This study presents a polarisation-independent metasurface harvester composed of an ensemble of novel electric-field-coupled inductive-capacitive (ELC) resonators. The ELC resonator has full symmetry in a way that its behaviour is highly insensitive to the polarisation of the incident wave. Loading the resonators with resistors (which model the input impedance of a power combining circuit in a harvesting system), it is shown that the metasurface absorbs the incident electromagnetic wave energy, with nearly unity harvesting efficiency, irrespective of its polarisation while simultaneously delivering the absorbed power to the loads. As a proof of concept, a metasurface harvester composed of a 9 × 9 resonator array working at 2.45 GHz was fabricated. Near-unity harvesting efficiency of the metasurface was demonstrated using full-wave numerical simulation for a wide range of polarisation angles. Laboratory tests showed strong agreement between the simulation results and the measurements.

A novel magneto-electric dipole antenna with wide H-plane beamwidth, triple-linear polarisation and frequency reconfiguration is proposed for 5G communications. In this study, the radiated dipoles are designed with the arc-shaped planes to exhibit wide H-plane performance. A bent cross-dipole feed with PIN diodes and varactor diodes inserted into its four arms at different altitudes is utilised to excite and control the antenna. Consequently, a measured wide beamwidth ranging from −67° to 67° can be achieved in H-plane. In addition, the height of the proposed antenna decreased about 30% due to the bent designs. Finally, by controlling the PIN diodes and varactor diodes, the three kinds of linear polarisations and frequency reconfiguration functionalities for 2G/3G/LTE/5G applications can also be easily obtained. With the above-mentioned features, the proposed antenna well suits for intelligent base-station communications.

The deformation of reflector surface can be obtained by Misell algorithm using two far-field amplitude patterns: one with the antenna in focus and the other with the antenna defocused. For reflector antennas with active surface, the defocused pattern can be measured by adjusting the panels to get a more effective phase factor instead of offsetting the sub-reflector. The shape and size of phase factor have a great influence on the accuracy of convergent solution. To improve the performance of Misell algorithm, this study proposed an optimisation method for phase factors under different surface deformations. This method utilises Levenberg–Marquardt algorithm to get an estimation of the aperture distribution and then applies the particle swarm optimisation to optimise the phase factor parameterised by Zernike polynomials. Numerical simulations show that the proposed method is an efficient tool to achieve applicable phase factors under different surface deformations. Using the optimised phase factor, Misell algorithm can get a better convergent performance than traditional Misell algorithm.

This study presents the study of beamforming capabilities of arrays installed on a non-conductive unmanned aerial vehicle (UAV). The main purposes of this study are the application of a beamforming algorithm by including the airframe in the optimisations and the study of simplifications of the aircraft model, so as to allow performing full-wave simulations, even though the UAV is much larger than the operating wavelength. To validate the simplified electromagnetic model, antenna arrays have been designed and installed onto the UAV. Radiation pattern measurements demonstrate that the proposed simplifications yielded very good radiation pattern predictions and can be used as guidelines for simulation of other kinds of non-conductive aircrafts.

A gaseous plasma antenna array (PAA) is an aggregate of plasma discharges and possibly conventional metallic radiating elements, and it constitutes a promising alternative to metallic antennas for applications in which fast reconfiguration of radiation pattern, and gain is desired; such properties can be achieved by exploiting the electronic switch on/off condition of plasma discharges, and tuning of the plasma parameters. Here, the authors present a reconfigurable PAA that features a central metallic half-wavelength dipole working around 1.45 GHz, surrounded by a planar circular lattice of cylindrical plasma discharges. Customised plasma discharges have been realised, and filled with argon gas at 2 mbar so as to have a complete control on the plasma discharge properties (e.g. plasma frequency, collisional frequency). The magnitude of the reflection coefficient, and the gain pattern on the H-plane have been investigated numerically and experimentally; numerical and experimental results exhibit a good agreement and show that the central intrinsically omnidirectional antenna can provide simple beamforming capabilities upon turning on a subset of plasma discharges; as these plasma discharges are turned on, the authors have observed a maximum gain of ∼5 dBi, a half-power beam width of , and an angular steering resolution of ∼.