利用Python与HFSS联合仿真设计一个微带天线

说明：本文中的微带线设计案例来自李明洋老师的《HFSS电磁仿真设计应用详解》一书的第10章----HFSS微带天线设计实例。

部分api设计参考使用了Matthew Radway在github中分享的Interact with ANSYS HFSS via the HFSS Windows COM API。地址：http://mradway.github.io/hycohanz/

我们知道HFSS是一款电磁仿真商用软件，用其进行天线的设计十分方便。而该软件也预留了可以运行脚本的接口，使用者可以使用脚本对软件进行控制，实现模型的建立、求解等等。由于后期可能会用到联合仿真，而大多数联合仿真的脚本都是使用的Matlab进行编程，网上也有不少现成的api，因为对python比较熟悉，且python除了数值计算其他的功能也相当强大，并且免费开源，于是决定用python写一个建模的脚本（其实是我matlab学得太烂了），折腾了两天，终于把微带天线的模型建立与仿真的过程搞定了，当然是基于有Matthew Radway这位大牛的基础上。这个例子也是接触HFSS时手绘天线做的第一个例子，现在用代码做一遍，也是很有意思的事情。下面分享给大家。

1、连接软件

第一步当然要用脚本实现打开软件了。关于这个步骤，HFSS帮助文档中是这样写的

GetAppDesktop

Use:     GetAppDesktopis a function of    oAnsoftApp. This function does not take an input and it returns an object. The object is assigned to the variable   oDesktop.

Syntax:              GetAppDesktop()

Return Value:    Object.

Parameters:      None

Example:     

Set oDesktop = oAnsoftApp.GetAppDesktop()

给出了函数名，参数值，返回值，以及一个实例（这个帮助文档写得很不错，但是后面阅读过程中也发现了一些小错误，当然很可能是因为我用的是daoban）。这个返回值 oAnsoftApp就是后面进行一系列操作要使用的对象，所有的操作的形式都是下面这样：

oAnsoftApp.<CommandName>


python中编写了一个接口函数把这个函数封装在里面。代码如下（不是我写的）：

from __future__ import division, print_function, unicode_literals, absolute_import

import win32com.client

def setup_interface():
    """
    Set up the COM interface to the running HFSS process.
    
    Returns
    -------
    oAnsoftApp : pywin32 COMObject
        Handle to the HFSS application interface
    oDesktop : pywin32 COMObject
        Handle to the HFSS desktop interface
    
    Examples
    --------
    >>> import Hyphasis as hfss
    >>> [oAnsoftApp, oDesktop] = hfss.setup_interface()
    
    """
    # I'm still looking for a better way to do this.  This attaches to an 
    # existing HFSS process instead of creating a new one.  I would highly 
    # prefer that a new process is created.  Apparently 
    # win32com.client.DispatchEx() doesn't work here either.
    oAnsoftApp = win32com.client.Dispatch('AnsoftHfss.HfssScriptInterface')

    oDesktop = oAnsoftApp.GetAppDesktop()

    return [oAnsoftApp, oDesktop]

作者用了win32com.client.Dispatch()这个函数，这个函数是专门用来连接接口的，返回值中的那个oDesktop就是生成的对象。

实际调用代码：

[oAnsoftApp, oDesktop] = hfss.setup_interface()

2、新建一个project

oProject = hfss.new_project(oDesktop)

这里就是用了上面生成的oDesktop对象新建了一个object，具体查阅help文档和编写api的工作和上一步一致，并且平时使用时直接使用接口调用即可。注意，下面进行的操作都在这个project中，所以下面操作的对象就是oProject了。这个时候HFSS里应该长这样了。

3、保存project

养成良好习惯，新建的文件之后先保存，在编写过程中因为没有先保存，生成了一堆临时文件，挺讨厌的。这个传人的参数可以包含路径。

hfss.save_as_project(oDesktop,"E:/dj/test/microstrip_antenna.hfss")

4、新建一个design

这里传人的参数为design的名字，设计模式。

oDesign = hfss.insert_design(oProject, "HFSSDesign1", "DrivenModal")

