Introduction to Antennas

Updated on 2017/06/20 03:24

Abstract

In the world of modern wireless communication, engineer who wants to specialize in the communication field needs to have a basic understanding of the roles of electromagnetic radiation, antennas, and related propagation phenomena.

Antenna is an important part of any wireless communication system as it converts the electronic signals (propagating in the RF Transreceiver) into Electromagnetic Waves (Propagating in the free space) efficiently with minimum loss.
We use antennas when nothing else is possible, as in communication with a missile or over rugged mountain terrain where cables are expensive and take a long time to install. The performance characteristics of the parent system are heavily influenced by the selection, position and design of the antenna suite.
To understand the concept of antenna one should know the behaviour of Electromagnetic waves in free space. 

Antennas are classified based on Frequency, aperture, polarization and radiation pattern.
Their performance parameters are Gain, Directivity, Beam area and beam efficiency, radiation pattern, VSWR/ Return loss, polarization, Efficiency.

Electromagnetic Frequency Bands and Applications

Frequency Band NameFrequency RangeWavelength (Meters)Application

Extremely Low Frequency (ELF)

3-30 Hz

10,000-100,000 km

Underwater Communication

Super Low Frequency (SLF)

30-300 Hz

1,000-10,000 km

AC Power (though not a transmitted wave)

Ultra Low Frequency (ULF)

300-3000 Hz

100-1,000 km

 

Very Low Frequency (VLF)

3-30 kHz

10-100 km

Navigational Beacons

Low Frequency (LF)

30-300 kHz

1-10 km

AM Radio

Medium Frequency (MF)

300-3000 kHz

100-1,000 m

Aviation and AM Radio

High Frequency (HF)

3-30 MHz

10-100 m

Shortwave Radio

Very High Frequency (VHF)

30-300 MHz

1-10 m

FM Radio

Ultra High Frequency (UHF)

300-3000 MHz

10-100 cm

Television, Mobile Phones, GPS

Super High Frequency (SHF)

3-30 GHz

1-10 cm

Satellite Links, Wireless Communication

Extremely High Frequency (EHF)

30-300 GHz

1-10 mm

Astronomy, Remote Sensing

Visible Spectrum

400-790 THz (4*10^14-7.9*10^14)

380-750 nm (nanometers)

Human Eye

References

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Created by Vishal E on 2017/05/05 19:17