Introduction

This Getting Started guide describes how to use HFSS to model a Monostatic Radar Cross Section (RCS) of a metal trihedral reflector using an SBR+ Hybrid Region. You will use an RCS example model that is already set up and ready to solve. This guide shows you how to verify the excitation and solution setup, analyze the model, and produce reports.

In this tutorial the following tasks are performed using HFSS:

• Verify the incident wave excitation
• Verify solution setups
• Run HFSS simulations
• Create 2D (XY) plots
• Create a 3D polar plot and overlay it on the model

Monostatic RCS of a Tridehral Reflector using an SBR+ Hybrid Region

Metal trihedrals are commonly employed as radar calibration targets because they provide strong, aspect-stable, and predictable Radar Cross Section (RCS) results over a wide range of angles. They are also easy to construct. In this example project, the monostatic RCS of a trihedral reflector is computed over a full azimuth (Theta) cut in the XY-plane (at Theta = 90°) using the HFSS SBR+ solver.

Model Description: The trihedral reflector is composed of three right-isosceles triangles, each of whose leg lengths is s = 0.5 m, as set by the HFSS project design variable, sideLength, in TriHedral_RCS.aedt. These triangular sides are arranged as a tetrahedron with one open face perpendicular to the +x axis and bounded by the hypotenuse of each triangle. The open face is an equilateral triangle whose sides are √2 s = 0.7071 m. The trihedron's apex, where the 90^o corners of the right-isosceles triangles meet, is at the global coordinate origin.

The trihedral reflector is assigned a Perfect-E (PEC metal) boundary. With this construction, plane waves incident near the +x-axis will backscatter strongly, yielding a large RCS. In a geometric optic (GO) ray interpretation, each ray arriving from near the +x-axis direction will bounce successively off each of the three faces and then escape in the precise backscatter direction, all with the same path length, providing a strong, coherent backscatter return. In the asymptotic GO limit, the head-on RCS looking along the x-axis is given by:

where λ is the wavelength. At a frequency of 10 GHz, with s = 0.5 m, we obtain σ = 291.3 m² = 24.6 dBsm (dB square-meters).

Launch EDT and Open the Example Model

You can open the example project from the Ansys Electronics Desktop (EDT) application, as follows:

1. Double-click the Ansys Electronics Desktop shortcut on your desktop (or click the equivalent Start Menu shortcut) to launch the application.
2. On the Desktop ribbon tab, click Open Examples.

The Open dialog box appears displaying the contents of the Examples folder.

3. Double-click the HFSS subfolder and then double-click the RCS subfolder under HFSS.
4. Select the TridHedral_RCS project and click Open.

The example model loads.

5. Expand the TriHedral_RCS branch of the Project Manager.

The project already contains a MonoStaticTriHedral (Hybrid Modal Network) design: