Reflection from the ionosphere. Consider the propagation of waves by reflection from the i...

Reflection from the ionosphere. Consider the propagation of waves by reflection from the ionosphere as shown in Figure (a) On a particular date and time of day, and above a particular geographic location, the highest electron density occurs at an altitude of ∼400 km, and the plasma frequency at this altitude is fp ≃ 5 MHz. Neglecting any ionization below this densest layer (i.e., assume electron density to be zero below 400 km altitude), determine the greatest possible angle of incidence θi at which an electromagnetic wave originating at a ground-based transmitter could possibly strike the layer. (b) How far away from the transmitter will the reflected radiation return to earth? (c) What is the highest frequency at which this obliquely incident radiation will be totally reflected?

Figure Reflection from the ionosphere. Problem.