UCLA

In the first part of this thesis, non-periodic metasurfaces are explored to realize blazing effects under oblique plane-wave illumination. Genetic Algorithm is used to optimize the surface’s local reflection phase over the entire finite aperture, for a particular scattering response (e.g. blazing). Such non-periodic and random surfaces can open doors for the design of blazing surfaces beyond typical periodic gratings and their limitations, e.g. reducing and flattening of side-lobe levels, as well as other scattered beam characteristics such as beam-splitting. The theoretical method is verified by full-wave electromagnetic simulations at X-band, and measurements.

In the second part, a novel leaky waveguide is proposed which is assisted by metasurfaces. This waveguide can support a half TE10 mode using a perfect magnetic conductor for one wall, and therefore is more compact in size. The principle of operation and the dispersion diagram are then presented. The structure has the advantage of being simple, low cost, easy to fabricate, and requiring no vias, pins, or dielectric blocks. The guided wave shows leakage (radiative loss) along propagation by spilling energy to the orthogonal polarization (parallel plate mode) and radiating into free space from the sides. Based on this, one potential leaky wave antenna application is proposed.