This app prompts the user to enter the distance from the satellite to earth in km, the radiated power from the satellite in Watts and the gain in dB in the direction of the observer and the effective area of the receiving antenna. Once entered, push the "Calculate" button and the output is F, the flux density in W/m^2, the power received Pr in Watts as well as the flux density in dB and the received power in dBW.

For example, enter 40,000 for the distance, 10 for the power of the sending antenna and 17 for the gain, then 10 for the effective area of the receiving antenna, push "Calculate" and your results should be 2.49E-14 W/m^2, 2.49E-13 Watts, -136.03 dB(W/m^2) and -126.03 dBW.