Ultra-Thin Broadband Transmission FSS for Linear Polarization Rotation

Abstract

Frequency-selective surfaces (FSSs), have various applications in microwave electromagnetics. This paper reports a solution to the current FSS challenges of flexibly, low profile, simple fabrication and polarization control using a novel structure operating across X and Ku frequency bands where a linearly polarized wave is rotated by 90°. The FSSs were fabricated by laser engraving a thin layer of $5\mu \text{m}$ aluminum on a $65~\mu \text{m}$ Mylar substrate with a relative permittivity of 2.7, and separated by a dielectric spacing layer of 0.9 mm polypropylene substrate, with a relative permittivity of 3. The co and cross-polarized reflection and transmission response of the structure was investigated using numerical modeling and was measured experimentally. A parametric study was also conducted focusing on key performance indicators, and specifically the bandwidth of the structure. The novelty of this polarization rotation structure lies in its ultra-thin profile ( $0.034~\lambda _{0}$ ), flexibility and significant transmission bandwidth. The fabricated prototypes experimental results were in good agreement with the simulated results, with a simulated −6 dB bandwidth of 61% and a measured −6dB bandwidth of 60%. Applications include antenna radomes where polarization is particularly important, as well as other polarization filtering applications which require a conformal low profile structure.

Keywords

• Flexible
• frequency selective surface (FSS)
• microwave filters
• polarizer
• ultra-thin