Harmonic Filter Characteristics Optimization on the Basis of a Rectangular Waveguide with an Impedance Narrow Wall Partially Filled with Dielectric

In the considered variant of the projective method the fields presented by proper functions of regular and non-regular waveguides are joined on these waveguides interfaces. The system of functional equations results. Taking into account the orthogonality of a regular waveguide proper functions, it was passed from the system of functional equations to the infinite system of linear heterogeneous algebraic equations. After certain mathematical transformations the number of unknowns in the system reduces. This system is solved by the reduction method. The problem of filter characteristics optimization is solved numerically in Turbo Pascal medium. As a result of numerical solution of a disperse equation, dependences of a non-regular waveguide propagation constants in a wide range of a surface impedance value change as well as dielectric plate parameters change on frequencies up to the third harmonic was shown. Calculations show that in such a structure propagation of both bulk and surface dielectric waves is possible. Quantity of propagation waves and frequency of their cut-off significantly depend on the surface impedance value and reactivity character as well as on dielectric plate parameters. Diffraction problem solution enables to optimize the filter characteristics. As a result of calculations dependences of main filter parameters were determined: reflection coefficient and transmission factor as well as attenuation constant on the complex impedance value and type of its reactivity; and power losses in a wide wave range including the first three harmonics.