A New Cavity Pertubation Method Of Measuring Permeability Of Medium Based On Substrate Integrated Waveguide

Along with the constantly mention of the material electromagnetic characteristics, it’sbecoming more and more important to measure the permittivity and permeability of differentmaterial samples rapidly and accurately. Through the theoretical analysis and simulation, thispaper discussed a new method of measuring materials’ permeability. This paper’s main workincludes:1. Analysised the advantages and disadvantages of several common measuring methods, andchoosed a method from them. Given the calculation formulas both on the situations whenthe filling material is nonmagnetic material and magnetic material, together with theperturbation condition.2. Choosed the substrate integrated waveguide (SIW) as the basic structure of the device whichthis paper used to measuring. Analysised the propagation characteristic of substrateintegrated waveguide simply. Given the equivalent formula between the substrate integratedand the native rectangular metal waveguide. Also, verified the correctness of the equivalentformula through simulation.3. Designed the substrated integrated waveguide cavity which meets the parameterrequirements. Csonstructed the substrate integrated waveguide cavity model in theelectromagnetic simulation sofeware, Showed the electromagnetic field distribution of thecavity before and after inserting the material, analysised the change of magnetic field frominserting the samples, thus calculater the dielectric permeability of samples.4. In eigen mode, simulate the medium filling less high rectangular waveguides both on thesituations when the filling material is nonmagnetic material and magnetic material, receivethe resonance frequencies and quality factors before and after filling the material samples.Then analysised the reason why the computational accuracy was different. After that,replaced the medium filling less high rectangular waveguide with the substrate integratedwaveguide, does the same simulations. Proved that the use of substrate integrated waveguidecavity instead of medium filling to reduce high rectangular waveguide is feasible, insertedthe permeability data of the sample at the same time.5. Desinged several substrate integrated waveguide cavities with different feeds, including:coaxial feed, microstrip single loaded, microstrip doubly loaded. With help of electromagnetic simulation software, simulated and optimized the parameters so that thecavity can meet the requirements of feed coupling.6. Simulated different feed models, obtained the resonant frequency points and quality factorsbefore and after inserting the samples. Calculated permibility of the samples according toexperimental data and compared with the real value. The error analysis was considered too.