Electromagnetic Spectrum and Radio Waves

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Radio Waves Electromagnetic

Radio waves are electromagnetic waves that have wavelengths longer than infrared radiations. The range of radio waves is between 30 kHz and 300 GHz in an electromagnetic spectrum. 

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Radio waves have the best use in communication systems like television, mobile phones, radios, etc. 

Natural radio waves occur or emit by lightning, astronomical objects, while artificial radio waves are produced with the help of transmitters, and radio receives it by using antennas. These signals are transformed into mechanical vibrations in speakers to generate sound.

Radio waves have many real-life applications. In this article, we will learn about the radio electromagnetic spectrum and its uses.


Radio Waves Uses

Radio waves in the electromagnetic spectrum are located in the low range frequencies. The wavelength of these waves ranges from 30 cm to 1 km and Radio electromagnetic spectrum is a part of the electromagnetic spectrum with frequencies from 30 Hz to 300 GHz. These waves have great use in communication systems.

In the air, radio wave communication signals traverse a straight path, emit clouds/layers of the ionosphere, or are relayed by satellites in space. 


Radio Waves Are Employed in Various Places; These Are:

  • Standard broadcast and television

  • Navigation of aircraft

  • Airplane traffic control (ATC)

  • Cellular telephony, 

  • Shortwave radio

  • Remote-controlled toys


Radio Wave Frequency Spectrum

A radio band is a continuous series of the radio wave frequency spectrum. These bands are called the channels and each channel has its specific purpose. To overcome the interference and the overlapping of bands and allow for the efficient use of the radio wave spectrum, alike services are allocated in bands.

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For each channel, ITU (International Telecommunication Union) has a band plan that indicates how each channel has to be used and shared, to prevent interference, overlapping and to set protocol for the affinity of transmitters and receivers. 


What Does ITU Do?

ITU radio bands are specified in the ITU Radio Regulations. It divides the radio frequency spectrum into 12 bands, each of which begins at a wavelength with a power of 10n, with the respective frequency of 3  x 108-n Hz.

The table mentioned below discusses the radio wave frequency bands with their respective ITU band numbers and functions. These recommendations were approved by the International Radio Conference held at Atlantic City, New Jersey, in 1947. Let’s look at these:

Name of the Band

Abbreviation of the Band Name

ITU Band Number

Frequency Range of Radio Waves

         &

Radio Waves Wavelength

Functions 

Extremely low frequency

ELF


1

3-30 Hz

100,000 - 10,000 km

In communication with Marines

Super low frequency

SLF

2

30-300 Hz

10,000 - 1000 km

These are also used for communications in submarines

Ultra low frequency

ULF

3

300 - 3,000  Hz

1,000 - 100 km

Communication with submarines; communication in mines

Very low frequency 

VLF

4

3 - 30 kHz

100 - 10 km

Navigation

Time signals

Submarine communication

Wireless heart rate motors

Geophysics


Low frequency

LF

5

30 - 300 kHz

10 - 1 km

Navigation

Time signals

Amplitude modulation longwave broadcasting in Europe and parts of Asia

RFID

Amateur radio

Medium frequency

MF

6

300 - 3,000 kHz

1,000 - 100 m

Amplitude modulation (medium-wave) broadcasts, amateur radio, avalanche beacons

High frequency

HF

7

3 - 30 MHz

100 - 10 m

Shortwave broadcasts

Citizens band radio

Amateur radio and over the horizon aviation communications

RFID

ALE (Automatic link establishment) or NVIS (near-vertical incidence skywave radio) communications

Marine communication

Mobile phone telephony

Very high frequency

VHF

8

30  - 300 MHz

10 -  1 m

Frequency modulation

Television broadcasts

Line-of-sight communications for the ground to aircraft and aircraft to aircraft Land mobile maritime and mobile communications

Amateur radio, weather radio

communications

Ultra-high frequency


9

300 - 3,000 MHz

1 - 0.1 m

Television broadcasts 

microwave devices or communications Microwave oven radio astronomy mobile phones wireless LAN Bluetooth

ZigBee

GPS

Two-way radio communications viz: land mobile

 FRS

GMRS radio communication

Amateur radio Satellite radio Remote control Systems

Super high frequency

SHF

10

3 - 30 GHz

10 - 1 mm

Radio astronomy

Microwave communications

Wireless LAN DSRC,

Modern radars Communications satellites

Cable and satellite television broadcasting 

DBS 

Amateur radio Satellite radio

Extremely high frequency

EHF

11

30 - 300 GHz

10 -  1 mm

Radio astronomy high-frequency microwave radio relay, ADSB

microwave remote sensing

amateur radio directed-energy weapon 

millimeter-wave scanner

wireless LAN (802.11ad)

Tremendously high frequency (or TeraHertz)

THF (or THz)

12

300 - 3,000 GHz

1 - 0.1 mm

Ultrafast molecular dynamics, 

Experimental medical imaging to replace X-rays

Condensed-matter physics

Terahertz time-domain spectroscopy terahertz computing or communications remote sensing


From the above table, we can see the descending order of frequency and wavelengths. Also, the electromagnetic waves radio waves specifically designate a section of the electromagnetic spectrum having frequencies ranging between 300 GHz and 3 kHz and wavelengths ranging from 1 millimeter to 100 kilometers.

FAQ (Frequently Asked Questions)

1. What does the electromagnetic spectrum specify?

The electromagnetic spectrum shows the major classification of electromagnetic waves. The range of frequencies and wavelengths is remarkable (striking). 

The division line between some lists is distinct, whereas other categories overlap. Microwaves encompass the high-frequency portion of the radio portion of the electromagnetic spectrum.

2. Write applications of radio waves.

The real-life applications of radio waves are:

  • Radio waves are used in AM and FM radio, TV, and cellular phone communications.

  • The electromagnetic waves of frequency ranging from 530 kHz to 1710 kHz form amplitude modulation, it is used in ground wave propagation.

  • The electromagnetic waves of frequency ranging from 54 MHz to 890 MHz are used in television broadcasting.

  • The electromagnetic frequencies ranging from 300 MHz to 3,000 MHz are used in mobile phone communications.

3. Among radio waves and microwaves, which is better in Radar communications, and why?

Since microwaves are of smaller wavelengths, hence they can transmit as a beam of signal in a particular direction much better than radio waves. Also, microwaves do not bend around the corners of any obstacle coming along their path.

4. Are radio waves harmful?

Yes!

When high-frequency RF is exposed to the human body, it can lead to biological heating and a rise in body temperature.