Unguided Transmission Media

Hey!

I do hope you read my articles on Guided Transmission Media and Types of Transmission Media before coming to read this. If not, I'd strongly recommend you to see them.

Back to the things that matter, Unguided Transmission Media! These are transmission media that are used for used when either the distances are HUGE, or the communications need no security of any kind because these forms or communications are relatively insecure as compared to Guided Transmission Media, or, the communication is a form of broadcast and needs to be sent to many people at the same time. The signals travel through Air, Water or Vacuum. As an example, the WiFi Internet Access that you enjoy happens because of a WiFi Chip in your device AND, the radio signals that spread out from the router antennae. As a general rule of thumb, anything that involves "waves" as a form of propagation media (radio waves here) are a form of unguided transmission media. So lets delve into the related technologies.

Types of Unguided Transmission Media we're going to study in this article:

1. Radio Waves
2. Satellite Microwave
3. Terrestrial Microwave
4. Infrared

Hence lets get started.

Radio Waves

The transmission making use of radio frequencies is termed as radio wave transmission. In general, private citizens and business users are licensed to operate in about a radius of about 10 miles. All radios today use continuous sine waves to transmit information. Each different radio signal uses a different sine wave frequency, and that is how they are all separated. 

Any radio setup has two parts:

1. Transmitter
2. Receiver

The transmitter takes some sort of message, encodes it onto a sine wave and transmits it with radio waves. The receiver receives the radio waves and decodes the message from the sine wave it receives. Both the transmitter and receiver use antennae to radiate and capture the radio signal.

Advantages and Disadvantages of Radio Communications

Security of such communication links is almost non-existent. Even so, this technology is widely used by taxi, repair, courier and delivery services due to its huge coverage and minimal costs of operation involved.

Satellite Microwave

Electromagnetic waves can be classified by frequency and wavelength. When the frequency is higher than 3 Ghz, it is named Microwave. Satellite Communication is a special case of microwave relay system. Satellite Communication uses the synchronous satellite to relay the signal transmitted from ground station. Compared to the traditional fixed wire terrestrial networks, satellite and microwave communications features the time-saving, fast implementation and broad coverage characteristics. It provides voice, fax, data and video services and well as E-Mail, files transfer, WWW internet applications. When fixed wire terrestrial networks are crushed by disasters, the satellite and microwave systems as an emergency backup facility are used. 

In satellite communication the earth station consists of a satellite dish that functions as an antenna and communication equipment to transmit and receive data from satellite passing overhead.

Advantages and Disadvantages of Satellite Microwave

Let us now see both the technologies we've discussed through this diagram.

Satellite Microwave and Radio Wave; Image Courtesy: bbc.co.uk

Terrestrial Microwave

Microwave signals are used to transmit data without the use of cables. The microwave signals are similar to Radio and television signals and are used for long distance communication. The microwave transmission consists of a transmitter, receiver and the atmosphere. 

In microwave communication antennae are mounted on towers to send a beam to other antennae tens of kilometers away. Higher the tower, greater the range. With a 100m high tower distances of 100 kilometers between towers are feasible. The microwave transmission is a line-of-sight transmission.

Advantages and Disadvantages of Terrestrial Microwave

Image Courtesy: ecomputernotes.com

Infrared Communications

This type of transmission uses Infrared light to send data. TV Remotes, Automotive doors, wireless speakers, etc. all make use of Infrared as transmission media. The infrared light transmits data through the air and can propagate throughout a room (bouncing off surfaces), but will not penetrate walls. It is considered to be a secure means of communication.

Image Courtesy: www.e-globaledge.com

And right here we finish off with this article. But WAIT! Dont Go! There is an amazing amount of information to be gained and we can help you by providing some. Please take some time and check out our other articles. I'm sure you'd find them interesting.