Ultrathin Complementary Metasurface for Orbital Angular Momentum Generation at Microwave Frequencies

TL;DR

This paper introduces an ultrathin complementary metasurface that efficiently generates microwave orbital angular momentum waves with arbitrary orders, simplifying design and reducing simulation time.

Contribution

The work presents a novel ultrathin metasurface design and simplified models for efficient OAM wave generation at microwave frequencies.

Findings

High transmission efficiency achieved.

Simplified models reduce design complexity.

Effective generation of OAM with arbitrary orders.

Abstract

Electromagnetic (EM) waves with helical wavefront carry orbital angular momentum (OAM), which is associated with the azimuthal phase of the complex electric field. OAM is a new degree of freedom in EM waves and is promising for channel multiplexing in communication system. Although the OAM-carrying EM wave attracts more and more attention, the method of OAM generation at microwave frequencies still faces challenges, such as efficiency and simulation time. In this work, by using the circuit theory and equivalence principle, we build two simplified models, one for a single scatter and one for the whole metasurface to predict their EM responses. Both of the models significantly simplify the design procedure and reduce the simulation time. In this paper, we propose an ultrathin complementary metasurface that converts a left-handed (right-handed) circularly polarized plane wave without OAM to a right-handed (left-handed) circularly polarized wave with OAM of arbitrary orders and a high transmission efficiency can be achieved.