Antenna radiation describes the generation and propagation of electromagnetic energy from a radiating structure into its surrounding environment. Accurate prediction of radiation behavior is essential for the design and optimization of antennas used in wireless communications, radar, sensing, and high-frequency electronic systems.

Radiation is computed using fast time-domain simulation, capturing the full electromagnetic response of the antenna, its materials, and nearby structures as fields evolve in time. This approach naturally supports broadband excitation, transient analysis, and complex geometries, providing a complete view of antenna behavior across wide frequency ranges within a single simulation.

Electromagnetic fields are resolved directly in the near field, where energy storage, coupling, and interactions with surrounding objects dominate. From these near-field solutions, near-to-far-field transformations are applied to accurately reconstruct radiated fields at arbitrary distances. This enables efficient extraction of key far-field metrics, including radiation patterns, gain, directivity, polarization, and radiation efficiency, without requiring excessively large computational domains.

The approach supports a wide range of antenna types, including wire antennas, patches, arrays, embedded radiators, and highly integrated designs. It is particularly effective for electrically small antennas, wideband systems, and antennas operating in the presence of complex materials or nearby structures where traditional approximations break down.

By combining fast time-domain simulation with robust near-to-far-field transformation, antenna radiation can be predicted with high accuracy and physical consistency, enabling rapid design iteration and confident deployment in real-world electromagnetic systems.