To optimize the connectivity of the car, the position of the antennas is of high importance. The car is normally made of metal parts which are acting as a ground plane, therefore the body of the car, i.e., the shape is very much affecting the antenna performance and thereby the connectivity. A relatively common vehicle antenna type is the shark-fin antenna that normally is placed on the roof of the car. It is important that the position of the antenna is optimized to get the best possible performance, both regarding the radiation pattern of the antenna and the connectivity.

The material of the roof has, of course, also a big impact on the overall performance of the system. The roof can be made of, for example, carbon fiber or glass (2). The roof can also be missing as in convertible cars (3), and then an alternative placement of the antenna is needed. This will for sure have an impact on the communication system performance.

An antenna mounted on a glass roof can be an attractive design but is not optimal for the performance of the communication system. The same applies to a car without a roof because the antenna must be placed in an alternative location, for example at the back of the car. In this application note, we will give examples on how different placements of the antenna can result in a reduction of the communication distance.

To be able to position the antenna with best possible communication quality as a result, there is a need of accurate test methods. Tests of a whole car are rather complex processes and expensive test facilities are needed. The needed test equipment is advanced and there is only a few of these test facilities available which make the verification cumbersome.

This is not a practical way forward; the engineers need to perform measurements throughout the whole development process. A misplaced antenna will result in unnecessary bad communication system performance such as, for example, to short communication distance and low communication capacity. RanLOS test setup is designed to be an easy-to-use measurement tool for antenna and throughput measurements. The test equipment is designed to be used in existing chambers or in open areas with weather protection. A long series of verifications and tests have been carried out to verify the quality of RanLOS test technology and these have shown that the technology is very reliable