Question

The ionosphere consists of several layers ranging from 60-1,0000 km above the Earth’s surface; it consists of charged particles (ions - thus its name) that plays an important part in communication. A simplified version consists of two layers: a lower layer having thickness 60 km at the height of 200 km above Earth surface and a higher level with thickness 39 km. The index of refraction of the ionosphere depends on the frequency of radio waves. We assume that the antenna produces a signal at 50◦ -angle with the Earth surface: radio waves with frequencies lower than 20 MHz are reflected at the lower ionosphere-atmosphere boundary, while radio waves with frequencies higher than 20 MHz enter the ionosphere. Radio waves with frequencies frequency 100 MHz are bend towards the Earth at 32◦ and 8◦ -angles with the Earth surface, respectively. Assume that the atmosphere (other than the ionosphere) has index of refraction n = 1.

a) What can we conclude about the index of refraction of the ionosphere that is valid for all frequencies of radio waves? [Explain!]

b) What is the index of refraction of the ionosphere for radio waves with frequency 20 M

c) What are the index of refraction of the lower and upper ionosphere for radio waves with frequency 100 MHz?

Answer 1