Calculating the Phase Center of an Antenna: A Simple Experimental Method Based on Linear Near-Field Measurements. [Measurements Corner]

In this article, a simple experimental method based on linear near-field (NF) measurements for finding the real position of the phase center of an antenna is presented. To do that, measurements along both principal axes of the antenna are carried out. Then, each set of data is treated individually to determine the phase center for each principal plane. In this method, the measured phase is expressed in terms of the relative position to the axis as a quadratic expression, in which the independent term gives the perpendicular distance from the points of the measurement to the estimated phase center. Thus, this value is obtained by adjusting a second-order polynomial expression to the curve of the measured phase. The operational limits of the method are generally determined by the amplitude variation of the measured field. To establish these limits and verify their functionality, a series of simulations is carried out. Finally, the method is used to characterize some real antennas.