Approaches based on the method of moments for development of glass automotive antennas

To satisfy the high expectations of signal reception quality for the multiple multimedia services, several antennas differing in location and frequency range of operation are installed in present-day vehicles. One challenge of antenna engineering is to be able to make important decisions about the location of antennas in early stages of development. The body shell should be taken into account due to its influence on the antenna characteristics. For the development of car antennas numerical simulation based on the method of moment (MoM) is used. In a virtual model of the car all important parameters like the glass of the windows have to be considered. Different approaches can be applied to account for these parameters appropriately. In this article, three approaches based on the MoM which are implemented in the simulation framework EMC Studio from the company EMCOS, are discussed as solution to the problem. By means of these, it is possible to take the antenna substrate into consideration, which is an improvement as compared to the basic MoM. A practical case represented by the calculation of the reflection factor (S11-parameter) of an FM-antenna which is placed on the back window of an AUDI A5 was investigated. To compare the proposed approaches, a simulation using each one was performed. A comparison between simulation and measurement results for the described FM-glass antenna is presented. Furthermore, a short insight into virtual development of car antennas is delivered.