True-time-delay reflectarray and transmitarrays based on miniaturized element frequency selective surfaces

In this paper, we propose a broadband true-timedelay reflectarray antenna composed of a low-profile planar MEFSS-based reflectarray fed with a horn antenna. The proposed reflectarray exploits the unit cells of ground-plane-backed miniaturized-element frequency selective surfaces (MEFSS) as its spatial time delay units (TDU) to operate in a true-time-delay (TTD) fashion and to reduce chromatic aberrations within a wide frequency band. A prototype of the proposed reflectarray with focal length to aperture diameter f/D of 0.87 is designed to operate at the center frequency of 10 GHz with an operational bandwidth of more than 40% in TTD fashion. It is demonstrated that the designed reflectarray shows a relatively consistent radiation properties over its frequency band of operation. The results also confirm the wide scanning properties of the proposed antenna in the ±45° range when the reflectarray is fed with multiple antennas to achieve a multi-beam aperture.