In this paper, we describe the principle, hardware/software setup, calibration and verification measurement results of a wave field synthesis (WFS) over-the-air (OTA) testbed for global navigation satellite systems (GNSS). It represents a new approach that, in contrast to conventionally conducted and open-field tests, realistically emulates real world scenarios under controllable and repeatable conditions. This enables the realistic comparison of receivers and algorithms especially for multi/beamforming antenna receivers as well as for receivers with integrated antennas. Having outlined the architecture and hardware setup of the WFS OTA testbed together with the GNSS constellation simulator, we describe the current 2D setup and the upcoming 3D installation. Then we discuss and present results of two different ways of calibration and validation carried out in the 2D setup: firstly, using an electromagnetic field probe, and secondly, using a commercial geodetic GNSS antenna with reference receiver in a 2.5D emulation.