新建完成后发现和我们手动操作是一样的。

5、建立模型

教程中首先新建了一个地板，并设置为PEC。这里也分别调用了这两个函数，尺寸可以用字符串输入，很方便灵活，不需要自己转换为一堆小数点的数字。设置PEC表面首先需要获得平面的faceid，再给这个表面设置边界条件。

raw_input('Press "Enter" to draw a ground plane>')

ground = hfss.create_rectangle(
    oEditor,   
    "-45mm", 
    "-45mm", 
    0,
    "90mm", 
    "90mm",
    Name='ground',
    Transparency=0.8)

raw_input('Press "Enter" to assign a PerfectE boundary condition on the ground.>')
ground_faceid=[]
ground_faceidnum = hfss.get_face_by_position(oEditor, ground, 0, 0, 0)
print ground_faceidnum
ground_faceid.append(ground_faceidnum)
hfss.assign_perfect_e(oDesign, "ground", ground_faceid)

由于建模过程比较类似，这里就不逐个给出了，模型建立完毕如下图（包括了设置边界条件和设置端口）：

6、设置求解和扫频

这里求解函数传人了中心频点；扫频传入了扫频方式，起始频率和终止频率，频率间隔。

raw_input('Press "Enter" to insert analysis setup.>')  

setuplist=[]

setupname = hfss.insert_analysis_setup(oDesign, 2.45)

setuplist.append(setupname) 

raw_input('Press "Enter" to insert frequency sweep.>')  

hfss.insert_frequency_sweep(oDesign,
                            setupname,
                            "Sweep1",
                            1.5,
                            3.5,
                            0.1,
                            IsEnabled=True,
                            SetupType="LinearStep",
                            Type="Discrete",
                            SaveFields=True,
                            ExtrapToDC=False)

7、求解

对于每个setup进行求解。是不是和手动操作是一样的？

hfss.solve(oDesign,setuplist)

8、退出HFSS

hfss.quit_application(oDesktop)

结束语：

今天暂时研究到这儿，还有很多比如查看求解完成后的驻波、增益曲线等等还有设置主从边界啦很多的api还没有编写，有时间会继续完善。

做了个有趣的小玩意儿，分享给大家~

完整主函数源码（api部分还不是很完整，哦，相当不完整，就先不给出了）：

# -*- coding: utf-8 -*-
"""
Created on Fri Apr 22 14:29:38 2016

@author: DJ
"""

from __future__ import division

import hycohanz as hfss

raw_input('Press "Enter" to connect to HFSS.>')

[oAnsoftApp, oDesktop] = hfss.setup_interface()

raw_input('Press "Enter" to create a new project.>')

oProject = hfss.new_project(oDesktop)

raw_input('Press "Enter" to save the project.>') 

hfss.save_as_project(oDesktop,"E:/dj/test/microstrip_antenna.hfss")

raw_input('Press "Enter" to insert a new DrivenModal design named HFSSDesign1.>')

oDesign = hfss.insert_design(oProject, "HFSSDesign1", "DrivenModal")

raw_input('Press "Enter" to set the active editor to "3D Modeler" (The default and only known correct value).>')

oEditor = hfss.set_active_editor(oDesign)

raw_input('Press "Enter" to draw a ground plane>')

ground = hfss.create_rectangle(
    oEditor,   
    "-45mm", 
    "-45mm", 
    0,
    "90mm", 
    "90mm",
    Name='ground',
    Transparency=0.8)

raw_input('Press "Enter" to assign a PerfectE boundary condition on the ground.>')
ground_faceid=[]
ground_faceidnum = hfss.get_face_by_position(oEditor, ground, 0, 0, 0)
print ground_faceidnum
ground_faceid.append(ground_faceidnum)
hfss.assign_perfect_e(oDesign, "ground", ground_faceid)
    
raw_input('Press "Enter" to insert some substrate properties into the design.>')

hfss.add_property(oDesign, "w", hfss.Expression("80mm"))
hfss.add_property(oDesign, "h", hfss.Expression("5mm"))

raw_input('Press "Enter" to draw a substrate using the properties.>')

