A case of the analysis of Cavity-Backed Slot Antenna using Electro-Magnetica version 1 are introduced here.
The antenna has a monopole antenna in the cavity box and the box has a slot to emit microwave for radio comunication (Omiya et. al (1998)). When you use conventional FD-TD tool, this type of device is very difficult to have a good grids for it. You have to concentrate grids around the monopole and the slot. But the conventional FD-TD grids have to be the fine grid in the cross section including both of the monopole area and the slot area.
Blocked Cells Adaptive Mesh method, which is developed by Three Wells is a mixture of structured FD-TD grid and unstructured grid. It can concentrate grids only on the necessary area. So the method should be memory economical.
EM1 has a simple modeling tool but it is hard to model the device, so we take another CAD tool, like FreeCAD, to generate the cavity box.
The monopole is modeld using the EM1 modeling tool. You can download the EM1 file and the CAD data (STL) from bottom of this report.
The procedure for EM1 will be explained here.
Launch EM1 and select Open File from the menu bar to load a file "AT_Cavity_Slot.em3" which is available from the Attatchment at the bottom of the report.
Then you can see the view of the right figure. You might press key "D" to see the figure after clicking the 3D View area. If you want to see the clipped figure, click the y-clip button in the View Tab.
You almost finish the necessary procedure to run the simulator. Before starting the simulation, you have to generate the numerical grids.
Click Control-tab and set the grid generation level 3-5 and then click the Grid Generation button. After a while you will get the adaptive mesh. You can confirm in the 3D View area. You might need clikt to see the new grids.
Now, you can click Start button to start the simulation. The simulation of the model is very large one and it would take several days to finish the simulation. But very easy, isn't it?
If you see a message "Simulation Stopped" in the log window, the simulation is finished. So you flip the tab to View tab and select "RCS" from selection menu located in the middle of the tab panel. Select "2.45GHz" from pull-down menu in RCS setting panel and then click "Update Data" button to see the 3D image as is shown in the figure below.
You can save data to external file by clicking "Save File" button in the RCS setting panel. The bottom figures are made with GNUPLOT using the data. These data are very fit to the data in Omiya's paper.
 CBSA.zip | [Simulation Data for CBSA Analysis.] | 1 kB |
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