Application of the Finite Volume Time domain method for evaluation and development of wideband automotive antenna systems

In present-day vehicles a multitude of high frequency services are offered. These services need antennas which often must be placed very close to each other. This is the case with roof antennas that operate in different frequency ranges for GSM, UMTS, GPS and SDARS applications. The development of such antenna systems poses a new challenge due to the fact that more antennas shall occupy the same place reserved for the existent systems as the exterior design should stay the same. This will be the case with the additional integrated LTE, WIMAX and Car-2-X antennas. Besides that, the performance of individual services should be kept constant independently of the antenna system configuration. In other words, should a customer have the possibility to order a system without one or more services, the remaining antennas must keep the same individual performance. In order to expedite the development process and reduce the costs related to the usage of prototype cars, numerical computations based on the surface discretising method of moments (MoM) are successfully used for development of different glass antenna systems. For the roof antenna systems volume discretising simulation approaches appear, however, to be a better choice. With the implementation of the method of Finite-Volume Time domain FVTD, in the used simulation framework, a complete system evaluation based on simulations using volume discretisation is now possible to be carried out accurately. In this work, a comparison between simulations realized with the old MoM used solver and simulations based on the FVTD method will be presented. In addition, the simulation results are validated by measurements. Furthermore, potential coupling between different antennas are investigated. Finally, suggestions for optimal individual antenna placement inside the roof antenna system are given.