Radio waves - propagation of Radio waves

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Introduction:

Radio Waves are a part of electromagnetic waves .The  applications and the importance of radio waves have  forced me to write an article about them. That's why in today's article I would like to share with you an interesting topic related to the radio waves and their propagation. 

Propagation of Radio waves

Radio Waves  can travel over a long distances. However , the radio signals are mostly affected by the medium in which they are travelling and this can affect the radio waves propagation and the distances , the radio signals can propagate. 

There are Some types of radio signals which can travel or propagate around the globe, whereas other types of radio signals may only travel over a much smaller distances.

It is an important topic for any radio communications systems. Radio propagation is the way the radio signals travel or propagate when they are transmitted from one place to another.

Radio waves propagation

These  are a type of electromagnetic rays having wavelengths in the electromagnetic spectrum longer than that of infrared light. 

These are the waves having frequency from few KHz to several thousand mega Hertz.

The various frequency ranges used in radio waves communication system are :

1.  Low Frequency Band (LF):

In this  the frequency of radio signals ranges from 30 KHz to 300 KHz.

2.  Medium Frequency Band (MF):

This frequency band ranges from 300 KHz to 3000 KHz.

3.  High Frequency Band (HF) :

This band ranges from 3 MHz to 30 MHz.

4.  Very High Frequency Band (VHF) :

This type of frequency Band ranges from 30 MHz to 300 MHz.

5.  Ultra High Frequency Band (UHF) :

ultra high frequency band ranges from 300 MHz to 3000 MHz.

6.  Super High Frequency Band (SHF) :

This frequency band ranges from 3,000MHz to 30,000 MHz.

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Propagation is  done in the  following three ways :

A. Amplitude Modulated Transmission:

The amplitude modulation transmission is formed by the electromagnetic waves of frequency less than 30 MHz. These waves can pass through the lower atmosphere of the earth. Also,  these waves can be reflected by the ionosphere. 

There are two possible ways to transmit amplitude modulated waves :

I) Ground wave propagation :

First of all ,we have to understand the concept of ground waves?

"The Radio Waves, which are traveling along the surface of the earth are known as the ground waves" . This type of propagation is called the ground wave propagation.

 The frequency of ground waves can be up-to 1.5 MHz. These waves cannot move up-to a very large distances because the ground waves can bend around the corners of the objects on the Earth. 

II)  Sky Wave Propagation:

skywave or skip refers to the propagation of radio waves reflected or refracted back to  Earth from the ionosphere part of the atmosphere .

Sky waves are those types of amplitude modulated waves,  which are received after being reflected from the ionosphere which is an electrically charged layer of the upper atmosphere . The frequency of Sky waves ranges from 1.5 MHz to 30 MHz. This type of propagation is called sky wave propagation. 

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Note:

These two amplitude modulated waves mentioned above are normally referred to as medium wave and short wave bands.

B. Frequency Modulated Transmission:

This type of modulation is formed by the electromagnetic waves , which have frequency from 80 MHz to 200 MHz. These waves neither get reflected from the ionosphere nor they follow the surface of the earth. 

Therefore it becomes clear that their propagation through ground wave or sky wave is not possible. The TV signals have frequency from 100 MHz to 200 MHz.

There are two possible ways to receive TV signals :

I)  By using tall receiver antenna, which may directly intercept signals. 

II) By using the geo-stationary satellites.

C. Microwave transmission :

These are the types of electromagnetic waves which are having frequency greater than those of TV signals . These types of microwaves are most commonly used in Radars to locate the flying objects in space and to estimate their distance from the radar station .

Now a days by using geostationary satellite, it is, possible to transmit a microwave signal from one point to the another point with greater accuracy. In fact , the microwaves have revolutionized the communication system. 

Conclusion:

As you already know that the article has discussed  the concept of radio waves and the propagation of Radio waves . It also includes the concept of radio waves and the ways in which the Radio Waves can be transmitted. Radio waves form an important part of electromagnetic spectrum which is discussed above.

 I hope the article was helpful for you. please help others and share this on social media. Thank you for your visit.