LW RF Studio: Desktop program made for printed PCB antennas: import the board, simulate S11, impedance, efficiency and radiation pattern with openEMS, then build the matching network on a Smith chart with real parts.
openEMS: Free and open-source FDTD electromagnetic solver. The model, mesh and post-processing are written as MATLAB/Octave or Python scripts.
Ansys HFSS: Industry-reference 3D full-wave simulator based on the finite element method, with adaptive meshing and many companion solvers.
CST Studio Suite: General 3D electromagnetic suite whose time-domain solver (finite integration technique) is close to FDTD and well suited to broadband antennas.
Altair Feko: Electromagnetic suite strong in method of moments and its fast variants, popular for antenna placement and large structures.
Keysight ADS (Momentum, RFPro): RF circuit design environment; Momentum simulates planar layouts with a 2.5D method of moments, combined with circuit simulation.
Cadence AWR Microwave Office (AXIEM): Microwave circuit design software with the AXIEM planar method-of-moments solver and the Analyst 3D FEM solver.
Sonnet Suites: High-accuracy planar solver that models the layout inside a shielded box; antennas need care with the box walls.
COMSOL Multiphysics (RF Module): General multiphysics FEM software; the RF Module adds electromagnetic wave simulation including antennas.
MATLAB Antenna Toolbox: Toolbox with a catalogue of parametric antennas and a method-of-moments solver, scripted in MATLAB. PCB antennas via pcbStack.
4nec2 (NEC-2): Free graphical front-end to the NEC-2 thin-wire method-of-moments engine. Not suited to PCB antennas with a substrate.
MEEP: Free FDTD solver from MIT, mostly used in photonics, scripted in Python. Usable for antennas with effort.