High-Frequency Electromagnetic Solvers

ANSYS HFSS uses the highly accurate finite element method (FEM), the large-scale method of moments (MoM) technique and the ultra-large-scale asymptotic method of shooting and bouncing rays (SBR) with advanced diffraction and creeping wave physics for enhanced accuracy (SBR+). The ANSYS HFSS simulation suite has the following solvers to tackle manifold EM problems involving electrically small to enormous structures:


  • Frequency Domain
  • Time Domain
  • Integral Equations
  • Hybrid Technologies


  • Shooting and Bouncing Ray
  • Physical Optics
  • Physical Theory of Diffraction
  • Uniform Theory of Diffraction
  • Creeping Wave

HFSS contains multiple simulation engines in one package, each targeted toward a specific application or simulation output.

HFSS Hybrid Technologies
The FEM-IE hybrid technology is built upon HFSS FEM, IE MoM and the patented ANSYS domain decomposition method (DDM) to solve electrically large and complex systems. By applying the appropriate solver technology, local regions of high geometric detail and complex materials are addressed with finite element HFSS, while regions of large objects or installed platforms are addressed with 3D MoM HFSS-IE. The solution is delivered in a single setup through a single, scalable and fully coupled system matrix.

Finite Element Method (Frequency Domain)
This is the high-performance 3D, full-wave, frequency domain electromagnetic solver based on the proven finite element method. Engineers can calculate SYZ parameters and resonant frequency; visualize electromagnetic fields; and generate component models to evaluate signal quality, transmission path loss, impedance mismatch, parasitic coupling and far-field radiation. Typical applications include antennas/mobile communications, integrated circuits, high-speed digital and RF interconnects, waveguides, connectors, filters, EMI/EMC, etc.

ANSYS HFSS Finite Element Solver

Finite Element Transient (Time Domain)
The Finite Element Time Domain solver is used to simulate transient EM field behavior and visualize fields and system responses in typical applications like time domain reflectometry (TDR), lightning strikes, pulsed ground-penetrating radar (GPR), electrostatic discharge (ESD) and electromagnetic interference (EMI). It leverages the same finite element meshing approach as the frequency domain solver, without the need to switch meshing technologies to switch simulation domains. The transient solver complements the frequency domain HFSS solver, and enables engineers to understand the EM characteristics on the same mesh in both time and frequency domains.

ANSYS HFSS Transient Solver

Integral Equations
The integral equations (IE) solver employs the 3D Method of Moments (MoM) technique for efficiently solving open radiation and scattering problems. It is ideal for radiation studies like antenna design and/or antenna placement, and for scattering studies such as radar cross section (RCS). The solver can employ either multilevel fast multipole methods (MLFMM) or adaptive cross-approximation (ACA) to reduce memory requirements and solve times, allowing this tool to be applied to very large problems.

ANSYS HFSS Integral Equations Solver

HFSS Fast Mode
For the early part of a product’s design cycle — where rapid simulation results can provide invaluable insight regarding design trends — HFSS includes a fast simulation mode. The fast mode tunes the solver and adaptive mesher to return results as fast as possible, without significantly compromising solution accuracy. Then, as the design nears completion, a simple slider bar setting sets the HFSS solver to return validation-level signoff accuracy using the industry tested, gold-standard accuracy capability of HFSS.


SBR+ is the only commercial electromagnetic solver to empower Shooting & Bouncing Ray (SBR) technology with simultaneous and consistent implementations of Physical Theory of Diffraction (PTD), Uniform Theory of Diffraction (UTD), and Creeping Wave for simulating installed antenna performance on electrically large platforms that are hundreds or thousands of wavelengths in size.

SBR uses a ray tracing technique to model induced surface currents on the antenna platform or scattering geometry composed of conductors and dielectrics. With the SBR+ solver, engineers can obtain fast and accurate prediction of far field installed antenna radiation patterns, near-field distributions and antenna-to-antenna coupling (S-parameters) on electrically medium, large and enormous platforms. Transmissions and reflections can be modeled in large structures like vehicles, aircraft, radomes, etc. HFSS SBR+ also provides efficient radar signature modeling, including ISAR images of electrically large targets.

Physical Theory of Diffraction
The Physical Theory of Diffraction (PTD) wedge correction feature is used for correcting PO currents along sharp edges of installed antenna platforms to refine EM field diffraction.

Uniform Theory of Diffraction
Engineers can model Uniform Theory of Diffraction (UTD) edge diffraction rays created by illuminated geometry edges and identified by PTD wedges. This is important for cases where the significant parts of the scattering geometry are otherwise shadowed from direct or multi-bounce illumination.


Creeping Wave Physics for RCS and Installed Antenna Analysis
ANSYS HFSS SBR+ is the only commercial asymptotic field solver to offer creeping wave physics for both radar signature and installed antenna modeling.

Creeping waves provide an important component of radar scattering from objects with curvature. When a radar signal impinges on a rounded target, the currents induced on the object reach around the back and create delayed signal echoes. In modeling electrically large targets, ray-tracing approaches like HFSS SBR+ must be employed to model the radar signature, but traditional ray-tracing approaches have no way to model the backside currents or their influence on target scattering. Creeping wave physics is a ground-breaking addition to HFSS SBR+ to capture this important characteristic of radar scattering. It yields unprecedented accuracy for radar signature modeling of large targets.

Creeping waves are also used to model the installed antenna performance when integrated into curved surfaces found on aircraft fuselages, rockets and missile bodies, automobile bodies and ship topsides. They are used to model radiation in shadowed regions for shooting and bouncing ray (SBR) simulations. SBR is accurate for modeling radiation in regions directly lit by the antenna or indirectly through multi-bounce interactions. However, for the back lobe or deep sidelobe regions shadowed from view by the curved host platform it is essential to use creeping wave physics to extend the ground-induced currents beyond line of sight across these smoothly curved surfaces. The analysis contributes to a higher-fidelity characterization of the back radiation. Increased accuracy of modeling antenna-to-antenna coupling is another benefit of this capability.

Creeping wave physics - HFSS

ACT Extensions RadarPre and RadarPost for Radar Processing Delivered with HFSS
HFSS and HFSS SBR+ provide you with a powerful capability to model radar cross section (RCS) and time domain radar response for large targets like aircraft, automobiles and ships. Radar signatures involving time domain range profiles, inverse synthetic aperture radar (ISAR) plots and waterfall/sinograph plots yield insight into radar design and stealth. The RadarPre and RadarPost toolkits simplify and speed the process of setting up these complex radar simulations and provide streamlined post-processing for graphically rich analysis results. The RadarPre and RadarPost ACT toolkits are delivered with the standard installation of the ANSYS Electronics Desktop.

Accelerated Doppler Processing
Accelerated Doppler processing (ADP) accelerates simulation of long-, medium- and short-range pulse-Doppler and chirp-sequence frequency-modulated continuous-wave (FMCW) radars used in ADAS, autonomous vehicles and other near-field radar systems by more than 100x. ADP includes integrated range-Doppler image map post-processing and animation in the ANSYS Electronics Desktop. In addition to ADP, a gain and self-coupling antenna link streamlines the complete radar design process, so radar sensor simulation results can be used seamlessly in installed performance modeling and in radar-environment range-Doppler simulations. The workflow simplifies the collaboration between radar sensor designers and the OEMs that incorporate the sensors on vehicles and in large-environment radar simulations.

Accelerated Doppler processing is available as part of the ANSYS Electronics Enterprise product suite.