On the realizability of the impedance matrix for lossy dielectric posts in a rectangular waveguide

The equivalent T-network for some lossy dielectric posts in a rectangular waveguide is found to have a negative resistance in the parallel arm although the realizability conditions for the impedance matrix are strictly satisfied. Furthermore, the reactive part of the same impedance is found to be a monotonically decreasing function of frequency. These difficulties are overcome in the case of symmetrical post structures by using lattice networks. A simplified lattice network of lumped elements is developed to approximately realize the impedance matrix for resonant lossy post structures in the bandwidth.<
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