Look up: EIRP

1. 
   EIRP
   The Effective Isotropic Radiated Power (EIRP) of a transmitter (uplink) is the power that the transmitter appears to have if the transmitter was an isotropic radiator, i.e., if it radiated equally in all directions. By virtue of the Gain of a radio antenna, dish, radio telescope or optical telescope, a beam is formed that preferentially transmits the energy in one direction. The EIRP is given by the product of the Gain and the transmitter power.
   Found on http://www.coseti.org/glossary.htm
   
   
2. 
   EIRP
   Equivalent Isotropically Radiated Power. The power radiated by a radio transmitter including gain from the antenna. For example, an antenna with 3 dB gain concentrates the power in a particular direction such that twice as much power is transmitted in the concentrated direction. So if the total power transmitted is one watt then the EIRP is two watts. The regulator for a particular piece of spectrum will limit the EIRP because that figure gives a better indication of the possibility of interference from a transmitter.
   Found on http://www.flying-boat.co.uk/glossary/
   
   
3. 
   EIRP
   Effective Isotropic Radiated Power
   Found on http://www.dtmedia.co.uk/e.htm
   
   
4. 
   EIRP
   equivalent isotropically radiated power
   Found on http://www.radio-tech.co.uk/support/info