GrdBi
GrdBi is a term occasionally encountered in RF literature and product datasheets, but it is not a standard unit in antenna engineering. Its exact meaning can vary between sources, which can lead to confusion. In general, GrdBi is used to convey antenna gain with some form of ground reference, such as a ground plane or a ground environment, rather than a purely free-space isotropic reference. Because there is no universally agreed definition, it is important to consult the specific source to understand the reference conditions used to derive GrdBi.
By comparison, standard antenna gain is typically expressed in dBi (gain relative to an isotropic radiator
Measurement considerations for GrdBi should specify several factors: the frequency, the direction of measurement (boresight), the
In summary, GrdBi is not standardized and can be ambiguous. When encountered, verify the reference conditions