it provides a detail information about plasma antenna . it is very help full for seminar presentation

1. A SEMINAR PRESENTATION
ON
PLASMA ANTENNA
Presented by
Hari Om Shanker Mishra
M.Tech (ECE)
Enrollment No.-12302255

2. Outline of the presentation
1- Introduction
2- What is Plasma
3- Plasma antenna
4- Advantages of plasma antenna
5- Disadvantages of plasma antenna
6- Plasma antenna theory
7- Working principle of plasma antenna
8- Application
9- Recent development
10- Conclusion
11- References

3. 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.
4- The detached negative electrons are free to move.
5- The atoms are left with positive charge.

4. 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.

5. 9- The degree of ionization in plasma –
“The rate of ionized particles against the total present particles”.
10- It depends mainly on temperature. And it is calculated by 2
i
3
2
n
 ui 
= CT exp  −
nn
KT 


Where C=2.4x1021/m3 ,
ni is the ion concentration - which have lost
one electron,
nn is the neutral particles concentration,
ui is the ionization potential,
T is the plasma temperature.

6. 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.
4- A ionized volume can take a variety of forms. It can be
established in air at atmospheric pressure by using Lasers, high
power microwave beams or ultraviolet rays.

7. 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…

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

9. 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.

10. 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.

11. Disadvantage of plasma antenna
1-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.

12. Thus it is imperative that the volume of plasma generated each
time should be the same.
The amount of plasma existing during a transmission or
reception should also be the stable and not fluctuate. Only then
will the electromagnetic waves transmitted be stable.

13. Plasma antenna theory
1- Let center-fed dipole plasma antenna with triangular current.
2- let plasma dipole antenna oriented along the z-axis.
3- The dielectric constant for the plasma is defined
as2
ω
p
ε =1 −
(
ωω− jν)
where
ne 2
ωp=
ε 0m
ω p is the plasma frequency, and m is the mass of the electron, is the electron
ν
velocity ,e is the charge on electron , ω the applied frequency in radian per
is
second.

14. The dipole moment of the plasma antenna is given by
e2n0 E 0d
P = a
2
 2π ω(ω + jν ) −ωp

[
]




where a is the cross- section area of the plasma
antenna and d is the length of the plasma antenna.
The total radiated power is-
k 2ω 2
P rad =
p2
12πε 0c
where k = 2π is the
λ
wave number. Thus the radiated power depends on the plasma
frequency and collision rate.


2
(ωE 0 ) 2
ε 0a 2
4 
( kd ) (ω p ) 2 2 2 2 2 
P rad =
[(ω −ω p ) +ν ω ] 
48πc



15. GENERATION OF ELECTRIC AND
MAGNETIC FIELD
1- 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.

18. 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.

19. WORKING PRINICIPLE FIGURE

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

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

22. 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.

23. Application
MILLITARY APPLICATIONS1-Shipboard/submarine
antenna replacements.
2-Unmanned air vehicle
sensor antennas.
3- land-based vehicle
antennas.
4-Stealth aircraft antenna
replacements.

24. COMMERCIAL APPLICATIONS1- Telemetry & broad-band
communications.
2- Ground penetrating radar.
3- Navigation.
4- Weather radar and wind
shear detection.
5- Collision avoidance .
6- High-speed data
communication.

25. Recent development
The 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.

26. Conclusion
The 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.

27. 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. 1207–1211.
[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”.

28. Thank you