Sinusoidally Modulated Substrate Integrated Folded Waveguide as a Filter for Multiband Applications

The propagation of electromagnetic (EM) waves within a substrate integrated folded waveguide (SIFW of changing widths is investigated. The width of the SFW changes sinusoidally. This research illustrates the EM field components and propagating dispersion characteristics for the proposed sinusoidally modulated substrate integrated folded waveguide (SMSIFW). The proposed SMSFW has half the width of its unfolded counterpart, the sinusoidally modulated substrate integrated waveguide (SMSIW. The propagation constant of the proposed SMSFW is determined using variational analysis. Because the proposed structure is periodic in nature, it exhibits filter characteristics. The filter property is investigated at two values of modulation indices.