substrate = hfss.create_box(
    oEditor,   
    -hfss.Expression("w")/2, 
    -hfss.Expression("w")/2, 
    0,
    hfss.Expression("w"), 
    hfss.Expression("w"),
    hfss.Expression("h"),
    Name='substrate',
    Transparency=0.8)
    
raw_input('''Press "Enter" to change the substrate's material to Rogers 4003>''')

hfss.assign_material(oEditor, [substrate], MaterialName="Rogers RO4003 (tm)")

raw_input('Press "Enter" to insert some patch properties into the design.>')

hfss.add_property(oDesign, "w_p", hfss.Expression("31.0mm"))
hfss.add_property(oDesign, "l_p", hfss.Expression("41.4mm"))

raw_input('Press "Enter" to draw a patch>')

patch = hfss.create_rectangle(
    oEditor,   
    -hfss.Expression("w_p")/2, 
    -hfss.Expression("l_p")/2, 
    hfss.Expression("h"),
    hfss.Expression("w_p"), 
    hfss.Expression("l_p"),
    Name='patch',
    Transparency=0.8)

raw_input('Press "Enter" to assign a PerfectE boundary condition on the patch.>')
patch_faceid=[]
print hfss.Expression("h")
patch_faceidnum = hfss.get_face_by_position(oEditor, patch, 0, 0, 0.005) #hardcode!!
#print ground_faceidnum
patch_faceid.append(patch_faceidnum)
hfss.assign_perfect_e(oDesign, "patch", patch_faceid)

raw_input('Press "Enter" to draw a Coaxial core>')

Coaxial_core = hfss.create_cylinder(
    oEditor,   
    "9.5mm", 
    0, 
    0,
    "0.5mm", 
    "5mm",
    Name='Coaxial_core',
    Transparency=0.8)
    
raw_input('''Press "Enter" to change the Coaxial_core's material to copper>''')

hfss.assign_material(oEditor, [Coaxial_core], MaterialName="copper")

raw_input('Press "Enter" to draw a Signal transmission port>')

port = hfss.create_circle(
    oEditor,   
    "9.5mm", 
    0, 
    0,
    "1.5mm", 
    Name='port',
    Transparency=0.8)

raw_input('Press "Enter" to subtract the transmission port from the ground.>')

hfss.subtract(oEditor, [ground], [port], KeepOriginals=True)

raw_input('Press "Enter" to draw an air box>')

air = hfss.create_box(
    oEditor,   
    '-80mm', 
    '-80mm', 
    0,
    '160mm', 
    '160mm',
    '75mm',
    Name='air',
    Transparency=0.8)
    
raw_input('Press "Enter" to assign a Radiation boundary condition for the air box.>')
air_objectid=[]
air_objectidnum = hfss.get_object_id_by_name(oEditor, "air")
#print ground_faceidnum
air_objectid.append(air_objectidnum)
print air_objectid
hfss.assign_radiation(oDesign, objectname=['air'], Name='Air')

raw_input('Press "Enter" to assign a lumped port on the port.>')

port_faceid=[]

port_faceidnum = hfss.get_face_by_position(oEditor, port, "9.5mm", 0, 0) #hardcode!!
#print port_faceidnum
port_faceid.append(port_faceidnum)
hfss.assign_lumpedport_multimode(oDesign, "port", port_faceid,["10mm","0mm","0mm"],["11mm","0mm","0mm"])

raw_input('Press "Enter" to insert analysis setup.>')  

setuplist=[]

setupname = hfss.insert_analysis_setup(oDesign, 2.45)

setuplist.append(setupname) 

raw_input('Press "Enter" to insert frequency sweep.>')  

hfss.insert_frequency_sweep(oDesign,
                            setupname,
                            "Sweep1",
                            1.5,
                            3.5,
                            0.1,
                            IsEnabled=True,
                            SetupType="LinearStep",
                            Type="Discrete",
                            SaveFields=True,
                            ExtrapToDC=False)

raw_input('Press "Enter" to solve the setup.>') 

hfss.solve(oDesign,setuplist)

raw_input('Press "Enter" to quit HFSS.>')

hfss.quit_application(oDesktop)

del oEditor
del oDesign
del oProject
del oDesktop
del oAnsoftApp