Understanding Matching Circuits; Plastic Made Quasioptical Multilayer Matching Unit Design at X-band

mm thick rectangular plastic cards having a dimension of 800mm £ 500mm have been used as quasi-optical matching unit at X-band frequencies. Varying number of plastic cards were placed in varying positions between transmitting and receiving antennas, and complex S21 and S11 parameters were measured for each position in order to calculate transmission and re∞ection coe-cient of designed setup. Obtained results showed that increased number of plastic cards from 1 to 6 resulted in decreasing transmission as expected, but certain number of plastic (5 plastics) at a frequency range of 7GHz{9GHz behaves as resonating circuit. Manually adjusted multilayered plastic slots can be atomized as continuous microwave adaptation, and proposed setup is quite understandable by students. Many applications of electromagnetic theory are related with electromagnetic waves' re∞ection and transmission on dielectric interfaces with difierent characteristics (1,2). Measuring dielectric permeability of difierent materials by means of dielectric interfaces is one of the important practical applications. Vector network analyzer is a 2 or 4 port microwave receiver which was designed to measure amplitudes and phases of the waves which are transmitted to or received from the network. An inner computer computes some values such as standing wave ratio, return loss, group delay, impedance by using scattering parameters and shows them on the screen. Kurnaz (3) used same setup for detecting metals embedded in non-conductive materials by radar measurement at X-Band, and Kurnaz etal. (4,5) proposed two studies using same setup. Kurnaz etal. (5) investigated transmittance and re∞ection dependence of monstera leaf on moisture at X- band. In measurement campaign, forward transmission and forward refection coe-cients S21 and S11 were observed with respect to the change of moisture content within the leaf. It is well known that in millimeter waves, the analysis of electro dynamical systems should be carried out taking into account the structural features of the real electromagnetic fleld. The resul- tant fleld can be characterized by in-homogeneity amplitude and phase in transverse direction (2). In this study, varying number of plastic made cards were placed at varying distances that they are following each other, and a vector network analyzer has been used for scanning at X-band. Scope of this study is mainly to teach how multiple interfaces (including distance between layer) afiect re∞ection and transmission of electromagnetic waves passing through the system. 2. THEORY 2.1. Multilayer Structures Vertiy etal. (2) proposed a study about high-quality open resonator system which allow to study, control and afiect on the physical process proceeding in the material medium under the in∞uence of various factors. As he proposed, an efiective resonator method, where multiple quvette placed in resonator volume employing operational measurements of permittivity of weakly absorbing liquids by means of analyzing the resultant spectrum when the liquid is following through the quvette was described.