請(qǐng)問(wèn)Eigenmode solver 設(shè)置的一個(gè)問(wèn)題.
請(qǐng)問(wèn)Eigenmode solver 設(shè)置下的solver settings中的method里面的三種設(shè)置都是什么意思？分別在什么時(shí)候用？請(qǐng)高手指教！謝謝?。ㄈ鐖D）
The eigenmode solver calculates a finite number of modal field distributions in a closed
device. CST MICROWAVE STUDIO® provides two different eigenmode solvers: AKS
(Advanced Krylow Subspace) and JDM (Jacoby Davidson Method).
These methods work on a completely different mathematical foundation. The JDM solver
can be considered as a more robust solver technology, but the AKS solver may be faster
if many modes are to be calculated. Therefore we recommend the JDM solver only if a
small number of modes (e.g. 1-5) has to be calculated. Otherwise the AKS solver should
be used.
Since the eigenmode analysis does not require the definition of excitation ports, this step
can be omitted. The definition of monitors is also not necessary because the modes
themselves contain all available information about the device.
The solution of lossy eigenmode problems is a challenging task which implies that the
proper consideration of losses will significantly slow down the simulation. Even if the
JDM solver is able to directly solve the lossy eigenmode problem, it may sometimes be
advisable (especially for very small losses) to first calculate the loss free eigenmode
problem and then obtain losses and Q-factors of the device using a perturbation method
in the post processing.
The perturbation method requires material losses to be defined before the eigenmode
simulation is started. Running the AKS solver will always calculate the loss free problem
by simply ignoring the loss definition. The JDM solver can be advised to do so by
activating the Use perturbation method box as shown below:
In the eigenmode solver control dialog box, the most important controls are the Method
(as discussed above) and the number of Modes.
The typical simulation procedure is as follows:
1. Depending on the number of modes, choose the proper solver method:
For the direct solution of lossy problems choose JDM.
For loss free problems with a small number of modes (e.g. 1-5) choose
JDM.
For loss free problems with many modes (e.g. >5) choose AKS.
2. Enter the desired number of Modes (N). The solver will then compute the first N
modes of the device. For the AKS solver, it is often advantageous to specify more
modes to be calculated than you actually need, e.g. enter 20 modes to be
calculated if you actually need 15. In most cases it is a good choice to calculate at
least the first 10 modes of the device.
3. Click the Start button
When using the AKS solver, sometimes a few of the higher modes will not be calculated
with sufficient accuracy and thus be marked with “*”. However, this does not affect the
accuracy of the lower modes and is the reason you should specify more modes to
calculate than you actually need.
The AKS eigenmode solver internally needs an estimation for the frequency of the
highest mode of interest. Usually this frequency is estimated automatically and improved
by refinement passes if necessary.
Performing estimation refinement passes reduces the performance of the AKS
eigenmode calculation. To speed up the AKS eigenmode calculation in these cases, you
can manually enter a guess for the frequency of the highest mode you are looking for.
The AKS eigenmode solver automatically derives such a guess from previously
calculated results and prints this value in the message window.
其實(shí)幫助文檔里就有的，在cst2006的getting start 的page115
能不能用中文給解釋一下？這個(gè)我看了，但是究竟什么時(shí)候用AKS，什么時(shí)候用JD？弄不太明白啊，我現(xiàn)在一般就是用CST仿一下諧振頻率和耦合窗的大小，最近才注意到這個(gè)，不知道有什么區(qū)別:L :L
一般1～5個(gè)模式的采用jdm求解，其他的采用aks求解
qi ta de fan yi yixia jiu keyi le ,bushi hen nan de ,shizai bu xing ,natian wo geini fanyi yixia ,huo zhe gei ni zhao ge yingwen de jieshi
Thanks:hi
本征模求解器用來(lái)計(jì)算封閉器件內(nèi)有限個(gè)模式的場(chǎng)分布，cst里有兩種不同的本征模求解器：AKS和JD.lossy
JD.loss free
這兩種求解器的數(shù)學(xué)基礎(chǔ)完全不同。JD求解器更穩(wěn)定，但在算多個(gè)模式時(shí)，使用aks求解器會(huì)更快。
如果只計(jì)算少量模式如1～5個(gè)模式，最好使用jd求解器，否則使用aks求解器求解
因?yàn)閲?yán)格的考慮損耗會(huì)顯著的降低仿真速度，故有耗本征模問(wèn)題的求解是非常具有挑戰(zhàn)性的任務(wù)，即使
專(zhuān)用的JD。lossy 算法能夠直接求解有耗本征模問(wèn)題，但在損耗非常小的時(shí)候，我們也建議你先計(jì)算無(wú)
耗本征模問(wèn)題，即使用jd。lossfree 或者aks求解器。然后在后處理中采用微擾法求出器件的損耗和Q值
既然本征模分析無(wú)需定義激勵(lì)端口，這一步就可以忽略掉了。由于模式本身就已經(jīng)包含了器件的所有有用
信息，故監(jiān)視器也不用定義了
因此建模完成后便可以記入本征模求解對(duì)話框
一般采用下面的原則：
1.依據(jù)模式數(shù)量，選擇適當(dāng)?shù)那蠼馄魉惴?br />直接求解有耗問(wèn)題，選擇Jd lossy
少量模式 如1～5個(gè) 選用jd loss free
較多模式，多于5個(gè)，的無(wú)耗問(wèn)題，選擇aks
2.輸入求解的模式數(shù)量，求解器將要算出器件的前n個(gè)模式，對(duì)aks求解器，一般指定比您實(shí)際需要的
模式數(shù)量多的會(huì)比較好，比如你需要15個(gè)模式，可以輸入20，在大多數(shù)情況下，至少要計(jì)算器件的頭10
個(gè)模式
