Max usable frequency

The maximum possible frequency for which the wave is reflected back for a given distance of propagation in the ionosphere layer is called as_______

• a) Maximum usable frequency

• b) Critical frequency

• c) Resonance frequency

• 
  d) Dominating frequency

Answer explanation

The maximum possible frequency for which the wave is reflected back for a given distance of propagation in the ionosphere layer is called as maximum usable frequency (MUF). For a specified angle there will be a maximum frequency for which the wave is reflected back. If wave exceeds MUF then it’s not reflected back.

If wave exceeds the MUF then it is not reflected back.

• True

• False

Answer explanation

Maximum usable frequency (MUF) is defined as the maximum possible frequency for which the wave is reflected back for a given distance of propagation in the ionosphere layer. If the wave exceeds MUF then it’s not reflected back and is transmitted to other upper layers and signal is lost.

Suppose a ray is incident normally in the ionosphere region with electron density 36×10¹⁰/cm³, then the critical frequency is _____

• 5GHz

• b) 54MHz

• c) 5.4MHz

• d) 324GHz

Answer explanation

Relation between MUF and critical frequency is ______

• a) f_c = f_MUF secθ_i

• b) f_MUF = f_c sec² θ_i

• c) f_c = f_MUF sinθ_i

• d) f_MUF = f_c secθ_i

Answer explanation

Explanation: The f_MUF in terms of critical frequency is given by f_MUF = f_c secθ_i for a given angle of incidence between two locations.

What is the value of maximum usable frequency when the incident angle is 60° and the critical frequency is 4.5MHz?

• a) 4.5MHz
  

• b) 2.25MHz
  

• c) 9MHz
  

• d) 18MHz

Answer explanation

MUF = F(c) / cos theta

Which of the following is true when a ray is incident normally in an Ionosphere region?

• a) MUF is equal to critical frequency

• b) MUF is greater than critical frequency

• c) MUF is less than critical frequency

• d) MUF is zero

Answer explanation

f_MUF=f_c / cosθ_i

_when θ equal zero cos 0 = 1