Configurable multi-port radiators

Abstract

A configurable aperture antenna is a type of antenna that can dynamically adjust its radiation pattern, gain, or frequency response through electronic or mechanical means. This flexibility allows the antenna to adapt to varying operational conditions, optimizing performance for different scenarios such as changing communication environments, targeting specific directions, or improving signal reception. In this thesis, we introduce design methodologies to implementconfigurable multi-port antennas that can provide far more design flexibility. Using a small-scale abstraction of the multi-port network, we develop scalable circuit-level interpretations of the radiators that overcome the need for full-wave design and simulation of the apertures. As a proof of concept, we developed some large-scale multi-port antenna prototypes with the ability to adjust their center frequency while synthesizing a desired far-field pattern only by modulating the excitation phasors applied to the input ports. In our first project, we present a scalable design methodology to implement configurable apertures based on an abstract modeling and representation of multi-port coupled antennas. As proof of concept, we design, fabricate, and measure an 11-port wire antenna based on the proposed approach. The prototype shows both frequency and beam reconfigurability and reasonably matches design predictions. Additionally, we provided a strategy for synthesizing the power spectrum in multi-port antennas through phase profile optimization of port excitations. The proposed method enables wideband operation while selectively accepting power within desired frequency bands, effectively handling part of the RF filtering on the receiver side. Experimental results on a multi-port wire antenna prototype demonstrate the ability to maximize accepted power at target frequencies and reduce the accepted power level at undesirable frequencies. Our second project introduces the concept of a multi-port periodic antenna for generic beam synthesis in 2D apertures. We propose the use of a periodic structure based on a strategically designed unit cell excited at its boundaries, forming a multi-port traveling wave structure. We introduce an analytical method to predict the large-scale radiation properties of the antenna only based on the S-parameters of the unit cell and by incorporating Bloch eigenmodes of the periodic structure. As a proof of concept, we design and fabricate a 12-port Dirac periodic antenna prototype capable of synthesizing a desired 2D far-field pattern by modulating the excitation phasors applied to the input ports. Measurements demonstrate that the proposed configurable aperture can directly synthesize, radiate, and steer single or multiple beams. Our final project explores the use of multi-port patch antennas as configurable radiators in modern wireless systems for beamforming applications. We introduce an analytical design method based on the cavity model. We illustrate two mm-wave antenna design examples as the practical use of our proposed method to achieve both two-dimensional beam scanning and multi-beam capabilities with the multi-port patch antennas.