Design and Implementation of a 4-Antenna Rx Beamforming System with Real-Time Calibration

Real-time calibration for a beamforming receiver is a popular topic. We designed and implemented a 4-antenna Rx beamforming system with real-time calibration. This system sends an out-of-band calibration signal from the transmitter ($T x$) side to calibrate the phase error of in-band received signals in real time at the receiver (Rx) side. The system was successfully implemented and validated on the M3force Software Defined Radio (SDR) platforms. It was verified using not only the accuracy of the direction of arrival (DOA) on the beampattern but also the array gain from the error vector magnitude (EVM) of the demodulated signals with beamforming in the receiver. The system achieved 4.60 dB of array gain and 2.9 degrees of the accuracy of DOA with calibration.