Introduction
This Getting Started Guide is based on an HFSS Transient analysis of a coax cable. Specifically, you will create a parameterized model of a bend in a coax cable and perform a time-domain reflectometry (TDR) analysis. Using the techniques detailed herein, you will observe disturbances in the characteristic impedance of the coax bend as the signal propagates through the model and passes geometrical discontinuities.
This Getting Started Guide differs from others in that it assumes you already have a working knowledge of basic model construction, ribbon / menu navigation, and so forth. You are given the parameters of objects to build, excitations to apply, and setups to define. However, the step-by-step command and entry procedures are not included for commonly performed and unambiguous tasks. As such, this guide is more appropriate for intermediate to advanced users of the Ansys Electronics Desktop application, or at least beginners who have completed a couple of other Getting Started Guides and are comfortable with the user interface. If you would like to first complete a coax example that includes explicit step-by-step instructions, please see one of the following exercises:
- HFSS Getting Started Guides:
- HFSS Coax Tee (relatively simple model)
- HFSS Coax Connector (more complex model)
Model Geometry
The model geometry is shown in the following figure. It consists of two straight sections and a bend between them. The region between the inner and outer conductors is mostly filled with air (transparent blue object). The inner conductor (red object) is held in place by two Teflon slugs (green cylindrical objects). At the slugs, the radius of the inner conductor has been adjusted to keep the characteristic impedance close to 50 ohms. The air body is sectioned to form a sheet object along the XZ plane as a target for overlaying field results.
Figure 1-1: Coax with Bend – Model Geometry