Design and optimization of dielectric resonator antenna arrays based on substrate integrated waveguide technology for millimeter-wave applications

Abstract

With the lower frequency bands heavily crowded, the millimeter wave (MMW) frequency band has attracted a lot of attention, offering a wide range of applications. It also introduces new challenges to the research community. Antennas and MMW circuits with compact size, low cost, high efficiency, and low loss are much needed to meet the new requirements of these applications. This research focuses on the design and optimization of dielectric resonator antenna (DRA) arrays based on substrate integrated waveguide (SIW) technology, which has been proven to be promising for MMW applications. The objectives include both the development of highly efficient computer aided design and optimization techniques, and the development of new designs based on the SIW-DRA technology. Toward these objectives, an efficient and accurate circuit model is developed first. A previously reported structure of DRA array is investigated based on two different slot orientations. The total mutual coupling between antennas is firstly extracted and modeled as a two port S-parameters. Two different methods are used to extract the total mutual coupling due to the difference of the slot configurations. Next, a new and fully adjustable model for the mutual coupling is developed for DRA array, resulting in a flexible circuit model allowing the design parameters to be varied. A comparison with full wave simulation and measurement results proves that the circuit model can be used as an efficient design and optimization tool. The model is further verified through a new design of SIW-series fed DRA parasitic array, in which an additional parasitic DRA is added on both sides of each active element to improve the gain. The antennas are fed using longitudinal slots on SIW. Due to the configuration of the antenna elements, there is strong mutual coupling between the antenna elements. The good agreement between the electromagnetic (EM) simulated and circuit model results for this design further proves the efficiency of the model.Next, a new design of an eight-element SIW middle fed series rectangular DRA array with 45° linear polarization is developed. The implicit space mapping (ISM) technique is applied for the optimization of the complex structure. The new circuit model plays an important role in the optimization method serving as the coarse/surrogate mode, and a full wave solver is used as the fine model. Parameters in the surrogate model are divided into pre-assigned parameters and design parameters. In each iteration, the preassigned parameters are extracted so that the fine model and surrogate model outputs match. The design parameters are then re-optimized and fed to the fine model. As demonstrated with this DRA array design, the optimization approach combining the developed circuit model with ISM technique is highly efficient. Only three iterations are needed to reach an optimized solution for such a complex structure. The optimized design has been fabricated using a low cost Printed Circuit Board (PCB)-based technology for validation of both performance of the design and modeling techniques. The comparison between the simulated and the measured results shows very good agreement.