Question

A ground receiver station is receiving a signal at (i) 5 MHz and transmitted from a ground transmitter at a height of 300 m, located at a distance of 100 km from the receiver station. The signal is coming via - (Radius of earth $=6.4\times {10}^{6}m$. $N_{max}$ of isosphere $={10}^{12}{m}^3$)

• A. Space wave
• B. Sky wave propagation
• C. Satellite transponder
• D. All of these

Answer 1

The correct option is B Sky wave propagation

Maximum distance covered by space wave communication $\sqrt{2Rh}=62km$
Critical frequency $=f_c=9(N_{max}{)}^{1/2}\approx 9MHz$
$5MHz<f_c$, sky wave propagation (ionospheric propagation)