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Home > ANSYS HFSS 教學 > Dual Mode Waveguide Horn Antenna
本文的重點在 學習Driven Modal下的Wave port設定，與看圓極化場型。
Please refer to Stripline Differential Pair step1, but select [Modeler Units] as "in" (inches) and [Solution Type] as [Driven Modal].
2.1 先把裡面空心部分的喇叭狀waveguide畫出，外面再畫一個材質金屬的圓柱，兩者相減即得一個waveguide horn，外面再畫一個距離l/4的圓柱設為radiation boundary，過程中只需用到以下四個指令
[Draw] \ [Cylinder]
[Draw] \ [Cone]
[Modeler] \ [Boolean] \ [Subtract]
[HFSS] \ [Boundaries] \ [Assign] \ [Radiation]
2.2 Create the wave port sheet
[Draw] \ [Circle]
2.3 Assign wave port
select "p1" sheet, then [HFSS] \ [Excitations] \ [Assign] \ [Wave Port]
assign port name "p1", then set [Number of Modes] as "2" (兩個正交激勵模態，可以形成圓極化場)
In general case, choose [Set mode polarity using integration lines]. (不需要align E-field)
並非所有的wave port都需要設積分線, 只有需要mode alignment的情況, wave port才需積分線 。讀者可以自行嘗試，在此步驟中，不要設積分線，一樣跑得出結果，只是你的場不會像本文step4.4, 4.5會旋轉。
3.1 Create Radiation Setup
[HFSS] \ [Radiation] \ [Insert Far Field Setup] \ [Infinite Sphere]
3.2 Create Analysis Setup
[HFSS] \ [Analysis Setup] \ [Add Solution Setup]
3.3 Run Analysis
HFSS \ Validation Check
HFSS \ Analyze All
4.1 Edit Sources
HFSS \ Fields \ Edit Sources
4.2 Plot 2D Radiation Pattern
HFSS \ Results \ Create Far Fields Report \ Radiation Pattern
4.3 Plot 3D Far Field Radiation
HFSS \ Results \ Create Far Fields Report \ 3D Polar Plot
4.4 讓3D model與3D radiation plot together (場結合後的位置是錯的, 詳見問題與討論5.3)
4.5 Plot E-field(右旋圓極化)
4.6 Plot E-field(左旋圓極化)
4.7 All Antenna Parameters
5.1 何謂圓極化 (circular polarization)
Ans：大小相等，相位差90度的兩個正交電場，會形成一個圓極化天線，此例是一典型的線極化轉圓極化的轉換器
5.2 在step2.3中，Alignment Groups設兩個或一個，為什麼看起來沒差?
Ans：只有選了[Align modes using integration lines]，才會出現[Alignment Groups]欄位。help的解釋是說：確保同一個group內的mode在積分線上非零電壓，還是看不懂是什東東
5.3 為何step4.4的3D far field不是從wave port開始打出能量，而是從wave guide的出口處才有field?
Ans：其實step4.4打出的場圖相對位置是有問題的，因為far field radiation setup內的座標選定沒設對
