Reconfigurable transmissive metasurface with a combination of scissor and rotation actuators for independently controlling beam scanning and polarization conversion.

Polarization conversion and beam scanning metasurfaces are commonly used to reduce polarization mismatch and direct electromagnetic waves in a specific direction to improve the strength of a wireless signal. However, identifying suitable active and mechanically reconfigurable metasurfaces for polarization conversion and beam scanning is a considerable challenge, and the reported metasurfaces have narrow scanning ranges, are expensive, and cannot be independently controlled. In this paper, we propose a reconfigurable transmissive metasurface combined with a scissor and rotation actuator for independently controlling beam scanning and polarization conversion functions. The metasurface is constructed with rotatable unit cells (UCs) that can switch the polarization state between right-handed (RHCP) and left-handed circular polarization (LHCP) by flipping the UCs to reverse their phase variation. Moreover, independent beam scanning is achieved using the scissor actuator to linearly change the distance between the UCs. Numerical and experimental results confirm that the proposed metasurface can perform beam scanning in the range of 28° for both the positive and negative regions of a radiation pattern (RHCP and LHCP beams) at an operational frequency of 10.5 GHz.

Thermal spiral inductor using 3D printed shape memory kirigami.

Spiral inductors are required to realise high inductance in radio frequency (RF) circuits. Although their fabrication by using micro-electrical-mechanical systems, thin films, actuators, etc., has received considerable research attention, current approaches are both complex and expensive. In this study, we designed and fabricated a thermal spiral inductor by using a three-dimensional (3D) printed shape-memory polymer (SMP). The proposed inductor was inspired by kirigami geometry whereby a two-dimensional (2D) planar geometric shape could be transformed into a 3D spiral one to change the inductance by heating and manually transform. Mechanical and electromagnetic analyses of the spiral inductor design was conducted. Hence, in contrast with the current processes used to manufacture spiral inductors, ours can be realised via a single facile fabrication step.

Dynamically Self-Reconfigurable Multifunctional All-Passive Metasurface.

Reconfigurable metasurfaces have shown their great potentials and are needed in multiple applications, such as radar, wireless communication systems, and security. To date, however, it is challenging to realize low-cost and simple reconfigurable and multifunctional metasurfaces. In this proposed work, we present a low-cost and simple multifunctional all-passive metasurface that achieves a self-switching characteristic relying on a modulating incident wave without additional supporting devices. As proof-of-principle application examples, we realize a prototype of the proposed all-passive metasurface with an antenna for radome applications, that can achieve self-switching operation between a high directional antenna at the transmitting mode, and radar absorbing structure and reflector at the receiving mode. The reported strategy will open up a new avenue for future smart devices and could extend to some smarter applications such as high-power pulse skin protection for electronic devices and self-reconfigurable beam switching metasurface.

Design and Analysis of Active Metamaterial Modulated by RF Power Level.

In this paper, a radio frequency (RF)-power-modulated active metamaterial loaded with a nonlinear Schottky diode is presented. Its operating mode is a function of the incident power level. It is switched by a change in the operating state (i.e., on/off) of the Schottky diode, which is directly triggered by a change in the incident power level. For instance, when a low-power RF radiation is incident on the proposed metamaterial, the Schottky diode is turned off, and the metamaterial passes a 2 GHz signal in the pass-band mode. By contrast, when a high RF power is incident, the diode is turned on, and the metamaterial reflects all frequencies in the reflection mode. The proposed active metamaterial was analysed by performing numerical simulations for both low- and high-power modes, and the proposed concept was successfully demonstrated by circuit analysis, full-wave simulation, and experimental results.