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alas, they are caused by pure multipath propagation, a self-made one. So always use a
combiner and another directional antenna if such arrangement is needed. Always.
combiner
correctly
incorrectly
Fig. 3.5: Main lobe
3.5. Network layout
In general a radio network layout is mostly (sometimes completely) defined by the application. When
the terrain allows for direct radio communication from all sites in the network, the designer can not do
too much wrong. Unfortunately for RF network designers, the real world is seldom that simple.
The conditions desireable for every single radio hop were discussed in previous paragraphs. If we are
lucky, assuming different layouts meeting those conditions are possible, we should exploit those layouts
for the benefit of the network operation. The following options should be considered when defining the
layout of a radio network:
• Placing a single repeater, which serves most of the network, on the top of a hill is a straightforward
and very common option. Sometimes it is the only feasible option. However, there are a few things
we must consider with this design. First, a dominant hilltop site is exposed to interference from a
large area; second, these sites are typically crowded with radio equipment of all kinds and it’s a
dynamic radio environment, so local interference may appear anytime; third, it makes the majority
of communication paths dependent on a single site, so one isolated failure may stop almost the
RipEX Radio modem & Router – © RACOM s.r.o. 38
Network planning