HFSS分析求解類(lèi)型 Solution Type如何選擇？,Driven Modal 還是 Driven Terminal？

2016-10-11 by:CAE仿真在線來(lái)源:互聯(lián)網(wǎng)

在幫助文件中,Driven Modal 和 Driven Terminal 的定義非常相似,如何進(jìn)行區(qū)分呢?

HFSS有四種求解類(lèi)型,其中Driven Modal和Driven Terminal都是用于有源驅(qū)動(dòng)(需要端口激勵(lì))情況。這里重點(diǎn)介紹一下這兩個(gè)求解器的區(qū)別:
— Driven Modal的求解主要是微帶線、波導(dǎo)等傳輸結(jié)構(gòu),這種求解類(lèi)型得到的S 參數(shù)是基于主模到高次模的各種模式的廣義S參數(shù),因此常用于天線和微波器件仿真;
— Driven Terminal的求解主要是終端為多根導(dǎo)體的傳輸線,比如差分線,這種端口需要定義終端線,求解得到的S參數(shù)是基于終端的,因此常用于電路、高速互連等SI設(shè)計(jì)。

Driven Modal

驅(qū)動(dòng)模式

For calculating the mode-based S-parameters of passive, high-frequency structures such as microstrips 微帶, waveguides波導(dǎo), and transmission lines 傳輸線 which are "driven" by a source, and for computing incident plane(入射面) wave scattering 散射.

計(jì)算基于s參數(shù)的模型,一般天線使用這種模式,但不適合一個(gè)端口多個(gè)終端的情況,此時(shí)需要使用終端驅(qū)動(dòng)。

Driven Terminal

終端驅(qū)動(dòng)

For calculating the terminal-based S-parameters of passive, high-frequency structures with multi-conductor transmission line ports which are "driven" by a source.

This solution type results in a terminal-based description in terms of voltages and currents. Some modal data is also available.

用于多導(dǎo)體傳輸線的端口情況,根據(jù)終端電壓和電流計(jì)算s矩陣

Eigenmode

本征模

For calculating the eigenmodes, or resonances, of a structure. The Eigenmode solver finds the resonant frequencies of the structure and the fields at those resonant frequencies. Eigenmode designs cannot contain design parameters that depend on frequency, for example a frequency-dependent impedance boundary condition.

相當(dāng)于結(jié)構(gòu)分析的模態(tài)分析,本征模用于求解找到天線結(jié)構(gòu)的諧振頻率。

Transient

瞬態(tài)

For calculating problems in the time domain. It employs a time-domain (“transient”) solver. SelectingTransientenables a radio button forNetwork Analysis. Your choice affects the options for the setup. If you selectNetwork Analysisthe setup includes an Input Signal tabfor the simulation.

Typical applications include, but are not limited to:

? Simulations with pulsed excitations, such as ultra-wideband antennas, lightning strikes, electro-static discharge;

? field visualization employing short-duration excitations;

? time-domain reflectometry.

求解隨時(shí)間變化的電磁問(wèn)題、電磁場(chǎng)變量

1、從help的解釋來(lái)看,Eigenmode solution主要用于諧振結(jié)構(gòu),而Driven Modal和Driven Terminal主要用于傳輸線、波導(dǎo),包括天線等結(jié)構(gòu)。

但關(guān)鍵是兩者的區(qū)別是什么呢?

如果需要仿真的結(jié)構(gòu)是多導(dǎo)體結(jié)構(gòu)(如同軸線),可以傳播TEM模,存在電壓和電流的定義,這樣就可以用電壓波和電流波來(lái)描述該傳輸線,可以使用Driven Terminal模式。但如果需要仿真的結(jié)構(gòu)是單導(dǎo)體結(jié)構(gòu)如矩形,柱形波導(dǎo),則沿線電壓、電流不再有定義,只能用網(wǎng)絡(luò)理論中的內(nèi)向波、外向波描述端口的性質(zhì),此時(shí)用Driven Modal。對(duì)于微帶,傳播模式是準(zhǔn)TEM模,按help的解釋?xiě)?yīng)該用Driven Modal,但在ansoft的full-book對(duì)port的解釋中又有這樣一句:For structures like coupled transmission lines or connectors, which support multiple, quasi-TEM modes of propagation, it is often desirable to compute the Terminal S-Parameters.可見(jiàn)用Driven Terminal還是可以的

總結(jié):

1、driven modal的適用范圍很廣,不需要設(shè)置積分線,而driven terminal要在端口設(shè)置積分線

2.如果模型中有類(lèi)似于偶合傳輸線求偶合問(wèn)題的模型一定要用driven terminal求解,

3.driven modal適于其他模型, 但一般tem模式(同軸,微帶等)傳輸?shù)膯谓K端模型一般用driven terminal分析(tem波電壓一般由兩導(dǎo)體之間電場(chǎng)積分定義,電流為環(huán)線磁場(chǎng)的積分,阻抗Zvi=Zpi=Zpv區(qū)別于TE TM) 由于其直接對(duì)電流電壓求解而避免了對(duì)整個(gè)面上功率的計(jì)算從而比較簡(jiǎn)便.

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