Reduced Distance OTA Testing Methodologies for Automotive Applications

Over the Air (OTA) tests at reduced distances offer several advantages with respect to classical far field approaches based on large measurement distances or complex and expensive measuring devices (e.g. CATR). The most appealing benefits of such type of tests are the cost-effectiveness, achieved by the relatively small anechoic chambers, and the reduction of the system path losses (higher dynamic range). On the other hand, the possible loss of accuracy due to the reduced distance represents a concern. In this paper the uncertainty due to the reduced measurement distance will be investigated by means of simulations and measurements. The parallax compensation technique, useful in case of displaced antennas, will be also considered as possible tool to reduce the measurement uncertainty. Actual OTA measurements performed with two different approaches will finally be compared to remark the estimated uncertainties.