Circuit Modeling of Defected Waveguide Structure

Recently, waveguide has been applied widely in antenna and filter applications. Among these applications, substrate integrated waveguide has been implemented mostly in millimeter wave systems due to its compact and low loss approach. However, the configuration of waveguide itself receives less attention. Thus, the study of defected waveguide structure (DWS) is presented. The copper and DWS waveguide were designed in CST Microwave software. The basic geometry of square was used and then different types of connecting strips were added on in between the strips. Simulated reflection coefficient (S11) and transmission coefficient (S21) results were then modeled by equivalent circuit design. The circuit was constructed in Advanced Design System (ADS). Copper waveguide performed high pass at frequency more than cut off frequency of 2.76GHz. The square DWS with gap separation and square DWS with horizontal connecting strips showed pass band around 4GHz-8GHz. The square DWS with vertical connecting strips and square DWS with both horizontal and vertical connecting strips created band stop around 3GHz-9GHz.