【正文】 ence. In many instances, the impedance and calibration lines are the same! 251 HFSS Source Descriptions: Wave Port 252 HFSS Source Descriptions: Wave Port EXAMPLE WAVE PORTS EXAMPLE LUMPED PORTS ? Parameters: Mode Count, Calibration, Impedance, Polarization ? A port is an aperture through which guided electromagic field energy is injected into a 3D HFSS model. ? Wave Ports: The aperture is solved using a 2D eigensolution which locates all requested propagating modes ? Characteristic impedance is calculated from the 2D solution ? Impedance and Calibration Lines provide further control 253 X波段波導(dǎo)中的傳輸模式 254 Impedance and Polarization Lines ? Impedance line and polarization line are optional in port setup. ? They are located in the port and have a starting point and an end point. Port = cross section of waveguide I and/or P Line 255 Impedance Line ? Without impedance line, HFSS putes port impedance from power and current: Zpi ? With impedance line, a voltage can be defined: ? E?dl . ? Two more port impedances result: Zpv and Zvi . ? These are not the same for nonTEM transmission lines. 256 Integration Line （積分線） 257 Polarization Line （極化線） 258 HFSS Source Descriptions: Lumped Port ? Parameters: Mode Count, Calibration, Impedance, Polarization ? A port is an aperture through which guided electromagic field energy is injected into a 3D HFSS model. ? Lumped Ports: Approximated field excitation is placed on the gap source port surface ? Characteristic impedance is provided by the user during setup 259 HFSS Source Descriptions: Incident Wave 260 HFSS Source Descriptions: Incident Wave ? Parameters: Poynting Vector, Efield Magnitude and Vector ? Used for radar cross section (RCS) scattering problems. ? Defined by Poynting Vector (direction of propagation) and Efield magnitude and orientation ? Poynting and Efield vectors must be orthogonal. ? Multiple plane waves can be created for the same project. ? If no ?ports? are present in the model, Sparameter output is not provided ? Analysis data obtained by postprocessing on the Fields using the Field Calculator, or by generating RCS Patterns In the above example, a plane incident wave is directed at a solid made from dielectrics, to view the resultant scattering fields. 261 HFSS Source Descriptions: Voltage Drop and Current Source Voltage Drop Current Drop 262 HFSS Source Descriptions: Voltage Drop and Current Source Example Voltage Drop (between trace and ground) Example Current Source (along trace or across gap) ? Parameters: Direction and Magnitude ? A voltage drop would be used to excite a voltage between two metal structures (. a trace and a ground) ? A current source would be used to excite a current along a trace, or across a gap (. across a slot antenna) ? Both are ?ideal? source excitations, without impedance definitions ? No SParameter Output ? User applies condition to a 2D or 3D object created in the geometry ? Vector identifying the direction of the voltage drop or the direction of the current flow is also required 263 Sources/Boundaries and Eigenmode Solutions ? An Eigenmode solution is a direct solution of the resonant modes of a closed structure ? As a result, some of the sources and boundaries discussed so far are not available for an Eigenmode project. These are: ? All Excitation Sources: ? Wave Ports and Lumped Ports ? Voltage Drop and Current Sources ? Magic Bias ? Incident Waves ? The only unavailable boundary type is: ? Radiation Boundary ? A Perfectly Matched Layer construction is possible as a replacement 264 HFSS Source Descriptions: Magic Bias ? Parameters: Magnitude and Direction or Externally Provided ? The magic bias source is used only to provide internal biasing Hfield values for models containing nonreciprocal (ferrite) materials. ? Bias may be uniform field (enter parameters directly in HFSS)... ? Parameters are direction and magnitude of the field ? ...or bias may be nonuniform (imported from external Magostatic solution package) ? Ansoft?s 3D EM Field Simulator provides this analysis and output ? Apply source to selected 3D solid object (. ferrite puck) 265 HFSS Ports: A Detailed Look ? The Port Solution provides the excitation for the 3D FEM Analysis. Therefore, knowing how to properly define and create a port is paramount to obtaining an accurate analysis. ? Incorrect Port Assignments can cause errors due to... ? ...Excitation of the wrong mode structure ? ...Bisection by conductive boundary ? ...Unconsidered additional propagating modes ? ...Improper Port Impedance ? ...Improper Propagation Constants ? ...Differing phase references at multiple ports ? ...Insufficient spacing for attenuation of modes in cutoff ? ...Inability to converge scattering behavior because too many modes are requested ? Since Port Assignment is so important, the following slides will go into further detail regarding their creation. 266 HFSS Port Selection: Wave Port or Lumped Port? ? 什么時候你選擇 Lumped Port 而不是 Wave Port呢 ? ? 當(dāng)模型中導(dǎo)線之間的間隙太小時； ? 當(dāng)使用 Wave port很難確定一個端口的參考定位時； ? 當(dāng)你希望使用電壓降，而不是 S參數(shù)作為輸出