Question

What is the M.U.F (maximum unusable frequency of an electromagnetic wave initial frequency of 20MHz and incident at an angle of 60° in ionosphere propagation? 

(A) 20√2 MHz 

(B) 20 MHz 

(C) (20/√2) MHz 

(D) 40 MHz

Answer 1

The correct option is (D) 40 MHz.

Explanation:

Maximum usable frequency = MUF = f_c sec θ 

Here f_c = 20 × 10⁶ Hz 

θ = 60° 

∴ MUF = [(20 × 10⁶) / (cos 60)] = 40 MHz