A SEMINAR PRESENTATION ON PLASMA ANTENNA Presented by Ch . Hari Krishna B.Tech (ECE) Roll No.-11VE1A0459

Outline of the presentation 1- Introduction2- What is Plasma 3- Plasma antenna4- Features Classification of plasma antenna

5- Working principle of plasma antenna6- Advantages of plasma antenna7- Disadvantages of plasma antenna 8- Application9- Recent development 10- Conclusion11- References

4 States of Matter

Solid Liquid Gas Plasma (which may make up 99.99 % of the entire universe Universe)

Introduction What is plasma ?1- Plasma is the fourth state of matter ,the other three are solid, liquid, and gas.

2- A plasma is an ionized gas.

3- A gas becomes a plasma, when the addition of heat or other energy causes a significant number of atoms to release some or all of their electrons.

6- The electrically charged gas are said to be ionized.

7- When enough atoms are ionized to significantly affect the electrical properties of the gas, it is a plasma.

8- In short we can say that plasma is made of free electron and positively charged ions.

Plasma antenna 1- Plasma antenna employs ionized gas enclosed in a tube (or other enclosure) as the conducting element of an antenna.

2- Plasma, or ionized volume, simply replaces a solid conductors.

3- A highly ionized plasma is a good conductors, therefore plasma Filament can serve as transmission line elements for guiding waves.

5- A plasma might also be generated from a gas filled tube containing a noble gas like Neon or Argon.

6- Using of tube require less energy to excite and maintain the plasma state, because the gas is pure and the pressure of the tube prevents dissipation.

7- The use of a tube required that it must be protected from the environment, which increase the antenna weight and volume, and make the antenna less durables.

8-The following figure shows the some basic structure of plasma antenna

FeaturesAbility to focus a single beam.Can communicate signals in very short pulse.Are Reconfigurable for frequency, bandwidth, gain, length of plasma column and radius of glass tube.Can transmit and receive for same apertures if the frequencies are widely separated. It can operate up to 90 GHz. Plasma posses a high level of conductivity.

Types of Plasma Antennas

Laser Induced Antenna

Plasma Antennas Using Tube Structures

Explosively Formed Plasma Dielectric Antennas

IONIZED GAS PLASMA ANTENNA PLASMA TUBE ANTENNA Figure of Ionized gas and Tube Plasma Antenna

How does plasma antenna work ?1- When supply is given to the tube, the gas inside it gets ionized to plasma.

2- When plasma is highly energized, it behaves as a conductor.

3- Antenna generates a localized concentration of plasma to form a plasma mirror that deflects RF beam launched from a central feed located at focus of mirror.

GENERATION OF ELECTRIC AND MAGNETIC FIELD1- When voltage applied to an antenna, electric field produced.

2- Causes current to flow in antenna.

3- Due to current flow, magnetic field produced.

4- These two fields are emitted from an antenna and propagate through space over very long distances.

WORKING PRINICIPLE FIGURE

Comparison of radiation pattern from plasma (blue) and metal (red).

Advantages of plasma antenna 1- The length of an ionized filament can be changed rapidly, thereby retuning the antenna to a new frequency.

2- The antenna can be turned off to make it electrically invisible. This reduce scattering and eliminating coupling ,interference with other nearby antenna.

3- High gain.

4- Wide bandwidth.

5- Compact and light weight.

6- Maintence free.

7- The design allows for extremely short pulse, important to many forms of digital communication and radar.

8-When a plasma element is not energized it is difficult to detect by radar. Even when it is energized, it is transparent to the transmissions above the plasma frequency.

9- It can operate up to 90 GHz.

Disadvantage of plasma antenna1-The ionizer increases power consumption. More energy is required to ionize the gases or to make the silicon chips release electrons. Therefore, plasma antennas actually use more power than normal antennas.

2-Plasma volumes must be stable and repeatable. When a gas is ionized, not all 100% of the gas will ionize to become plasma. With silicon chips, it is reasonable to say that the amount of electrons released by the silicon when heated or charged will vary from time to time.

Reflectors If the frequency is lower than the plasma frequency ,thePlasma behaves as reflector and EM wave are attenuated.

comparison of radiation patterns from plasma and metal antennas. The plasma antenna shows lower side lobes, especially at wide angles, due to its higher surface resistivity compared to a solid conductor .

Plasma pattern has a better directivity, and the side lobe level is also better in the plasma pattern.

Application

MILLITARY APPLICATIONS-

1-Shipboard/submarine antenna replacements.

2-Unmanned air vehicle sensor antennas.

3- land-based vehicle antennas.

4-Stealth aircraft antenna replacements.

COMMERCIAL APPLICATIONS-

1- broad-band communications.2- Ground penetrating radar.3- Navigation.4- Weather radar and wind shear detection. 5- Collision avoidance .6- High-speed data communication.

Recent developmentThe future of high-frequency, high-speed wireless communications could very well be plasma antennas capable of transmitting focused radio waves that would quickly dissipate using conventional antennas. Thus, plasma antennas might be able to revolutionize not just high-speed wireless communications . Higher frequencies mean shorter wavelengths and hence smaller antennas. The antenna actually becomes cheaper with the smaller size .Plasma antenna to be used for next generation Wi-Gig (its version 1.0 was announced in December 2009) that can reach up to 7Gbps bandwidth over frequencies up to 60 GHz.

ConclusionThe plasma antenna works according to the same principles and physics laws as the normal antenna, with plasma replacing the metal conductors of the normal antenna. But because the conducting material used is plasma, it affords some advantages over a normal antenna. The most notable advantage of the plasma antenna is the fact that it is practically invisible to radar and can release short pulses of signals. Therefore, the military of US is currently racing to implement the plasma antenna into their existing systems.

References [1] Kumar V., Mishra M., and Joshi N.K., study of fluorescent tube as plasma antenna, Progress In Electromagnetic Research Letters, Vol. 24, 17{26, 2011}

[2] Li Wei, Qiu Jinghui and Suo Ying, analysis and design of plasma monopole antenna International Conference on Antenna Theory and Techniques, 6-9 October, 2009, Lviv, Ukraine pp. 200-202.[3] Gusein-Zade N. G., Minaev I. M., Rukhadze A. A., and Rukhadze K. Z., Physical Principles of Plasma Antenna Operation Journal of Communications Technology and Electronics, 2011, Vol. 56, No. 10, pp. 12071211.[4] Kraus J.D., Antennas for all applications, second edition, Tata McGraw-Hill 1988.[5] Balanis C.A. Antenna theory analysis and design second edition, John Wiley &sons, Inc 1997.

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