HFSS

HFSS, short for High Frequency Structure Simulator, is a commercial three-dimensional electromagnetic simulation package developed by Ansys (formerly Ansoft). It solves Maxwell's equations in complex geometries to model radio frequency and microwave devices. The software is widely used to design antennas, filters, microwave components, waveguides, connectors, and packaging, as well as to analyze electromagnetic interference and radiation patterns.

HFSS primarily employs a finite element method (FEM) solver with adaptive meshing to handle fine geometrical features and material inhomogeneities. It supports frequency-domain analysis for steady-state responses and can perform time-domain simulations for broadband behavior. Features include port definitions (lumped, wave, and Floquet ports), absorbing boundary conditions such as radiation boundaries and perfectly matched layers, and periodic boundary conditions for array and metamaterial studies. An eigenmode solver computes resonant modes and quality factors of closed or semi-closed structures, while the S-parameter solver provides scattering parameters over a user-defined band.

The tool integrates with the broader ANSYS environment for optimization and multi-physics workflows, enabling coupling with thermal and mechanical analyses and with other RF design tools. It can import CAD data, build structured meshes, and deliver near-field, far-field, and radiation pattern results, as well as loss, gain, and efficiency metrics.

History and usage: HFSS originated with Ansoft and was acquired by Ansys in 2008. Over successive releases it has expanded capabilities for high-frequency electromagnetics, improved solver performance, and deeper integration with simulation and optimization toolchains. It competes with other full-wave solvers in the RF engineering community, such as CST Studio Suite and COMSOL Multiphysics.

See also: Finite element method; Antenna theory; Microwave engineering.