Sky wave propogation

Its all about sky wave propagation

1. Sky wave propagation - Maheshwari Das Meghana BS Analog Communication

2. Wave propagation Wave propagation  is any of the ways in which  waves travel . With respect to the direction of the oscillation relative to the  propagation  direction, we can distinguish between longitudinal  wave  and transverse waves. For electromagnetic  waves ,  propagation  may occur in a vacuum as well as in a material medium.

3. Types of wave propagation Propagation of radio waves from a radiating transmitting antenna to the receiving antenna may take place in one of the following routes: Ground wave propagation Sky wave propagation Space wave propagation

4. The ground wave or surface wave is guided along the surface of the earth

5. In this mode of propagation the electro-magnetic waves reach the receiving point after reflection From the ionized region in the upper atmosphere

6. In this mode EM waves from the transmitting antenna reach the receiving antenna wither directly or after reflection from ground in the earth’s troposphere region.

7. Sky-wave propagation

8. It is also called Ionosphere propagation I this mode of propagation the EM eaves reaches the receiving point after reflection from the ionized region in the upper atmosphere called ionosphere. Ionosphere is situated between 50km & 400km above the earth. It is divided into three basic layers (D, E & F) based on ionization density. F layer is further divided into F1 and F2 sub layers.

9. D & E layers are weekly ionized & exist only during day light hours. They tend to observe medium waves . The primary effect of F layers is to cause refraction of Radio waves.

10. Ionosphere propagation permits extremely long distance communication 3MHz-30MHz range Above 30MHz frequency signals are not reflected.

11. Advantages and Disadvantages Most long-distance shortwave radio communication—between 3 and 30 MHz—is a result of  sky wave  propagation. Since the early 1920s amateur radio operators , limited to lower transmitter power than broadcast stations, have taken  advantage of sky wave  for long distance communication. The signal received are subjected to fading, in which signal strength varies with time. The receiving point, a large number of waves follow a different number of paths

12. Applications Short wave, AM radio broadcast. Long distance, point to point communication. Extremely long distance communication using multi-hope propagation.

13. Thank you..