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.