Evaluation of a simplified Random-LOS measurement setup for characterizing antennas on cars

The automotive industry is in need of reliable, accurate yet cost-effective over-the-air (OTA) characterization methods of the communications systems installed on cars. This paper analyses the scattering contributions to spurious variations of receive signals in a Random Line-of-Sight (Random-LOS) measurement setup in a semi-anechoic chamber. Figures of merit are the delay spread and the dynamic variations of the receive signals. Transmission measurements were performed on a two-element LTE shark-fin antenna mounted on the roof of a Volvo XC90. We show that by using a vertically oriented uniform linear array, with vertically polarized bowtie antenna elements, we can efficiently remove the unwanted ground reflection present when a single bowtie antenna is used. We also show that the improvement depends on the position of the antennas mounted on the car as well as on the azimuthal angle.