NEAR-FIELD MEASUREMENT METHOD OF A PHASED-ARRAY ANTENNA - MEASUREMENTOF ELEMENT AMPLITUDE AND PHASE FOR ARRAY

One of the measurement methods for a phased array is the rotation elem ent field vector (REV) method. With this method, the relative amplitud e and phase of the radiated field of each element antenna can be found from only the measurement of the amplitude. Hence, an arbitrary radia tion pattern made possible by the tested phased antenna can be realize d. To derive the far-field radiation pattern of a large aperture anten na, the nearfield measurement method is often used. When a phased arra y realizing various radiation patterns is measured by this method, a p rohibitive amount of time is required because the electric field distr ibution on the plane on which the probe antenna moves differs dependin g on the excitation phase distribution. Because it is not possible to obtain relative amplitude, the phase of the radiation field of each el ement antenna necessary for realization of an arbitrary radiation patt ern 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 an tennas at different locations in order to obtain the relative amplitud e 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 anten na being tested. A method is presented for finding the relative amplit ude and phase of the radiation pattern of each element antenna using o nly the measurement of the amplitude.