Substrate Integrated Waveguide (SIW) With Koch Fractal Electromagnetic Bandgap Structures (KFEBG) for Bandpass Filter Design

High-performance bandpass filters (BPFs) based on substrate integrated waveguide (SIW) and half mode SIW (HMSIW) with Koch fractal electromagnetic bandgap (KFEBG) patterns etched on the waveguide surface are proposed. These BPFs are designed using a new methodology. The BPF responses are improved by applying a chirped and tapered technique to the KFEBG patterns which exhibit a radius-to-period ratio r/a ≥ 0.5. Simulation results and experimental verification are presented. Good values for insertion losses and stopband rejection are achieved.