DBi Values Explained. DBd is a unit of measure for gain using a dipole as a reference. What Is The Difference Between Dbi And Dbd Everything Rf Power gain relative to the array antenna. . So an antenna with a gain of 3 dBd has a gain of 515 dBi. Power at antenna connector in dBm antenna gain in dBi Effective Power transmitted by. For example for an antenna with a gain of 16 dBd when the gain is converted to dBi it is 1815 dBi. The following equation represents the relationship between dBi and dBd. In that case the unit of measure is dBd Gain in dBd can be converted to dBi by adding 215 dB to the gain expressed in dBd. Dbi to dbm conversion dBi or dBisotropic is the forward gain of an antenna compared to the hypothetical isotropic antenna which uniformly distributes energy in all directions. Enter the values in one or two of the text boxes and press the corresponding Convert button. A reference dipole anten