NEC2 Wire Antenna Simulation
Simulate wire antennas (dipoles, yagis, loops) using the NEC2 method-of-moments engine. Get 3D radiation patterns, gain, impedance, and efficiency across a frequency sweep.
How It Works
NEC2 (Numerical Electromagnetics Code, version 2) solves Maxwell's equations for thin-wire structures using the method of moments (MoM). Each wire is divided into short segments; the code computes the current distribution on every segment, then derives far-field radiation patterns, input impedance, gain, and efficiency.
The tool includes pre-built geometries: a half-wave dipole (the fundamental reference antenna), Yagi-Uda arrays (3 or 5 elements for directional gain), and a square loop. Element lengths and spacing are automatically scaled to the specified frequency.
Three ground models are available: free space (no ground effects), perfect ground (ideal image theory), and real ground (finite conductivity using the Sommerfeld-Norton method). Ground effects significantly alter the radiation pattern, especially at low elevation angles.
Results include azimuth and elevation radiation patterns (in dBi), input impedance (R + jX), VSWR versus a 50 Ω reference, directivity, and radiation efficiency.
Related Calculators
FAQ
How accurate is NEC2 for my antenna?+
NEC2 is highly accurate for wire antennas where the wire diameter is much smaller than a wavelength (diameter < 0.01 lambda). It does not model solid surfaces, dielectrics, or very thick conductors well. For patch antennas or PCB antennas, use a full 3D EM solver instead.
What does the gain number mean?+
Gain is reported in dBi — decibels relative to an isotropic radiator. A half-wave dipole has about 2.15 dBi peak gain. A 3-element Yagi typically achieves 7-9 dBi, and a 5-element Yagi reaches 10-12 dBi.
Why does ground type matter?+
Antennas near the ground experience reflections that alter the radiation pattern. A perfect ground creates a clean image; real ground (with finite conductivity) introduces additional loss and pattern distortion. For VHF/UHF antennas mounted above ground, the real ground model is most realistic.
Can I simulate my own antenna geometry?+
Currently the tool offers pre-built dipole, Yagi, and loop geometries. Custom NEC deck input is planned for a future update. In the meantime, you can adjust the center frequency — the tool automatically scales all element dimensions.