Question

In space wave propagation, radio waves (having wavelength λ ) are transmitted from transmitter (having height T) and reaches the receiver (having height R) located at a distance, d, by two methods (d << T, d << R). The first is the direct transmisstion from transmitter to the antenna. The second is the transmisstion from transmitter to the earth surface, followed by reflection from the earth surface.

It may be assumed that the reflection, from the earth’s surface takes place from a point midway between the transmitter and the receiver. Considering that the amplitude of both the waves is E, then the resultant field strength amplitude (E_R) will be equal to,

(1) 12E sin\((\frac{4πTR}{λd})\)

(2) 12E sin\((\frac{2\pi TR}{λd})\)

(3) 12E cos\((\frac{4\pi TR}{λd})\)

(4) 12E cos\((\frac{2\pi TR}{λd})\)

Answer 1

(2) 12E sin\((\frac{2\pi TR}{λd})\)

The resultant field strength amplitude can be calculated as follows.