Analysis and Design of a High Pass Waveguide Filter of the Ferrite Blade with Tunable Rejection Band

In this paper, a novel high pass waveguide filter of the ferrite blade with a tunable rejection band is designed and analyzed. The first band-pass of this filter is obtained in the frequency bands where the proposed structure is in the left-hand region. The reason for the left-hand property is the negative effective permeability of the ferrite, and the effective permittivity of the structure is due to the plasmonic property of the waveguide below the cutoff frequency. Stopband occurs in the frequency bands that have positive permeability while the effective permittivity is still negative. As the effective permittivity of the structure is positive, the proposed structure acts as a regular waveguide with a right-hand nature and acts as a high pass filter. The rejection band of the proposed filter shifts due to the ferrite-adjustable property of the magnetic bias. The use of this method dramatically reduces the complexity of the external control system. To analyze the proposed waveguide filter, we proceed by solving the Maxwell equations and obtaining the distribution of the electric and magnetic fields inside the regions of the structure and applying the boundary conditions, to obtain the characteristic equation and then the dispersion diagram is achieved by the numerical solution. To confirm the analytical solution, the proposed structure is simulated using Ansoft HFSS software and finally, its scattering parameters are investigated.