CST 微波工作室邊界條件和激勵源

我現了模型矩形波導和介質層，邊界條件設置為y方向為E，x方向為H，z方向為open，背景材料為真空，有兩個警告：at least one propagating mod at port 1 is not considered in time domain calculation!it might be better to increase the number of modes at port 1.
some higher propagating modes at port 2 are not considered in time domain calculation.this possibly leads to an inaccurate enery balance.consider to reduce the port size or decrease the upper frequency limit. 怎么回事？

對于Empty Waveguide，CST幫助文件是這么說的：
CST MICROWAVE STUDIO® solvers generally allow using more than just the fundamental mode in the waveguide port. This becomes especially important when higher order modes need to be taken into account.
The number of propagating modes vary due to the chosen frequency range. As a rule, the number of modes to be considered at a waveguide port should at least be the number of propagating modes, because unconsidered modes will be reflected by the port operator.

謝謝了，能用漢語說說嗎？

這點兒英語應該不難理解吧……
對于有截至頻率的模型，仿真頻率很寬或者端口尺寸很大時，就有必要仿真多個模式，否則多余的能量會被端口反射回去，降低仿真的準確性。

有點不懂哎

at least one propagating mod at port 1 is not considered in time domain calculation!it might be better to increase the number of modes at port 1.
今天我也遇到了這個問題，我把波端口改小了就不報錯了
波導口大了，截止頻率就低了，如果設置的小一點截止頻率就高了，就不用“decrease the upper frequency limit”，不知道是不是這么回事

謝謝指教，明白了。是不是，就是出現了高階模態？

我也出現同樣問題，求解some higher order propagating modes at part 1 are not considered in time domain calculation,仿真結果沒s參量數據？