Modern cars today, use a range of wireless services including, mobile phones, satellite navigation, WiFi, door openers and more. The antennas for transmitting and receiving signals are usually mounted in the shark fins installed on the roof. But with the growing number of mobile communication systems and the high amount of data incurring, the systems need more complex antennas. The trend towards autonomous driving further exacerbates this problem.
Engineers at the Karlsruhe Institute of Technology (KIT) have now designed a reconfigurable antenna system that can handle large amounts of data from different services simultaneously. Transmitting large amounts of data to as many users as possible at the same time without errors provides different challenges depending on the environment. For example, anyone who wants to make a phone call in a busy place like an airport is typically facing a capacity problem since many people want to communicate here at the same time. Those who want to make a phone call in the Alps, on the other hand, often have no network coverage.
Since the data services of cars are often safety-relevant, they must function reliably everywhere. According to the KIT team, the decisive factor here is the radiation characteristic. Today, car antennas are used whose electromagnetic field spreads evenly in all directions. At first glance it seems to be the right choice, as signals from all directions can be received while the car is moving. The problem: In urban areas, for example, signals can be deflected from house walls. The result: incomplete transmission until complete data loss. In addition, there are the capacity and coverage problems mentioned. MIMO technology (Multiple Input Multiple Output), which is part of the new LTE mobile communications standard, is intended to solve this problem. However, this requires several antennas with transmitters and receivers, which makes the systems more complex, larger and more expensive.
At the Institute for High Frequency Technology and Electronics (IHE) at KIT, the researchers have therefore experimented with reconfigurable antenna systems in order to reduce the number of transmitters and receivers required to a minimum. Their electromagnetic fields are not static, but can change their radiation characteristics. "Individual segments of the antenna can be switched on or off alternately by means of electronic switches. This changes the directional characteristics of the respective transmitters and receivers. The parallel transmission of data over different propagation paths increases the capacity of the system and the data rate.
As a result, the KIT system requires fewer transmitters and receivers. This not only saves costs, but also space. Together with scientists from the Vienna University of Technology, the Karlsruhe researchers have also investigated whether their antennas can be lowered into the roof in the future in a space-saving and aerodynamic manner. Antenna cavities integrated into the body offer ten times higher data volumes than the conventional shark fin housings and can be completely concealed under the roof line.
The Karlsruhe researchers presented their results at the International Workshop on Antenna Technology.
