Antenna Beamwidth Estimate Calculator

Enter the antenna gain in dBi to estimate the half-power beamwidth.

How to use

  1. Enter your values in the fields above.
  2. Press Calculate to see your result instantly.
  3. Use the Share button to copy a link to your result.

About this calculator

An antenna's half-power beamwidth (HPBW) is the angular width of its main radiation lobe measured between the points where power drops to half (−3 dB) of the peak. There's a direct trade-off between gain and beamwidth: a highly directional, high-gain antenna necessarily has a narrow beam, and vice versa — approximated for a symmetric-beam antenna as HPBW ≈ √(41253 / G_linear), where G_linear is the gain converted out of decibels.

This quick estimate is widely used by RF and wireless engineers during initial antenna selection or link-budget planning — for example, sizing a satellite dish or point-to-point microwave link where the beamwidth determines how precisely the antenna must be aimed and how much coverage area it illuminates.

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