Wire Antenna Pattern Calculator
Radiation patterns, gain, beamwidth, front-to-back ratio and impedance for dipoles, Yagis and loops, from analytical antenna models across a frequency sweep.
How It Works
This tool uses closed-form analytical models of each antenna rather than a numerical field solver. The half-wave dipole pattern comes from the standard cos(π/2·cosθ)/sinθ expression; Yagi and loop patterns are shaped to the beamwidth and front-to-back ratio those antennas achieve in practice, and the impedance sweep uses a series-resonance model. Gain, beamwidth and front-to-back are all read back off the computed pattern, so the reported figures and the plotted pattern always describe the same antenna.
Because the models are analytical, results are instant and well behaved, but they do not capture element-by-element current distribution, mutual coupling between arbitrary geometries, or ground interaction the way a method-of-moments code such as NEC2 would. For antennas whose geometry departs from these standard forms, use a dedicated MoM solver.
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.
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FAQ
How accurate are these results?+
The dipole pattern and its 2.15 dBi gain and 78 degree beamwidth are exact closed-form results. Yagi and loop figures are representative of well-built antennas of that element count rather than a solve of your specific dimensions, so treat them as design-stage estimates. For a specific geometry, element spacing or ground interaction, model it in a method-of-moments code such as NEC2 or a full 3D EM solver.
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.