Transmitarray Design With Enhanced Aperture Efficiency Using Small Frequency Selective Surface Cells and Discrete Jones Matrix Analysis

Abstract

We present a four-layer transmitarray antenna using small and dense frequency selective surface (FSS) cells and a horn antenna operated in a Ku band satellite downlink (10.7 to 12.75 GHz in Europe). The FSS offers a full transmission phase range of 360° and low loss between the incident and the transmitted waves: the magnitudes of the transmitted waves were equal to or better than −3.5 dB for incident transverse electric and transverse magnetic waves up to 30° in oblique angle. The transmitarray was fabricated using FR-4 boards with a loss tangent of about 0.02. FR-4 boards with lower loss tangents at the operating Ku band were not used because of the requirement for low cost. We also present the design of the horn antenna used to illuminate the transmitarray. The design applies discrete Jones matrix analysis; the final full transmitarray (333 unit cells) with the horn antenna were co-simulated using a full-wave simulation tool. The measured and simulation results are in excellent agreement. With a cell pitch of 0.39 $\lambda _{0}$ , the transmitarray achieves a dynamic range of 20 dB. The measured gain of the transmitarray prototype is 26.2 dB at a center frequency of 11.7 GHz, resulting in an aperture efficiency of about 62%. The measured results were achieved with a very small transmitarray (backpack-fit versus truck-carried). The −1 dB gain bandwidth of the transmitarray antenna is 12.6% at the center frequency (11.7 GHz).