Reflectarray as plane wave generator for compact antenna test range in millimetre frequency band

Abstract

In this work, a reflectarray is proposed to be used as a plane wave generator (PWG).The reflectarray works at 28 GHz and produces a uniform plane wave in a certain region of the Fresnel region of the antenna, reaching an ultra-compact structure. In a first approach, a far-field focused reflectarray is analyzedto create the plane wave. However, the size where the plane wave is considered uniform is not large enough for its use in compact antenna test ranges (CATR). The desired wave must satisfy tight requirements, both in amplitude and phase, to be considered as auniform plane wave. The generalized Intersection Approach is used to improve the plane wave performances by doing a Phase-Only synthesis (POS)on the phase of the reflectarray elements. Simulations of the plane wave generated by the antenna before and after the optimization process are compared, showing an important enhancement on the uniformity of thewave. The obtained phase distribution is used to design and manufacture a reflectarray based on a three-parallel-dipoles cell. The prototype is measured in a planar range facility to evaluate the quality of the radiated plane wave. Measurements show a low ripple in both amplitude and phase, thus promising results are obtained.