Introduction to the meaning of EIRP/ERP
What is EIRP?
EIRP：Effective Isotropic Radiated Power.The EIRP power is the product of the power supplied by the radio transmitter to the antenna and the absolute gain of the antenna in a given direction. An ideal omnidirectional antenna with the same unity gain in all directions, typically used as a reference antenna for wireless communication systems. The EIRP power is defined as: EIRP = Pt * Gt, which represents the transmit power in the direction of the maximum antenna gain that can be obtained by the transmitter compared to the omnidirectional antenna. Pt represents the transmit power of the transmitter, and Gt represents the antenna gain of the transmit antenna. In wireless communication engineering, it is often used to measure the strength of interference and the ability of the transmitter to transmit strong signals.
ERP:Effective radiated power. The power supplied by the radio transmitter to the antenna and the gain of the antenna relative to the gain of the half-wave dipole in a given direction. In fact, the effective transmit power ERP is substituted for EIRP to represent the maximum transmit power compared to the half-wave dipole antenna. Note: The dipole antenna has a gain of 1.64 (2.15dB), so the ERP is 2.15dB lower than the EIRP.
dBm：Is a value of the absolute value of the test power, the formula is: 10lgP (power value / 1mw), for example, if the transmit power P is 1mw, converted to 0dBm after dBm.
dBi and dBd: dBi and dBd are the values of the gain (power gain), both of which are relative values, but the reference is not the same. The reference reference for dBi is an omnidirectional antenna, and the reference for dBd is a dipole, so the two are slightly different. It is generally considered that the same gain is expressed by dBi, which is larger than that expressed by dBd. [Example 3] For an antenna with a gain of 16 dBd, when the gain is converted into dBi, it is 18.15 dBi (the decimal place is generally ignored, 18 dBi). [Example 4] 0 dBd = 2.15 dBi. [Example 5] The GSM900 antenna gain can be 13dBd (15dBi), and the GSM1800 antenna gain can be 15dBd (17dBi).