Dual Mode Waveguide Horn Antenna

[Nic Chan]

http://home.educities.edu.tw/oldfriend/HFSS/horn_antenna.htm{$des}

Ansoft HFSS 教學 > Dual Mode Waveguide Horn Antenna

更 新 日 期：08/17/2012 13:10:12

本文的重點在 學習Driven Modal下的Wave port設定，與看圓極化場型。 Get Started Create 3D Model and Wave Port Analysis Setup Create Reports 問題與討論 Get Started   Please refer to Stripline Differential Pair step1, but select [Modeler Units] as "in" (inches) and [Solution Type] as [Driven Modal]. Create 3D Model   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)  如果一個wave port有degenerate mode(多模態組合)，那就需要以下的mode alignment (通常waveguide才會用到)      For analytic port type, choose  [Align modes analytically using coordinate system].      For non-analytic ports, choose [Align modes using integration lines]. 對port的幾何沒有限制條件  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。 Analysis Setup   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 Create Reports   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 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 問題與討論   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