Low-Cost Periodic Sparse Cavity-Backed Phased Array Based on Multiport Elements

Abstract

In this communication, an H-plane sparse cavity-backed antenna array is proposed, and by using multiport elements, the number of array control components such as transmitting/receiving modules, phase shifters, and power dividers is reduced, and therefore cost of the phased array is saved. In the array, each subarray consists of an active and a passive element, and the active element not only works as an antenna but also as a power divider to feed the passive one. A reflection-type phase shifter (RTPS) is designed and integrated between the two elements, whose phase shift is controlled by two reflective loads. The distance between the neighboring active elements is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.225{\lambda}_{0}$</tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\lambda}_{0}$</tex-math></inline-formula> is the free-space wavelength at the center of the operating frequency band), twice of that between the active and the passive elements. Meanwhile, cavity-backed structure is adopted to obtain unidirectional radiation patterns with high aperture efficiency. The proposed array can be used in both wide-angle scanning and limited field-of-view applications. Simulated and measured results are given and discussed to validate the proposed idea.