Vodafone Germany has outlined plans to provide more stable 5G coverage in tunnels through the use of conical multi-band mobile antennas.

In an announcement this week, the telco said it has commissioned the new type of conical antennas, revealing that five of the antennas are being used in the 1,400-meter-long Arlinger tunnel near Pforzheim.

Swedish vendor Ericsson has provided the antennas, which Vodafone notes are designed to support multiple frequency bands and are specifically designed for use in tunnels.

Vodafone said it plans to deploy the antennas in 20 more tunnels across the country.

“Closing dead spots in tunnels is particularly challenging for structural reasons alone. Passing cars and trains set large air masses in motion in tunnels, which can cause vibrations in the antenna technology and thus impair the transmission and reception performance of mobile phone antennas. This places special demands on the wind resistance of the antennas used and their installation,” said Marc Hoelzer, head of network development at Vodafone.

According to Vodafone, the antennas are wind-resistant and can support all frequency ranges, particularly high bandwidths in the 5G network.

“For drivers and passengers, the commissioning of the new antenna generation will result in fewer dropped calls and more stable data rates,” added Hoelzer.

Explaining the technology used to provide cell coverage in tunnels, Vodafone stated that in smaller tunnels, mobile phone antennas at the entrances and exits are often sufficient for mobile phone reception along the tunnel route.

Meanwhile, in deeper and longer tunnels, telcos will instead deploy optical amplifiers (repeaters), which transmit the mobile phone signal to numerous tunnel antennas installed in the tunnel and then return the signal to the mobile phone cell at the end.

The carrier also noted that there’s usually a specific mobile network operator that is responsible for the connectivity provided in each tunnel, to avoid multiple cable installations. The other providers connect their technology to the infrastructure.