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 $\sqrt{2Rh}$ = 62 km
Critical frequency = $f_c$ = 9 ${\left(N_{max}\right)}^{\frac{1}{2}}\approx 9MHz$
5 MHz < $f_c$, sky wave propagation (ionospheric propagation)