Fast Amplitude-Only Measurement Method for Phased Array Calibration

A novel amplitude-only measurement method is proposed to measure the signals (complex fields) of individual antenna elements for phased array calibration. The proposed method has minimum measuring time among the known amplitude-only measurement methods. The total number of power measurements with this method is about twice the number of antenna elements of phased array. Phase shifters are required to implement only three phase shifts (0 degrees, 90 degrees, and 180 degrees). Array signal power is measured when the phase setting of an antenna element is one of the three phase shifts. According to the superposition principle of electromagnetic field, array signal is a linear combination of antenna element signals. As signal power is the inner product of a complex signal and itself, a set of linear equations concerning the inner products of the antenna element signals are established and solved with the measured data. The element signals are obtained with the inner products analyzed with a set of nonlinear equations. Numerical simulations and experimental results validated the effectiveness of the proposed method in calibrating phased arrays.