Design of miniaturized beam scanning microstrip antenna with isolated ports and review of antenna miniaturization technics

Abstract

In this study, the first chapter explains the working models of patch antennas in simple language: the transmission line model, which provides a very good convergence method for determining the antenna dimensions and understanding the fringing effect. The cavity model helps us understand how the patch antennas radiate and which mechanisms affect the radiation pattern. In addition, antenna parameters are explained with examples and figures. The second part identifies and describes antenna miniaturization methods in the literature. The importance of miniaturization today is mentioned in the chapter. The miniaturization methods in the literature are examined and compared to each other. In addition, a rectangular patch antenna was designed to demonstrate miniaturization methods. Applying the described methods on this reference antenna evaluates the pros and cons of the methods. At the same time, to show that the methods can be combined, designs where the methods are used together are also realized. All the designs and methods applied in the chapter are evaluated at the end of the chapter. The third chapter found an antenna that can perform beam scanning using odd and even modes on the patch antenna found in the literature. Miniaturization was performed on this antenna, which has a structure consisting of a combination of two miniaturized antennas, and the isolation problem between the ports of the design was applied to the antenna in our hand by using another work in the literature. In the first step, a substrate with a higher dielectric coefficient was used for miniaturization, and the antenna structure was miniaturized by adding slots to the patch. At the same time, in the next steps, the design is modified to use an aperture-coupled feeding method as it offers a better solution for isolation. A reflector is added to the design to suppress the back-lobe radiation resulting from the modified design. Then, isolation between the ports was achieved using the Y parameters, as described in detail in the thesis. The proposed design is manufactured for validation, and the isolation method is confirmed via the measurement of S parameters with simulation. The thesis encompasses a comprehensive overview of patch antennas, delving into their fundamental principles while emphasizing the miniaturization of antenna designs. Notably, the research addresses and rectifies existing design limitations found in the literature through the process of miniaturization. On the other hand, at the design steps, the antenna is miniaturized using these methods and port isolation provided by the designed decoupling feeding network. The isolation steps are described in detail, explained with a literature review, and applied the antenna. As a result of these afford the beam scanning miniaturized antenna with isolated ports is obtained.