Utilization And Suppression Of Leaky-Wave On Microstrip Line

Microstrip line is a mostly used planar transmission line in hybrid microwave integrated circuit and monolithic microwave integrated circuit. Microstrip line continuously leaks power into space while the electromagnetic wave propagates along the metal strip. Sometimes this kind of leakage is harmful because it will generate cross-talk between nearby components to deteriorate the system performance. However, it is useful in other cases, such as deferent kinds of leaky-wave antenna and radar system using leaky-wave to detect and localize the objects etc. In this thesis, focused on the utilization and suppression of leaky-wave on microstrip line, the physical mechanism of leaky-wave for microstrip line is systematically analyzed. Based on which, we proposed how to utilize the higher order mode on microstrip line to form leaky-wave antenna, and how to suppress the higher order leaky mode on microstrip line.The physical mechanism of leaky-wave on microstrip line is briefly introduced at the beginning of the thesis. Then, a transverse scattering matrix approach based on mode matching technique is used to analyze the eigenvalue problem of microstrip guiding wave structures. This approach is not only appropriate for microstrip line structure, but also applicable for a large kind of waveguiding and transmission line structures. The accuracy and validity of this method is verified by the results obtained with other methods in the literate.Then, the leakage phenomena on microstrip line are analyzed. The leakage of microstrip line has two forms: the surface wave form and the space wave form, and the higher order modes on microstrip line mostly leak as space wave form. In the thesis, the leaky characteristics of the first higher order mode on several microstrip line structures are analyzed and the radiation characteristics of leaky-wave on microstrip line with different parameter are given. A modified suspended microstrip line with multilayer dielectric structure is proposed, and the leaky characteristics of the antenna structure are theoretically investigated. It is demonstrated that a suitable choice of the dimension of the structure can guarantee the antenna working in the antenna-mode region to make the antenna operate in an efficient way. Besides, very...