A radio system is used to communicate with submerged submarines. Its
transmitter operates at a frequency of 20 KHz and produces an electric field amplitude of 100 V/m, on the air immediately above the surface of the sea underneath which a particular submarine is. Assuming that Ei is a plane wave propagating normal to the air-sea interface, provide answers to the following questions:
a) Determine the intrinsic characteristic impedances of the air and the sea respectively
b) How much power (in Watts per meter square) does the transmitter shines at the sea surface?
c) How much power (in Watts per meter square) goes into the sea?
d) If for good quality communication the submarine receiver requires an electric field amplitude Et = 1μⅤ/m, determine the largest possible depth h it has to maintain in order to be able to receive the transmitter message.
At 20 KHz the sea water has ε = 81ε0, μ-μ0, and σ = 4 S/m.