UCLA

Real-life communications applications necessitate the development of antennas with different patterns and radiation characteristics. Antennas that can produce the beam scanning in a conical sweep can be advantageous for applications such as spaceborne wind scatterometers weather radars. This work presents the synthesis, prototyping and measurements of threeantennas that can produce the conical beam scanning: The 3D-printed shaped and materialoptimized lenses, the flat-layered meta-lenses, and the transmitarray antennas. The synthesis of the 3D-printed lens and meta-lens inhomogeneity requires the use of a software package hybridizing the computational electromagnetics method of Geometrical optics (GO) with the optimization strategy of Particle Swarm Optimization (PSO). Additionally, a new synthesis algorithm is presented for the design of transmitarrays that can produce the conical beam sweep based on the optimization of the feed location and a modified transmitarray phase compensation. Novel implementation and fabrication methods based on additive manufacturing and metamaterial structures are presented for the realization of the proposed antennas. In the last part of this work, Orbital Angular Momentum (OAM) beams for antenna applications are investigated. The theory and mathematical formulations of the far-field properties of OAM beams using the antenna aperture field method are presented in a systematic and comprehensive manner. Transmitarray antennas are proposed to generate circularly-polarized (CP) OAM beams with cone-shaped radiation patterns. Antennas with cone-shaped patterns can be advantageous for applications such as geosynchronous satellite based navigation and guidance systems that serve moving vehicles and ceiling-mounted indoor wireless systems. An ultra-thin “S-ring” transmitarray unit cell is introduced to support CP that can provide arbitrary CP phase compensation by proper rotation of the elements. The synthesis, prototyping and measurement validation of a proof-of-concept transmitarray prototype are presented and demonstrate that the proposed transmitarray antenna can be a unique apparatus that generates CP OAM cone-shaped patterns.