如何使用Lumped RLC Elements in HFSS Version 8.pdfVIP

Ansoft HFSS Engineering Note Lumped RLC Elements in HFSS Version 8 In Ansoft’s High Frequency Structure Simulator (HFSS), a specified impedance boundary condition has always referred to field values because HFSS is a full-wave field simulator. You may wish to model a physical lumped resistance (R), inductance (L), or capacitance (C) element that is connected to the field or distributed model. HFSS Version 8 enables you to specify any combination of parallel-connected lumped RLC elements on surfaces in terms of circuit definition by using lumped RLC boundaries. A typical application is the simu- lation of a Monolit Microwave Integrated Circuit (MMIC), in which the lumped elements are represented by thin sheets. HFSS Version 8’s fast and interpolating frequency sweep options support the frequency dependence of an impedance, which consists of either a lumped inductance or a lumped capacitance, with the use of lumped RLC elements. HFSS’s 3D Boundary Manager supports any combination of parallel-connected RLC elements on a surface. To model serial-connected lumped elements, define two serial-connected sur- faces for the serial elements. This engineering note explains the difference between field and lumped impedances and presents applications for both cases. Engineering Note AP03-0201 Field and Lumped Impedances Figure 1 shows a thin, rectangular sheet on which a lumped impedance boundary condition will be defined. Figure 1: Thin rectangular sheet where: • l is the length of the sheet • W is the width of the sheet • Et is the tangential component of the electric field on the impedance boundary surface • Ht is the tangential component of the magnetic field on the impedance boundary surface • I is the current flowing on the sheet • c is a closed curve surrounding the sheet •