Array antenna characterization technique based on evanescent reactive-near-field probing in an ultra-small anechoic box

This paper presents a new technique in which small array antenna performance is characterized based on reactive-near-field probing in an ultra-small anechoic box and with a multi-probe. Unlike conventional far- or near-field measurement methods, the radiation patterns in the proposed approach are computed from the currents only at discrete points picked up in the evanescent region of an array antenna´s elements. An equivalent weight vector is introduced to effectively eliminate the need for sensor scanning. Cross correlation coefficients between the far-field patterns of a conventional measurement and the reactive-near-field ones are as high as 0.933 to 0.998 for single-probe pick-up and as high as 0.885 to 0.988 for multi-probe pick-up. This shows that the proposed technique can replace large anechoic chambers currently used for characterizing small array antennas´ performance.