Basic concepts of EIRP/ERP
EIRP: Effective Isotropic Radiated Power, the product of the power of the antenna supplied to a radio transmitter by the absolute gain of the antenna in a given direction. An ideal omnidirectional antenna with the same unit gain in all directions, often used as a reference antenna in wireless communication systems. EIRP is defined as: EIRP=Pt*Gt, which represents the transmitted power in the direction of maximum antenna gain that can be obtained by the transmitter compared with the omnidirectional antenna. Pt represents the transmitting power of the transmitter and Gt represents the antenna gain of the transmitting antenna. In wireless communication engineering, it is usually used to measure the intensity of interference and the ability of transmitter to transmit strong signals.
ERP: effective radiated power. The product of the power supplied by a radio transmitter to an antenna and the gain of the antenna relative to a half-wave dipole in a given direction. In fact, the effective transmitting power ERP is used instead of EIRP to express the maximum transmitting power compared to the half-wave coupled pole antenna. Note: The coupler antenna has a gain of 1.64 (2.15dB), so the ERP is 2.15dB lower than the EIRP.
dBm: is a value measuring the absolute value of power, the calculation formula is :10lgP(power value /1mw), for example, if the transmitted power P is 1mw, it is 0dBm after converted to dBm.
dBi and dBd: dBi and dBd are the values of the measured gain (power gain). Both are a relative value, but the reference base is different. The reference for dBi is an all-directional antenna and the reference for dBd is a dipole, so they are slightly different. It is generally believed that the same gain represented by dBi is 2.15 greater than that represented by dBd. For an antenna with a gain of 16dBd, its gain is 18.15dBi when converted into the unit of dBi (generally, the decimal place is ignored, and it is 18dBi). 0dBd=2.15dBi. The GSM900 antenna gain can be 13dBd (15dBi), and the GSM1800 antenna gain can be 15dBd (17dBi).