Plasma-Based Intelligent Reflecting Surface for Beam-Steering and Polarization Conversion

Abstract

The design of a reflective surface operated in the GHz range is proposed to enable beam-steering and polarization conversion simultaneously. The concept presented in this work relies on plasma-based Intelligent Reflecting Surfaces (IRS) in which the plasma is magnetized. Plasma-based IRSs have been introduced recently and consist of rectangular plasma discharges placed on top of a metallic ground plane. The reflected signal can be reconfigured electronically by varying the plasma parameters (e.g., density). First, a theoretical model is exploited to evaluate the capability of a plasma-based IRS to implement beam-steering and polarization conversion simultaneously. Second, the preliminary design of two plasma-based IRSs is presented to combine beam-steering with 1) cross-polarization or 2) linear-to-circular polarization conversion. According to the numerical results, the proposed concepts are feasible assuming the plasma density can be reconfigured in the range 4.9 × 10 17 -13.7 × 10 17 m −3 and the intensity of the magnetostatic field in the range 60-183 mT; these values are consistent with the plasma technology at the state-of-the-art. The operation frequency is 10 GHz, and the bandwidth is between 0.5-0.8 GHz for the two plasma-based IRSs presented in this work.INDEX TERMS Gaseous plasma antennas, intelligent reflecting surfaces, beam-steering, polarization conversion, linear-to-circular, cross-polarisation.

Plasma-Based Reflecting and Transmitting Surfaces

“…These values are compatible with standard horn antennas [30]. Finally, the bandwidth of the plasma-based systems is generally large compared with more standard solutions [24], [27], consistently with the reflecting surface technology [9]- [11].…”

“…ξ pl identified to implement beam steering and polarization control are consistent with the plasma technology at the state of the art [29]. Clearly, this solution requires a larger value of ξ pl with respect to a plasma reflecting surface [9]- [11] to ensure a propagation path long enough to implement the desired features while maintaining |T | ≈ 1. Similarly, higher, but still realistic, values of B 0 are needed to exploit polarization conversion.…”

“…Finally, once E r and E t are known, the capability of a plasma surface to exploit polarization conversion is quantified in terms of Polarization Conversion Ratio (PCR) and Axial Ratio (AR) [10], [11]. The former describes the crosspolarization conversion while the latter conventionally defines a circularly polarized signal if AR < 3 dB [30].…”

“…1. Thus, a rectangular plasma block of thickness ξ pl is analysed assuming Floquet boundary conditions along the ηaxis and ζ-axis while open boundary conditions are imposed along the direction of propagation of the plane wave (i.e., the ξ-axis) [9]- [11]. The horn antenna is simulated assuming open boundary conditions in all directions.…”

“…Among GPAs, plasma-based reflecting surfaces are particularly suitable to implement beam steering [9], polarization control [10], and to combine these two features [11]. Numerical designs have been proposed to implement plasma-based reflecting surfaces via Cold Cathode Fluorescence Lamps (CCFL), which is a plasma production technology at the state of the art [12], [13].…”