In this example an SAT file of a 18 port connector is imported into XFdtd^® and the S-Parameters are calculated.

CAD views of the connector are shown in Figures 1, 2, and 3 after material assignments are made to different parts. Before the connector is meshed small feed pins are added using the XFdtd solid editor. These are used to connect the feed ports to the case and conductors of the connector. Other methods for feeding the connector pins might be used depending on how the connector will be utilized. The end of the connector with the 3 x 3 array of connector pins added is shown in CAD view in Figure 4 with one of the pins circled. Adding the array of pins on both ends of the connector is easy using XFdtd array capabilities.

To provide good spatial resolution the connector is meshed using about 34 million FDTD mesh cells. With the patent-pending XFdtd fast meshing algorithm this entire mesh is generated in about 30 seconds. The result mesh reproduces the CAD geometry very accurately. Figure 5 shows the 3D view of the mesh which corresponds to the CAD view of Figure 4. A view of part of the interior mesh is shown in Figure 6 with the corresponding CAD view shown in Figure 7.

The 18 ports are added to the connector mesh and a transient calculation is performed with one of the ports excited. Figure 8 shows the transient electric field in the plane of the excited port (lower left) after about 1500 time steps. The corresponding view at the receiving end of the connector is shown in Figure 9 after 2500 time steps. These same two fields are shown in Figure 10 superimposed over the interior of the connector.

All of the port voltages are available for plotting in XFdtd. For this calculation port 10 is fed and port 9 is the corresponding receiving end port. Ports 7 and 11 are the adjacent ports at each end of the connector. The port voltage vs time for each of these ports is shown in Figure 11. The plot shows the large voltage at the fed port 10 and the smaller delayed voltage at receiving port 9. Smaller voltages at port 11 (next to port 10) and port 7 (next to port 9) are also shown.

XFdtd uses these port voltages to calculate a complete column of the S-Parameter matrix vs frequency which is available for plotting. A few of these S-Parameter results are shown in Figure 12. Figure 12 shows insertion loss for ports 11-9 varying between about 1 and 3 dB out to about 8 GHz, above which the loss increases. For ports 11 and 7 the S-Parameter plot indicates cross-coupling to be at least 17 dB down over this bandwidth.