Wideband LP to CP converter using a reflectarray based on modulated admittance surfaces capable of wide-range beam-scanning for Ku/K band applications

Abstract

This study provides the design and demonstration of a Ku/K band horn-fed linear polarization (LP) to circular polarization (CP) converter using a reflectarray antenna based on the holographic technique and the generalized law of total reflection without any iterative algorithms. The proposed hologram performs wide-range frequency beam scanning with minimum gain losses and cross-polarization levels. It comprises 2,500 diagonal slotted octagonal subwavelength metasurfaces with a periodicity of 0.266λ 0 = 4 mm at 20 GHz as the center frequency. Two equations are defined to compute Y 11 of the proposed unit cell regarding its dimensions for TE(0,0) and TM(0,0) Floquet modes. They significantly simplify the coding procedure and reduce the computational time for synthesizing the hologram. The antenna is simulated using the CST software from 14 to 25 GHz. As a confirmation, a prototype is manufactured and measured at 16, 18, 20, 22, and 24 GHz to verify its performance. The simulated and measured results are well-matched. The presented hologram achieves 40% 1.8-dB axial ratio (AR) bandwidth (16–25 GHz), 40% 3.3-dB gain bandwidth (16–24 GHz), and above 30% 2-dB gain bandwidth (16–22 GHz). Moreover, the antenna can perform beam scanning from 42° to 24° by changing the frequency from 16 to 24 GHz with peak gain values greater than 20.33 dBi. The LHCP pencil beams are at least 24° off-broadside, so the proposed hologram avoids the feed blockage. These achievements make the hologram one of the best candidates for satellite communications, radar applications, short-range communication, and point-to-point communication.