Design Fundamentals: Iris Waveguide Filters Versus Substrate Integrated Waveguide (SIW) Bandpass Filters

A waveguide iris bandpass filter is designed in this paper. The proposed filter is created inside the structure by cutting inductive symmetrical windows known as irises. Later, using substrate integrated technology, its equivalent bandpass filter is released. In a dielectric material, SIW is created by adding a top metal over the ground plane and trapping the structure with rows of plated vias on either side. Compared to iris waveguide technique, SIW is an effective and efficient solution. The filters proposed were designed at the center frequency of 5 GHz. The simulated results, when designed using SIW software, show low losses and sharp roll-off characteristics in the passband. SIW has a bandwidth of 3 dB of 2.8 GHz and a fractional bandwidth of 15% in the passband. The filters proposed were suitable for use in applications for microwave communication systems.