Rigorous analysis of rectangular microstrip antennas with parasitic patches

It has been reported that the antenna bandwidth of a microstrip antenna can be significantly increased by adding parasitic patches. Recently, a new microstrip antenna structure with several parasitic patches called the microstrip Yagi array antenna has found applications in mobile satellite systems. One reason for such applications is that the antenna´s mainbeam radiation can be tilted away from the broadside direction, due to strong coupling between the driven and parasitic patches. Because of this strong coupling, the performance of a microstrip Yagi array is very sensitive to various array parameters. A rigorous analysis is thus required to accurately determine the performance of a microstrip Yagi array. This problem is studied by using a full-wave analysis and a moment-method calculation. The characteristics of a microstrip Yagi array are studied.