Low In-Band RCS Reconfigurable Metasurface With LP Feed for CP Transmission, LP Reflection, and Simultaneous Transmission-Reflection Modes’ Switching

This article introduces a novel 1-bit reconfigurable integrated transmission-reflection (RTRA) metasurface with low in-band radar cross section (RCS). The unit receiving layer in the x-polarization (x-pol.) direction consists of two pairs of goat horn structures with two p-i-n diodes loaded between them. By controlling the states of the p-i-n diodes, a 1-bit reflection bandwidth of 12.9% is achieved in the 00 and 11 states. In the y-polarization (y-pol.), the receiving layer consists of two pairs of rectangular branches with different sizes, achieving a 1-bit reflection bandwidth of 10.9% for static RCS reduction. The transmission layer is composed of a circularly polarized (CP) unit, achieving 1-bit x-pol.-CP transmission when the p-i-n diodes are in the 01 and 10 states. Compared to the RTRA unit provided in the literature, the proposed unit exhibits isolation greater than 60 dB between the x-pol. and y-pol., with a 1-bit reflection bandwidth exceeding 10%. In addition, it has the capability of converting linear polarization to CP, simplifying the feeding structure. The proposed units are arranged in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12\times 12$ </tex-math></inline-formula> array. In the reflection mode, ±60° beam scanning in the E-plane and H-plane is achieved, with cross-polarization between 30 and 50 dB. The aperture efficiency (AE) is 23.02%. In the transmission mode, by the random sequential rotation technique (SRT), the axial ratio bandwidth is enhanced, and ±60° scanning is achieved in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$xo\textit {z}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$yo\textit {z}$ </tex-math></inline-formula> planes. The AE is 15.2%. In the transmission-reflection mode, arbitrary dual-beam scanning is possible. Furthermore, the proposed RTRA metasurface array exhibits in-band RCS reduction characteristics.