UnGuided Transmission

Electromagnetic waves are transmitted without the use of a physical medium in an unguided transmission.
As a result, it’s often referred to as wireless transmission. The air is the medium through which electromagnetic waves can easily move in unguided media.

Unguided transmission can be categorized into three types:

1. Radio waves
2. Microwaves
3. Infrared

Radio waves

Radio waves are electromagnetic waves that travel through open space in all directions. The signals are transported in all directions by radio waves, which are omnidirectional. Radio waves have a frequency range of 3 kHz to 1 kHz. The sending and receiving antennas are not aligned in the case of radio waves, therefore the wave sent by the sending antenna might be received by any receiving antenna.

FM radio is an example of a radio wave.

Applications Of Radio waves:

1. When there is one transmitter and several receivers, a radio wave is useful for multicasting.
2. A radio wave can be found in FM radios, televisions, and cordless phones.

Advantages Of Radio transmission:

1. Wide-area networks and mobile cellular phones are the most common uses for radio transmission.
2. Radio waves have a wide range of coverage and can penetrate walls.
3. The transmission rate of radio transmission is higher.

Microwaves

Microwaves are of two types:

1. Terrestrial microwave
2. Satellite microwave communication.

Terrestrial Microwave Transmission

Terrestrial microwave transmission is a method of transmitting a radio signal’s concentrated beam from one ground-based microwave transmission antenna to another. Microwaves are electromagnetic waves with frequencies ranging from 1 to 1000 GHz. Microwaves are unidirectional because the transmitting and receiving antennas must be aligned, resulting in narrowly focused waves from the sending antenna. Antennas are put on the towers, in this case, to send a beam to another antenna located kilometers away. It uses line-of-sight transmission, which means that the antennas on the towers are in direct line of sight of each other.

Characteristics of Microwave:

• Terrestrial microwaves operate at frequencies ranging from 4-6 GHz to 21-23 GHz.
• Bandwidth: It has a bandwidth range of 1 to 10 Mbps.
• Short-distance: It is a low-cost option for short-distance travel.
• Long-distance: It is more expensive because a higher tower is required for a longer distance.
• Attenuation refers to the loss of signal.
  Environmental factors and antenna size have an impact.
•  Attenuation means loss of signal. It is affected by environmental conditions and antenna size.

Advantages Of Microwave:

• Microwave transmission is less expensive than cable transmission.
• It is not subject to land acquisition because the installation of cables does not necessitate any land.
• Microwave transmission allows for convenient communication in tough terrains where cable construction is problematic.
• Microwave transmission can be used to communicate across oceans.

Disadvantages of Microwave transmission:

• Eavesdropping: Eavesdropping makes communication insecure. By employing its own antenna, any malicious user can catch the signal in the air.
• Signal that is out of phase: A signal can be moved out of phase utilizing microwave transmission.
• Weather-susceptible: Microwave transmissions are subject to weather conditions.
  This implies that any change in the environment, such as rain or wind, can cause the signal to be distorted.
• In the case of microwave transmission, bandwidth allocation is limited.

Satellite Microwave Communication

A satellite is a physical entity that orbits the planet at a specific height. Satellite communication is now more reliable than cable and fiber optic networks because it provides more flexibility. Satellite communication allows us to communicate from anywhere on the planet.

How Does Satellite Technology Work?

The signal transmitted from the earth station is accepted by the satellite, which amplifies it.The signal is amplified and retransmitted to a different earth station.

Advantages Of Satellite Microwave Communication:

• A satellite microwave has a larger coverage area than a terrestrial microwave.
• The satellite’s transmission cost is unaffected by distance from the coverage area’s centre.
• In mobile and wireless communication applications, satellite communication is used.
• It is simple to set up.
• It has a wide range of applications, including weather forecasting, radio/TV signal broadcasting, mobile communication, and so forth.

Disadvantages Of Satellite Microwave Communication:

• The design and development of satellites take more time and money.
• To keep the satellite in orbit, it must be monitored and regulated on a regular basis.
• The satellite has a lifespan of 12 to 15 years. As a result, a new launch of the satellite must be prepared before it becomes dysfunctional.

Infrared

Infrared transmission is a wireless communication method that works over short distances. Infrared waves at frequencies ranging from 300 GHz to 400 THz. It’s used for short-range communication like data transfer between two mobile phones, TV remote control, and data transfer between a PC and a cell phone in a closed environment.

Characteristics Of Infrared:

• Since it provides large bandwidth, the data rate will be quite high.
• Infrared radiation is unable to get through the walls.
  As a result, infrared communication in one room cannot be disrupted by communication in adjoining rooms. Infrared communication gives greater security while causing the least amount of interference.
• Outside the building, infrared communication is unreliable because the sun’s rays interfere with infrared radiation.