Abstract
Recently, due to the improvement of solid microwave components and semiconductor technology, the applications of microwave components have been realized in cars, airplanes, wireless phones, burglar alarms and fire alarms, etc. The most concerned topic among these applications is microwave communications, because it has capacitance for huge amount of communication channels. One of the most popular types of planar transmission lines is the microstrip line, which is discussed thoroughly in this thesis, primarily because it can be fabricated by photolithographic processes and is easily integrated with other passive and active microwave devices. If we want to transmit signals of electromagnetic waves via microstrip, it is necessary to take the geometry of microstrip and properties of coating materials into consideration. For all of these will change the amount of electromagnetic wave loss, and, moreover, affect the amplitude of electromagnetic waves received. Now this experiment applies a concise and systematic procedure, which measures how the conductivity of different coating metals responds to frequency under DC and microwave spectra. The processes this experiment applies are mainly focused on thermal evaporation and sputtering methods. And the T-junction microstrips are produced with these processes mentioned above. At the beginning of this experiment, the microstrip is either applied with DC voltage or microwave signals to measure the conductivities of coating metals. The results are compared after measuring the conductivity variations under different temperatures and annealing conditions. It is found that as far as normal metallic films are concerned, the conductivities are approximately commensurate with the Drude model and do not change with the frequency. But when the frequency increases, the value of the conductivity decreases slightly due to the larger radiation loss. In addition, the mending of the lattices of metallic films causes larger value of the conductivity after annealing is performed. For abnormal metallic films, because the lattice contains more defects or higher concentration of impurities, the localization effect of electron occurs and the conductivity decreases sharply. At this time, however, the conductivity is not irrelevant with the frequency anymore; instead, it is directly proportional to the frequency, which can not be explained by the Drude model. Although the value of the conductivity increases after annealing, its direct-proportional relationship with frequency remains unchanged. Besides, it is found that the conductivity increases gradually when the measuring temperature decreases. Meanwhile, the resonant frequency also increases owing to these factors such as shrinkage of samples, decrease of dielectric constants…etc.