New Calibration Matrix Calculation Method for Removing the Effect of Mutual Coupling for Uniform Linear Arrays

In this paper, a new calibration matrix is proposed which helps to remove the effect of mutual coupling for transmitting and receiving uniform linear arrays (ULA) consisting of dipole antennas. In general, a calibration matrix has close relations with the impedance matrix defined by an equivalent circuit of antenna array. In our method, the circuit equation is re-defined whereby the terminal current is separated into two parts according to the different current distributions flowing over the surface of antennas, i.e., radiating and re-radiating current for transmitting mode, receiving and re-radiating current for receiving mode. In order to calculate the calibration matrix, the authors solve a coupling equation which is nonlinear simultaneous equations obtained by measuring the current (or voltage) of antenna terminals in the transmitting mode. This paper shows that the proposed technique allows more precise calibration compared to conventional calibration techniques.