Publikationen

Car-to-car communication has wide-ranging applications in the fields of traffic safety and optimization as well as minimization of emissions. For a seamless and reliable communication between the cars and their road environment, as may be evaluated through packet delivery ratio and received power measurements, an appropriate antenna placement is necessary. Accordingly, the field test discussed in this paper compares the performance of three different antenna placements on a test vehicle: 1. Roof-mounted monopole antenna pair contained in a shark fin housing, 2. Patch antenna pair embedded in the front-left B-column, and 3. Combination of two patch antennas with one in the front-left and the other in the front-right B-column. The concurrent use of three V2V modules allowed us to evaluate the performance of the three antenna set-ups simultaneously in a single run through a mixed terrain, allowing for straightforward performance comparisons. The power received by the roof-top monopole antennas was, on average, 8 dBm higher than the front-left/right B-column patch antenna combination and 13 dBm higher than the front-left B-column patch antenna pair. The reasons for these and other differences are appropriately addressed in the paper. While the roof-top monopole antenna combination performed overall better, we argue that using an appropriate amplifier could raise the performance of the B-column antennas to the same or even higher levels.

State-of-the-art antenna arrays require a significant installation area when envisaged for compact passenger cars, whose footprint area can be reduced by splitting the full array into two smaller, spatially distributed sub-arrays. The challenge of grating lobes develops while arranging the sub-arrays several wavelengths apart mounted on distant parts of a car. As a consequence, spatial sampling of the incident waves leads to ambiguous direction-of-arrival estimation. An inhomogeneous L-shaped orthogonal arrangement can, however, mitigate such drawbacks to some extent while allowing easier installation. The performance of such an array needs to be tested in a virtual electromagnetic environment in the course of the development process, even long before homologation. An example of such distributed array mounted on a conventional passenger car for satellite navigation is shown in this paper, and the array performance is tested in terms of positioning accuracy in presence of a jammer in our automotive antenna test facility.

A millimeter wave agile multi-beam front-end with an integrated 4 by 1 antenna array for 5th generation wireless communications is analyzed by antenna and digital communication measurements. The front-end core comprises a compact low-temperature co-fired ceramic multilayer module with a foot-print area of 74 mm × 74 mm. An over-the-air gain of 50.4 dB and a noise figure of 4.9 dB were measured. Link measurements with broadband single-carrier QAM and OFDM signals result in a data rate of 3.2 Gb/s for 400 MHz bandwidth SC-256QAM modulation with 1.2% error vector magnitude of the front-end determined by a detailed analysis.

Automotive radar systems in automobiles are key for automated and connected driving. Conventionally, functional tests and safety validation of automotive radar systems are carried out in field-operational tests, but are very resource-expensive and they offer neither reproducibility nor reliability. To improve efficiency and reliability, though at the expense of a partial loss of realism, a controlled test environment is required in which repeatability is guaranteed. We proposed previously a system concept for over-the-air testing of radar systems with a vehicle-in-the-loop approach in a virtual environment. For the test in a controlled environment, a realistic simulation of the radar scenario-under-test is necessary. Technological achievements in hardware, software, and computational power have made powerful radar target simulators and real-time capable control computers available. However, for the spatial degrees-of-freedom, which are key to emulate relevant test cases with dynamic evolution in the virtual environment, the illumination antennas of the radar target simulator must be positioned with high speed, accuracy, and over sufficient angular ranges. This paper describes our hybrid electronic-mechanical antenna positioner, offering three motional degrees-of-freedom. Initial trials with a modern commercially available automotive radar installed in a passenger car are presented and they indicate very promising results.