The "shark fin" on the car roof can hardly continue to handle the flood of data from mobile ser-vices. As most data services in modern cars are security relevant, they must function reliably and error-free everywhere. The antenna's radiation pattern is crucial for this purpose, explains Thomas Zwick, director of the Institute for High Frequency Technology and Electronics (IHE) at the Karlsruhe Institute of Technology ( KIT ). Car antennas whose electromagnetic fields spread out evenly in all directions are used today. This allows signals to be received from any direction. Problems occur where signals are deflected, such as in urban areas. The result is patchy data transmission or even the complete loss of data, says Jerzy Kowalewski from the IHE. Sometimes there are also capacity and coverage issues.
MIMO technology (Multiple-Input-Multiple-Output), which is part of the new LTE standard, promises to get to the root of the problem. MIMO technology requires multiple antennas with transmitters and receivers, making the systems more complex, larger and more expensive. To reduce the number of transmitters and receivers required, the researchers at IHE have devel-oped a reconfigurable antenna system. The emitted electromagnetic fields can change their radiation pattern rather than simply remaining static. "This changes the directional characteris-tics of the respective transmitters and receivers," explains Kowalewski. The r econfigurable antenna system thus requires fewer transmitters and receivers while increasing capacity and dataflow. This saves both costs and space, says Kowalewski. Antenna activity integrated into the car body provides ten times more volume than conventional shark fin casings. Moreover, they can be completely hidden under the roofline.