Explore antenna radiation and electromagnetic fields interactively
antennasim is a free, browser-based educational tool for experimenting with antenna geometries, interference, electromagnetic fields, and induced currents.
Instead of only looking at static radiation-pattern plots, you can adjust sources and passive elements and see how the calculated electric field, magnetic field, and energy flow respond.
Launch the interactive simulator →
What can you simulate?
- Dipole antennas: explore center-fed wires, ideal Hertzian dipoles, and how current distribution and geometry affect the fields.
- Loop antennas: compare small-loop behavior with other antenna configurations.
- Phased arrays: vary spacing, relative phase, and amplitude to study constructive and destructive interference and beam steering.
- Passive PEC wire elements: visualize approximately induced current distributions and their influence on the fields.
- Field visualization: switch between electric fields, magnetic fields, and energy flux; examine near-field structure and wave propagation.
Try these built-in examples
Half-wave dipole: inspect the field around a center-fed antenna. Yagi–Uda antenna: explore the effect of a reflector and directors on an antenna's radiation. Electric quadrupole: see how two closely spaced, oppositely excited dipoles modify the field. Rotating dipoles: examine phase-dependent behavior and polarization.
How to use the simulator
Open the workspace and choose a preset from the Examples menu, or use Add to place components. Select an element to adjust its parameters, use Pan to move across the scene, and use the mouse wheel or zoom buttons to change your view. Change the selected field mode to see different electromagnetic quantities.
Model assumptions and limitations
antennasim is intended for learning and qualitative exploration. It uses idealized source models and numerical approximations, including a simplified method for estimating passive-wire currents. Representations in the visualization plane should not be interpreted as a complete three-dimensional field solver. Results depend on model choices and numerical resolution.
For antenna design, impedance prediction, efficiency estimates, or safety-critical decisions, validate results with an appropriate full-wave solver or measurements.
Source code
The project is available on GitHub. You can inspect the implementation, report issues, or suggest educational examples.