Antenna Gain Converter
The everyday antenna conversions in one place: gain between dBi and dBd, the equivalent isotropically radiated power (EIRP) from gain and transmit power, the effective aperture that gain corresponds to at a given frequency, and the far-field (Fraunhofer) distance beyond which the antenna's pattern is fully formed.
Equations & Parameters ▸
\(G_{dBd}=G_{dBi}-2.15 \qquad \text{EIRP}=P_t+G_{dBi} \qquad A_e=\dfrac{G\,\lambda^2}{4\pi}\)
\(R_{ff}=\dfrac{2D^2}{\lambda} \qquad \lambda=\dfrac{c}{f_0}\)
\(R_{ff}=\dfrac{2D^2}{\lambda} \qquad \lambda=\dfrac{c}{f_0}\)
| G | Antenna gain (dBi). |
| f0 | Frequency (GHz), for the effective aperture and far field. |
| Pt | Transmit power (dBm), optional — gives EIRP. |
| D | Largest antenna dimension (m), optional — gives the far-field distance 2D²/λ. |
Reference: C. A. Balanis, Antenna Theory, 4th ed., 2016. dBd is referenced to a half-wave dipole (2.15 dBi).
Inputs
dBi
Isotropic ref.GHz
For Ae & far fielddBm
For EIRPm
For far fieldResults
Gain & power
Gain (dBd)—
Gain (linear)—
EIRP—
EIRP (W)—
Aperture & range
Wavelength λ—
Effective aperture Ae—
Far-field distance—
Diagram