A satellite communications system operates at a wavelength of 6cm with a spherical balloon of equivalent echoing area 10m² and identical antennas of 50dBi gain for transmission and reception. The transmitter power is 10kW, the receiving antenna noise temperature is 20K and the receiver noise temperature is 30K. The distance from balloon to the transmitting and receiving antennas are 2000 and 3000km respectively. Calculate the SNR at the receiver output assuming a receiver bandwidth of 10kHz. (k = 1.38x10 J/K, SNR = Ps/PN) The Power density [P'a] at the balloon is;