24-07-2012, 10:41 AM
Plasma Antenna
[attachment=28597]
ABSTRACT
A plasma antenna represents a completely new technology of antennas that relies on
plasma elements rather than in traditional metallic wires or surfaces. The feasibility of a
plasma antenna is provided by plasma conductivity, that is given by free electrons obtained
by gas ionization with the application of an intense electromagnetic field. The main
advantage of plasma antennas results from the possibility of changing electromagnetically
their parameters.This characteristic provide a plasma antenna with peculiar properties that
make it suitable for several applications (e.g, stealth application, antenna arrays, smart
antennas,frequencyselective shields).
The pump signal and gas discharge parameters have to be carefully chosen in order to
optimize plasma antenna design and realization, in particular discharge working conditions
have to be defined in order to obtain the desired antenna properties in terms of efficiency,
effective length and so on.
3
INTRODUCTION
On earth we live upon an island of "ordinary" matter. The different states of matter
generally found on earth are solid, liquid, and gas. Sir William Crookes, an English physicist
identified a fourth state of matter, now called plasma, in 1879. Plasma is by far the most
common form of matter. Plasma in the stars and in the tenuous space between them makes up
over 99% of the visible universe and perhaps most of that which is not visible. Important to
ASI's technology, plasmas are conductive assemblies of charged and neutral particles and
fields that exhibit collective effects. Plasmas carry electrical currents and generate magnetic
fields.
Plasma antennas have a number of potential advantages for antenna design.
Plasma antenna has following basic capabilities:
1) rapid change of antennas and antenna arrays configuration. Controlling their beam
pattern and its orientation by electronic control of plasma parameters.
2) small effective radar cross-section (RCS) of such antennas in a wide frequency band.
3) effective suppression of multipath reflection while transmitting short high-power
signals.
4) design of the compact extendable antennas for use with the high-power pulse
generators.
5) energized and de–energized in seconds, which prevents signal degradation.
6) Difficult to be detected by radar.
Due to these advantage plasma antenna attracts the interest of the industrial groups involved
in such diverse areas as fluorescent lighting, telecommunications and radar.
4
PLASMA ANTENNA TECHNOLOGY
Since the discovery of radio frequency ("RF") transmission, antenna design has
been an integral part of virtually every communication and radar application. 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. In its most common
form, an antenna represents a conducting metal surface that is sized to emit radiation at one
or more selected frequencies. Antennas must be efficient so the maximum amount of signal
strength is expended in the propogated wave and not wasted in antenna reflection.
Plasma antenna technology employs ionized gas enclosed in a tube (or other enclosure) as the
conducting element of an antenna. 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
5
antenna design are eliminated. The design allows for extremely short pulses, important to
many forms of digital communication and radars. The design further provides the opportunity
to construct an antenna that can be compact and dynamically reconfigured for frequency,
direction, bandwidth, gain and beamwidth. Plasma antenna technology will enable antennas
to be designed that are efficient, low in weight and smaller in size than traditional solid wire
antennas.When gas is electrically charged, or ionized to a plasma state it becomes conductive,
allowing radio frequency (RF) signals to be transmitted or received. We employ ionized gas
enclosed in a tube as the conducting element of an antenna. When the gas is not ionized, the
antenna element ceases to exist. This is a fundamental change from traditional antenna design
that generally employs solid metal wires as the conducting element. We believe our plasma
antenna offers numerous advantages including stealth for military applications and higher
digital performance in commercial applications. We also believe our technology can compete
in many metal antenna applications. Our initial efforts have focused on military markets.
General Dynamics' Electric Boat Corporation sponsored over $160,000 of development in
2000 accounting for substantially all of our revenues.
Initial studies have concluded that a plasma antenna's performance is equal to a
copper wire antenna in every respect. Plasma antennas can be used for any transmission
and/or modulation technique: continuous wave (CW), phase modulation, impulse, AM, FM,
chirp, spread spectrum or other digital techniques. And the plasma antenna can be used over a
large frequency range up to 20GHz and employ a wide variety of gases (for example neon,
argon, helium, krypton, mercury vapor and zenon). The same is true as to its value as a
receive antenna.
6
WORKING
In an ionized gas plasma antenna, a gas is ionized to create a plasma. Unlike gasses,
plasmas have very high electrical conductivity so it is possible for radio frequency signals to
travel through them so that they act as a driven element (such as a dipole antenna) to radiate
radio waves, or to receive them. Alternatively the plasma can be used as a reflector or a
lens to guide and focus radio waves from another source.
PUMPING :
1. The gas inside the antenna is turned into plasma by applying a "pump signal" of high
power RF energy.
2. The RF energy is applied to the plasma tube using a device called a "launcher" or a
"coupler".
LAUNCHER :
1. Launcher is a metallic collar that is wrapped around the plasma tube.
2. In conjunction with a ground plane, this provides the high electric field required to initiate
and maintain a plasma within the tube.
3. It uses RF power levels of around 100 W at 500 MHz for the antennas as the pump signal.
PRINCIPLE OF OPERATION :
Antenna generates concentration of plasma to form plasma mirror. A central field is located
at the focus of mirror which deflects RF beam. Ionized region is produced by electronically
controlled device(plasma when dense act as conductor).Plasma is moved by switching device
on and off. One reflector becomes active at a time and beams are steered without the need of
mechanical motion. SI disc act as lens to form reflector system that enable RF energy to be
collimated and when gas is not ionized element ceases to exist.
