Space Wave Propagation

Space wave propagation is a type of EM wave propagation where waves are either directly transmitted from a transmitter to a receiving one or reflected from the ground. Line-of-sight communication is used to achieve direct signal transmission in space wave propagation.

What are space wave propagations?

Electromagnetic waves are transferred in space wave propagation when a direct route of interaction exists between the transmitter and recipient. Waves are often transmitted by being reflected from the earth’s surface. Sky wave propagation is often referred to as a line of sight transmission. This is because of the need for a direct route for the purpose of transmission of high-level frequency of these EM waves.

Space waves are radio signals with especially high frequencies. Such waves can travel through the troposphere. In general, the troposphere extends up to 10 to 20 km above the earth’s surface. Thus, space wave propagation occurs in the earth’s atmosphere at a level of about 20 km.

Need for space wave propagations

Ground wave propagation causes signal loss due to the absorption of energy by the surface of the earth when the distance of transmission is high. Resulting in a lower frequency at which the signal is to be transmitted. In order to avoid significant signal attenuation, the propagation distance is kept as short as possible. 

Sky wave propagation, on the other hand, allows for the transmission of signals with a higher frequency than ground wave propagation with less attenuation. However, when a high level of signals must be transmitted, even this propagation fails. This is due to the fact that in sky wave propagation, signals are transmitted by being reflected from the ionosphere, and at higher frequency, the same can penetrate the ionised layer of the ionosphere.

To overcome the limitations of both Propagations, there was a need for an efficient transmission system that can cover greater distances and larger frequencies, thus the need for space wave propagations.

Types of space wave propagations

Tropospheric wave – EM waves reach the receptor after being reflected from the troposphere.

Direct waves – EM waves that are collected directly by the receptor after broadcasting by the transmitter.

Ground reflected waves – EM waves reach the receiving antenna after getting reflected by the earth’s surface.

Space waves and Microwaves:

The way of propagation defined for space waves also implies microwave frequencies, with a few additional requirements. When it comes to microwaves, absorption by atmospheric conditions and humidity play a role. Furthermore, it is important to note that short wavelengths cause a faster tendency for changes in everything. Waves, interference, and evaporation are all heightened. Super-refraction, also known as ducting, is a new phenomenon that occurs.

Benefits of space wave propagations:

• Little absorption of higher frequencies
• Effective for greater distance of communications
• No effect of atmospheric or time variations

Limitations of space wave propagations:

• Impact of curves of the Earth’s surface
• These waves propagate across the line of sight location, which is defined as the distance between the transmitter and receiver reflectors and is also known as the transmission range.

Applications of the space wave propagations:

• Communications using Satellite
• Communication using Radar
• Direct route communication
• Microwave Propagation
• TV Broadcasting

Key points

• These waves propagate through the troposphere, hence these propagations are also known as troposphere propagations.
• These waves transmit and receive signals, propagating through a direct line, this type of propagation is also called the line of sight propagations.
• Space waves propagation follows a frequency of greater than 30 MegaHertz.
• Space waves propagations came into use to overcome the shortcomings of Ground wave and sky wave propagations. These shortcomings were loss of power in ground waves and loss of communication in the ionosphere in sky wave propagations.
• Used in aerospace communication and satellites.

Conclusion

Space waves, on the whole, behave in a simple manner. They travel in lines that are straight, that is why they are often referred to as the line of sight propagations. However, because they are dependent on line-of-sight conditions, space waves are limited in their propagation by the curvature of the earth, unless extremely unusual circumstances exist. They propagate very similarly to electromagnetic waves in free space. Because their signal frequencies are quite Short to get reflected from the ionised layer of the sky, and as the surface wave vanishes when near to the antenna due to tilt, they are forced to behave in this manner. Thus, Space waves have been utilised by varied intentions and for various purposes. Space wave propagation overcomes the limitations of ground waves and sky waves and has increased the efficacy of transmission of EM waves.