order to maintain speeds of around 360 kilometres per hour, very
fast trains demand very straight rail tracks. In the case of the
high speed route between the Spanish cities of Madrid and Barcelona, this
has led to the construction of a new train line that incorporates 16 tunnels
to prevent the 600-kilometre Ave Madrid-Barcelona line from curving with
the contours of the countryside.
Yet as locomotives power through hills and under cities, it remains imperative
to maintain on-board safety and emergency communications. The European
railway safety communications standard, GSM-R, operates in the 876 to
925 MHz band, and is used for all European rail networks. To be detected
only by a trains roof-mounted antenna, GSM-R was the first wireless
communications service deployed along the new Ave Madrid-Barcelona line.
Low coupling loss
In support of GSM-R, Radio Frequency Systems has supplied confined coverage
RF infrastructure for the 16 new tunnels along the new route. Three of
the longest tunnels feature redundant lengths of RFSs RADIAFLEX
1-1/4 inch RAY foam dielectric radiating cablea unique cable exhibiting
very low coupling loss. The coupling loss is particularly low when
the RAY cable is optimized for vertical polarization, said Enric
Lara, Director General of RFSs new Madrid office. This is
an especially important feature for supporting the GSM-R service, which
is targeting the trains single antenna.
Lara explained further that the low coupling loss was not compromised
by the special tape integrated into the cable jacket to ensure low smoke
emissions, owing to the unique method of its application.