Techniques For Measuring The Electromagnetic Parameters Of Ferroelectric Materials With High Permittivity

In recent years, microwave techniques are developed in a high speed. A great variety of antennas and microwave devices are of comprehensive use. As a main element, phase shifter plays an important role in the phased array antenna. Ferroelectric ceramic phase shifters become a pop research issue in the home and overseas. The research and development of ferroelectric materials have attracted many scientists'attention. Following this development, techniques for measuring the parameters of ferroelectric materials in wide band become more and more urgent. But until now, there is no uniform and ripe criterion and technique. Therefore, the research of the technique for testing the permittivity of the ferroelectric material at high frequency is of profound theoretical significance and practical value.Firstly, based on the transmission line theory, the microwave theory and the rectangular waveguide theory, this thesis presents techniques for measuring the parameters of microwave materials at high frequency, and discusses some issues existing in these techniques. Some methods for measuring the microwave materials, such as the transmission/reflection method, the odd/even method, the double-short-circuit method and the partly filling methods, are introduced. The S parameter method, including the transmission/ reflection method and the odd/even method, are described in detail. Problems of these two methods are also discussed.Secondly, the thickness resonance problem is discussed, which help us to choose the proper thickness of the sample. Emphasis is placed on the measurement of the ferroelectric material samples by using the S parameter method and the partly filling method. Compared results show that the S parameter method is suitable for measuring the microwave materials with high permittivity. Moreover, the higher and lower temperature measurements for the ferroelectric materials are carried out. The test results indicate that the permittivity of the ferroelectric material is relatively high, up to 100.Finally, the research work in the thesis is summarized, and the problems remain to be studied and improved further are pointed out.