Gira 5110 00 Product Documentation page 47

Building structure
The frequency band at 868 MHz as used by the KNX RF has good signal radiation in buildings,
since the attenuation due to walls, concrete reinforcements and metal parts close to the
transmitter keeps within reasonable limits. This is positive when - for example in a detached
house - one storey or even multiple storeys are to be covered with one and the same RF line.
The media coupler should then be positioned as close to the centre of the building as possible
(Figure 18).
The good signal radiation may be a disadvantage in real estate if the RF lines influence each
other physically, are only partially within their radio ranges due to a small spatial distance or
through insufficiently large attenuation due to wooden ceilings or thin walls (Figure 19). Here, it
is wise not to create two or more RF lines (each with their own media couplers), but to use
repeaters which increase the radio range of one RF line (Figure 20). Here too, the media
coupler should be positioned as close to the centre of the building as possible.
Repeaters should ideally be located on the edges of the building although still within the range
of the media coupler and also within the ranges of other repeaters.
i Gira media couplers can only work as media couplers, as media couplers and repeaters or
only as repeaters. The operating mode is defined by the parameter setting and the physical
address of the media coupler. The functional description of the media coupler describes
this in more detail.
Combined operation of the media coupler and repeater function is helpful if, within a radio
domain, all the RF subscribers are within radio range of the media coupler but are not
however in the radio ranges of other RF subscribers. Here, the repeater integrated in the
central media coupler ensures that telegrams from RF subscribers also actually reach all
the other RF subscribers of the radio domain.
Order No. 5110 00
Figure 18: Building with a KNX RF line (example)
Software "Media coupler / repeater"
Parameters
Page 47 of 57