Mobile coverage in tunnels has always been one of the most difficult challenges for network operators. Concrete walls, restricted space and the constant movement of air caused by passing vehicles all interfere with signal stability. Vodafone Germany has now taken a major step forward in overcoming these barriers with the deployment of a new generation of conical antennas. Designed by Ericsson, these antennas are engineered specifically for tunnel environments and have been introduced in the 1,400 metre Arlinger Tunnel near Pforzheim.
The new solution is based on a conical multi-band antenna that combines wide frequency support with a form factor able to withstand tunnel-specific conditions. Traditional antennas in tunnels often struggle with vibrations and pressure changes that occur whenever trains or cars move large volumes of air. These effects can cause instability in reception and transmission performance. The conical design offers superior resistance to these forces. Its aerodynamic shape reduces the impact of airflow and turbulence, which results in more stable signal propagation and higher reliability.
Ericsson’s antenna, known as the Antenna 9011 1LM (KRE 101 2571/1), operates across the 617 to 4200 MHz range. This wide frequency coverage ensures compatibility with all major mobile technologies from legacy 2G through to 5G mid-band and even C-band. The antenna achieves a gain of around 10 dBi and uses cross polarisation to support advanced features such as MIMO. It has been tested under demanding tunnel conditions, including alternating pressure cycles that simulate the effect of trains passing at high speed. These design elements make it particularly suitable for deployment in both road and rail tunnels.
In the Arlinger Tunnel, five of these antennas have been installed. Together they provide seamless coverage along the full tunnel length, ensuring that drivers and passengers can stay connected without interruptions. For commuters this means fewer dropped calls and more consistent data performance, while for Vodafone it represents a significant step in eliminating dead spots in challenging locations. The project also demonstrates how antenna engineering is evolving to meet the requirements of complex environments.
Delivering mobile coverage in tunnels is more complicated than simply placing antennas inside the structure. In shorter tunnels, antennas positioned at the entrance and exit can often suffice. In longer tunnels, however, operators must deploy signal repeaters and distribute the signal along the length of the tunnel using multiple antennas. This requires the installation of cabling and associated equipment, usually during periods when tunnels are closed for maintenance. To avoid duplication, one operator typically provides the infrastructure and others connect their networks to it.
Germany has a particularly extensive tunnel network with more than 270 tunnels on federal highways, over 400 on district and urban roads, and 761 railway tunnels. Collectively these extend for more than 1,200 kilometres. The introduction of conical antennas marks a practical response to the specific difficulties these environments present. Vodafone has already announced that it intends to use the new antenna type in 20 further tunnel projects across the country.
From an infrastructure perspective, the Arlinger Tunnel deployment highlights a broader trend towards highly specialised antenna systems. Rather than adapting generic equipment, manufacturers such as Ericsson are now producing models tailored for environments where airflow, vibration and space constraints dominate. The Antenna 9011 1LM shows how much progress has been made. Its mechanical robustness, compact size and wideband capability make it a versatile component for future-proof tunnel deployments.
Vodafone Germany’s network already reaches more than 93 percent of the population with 5G and the addition of tunnel coverage strengthens this footprint. For the growing number of travellers who depend on uninterrupted connectivity, solutions like the conical antenna are not just a technical achievement but also a practical improvement to everyday digital life. They also underline the importance of collaboration between operators and equipment vendors in tackling some of the toughest remaining infrastructure gaps.
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