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Case Studies

Channel Tunnel Rail Link and London St Pancras Communication Antennas

Cobham Antenna Systems designed and manufactured antennas for Thales for use on Section 2 of the Channel Tunnel Rail Link (CTRL) project between Fawkham Junction in Kent and London St Pancras International station.

Section 2 of the CTRL includes the provision of 65km of new high speed track allowing speeds of up to 186mph (300km/hr), bridges and structures along the route, and the construction of the three developments at St Pancras, Stratford and Ebbsfleet stations.
Thales was targeted with several key tasks relating to communications within CTRL. These included the provision of improved GSM-R and Cab Secure Radio (CSR) coverage for the railway operators to maximise safety and to provide coverage for the London Fire Brigade in the evacuation shafts from CTRL tunnels and passenger exit shafts.

After evaluating suppliers, Thales appointed Cobham to design and manufacture a range of single and multi-band antennas. From previous association Thales were confident that Cobham would provide exactly what was required, knowing that their service for antenna design, engineering, manufacturing and performance testing would support the needs of their customer.

The prestigious but demanding CTRL civil engineering project presented unique challenges for wireless communications with 25% of the new route in tunnels with trains travelling through at speeds of up to 150mph.

An environmental feature of this application was the wind speed caused by trains within tunnels and resultant vibration that would have to be absorbed. Antennas would therefore need to be impervious to their surroundings, be tough, reliable, have low wind loading and meet the RF requirements to an uncompromising specification. Antennas for installation within St Pancras International would need to be discreet in appearance to merge within the magnificent new station.

Cobham designed eight antennas to meet these requirements. All the newly designed antennas had specific power levels and cover the frequencies for GSM-R, Cab Secure Radio and the London Fire Brigade services.

One of the development projects undertaken was that of a slim panel antenna that was designed to support the emergency services system in London tunnels and the associated emergency evacuation routes. Mounted inside a firewall of an evacuation tunnel, this antenna features long length insulated cable so that the radio could be mounted at a safe distance to ensure its use in an emergency. The antenna still maintained 8.4dBi gain and full coverage down the shaft.


Thales is a leading international electronics and systems group, addressing defence, aerospace and security markets worldwide.