Question

For sky wave propagation of 10 MHz signal, what should be the minimum electron density in ionosphere?

• A. ∼ 1.2 x 1012 m-3
• B. ∼ 106 m-3
• C. ∼ 1014 m-3
• D. ∼ 1022 m-3

Answer 1

Answer: (A)

∼ 1.2 x 1012 m-3

Answer 2

The critical frequency of sky waves undergoing reflection from an atmospheric layeris ${{f}_{c}}=\sqrt[9]{{{N}_{\max }}}$
where N is electron density per m3
$\therefore$ Nmax = $\frac{{{f}_{c}}^{2}}{81}=\frac{{{(10\times {{10}^{6}})}^{2}}}{81}$

= ∼ 1.2 x 1012 m-3