ABC Tools
Antenna Radiation Pattern Explorer illustration

Antenna Radiation Pattern Explorer

Draws the radiation pattern of classic antennas on an interactive polar plot: isotropic reference, half-wave dipole (the textbook cos(π/2·cosθ)/sinθ donut), quarter-wave monopole over ground, 3-, 5- and 7-element Yagis via an array-factor approximation, and a two-element phased pair with live spacing and phase sliders. Switch between azimuth and elevation cuts, and raise the antenna above ground to watch two-ray reflection carve the elevation pattern into lobes. Readouts give the maximum gain in dBi, the −3 dB beamwidth and the front-to-back ratio. The core lesson is visible immediately: every added element narrows the beam and raises the gain, because an antenna never creates power — it only focuses it.

Runs 100% in your browser — simulations are computed locally on your device.

Read the full guide to this tool

Notes

  • Yagi patterns use an idealized endfire array factor with typical element spacing, not a full electromagnetic simulation — real element currents differ, so sidelobe details are approximate while the beamwidth and gain trends are right.
  • Quoted gains are the standard textbook figures: dipole 2.15 dBi, monopole over perfect ground 5.15 dBi, typical 3/5/7-element Yagis about 7.5/9.5/11 dBi.
  • The ground-reflection model is the two-ray approximation over a perfect conductor: lobes appear at elevations where the direct and reflected waves add in phase — the reason HF antennas are mounted high.
  • The dB scale on the plot is normalized to the pattern maximum; rings mark −10, −20 and −30 dB.

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