Study On The Measurement System Based On The Novel Coupler For Complex Permittivity

With the rapid developing of the modern electronic information technology, theresearch and measurement of dielectric material plays an important role in the researchof basic science, and is also widely applied in the electronics, communications,biotechnology, medical treatment and energy engineering. The design and analysis ofdielectric permittivity test system is the key role in the research of the material dielectricproperties. In this paper, based on the new coupler the design of broadband multi-pointcomplex permittivity test system has been researched and dielectric properties of thegraphene oxide have been measured. The following several theoretical and experimentalresults which bring forth new ideas and innovation have been completed:1) From the theory of the electromagnetic field, the formula of the dielectric losscase complex permittivity perturbation method based on cavity perturbation theory hasbeen derived, and applied in the TE011mode cylindrical cavity. From the network modelof two-port network equivalent circuit model, we extend it to the single-port resonatorsystem, and systematically derive the precise formulas based on S11half-power pointvalue. Then we can obtain the quality factor of the resonant system. Throughthree-dimensional electromagnetic simulation using CST software, the formula isverified by the simulated S parameter and field distribution.2) According to the couple theory of the cavity system, the algorithm to judge thecouple state of the resonant system has been proposed by S11phase information. Thecouple state of the system can be quickly, conveniently judged based on the networkanalyzer, and get the coupling coefficient of the system. Then the intrinsic quality factorof the system can be got.3) For the resonant cavity mode interference problems, the design and developmentof the novel coupler has been proposed. The novel coupler has simple stucture and islow cost and convenient tuning. In the case of no external structure, the effectivecoupling of the electromagnetic signal of a high-speed multi-point in the resonancesystem can be achieved, at the same time interference mode can be effectivelysuppressed in the test frequency. The cavity coupler have been simulated and validated through CST software in the broadband multi-point frequencies.4)3D electromagnetic design, mechanical structure design, experimental test, datatransmission and computing interface have been integrated within the framework of theVisual2005, which include the cavity, couplers and lift system. The soft can completethe entire system flow from the initial electromagnetic design to the mechanicalprocessing, and experimental testing.5) Based on the theoretical model we have constructed the TE011cylindrical cavitycomplex permittivity test system by the perturbation method, which include the cavity,coupler, vector network analyzer, mechanical lifting system. We have developed areasonable test process, and build standard test samples. The main factors whichpossibly affect the test system accuracy have been analyzed.6) The graphene oxide test samples have been prepared by the way of the improvedHummer method, the complex permittivity of graphene oxide has been measured inbroadband multi-point frequencies.