Design of Microwave Lossy Filter Based on Substrate Integrated Waveguide (SIW)

In this letter, we propose a lossy three-pole Chebyshev filter centered at 5.15 GHz, based on the substrate integrated waveguide (SIW) with scattering characteristics shifted down by 5.68 dB. The filter is composed of three directly coupled SIW cavities with three lossy couplings between nonadjacent resonators. These additional couplings are realized using mixed coupled slot and microstrip lines connected with metal electrode leadless face (MELF) resistors. The filter was fabricated using a standard printed circuit board (PCB) process, and good agreement between the simulated and measured results has been achieved.