Near-field measurement method of a phased-array antenna - Measurement of element amplitude and phase for array

One of the measurement methods for a phased array is the rotation element field vector (REV) method. With this method, the relative amplitude and phase of the radiated field of each element antenna can be found from only the measurement of the amplitude. Hence, an arbitrary radiation pattern made possible by the tested phased antenna can be realized. To derive the far-field radiation pattern of a large aperture antenna, the nearfield measurement method is often used. When a phased array realizing various radiation patterns is measured by this method, a prohibitive amount of time is required because the electric field distribution on the plane on which the probe antenna moves differs depending on the excitation phase distribution. Because it is not possible to obtain relative amplitude, the phase of the radiation field of each element antenna necessary for realization of an arbitrary radiation pattern cannot be obtained. When the REV method is applied for near-field measurement, the direction of the probe antenna seen from each element antenna differs with respect to the reference direction installed on the phased-array antenna. Therefore, it is necessary to find both the amplitude and the phase of the electric field received by the probe antennas at different locations in order to obtain the relative amplitude and phase of the radiated field of each element antenna in the same direction needed for the radiation pattern synthesis of the far field. In this paper, a phased-array antenna is used as a probe antenna. The REV method is applied to both this antenna and the phased-array antenna being tested. A method is presented for finding the relative amplitude and phase of the radiation pattern of each element antenna using only the measurement of the amplitude.