Polarization-Preserving Quadruple-Ridge Waveguide Filter and Four-fold Symmetric Transformer

Current astrophysical and space applications require waveguide filters to exhibit wide stop-band performances and to preserve the dual polarization states of the electromagnetic field. The aim of this work is to present a waveguide filter that exhibits four-fold symmetry and significant stop-band improvements over the performances of standard circular and square waveguide technologies. Positive results have been achieved using quadruple ridge waveguide cross-sections and attenuation poles. This work also presents a polarization preserving transformer that converts a quadruple ridge waveguide cross-section into a square cross-section. Design examples are presented to show good performances of both filter and transformer