Analysis of wide-band infinite phased arrays of printed folded dipoles embedded in metallic boxes

A theoretical method is presented to analyze the scan performance of infinite phased arrays of printed folded dipoles embedded in metallic boxes. By using the equivalence principle, each unit-cell is divided into an inhomogeneous interior region and a homogeneous exterior region. The exact dyadic Green's function for both regions is derived. The current distribution on the antenna elements and the corresponding active impedance are found by solving the pertaining integral equations with the method of moments. Numerical results show that the E-plane scan performance is improved significantly by placing the folded dipoles inside metallic boxes. Without the use of additional matching circuits a bandwidth of more than 16% was obtained over a wide scan range. A disadvantage of the use of metallic boxes is the strong appearance of a blind scan angle at the higher frequencies. Measurements of the element pattern of an 1152-element prototype show a very close agreement with the presented theoretical computations.