Calibration Array Based Near-Field Multi-Probe OTA Calibration for 5G Phased Arrays

In order to quickly and efficiently calibrating a large number of 5G phased arrays operating in 1.8~6.0 GHz, a novel near-field multi-probe OTA (over the air) calibration method is presented in this paper. In this method, the reference data is firstly extracted from a calibration array, Then the channels’ amplitudes and phases of DUT (device under test) are calibrated according to the linear transfer functions of the calibration array from the near field to the far field. The reasons for the calibration errors and their influences have also been studied. A principle verification system with a 4×4 near-field probe array is fabricated to validate the feasibility and accuracy of the proposed method. The measured results show that the amplitude and phase of the calibration error are within ±0.5dB and±5°, respectively. Comparing the existing OTA calibration systems, the new system has much smaller size, higher efficiency, the very close calibration accuracy, which demonstrate a promising ability of fast calibrating batched 5G phased arrays on production lines.