Free-space evaluation of well-matched periodic structures

In early design stages of connected array radiators, passive evaluation using reflected illumination of test coupons without feed electronics provides a quick and inexpensive validation of design models. Inherent in the measurement setup are assumptions about array antenna behavior and acceptable approximations. Particular questions include the minimum number of unit cells necessary to adequately reproduce array characteristics and appropriate illumination functions. In this paper, those assumptions are examined and the implications for performing such measurements are discussed.