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Conversions | EIRP | Notes



Here are some RF/WiFi calculators including a milliWatt/dBm converter and an EIRP calculator.

Also see the notes section at the end of this page for a description of the various terms and equations.


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Scripts by WiFiNerd


Script by WiFiNerd
milliWatts: dBm:
dBm: milliWatts:




EIRP Script by WiFiNerd

Transmitter power
(in milliWatts):

Antenna Gain (in dBi):
Cable Loss (in dB):
Result: Watts:







Decibel - A logarithmic expression of ratios. Can be found by taking ten times the common logarithm of the ratio of two power levels, or 20 times the common logarithm of the ratio of two voltage levels.



Decibels related to isotropic. Relates the gain of an antenna relative to an isotropic (perfectly spherical pattern) antenna.



Decibels related to 1mW - the standard unit of power level used in microwave work. For example, 0dBm= 1mW, +10 dBm = 10mW, +20dBm=100 mW, etc.




Effective Isotropic Radiated Power

(Please note that the cable attenuation should be measure only from the last transmission point.   For example, if an outside amp is used that is near the antenna then the attenuation should be measure for the cable between the amp and the antenna and not the entire cable length.)

EIRP = P ´ 10 dBi/10

(P = transmitter-amp power in Watts.  dBi = gain in dBi - cable attenuation in dB.  This result is in Watts.)

or EIRP = P - A + G

(P =  transmitter-amp power in dBm, A = Atennuation in dB, G = Gain in dBi. The result is in dBm)






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Copyright © 2004 Eric Wagner All rights reserved.