如何建立復選框shield your waveguide ports

背面開槽之后仿真老是出錯，
求解過程中出現The calculation seems to be unstable！A possible source of instabiliy could be given by inaccurate definition of internal waveguideports.Please consider to increase the dimension or shield your waveguide ports.
我百度了很久，只得到以下資料
CST MWS幫助文件《Waveguide Port》：
Electric shielding: Activate the check box to let the boundary of the waveguide port be treated as a perfectly shielding (PEC) frame.
CST MWS幫助文件《Special Solver Parameters - General》：
Electric shielding for all ports: A perfectly shielding (PEC) frame surrounding each waveguide port region will be added. This option causes higher reflections at ports. Therefore, it should only be used if a calculation has become unstable.
百度翻譯：
電屏蔽：啟動復選框讓波導端口邊界被視為一個完全屏蔽（PEC）框架。
電屏蔽所有的港口：一個完全屏蔽（PEC）框架周圍每個波導端口區域將增加。此選項會導致更高的反射端口。因此，它應該只是如果計算已成為不穩定的使用。

當母語已無法表達清楚之時，請傳上圖檔。

英語沒學好，母語也不咋地……。
要么在waveguide port properties里設置：

要么在time domain solver里設置：