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求波端口激励和集总端口激励的区别

时间:10-02 整理:3721RD 点击:
在设计微带电路时,用什么端口激励啊,例子里面两种都有。求大神指点迷津

都可以,
搜了点资料
With lump port=> the excitation is applied at a point/cell, as a voltage or current.
With wave-port=> the excitation is so-called eigen-wave, such as the quasi-tem wave supported by a microstrip line. It applies over a cross-sectional area.
voltage is scalar, wave is vector by nature, hence there are substantial difference between the two. So use waveport whenever possible, because "simulation of wave phenomenon" is what HFSS is designed for. And compare with the "correct" measurement whenever possible (i.e. measure "wave", not simply "voltage").
Why lumped port is there? It is easy to applied and people found that good/reasonable results can be obtained. Why? if the frequency is low enough or the excitation is applied at sufficiently small area, then the "wave" can be described by some "voltage" or "current", which must be "measured"/"calculated"/de-embedded/etc in the correct manner.
if the excitation can be applied on some locally uniform region=>waveport,
if geometry/material discontinuities are near/closer to the point of excitation=>lumped port might be the only way.
The subject of lumped vs wave port is actually complicated. people continue to study related matters, (e.g. arguing what is the "characteristic impedance").
Reading about the various de-embedding scheme should help with the understanding....
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Lumped ports:
Lumped ports are similar to traditional wave ports, but can be located internally and have a complex user-defined impedance. Lumped ports compute S-parameters directly at the port.The complex impedance Zs defined for a lumped port serves as the reference impedance of the S-matrix on the lumped port. The impedance Zs has the characteristics of a wave impedance; it is used to determine the strength of a source, such as the modal voltage V and modal current I, through complex power normalization. (The magnitude of the complex power is normalized to 1.) In either case, you would get an identical S-matrix by solving a problem using a complex impedance for a lumped Zs or renormalizing an existing solution to the same complex impedance.
By default, the interface between all 3D objects and the background is a perfect E boundary through which no energy may enter or exit. Wave ports are typically placed on this interface to provide a window that couples the model device to the external world.
Wave ports:
HFSS assumes that each wave port you define is connected to a semi-infinitely long waveguide that has the same cross-section and material properties as the port. When solving for the S-parameters, HFSS assumes that the structure is excited by the natural field patterns (modes) associated with these cross-sections. The 2D field solutions generated for each wave port serve as boundary conditions at those ports for the 3D problem. The final field solution computed must match the 2D field pattern at each port.
HFSS generates a solution by exciting each wave port individually. Each mode incident on a port contains one watt of time-averaged power. Port 1 is excited by a signal of one watt, and the other ports are set to zero watts. After a solution is generated, port 2 is set to one watt, and the other ports to zero watts and so forth.
With lumped ports you should know the characteristic impedance of the connected feeding line for calculating S-matrix, while with wave ports, if correctly sized, portZ0 defines the reference impedance for calculating S parameters, and it automatically takes the value of the Zo impedance of feeding line. If I were you, I would prefer wave ports, always if you are not obliged of defining an internal port.

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