53686813-final-ppt.ppt

Plasma Antenna

By:ANSARI MOHD ATIFT.E.A , EC ROL.NO.03

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CONTENTS IntroductionFeatures of Plasma antennaWorkingComparison between Plasma antenna and Traditional antennaAdvantagesDisadvantagesApplicationsConclusionReferences

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What is Plasma ?By supplying energy the states of matter changes: from solid to liquid and from liquid to gas. If further energy is added to a gas it becomes ionized and passes over into the Plasma state a fourth state of matter.

Plasma is a gas in which a certain portion of the particles are ionized. The presence of a non-negligible number of charge carriers makes the plasma electrically conductive so that it responds strongly to electromagnetic fields.

Plasma the fourth aggregate state of matter was identified by an English physicist Sir William Crooks in 1879.

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Plasma has properties quite unlike those of solids, liquids, or gases and is considered be a distinct state of matter.

Energy / Temperature Molecule Molecule (excited) Free electron Molecular fragment (high energy) Contd

Ions

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What is Plasma Antenna?

Plasma antenna are Radio frequency antenna that employ plasma as a guiding medium for electromagnetic radiation.

It uses ionized gas instead of metal conducting element of conventional antenna to transmit and receive signals, decreasing interference and boosting the functionality.

In this plasma discharge tubes are used as the antenna element.

When these Plasma tube is energized, they become conductor and can transmit and receive radio Signal .

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When they are deenergized they revert to non conducting element and do not reflect radio probing signals. Plasma antenna can be streed electronically.

Plasma can only exist while the gas is kept very hot; as soon as the heat source is shut off, the plasma antenna returns to its previous state, in which cold gas is non conductive, but the signal emitted or received by the antenna disappears only when the plasma cools down.

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What is plasma antenna technology?

Plasma antenna technology is that which employs ionized gas enclosed in a tube as conducting element.

This is a fundamental change from traditional antenna design that generally employs solid metal wires as the conducting element.

Ionized gas is an efficient conducting element with a number of important advantages. Since the gas is ionized only for the time of transmission or reception, ringing and associated effects of solid wire antenna design are eliminated.

This technology has advanced to provide unique antenna designs for applications ranging from general broadcast of radio frequency signals for public use to complex weapon systems.

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Features Of Plasma AntennaPlasma antenna has the ability to focus a signal beam easily and to communicate signals in very short pulses, which could prove extremely useful in the areas of digital communications and radar. One important feature of Plasma antenna is that the gas ionizing process can manipulate resistance.

A second fundamental distinguishing feature is that after sending a pulse the plasma antenna can be deionized, eliminating the ringing associated with traditional metal elements. Ringing and the associated noise of a metal antenna can severely limit capabilities in high frequency short pulse transmissions.

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Contd

Changes in the ion density can result in instantaneous changes in bandwidth over wide dynamic range.

Plasma Antenna are reconfigurable for frequency, bandwidth, gain, length of plasma column, radius of glass tube.

Plasma Antenna can transmit and receive from same aperture provided the frequencies are widely separated.

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How does Plasma antenna works?A plasma antenna generates localized concentrations of plasma to form a plasma mirror which deflects an RF beam launched from a central feed located at the focus of the mirror.

An ionized region, or solid state plasma, can be generated in silicon using electronically controlled devices (plasma diodes) that are positioned between closely spaced metalized surfaces which constrain the beam.

The plasma can be freely moved by switching groups of plasma diodes on and off that follow the desired geometry of the reflector.

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The resulting pattern of plasma diodes forms a rosette of overlapping reflectors only one of which is active (i.e. reflecting) at any one time. This enables the beam to be steered quickly without the need for mechanical motion.

In some realizations, the silicon disc (ie Si wafer) can act as a cylindrical lens, to form a lens or reflector system that enables the RF energy to be collimated. Working of Plasma antenna is shown in the figure:

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Diagram showing working of Plasma antenna

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How Plasma Antenna different from Traditional Antenna? Plasma Antenna Traditional Antenna1. Electronic movement is made even more easily inside the plasma antenna, because of electrons are in a free state inside the hot gas. Solid metal antenna can function because electrons move freely in the metal conductor. Conventional metal antennas can pick up various noises, or interference that bounce of the surrounding metal objects.

Plasma antenna greatly reduces the effects of interference.

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Contd..

Traditional antenna are less efficient, more in weight and larger in size.Traditional antenna cant be easily switched on and off. Plasma antenna are efficient, low in weight and smaller in size.

Plasma antenna can be switched on and off easily.

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Some types of Plasma antenna

Multiple Tube Plasma Antenna

Selectable Multibeam Antenna

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Advantages of Plasma antennaHigh gainLow interferenceLow latencyWide bandwidthAffordableCompact and light weightMaintainace freeModular

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Disadvantages of Plasma antennaAs follow

Plasma volumes must be stable and repeatable.

Ionizer adds weight and volume.

Ionizer increases power consumption.

Higher ionization energy than for a tube.

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Applications of Plasma AntennaPlasma antenna has a number of applications in defense, space and homal appliances.

Network Equipment Providers and Systems Integrators

Network Operator

Public Safety Networks Sensing Defense

In Microwave Communication Plasma Antenna Provide Ease for realignment of long range directional antennas. -Low Cost for the network owner.

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ConclusionAntennas constructed of metal can be big and bulky, and are normally fixed in place. The fact that metal structures cannot be easily moved when not in use limits some aspects of antenna array design. The plasma antenna is constructed using a hollow glass column which is filled with plasma. This can be ionized by the application of a strong RF field at the base of the column. Once energized, the plasma column can be made to exhibit many of the same characteristics of a metal whip antenna .

There are many potential advantages of plasma antenna.

To date, the research has produced many novel antennas using standard fluorescent tubes and these have been characterized and compare favourably with their metal equivalents.

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THANK YOU

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