Analysis and design of 1D metasurface antennas

Details

Supervisors

Craeye, Christophe ; Raskin, Jean-Pierre

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électricien, à finalité spécialisée

Abstract

Metasurfaces (MTS) are artificially engineered 2D structures that exhibit, in a given frequency band, macroscopic (at the wavelength scale) properties that go beyond those of usual surfaces. Metasurface sheets are commonly implemented as a dense array of subwavelength scatterers, possibly printed on a grounded slab. They can be designed to arbitrarily transform an incident wave in reflection or in transmission. In this thesis, metasurfaces are designed to manipulate the dispersion characteristics of excited surface waves (SW) to progressively transform those surface waves into leaky waves (radiation). A 1D metasurface antenna is considered, which is assumed to be fed by a plane wave SW launcher. The MTS is modelled as a modulated impedance sheet laying on a grounded slab. The design procedure proposed in this thesis is decomposed into three stages. First, the analysis of the current distribution along MTS antennas is performed through simulations based on the solution of integral equations for the electric field (EFIE). The resulting linear system of equations is solved into a set of orthogonal basis functions using the Method of Moments (MoM). Then, the design of MTS antennas is realized through the modification of the surface impedance to achieve the desired radiation characteristics. Based on the a priori knowledge of the currents from the desired radiation pattern, the surface impedance, decomposed into pre-determined basis functions, is computed. The last step of the design procedure is the implementation of the computed surface impedance with metal patches to obtain the physical structure of the antenna. The implemented design procedure is applied to different patterns of increasing complexity: a simple pencil beam, multibeams and a flat-top beam.