Antenna Gain Converter
Convert between dBi (isotropic) and dBd (dipole) antenna gain references.
Common Antenna Gains
| Antenna Type | dBi | dBd |
|---|---|---|
| Isotropic (theoretical) | 0 | -2.15 |
| Half-wave dipole | 2.15 | 0 |
| Ground plane vertical | 2-3 | 0-1 |
| Rubber duck | -1 to 2 | -3 to 0 |
| WiFi omni 5dBi | 5 | 2.85 |
| Yagi (3 element) | 7-8 | 5-6 |
| Yagi (10 element) | 11-12 | 9-10 |
| Panel/patch | 8-14 | 6-12 |
| Parabolic dish 2ft | 20-24 | 18-22 |
| Parabolic dish 4ft | 26-30 | 24-28 |
Key Conversion
dBd = dBi - 2.15
A dipole antenna has 2.15 dB gain compared to an isotropic radiator, so dBi values are always 2.15 higher than dBd for the same antenna.
Understanding Antenna Gain References
dBi - Isotropic Reference
dBi (decibels relative to isotropic) compares antenna gain to a theoretical isotropic antenna that radiates equally in all directions. This is the most common specification used by manufacturers and is required for regulatory calculations.
Used by: FCC regulations, most manufacturers, WiFi equipment, cell towers
dBd - Dipole Reference
dBd (decibels relative to dipole) compares antenna gain to a half-wave dipole antenna. This is popular in amateur radio because dipoles are simple, practical reference antennas that can be built and tested.
Used by: Amateur radio, some two-way radio equipment, antenna comparison charts