely intensive bundling
of the electromagnetic radiation to use repeatedly one and the same
frequency at a location and hence make efficient use of the precious
frequency resources. In particular for telecommunication companies, many
special constructions with in some cases huge dimensions have been
developed in the course of the past decades.
Above all, there is a widespread use of parabolic dishes
— in various sizes and with a range of properties. Dimensions between 30 cm
(1 ft) and 4.6 m (15 ft), in small steps, are common. In certain
conditions so-called shell-parabolic antennas are also being used
nowadays. This type is marked by a particularly intense focussing and the
highest possible cross polarisation decoupling. According to the concrete
situation and requirements, the microwave link planner will choose the
appropriate type. Andrew, Ericsson (Marconi/Bosch), Faini (Kathrein) und RFS are the most
important suppliers for microwave antennas.
In the case of short-haul microwave links, the antenna
and the microwave outdoor unit are often combined to form a single
constructive unit. It is either the case that the antenna is integrated
directly into the housing (e.g. in the case of Ericsson) or that the
antenna and the outdoor unit are connected via an installation bracket or
a coupling unit (e.g. in the case of Alcatel and NEC). In this way the
equipment is particularly compact and can be installed at low cost. A
separate installation is only unavoidable for larger antennas (at least
1.2 m / 4 ft diameter).
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For expanding please click on the images

Shell-parabolic antenna (Bosch/Marconi)
Outdoor-Unit with flanged (above) and integrated (below)
30-cm-parabolic antenna
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