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平面波激励源波长和入射角设置

录入：mweda 点击：

对于平面波激励的设置，有如下问题：
设置平面波的波长和入射角度问题，各参数的具体含义以及线性极化的问题。
对于propagation normal,好像是可以定义激励的位置,激励的位置变，好像角度可以变化，但是与我看类似文献不符。
Electric field vector:这个矢量大小怎么设置？如果设计一个与Y轴成60度的入射角，比如在Y-z平面的线性极化。
还有入射波的波长可以在哪里设置。
有没有哪里有详细介绍各参数的书啊，我查找了CST2008的帮助，也没有找到例子。

传播矢量就可以定义入射的角度，你只需要根据你的入射角算出其在xyz方向上的分量填入即可，电场矢量的设置也就代表了你的平面波入射场强
我觉得场强信息里就已经含有频率的相关信息了，不知道我的理解对不

Plane Wave OverviewThe plane wave excitation source provides you the opportunity to simulate an incident wave from a source, located a large distance from the observed object. In combination with farfield monitors, the radar cross section (RCS) of a scatterer may be calculated.Please note that the input signal of an excited plane wave is normalized due to the user-defined value of the electric field vector (unit: V/m).When exciting with a plane wave, several conditions must be satisfied, which will be discussed in the following section.Boundaries and background material
When exciting with a plane wave, several conditions must be satisfied. First, open boundary conditions must be defined at the direction of incidence.
In the picture below, a plane wave is passing the calculation domain in the (1, 1, 1) direction. At a minimum, the boundaries at xmin, ymin and zmin must be defined as open boundaries (for an undisturbed propagation, xmax, ymax and zmax must be open as well).

When using a plane wave source, other excitation ports must not be located on boundary conditions. Moreover the surrounding space should consist of a homogenous material distribution. This implies that the background material is set to a normal, not a conducting material. Unlike the other excitation sources, a plane wave can only be driven by a Gaussian pulse.
Decoupling plane
If the calculation domain is divided by a metallic plane (which needs to be parallel to a boundary condition), it is necessary to define a decoupling plane at the boundary of the metallic plane. This is possible either by an automatic detection or by user settings in the Plane Wave dialog.
The picture shows a plane wave hitting a metallic plane with three slots. The detected decoupling plane is marked with a pink frame. In front of the plane, a standing wave field pattern has been established; behind the plane, a typical interference pattern can be seen.

Polarization
It is possible to define three different kinds of polarizations for a plane wave excitation: linear, circular or elliptical. For linear polarization, one electric field vector exists for the excitation plane with a fixed direction. This electric field vector changes its magnitude according to the used excitation signal. A linear polarization is displayed as red plane with a green electric field vector and a blue magnetic field vector. The visualization of the linear plane wave excitation is displayed in the picture below.

For circular or elliptical polarization, two electric field vectors exist in the excitation plane perpendicular to each other. Each of these two vectors define one linear polarized plane wave. If these two linearly polarized plane waves are excited simultaneously, the resulting plane wave is elliptically polarized. Please note that circular polarization and linear polarization are special cases that may result from the definition of an elliptical polarization.
For a circular or elliptical polarization, the two electric field vectors are excited simultaneously according to the excitation signal with a certain time delay. This time delay is calculated for a given reference frequency and a phase shift between the two electric field vectors. In addition, the magnitude of the two electric field vectors may be different. The axial ratio defines the ratio of the magnitudes between the defined (first, primary) electric field vector and the perpendicular second vector.
The special case of a linearly polarized plane wave excitation is obtained if the phase shift between the two electric field vectors is 0 or 180 degrees. Please note that the phase shift is always related to the given phase reference frequency.
For a circular polarization the axial ratio is always 1 as well as the phase shift is always +90 or –90 degrees. Therefore, only two possible configurations exist for a circular polarization: left and right circular polarization. The circular polarization is displayed as a green circular arc starting at the primary electric field vector (gray color) using an arrowto indicate whether left or right circular polarization is used. The visualization of a left and right circularplane wave excitation is displayed in the two pictures below.

