Antenna is in size of 0.5[m] X 0.5[m], with transmit frequency of 10GHz. In a distance of 100m the electric field is 250 [V/m]. I calculated the density of power with the formula: 0.5*(E^2)/(120*pi) and got: 82.891 [W/m^2]. the question is: can I calculate the density of power again but un distance of 10m? My other question is: If I have a known G (G=a*D) can i find an expression for the total power comes from the antenna? Can I use the formula: Pt=S*(4*pi*r^2)/G ? where Pt is total power and S is power in distance r. after I get Pt do I need to multiply it by the size of antenna? Hi, I need the answer as quickly as possible. Thanks!!