We investigate the aptness of various $4^{th}$ order (90°) rotationally symmetric phase-transforming cells for the upper phase-gradient metasurface, which always receives an oblique incidence wave from the lower metasurface in a Near-Field Meta-Steering system. A comprehensive study on the behavior of various phase-transforming cells and corresponding supercells when a rotating oblique plane wave impinges on them is presented. First, we select the supercell with high transmission in the desired output Floquet modes, for both TE and TM input modes, when an oblique incidence wave is rotated. The selected supercell is then optimized using Floquet analysis in conjunction with particle swarm optimization (PSO). All the undesired modes are successfully suppressed below −32 dB in the optimized supercell, and the predicted broadside radiation pattern is free of spurious grating lobes. A Near-Field Meta-Steering system with an aperture diameter of $7.3\lambda _{0}$ (110mm @ 20 GHz) is presented. It has a pair of optimized phase-gradient metasurfaces and a dipole antenna array. A maximum peak directivity of 24.2 dB is achieved when the beam is in the broadside direction. The proposed steering system is capable of scanning a conical range with an apex angle of 126° when a 6 dB reduction in peak directivity is allowed. For a 3 dB variation in the peak directivity, the corresponding apex angle is 103°.

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Designing Efficient Phase-Gradient Metasurfaces for Near-Field Meta-Steering Systems

A compact, flat beam steerable antenna is described. The antenna includes a waveguide for conveying electromagnetic energy and an adjustable moire pattern assembly disposed adjacent to the waveguide. The moire pattern assembly is arranged to present varying moire patterns comprised of regions of contrasting conductivity. In use, a direction for transmission of the electromagnetic radiation through the moire pattern assembly can be varied by operation of the assembly to alter the moire pattern.

A directional flat-panel antenna

This paper presents a novel reconfigurable SOTM antenna subsystem that possess a complete planar leaky-wave structure, low cost, and 2D-continuous beam steering. The proposed Ka-band antenna is developed from a Substrate Integrated Imaging Guide (SIIG) structure mounted on a conducting ground layer; a number of periodic copper strips are placed on the top surface of SIIG in order to perturb the surface wave and produce fast wave radiation. The mechanical movement of telescopic arm is able to tune the distance between each adjacent strips that leads to a steerable radiating pattern. The proposed antenna design is modelled and successfully verified by full-wave simulation software package.

Gilmore Rowan John

Papers

A directional flat-panel antenna

Low-cost Ka-band Reconfigurable Planar Antenna for Satellite-on-the-Move Application