So, the term 'dB' is not a reference but is rather a method and a measurement standard. It has to be referenced to something else to provide meaningful measurement. Therefore dB is not an absolute measurement but rather a ratio.ĭB as a standalone unit represents loss or gain and does not have any dimension. outdoor antennas have better dBis than indoor antennas as they are directional antennas used in point to point and point to multipoint connections.ĭBi (gain) is related to VSWR in evaluating antennas: VSWR is another very key factor in antenna evaluation.ĭB refers to the decibel, which is the unit of measurement of sound though it is also a relative measure of the power between two levels. Therefore dBi is a term that is used when measuring the relative antenna gain of applications.ĭBis tend to vary with the most common indoor WiFi router antennas designed to work at 4-9 dBi, while outdoor antennas range between 15 and 24 dBi. In such an instance, dBi would refer to how effective the WiFi router’s antenna is. A good illustration of this is when you are using an application such as a Wi-Fi router. Linear polarization of the EM field is assumed unless noted otherwise.ĭBi refers to decibels measured against an isotropic reference antenna. The forward gain is compared with the hypothetical isotropic antenna, which uniformly distributes energy in all directions. The dBi value also reflects the antenna's electrical efficiency, differentiating between transmitting and receiving antenna for enhanced characterization of antenna performance.DBi = dB(isotropic): The forward gain of an antenna, measured in decibels (dBi), The dBi value reflects the antenna's directional / beamwidth characteristics, i.e., directional as opposed to omnidirectional: Generally, the higher the gain (dBi), the narrower the beamwidth - the more directional the antenna.

Decibel unit