Left Circular Polarization (LCP)Right Circular Polarization (RCP)
If the phase shift differs from +90 or –90 degrees or the axial ratio is not equal to 1, the polarization is elliptical. Elliptical polarization is displayed similar to circular polarization. An elliptical arc denotes the sense of the polarization and its magnitude in the plane regarding the course of time at the given reference frequency. The arc starts at the resulting electrical field vector at the time when the primary electric field vector (i.e., the field vector of the first linear plane wave) is at maximum. This resulting field vector is displayed as a green arrow if there is a significant difference to the primary field vector (gray).
If the phase shift at the reference frequency is positive, the time when the primary field vector reaches its maximum equals a phase of 0 degrees for an electric field monitor defined at the reference frequency. If the phase shift is negative, there will be an additional phase offset between the fields recorded by an electric field monitor at the reference frequency and the green arrow will be visualized when the plane wave definition is visualized.
The visualization of three different elliptical plane wave excitations is displayed in the three pictures below.

Axial ratio: 0.6667
Phase shift: 90 degreesAxial ratio: 1
Phase shift: 60 degreesAxial ratio: 0.6667
Phase shift: 60 degrees
The following picture shows the spatial field distribution of a plane wave excitation with right circular polarization for a fixed time. Please note that for a fixed time, the spatial rotation of the field along the propagation direction is in the left direction for a right circular polarized plane wave.

Within this dialog, you may define a plane wave excitation source. Unlike discrete ports or waveguide ports, no S-parameters will be calculated. Instead, the stimulation amplitude (unit is V/m) is recorded. To obtain further information, you might specify probes or different types of field monitors. Combined with farfield monitors, the plane wave source can be used to compute the radar cross section (RCS).Polarization frame
Here, you may enter the polarization of the plane wave and polarization specific settings. For more information on the different polarization types, please see the Plane Wave Overview.
Linear / Circular / Elliptical: Select here the type of plane wave excitation polarization.
Ref. frequency: If the selected type is circular or elliptical, enter here the reference frequency for the plane wave excitation. This field only applies to elliptical and circular polarized plane wave excitations.
Phase Difference: Enter here the phase difference between the two excitation vectors for elliptical polarized plane waves. This field only applies to elliptical polarized plane wave excitations.
Left / Right: Select here between left circular polarized or right circular polarized plane wave excitation. These settings only apply to circular polarized plane wave excitations. The respective radio buttons are only visible if a circular polarization is selected.
Axial ratio: Defines the ratio between theamplitudes of the two electric field vectors used for elliptical polarization. This field only applies to elliptical polarized plane wave excitations.
Propagation normal frame
X/Y/Z: Here you can specify the propagation vector by entering valid expressions for the X/Y/Z component.
Electric field vector frame
X/Y/Z: Specify the electric field vector components in V/m. The electric field vector must be orthogonal to the propagation normal.
Please note that the input signal of an excited plane wave is normalized due to the defined absolute value of the electric field vector.

The definition of the plane wave is visualized by a red plane. Colored arrows indicate the propagation direction as well as the electric and magnetic field vectors.
Here the electric field vector of a plane wave is hitting a metallic sphere. Correspondent to the picture on the left side the plane wave is excited with an electric field vector in z-direction and a propagation normal (1,1,0).
Decoupling plane frame
If a structure contains metallic walls dividing the calculation domain into two separate parts, it is necessary to consider a decoupling plane in the plane wave calculation. Note that this decoupling plane needs to be parallel to the calculation domain‘s boundaries (see also: Plane Wave Overview ).
Automatic detection: The selection of this checkbox will automatically detect possible metallic walls and consequently activate the correspondent decoupling plane. This detection procedure only recognize a complete metallic wall with no discontinuity at the boundary of the calculation domain. If the decoupling plane was not found, you can define one by yourself using the input fields below.
Use decoupling plane: This checkbox is only available if the automatic detection is deselected. Activate here a user-defined decoupling plane defining the following input fields.
Position: Determine the longitudinal location of the decoupling plane by entering valid expressions . If the metal wall has a finite thickness specify the walls boundary coordinate, where wave will be reflected.
Plane normal: Select a normal direction for the decoupling plane. Decoupling planes must be parallel to the calculation domain‘s boundaries, so you can choose between X, Y or Z.
OK
Accepts your settings and leaves the dialog box.