Antenna optimization techniques for wireless communication

Abstract

Antenna design optimization using full EM simulation is computationally expensive and does not include conventional design techniques or the working mechanism of antenna design. In order to design antennas in a smarter way, design techniques need to be incorporated into parameter optimization. One of the important ways to achieve this is to pixelate the metal on the designed surface. For the first research contribution, we incorporate N-port Characteristic Mode Analysis (CMA) into the formulation to obtain an objective function that characterizes the fundamental resonances of the pixel antenna. These fundamental resonant properties of the pixel antenna are found without requiring the selection of the feeding ports and therefore our method can provide optimization with better antenna performance without needing to optimize the feed positions simultaneously. For the second contribution feeding port optimization is proposed by using sequential feeding port selection. This can greatly reduce the search space and computational load. In addition, this approach does not require additional complex feeding networks or impedance matching circuits. This makes the design simple, compact and practical. For the third contribution, perturbation sensitivity is used to assist the optimization of pixel antennas, making it possible to use gradient based optimization algorithms. Specific algebraic techniques are used to calculate the perturbation sensitivity of each port, which avoids the inversion of impedance matrices at each evaluation of the objective function. This significantly reduces the computational load and results demonstrate better optimization performance compared to GA and SEBO. For the fourth contribution, space mapping (SM) is utilized to optimize multiple-input and multiple-output (MIMO) antennas. SM is formulated for the optimization of MIMO antennas and the scope of the coarse models is also expanded to include radiation efficiency. We extend parameter extraction (PE), to MIMO antennas, and also extend the IMPM approach to continuous tunable loads to optimize the isolation of external ports using SM. Throughout the thesis presentation, experimental results are provided to demonstrate the improvements that the new algorithms and techniques, developed during the thesis, provide.

Date of Award	2021
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Ross MURCH (Supervisor) & Qingsha CHENG (Supervisor)