Plane Wave Synthesis with Irregular Chamber Planar Antenna Arrays for Compact OTA Measurements

Over-The-Air (OTA) testing techniques shall meet cost- and time-efficiency as well as measurement accuracy constraints stemming from the characterization of massive multi-element array antennas in 5G systems. The Random-LOS (Line-of-Sight) OTA measurement setup aims at emulating a plane wave field in the test zone of the measurement chamber. The test zone is in the near-field of the chamber antenna used to emulate the far-field from a base station. In this paper, the thinned array antenna concept is applied to synthesize the plane wave field within the test zone. The thinning is performed by means of the Genetic Algorithm. Two planar array antenna configurations are considered for emulating a plane wave for 2D and 3D test zones at 2.7 GHz. The optimized thinned array achieves a 55% reduction of the number of antenna elements. In addition, amplitude and phase fluctuations in the test zone have been considerably reduced in comparison to other similar array antennas, in this way, improving the measurement accuracy in Random-LOS OTA measurement setups.