In this example a broad-bandwidth band-pass filter is simulated using XFdtd. The filter geometry employs a substrate integrated waveguide (SIW) with etched complementary split ring resonators (CSRRS). Simulated S-Parameters are compared to measured results. The filter design and measured data are taken from [1].
The SIW portion of the filter is comprised of a RT/Duroid 5880 substrate sandwiched between two copper plates. Metallic vias rows are located along the top and bottom edges of the top plate creating a waveguide structure. Etched out of the top plate are three CSSR structures sized to create a stop band from 9.5 GHz to 11 GHz. Microstrips are connected to the SIW transitioning with a planar taper. The geometry is shown in Figure 1.
Figure 1: CAD geometry of SIW filter
The simulation leveraged Remcom’s XStream technology using one NVidia Quadro 600 to complete in 32 minutes. Planar transient fields and three single frequency fields were collected showing the performance of the filter. The simulated S-Parameters compares well with the measured results, shown in Figure 2. Figures 3-5 show the single frequency electric field magnitudes inside the waveguide at 4 GHz, 8 GHz, and 10 GHz respectively.
Figure 2: Simulated and measured S-Parameters.
Figure 3: Electric field magnitude inside filter at 4 GHz.
Figure 4: Electric field magnitude inside filter at 8 GHz.
Figure 5: Electric field magnitude inside filter at 10 GHz.
References
X.-C. Zhang, Z.-Y. Yu and J. Xu, “Novel Band-Pass Substrate Integrated Waveguide (SIW) Filter Based on Complementary Split Ring Resonators (CSRRS),” Progress In Electromagnetics Research, PIER 72, 2007, pp. 39-46.