MARKET APPLICATIONS OF PLASMA TECHNOLOGY
Plasma antennas offer distinct advantages and can compete with most metal
antenna applications. The plasma antenna's advantages over conventional metal elements are
most obvious in military applications where stealth and electronic warfare are primary
concerns. Other important military factors are weight, size and the ability to reconfigure.
Potential military applications include:
1.Shipboard/submarine antenna replacements.
2. Unmanned air vehicle sensor antennas.
3. IFF ("identification friend or foe") land-based vehicle antennas.
4. Stealth aircraft antenna replacements.
5. Broad band jamming equipment including for spread-spectrum emitters.
6. ECM (electronic counter-measure) antennas.
7. Phased array element replacements.
8. Phased array element replacements.
9. EMI/ECI mitigation.
10. Detection and tracking of ballistic missiles.
11. Side and backlobe reduction.
[attachment=28597]
ABSTRACT
A plasma antenna represents a completely new technology of antennas that relies on
plasma elements rather than in traditional metallic wires or surfaces. The feasibility of a
plasma antenna is provided by plasma conductivity, that is given by free electrons obtained
by gas ionization with the application of an intense electromagnetic field. The main
advantage of plasma antennas results from the possibility of changing electromagnetically
their parameters.This characteristic provide a plasma antenna with peculiar properties that
make it suitable for several applications (e.g, stealth application, antenna arrays, smart
antennas,frequencyselective shields).
The pump signal and gas discharge parameters have to be carefully chosen in order to
optimize plasma antenna design and realization, in particular discharge working conditions
have to be defined in order to obtain the desired antenna properties in terms of efficiency,
effective length and so on.
3
INTRODUCTION
On earth we live upon an island of "ordinary" matter. The different states of matter
generally found on earth are solid, liquid, and gas. Sir William Crookes, an English physicist
identified a fourth state of matter, now called plasma, in 1879. Plasma is by far the most
common form of matter. Plasma in the stars and in the tenuous space between them makes up
over 99% of the visible universe and perhaps most of that which is not visible. Important to
ASI's technology, plasmas are conductive assemblies of charged and neutral particles and
fields that exhibit collective effects. Plasmas carry electrical currents and generate magnetic
fields.
Plasma antennas have a number of potential advantages for antenna design.
Plasma antenna has following basic capabilities:
1) rapid change of antennas and antenna arrays configuration. Controlling their beam
pattern and its orientation by electronic control of plasma parameters.
2) small effective radar cross-section (RCS) of such antennas in a wide frequency band.
3) effective suppression of multipath reflection while transmitting short high-power
signals.
4) design of the compact extendable antennas for use with the high-power pulse
generators.
5) energized and de–energized in seconds, which prevents signal degradation.
6) Difficult to be detected by radar.
Due to these advantage plasma antenna attracts the interest of the industrial groups involved
in such diverse areas as fluorescent lighting, telecommunications and radar.
4
PLASMA ANTENNA TECHNOLOGY
Since the discovery of radio frequency ("RF") transmission, antenna design has
been an integral part of virtually every communication and radar application. 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. In its most common
form, an antenna represents a conducting metal surface that is sized to emit radiation at one
or more selected frequencies. Antennas must be efficient so the maximum amount of signal
strength is expended in the propogated wave and not wasted in antenna reflection.
Plasma antenna technology employs ionized gas enclosed in a tube (or other enclosure) as the
conducting element of an antenna. 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
5
antenna design are eliminated. The design allows for extremely short pulses, important to
many forms of digital communication and radars. The design further provides the opportunity
to construct an antenna that can be compact and dynamically reconfigured for frequency,
direction, bandwidth, gain and beamwidth. Plasma antenna technology will enable antennas
to be designed that are efficient, low in weight and smaller in size than traditional solid wire
antennas.When gas is electrically charged, or ionized to a plasma state it becomes conductive,
allowing radio frequency (RF) signals to be transmitted or received. We employ ionized gas
enclosed in a tube as the conducting element of an antenna. When the gas is not ionized, the
antenna element ceases to exist. This is a fundamental change from traditional antenna design
that generally employs solid metal wires as the conducting element. We believe our plasma
antenna offers numerous advantages including stealth for military applications and higher
digital performance in commercial applications. We also believe our technology can compete
in many metal antenna applications. Our initial efforts have focused on military markets.
General Dynamics' Electric Boat Corporation sponsored over $160,000 of development in
2000 accounting for substantially all of our revenues.
Initial studies have concluded that a plasma antenna's performance is equal to a
copper wire antenna in every respect. Plasma antennas can be used for any transmission
and/or modulation technique: continuous wave (CW), phase modulation, impulse, AM, FM,
chirp, spread spectrum or other digital techniques. And the plasma antenna can be used over a
large frequency range up to 20GHz and employ a wide variety of gases (for example neon,
argon, helium, krypton, mercury vapor and zenon). The same is true as to its value as a
receive antenna.
6
WORKING
In an ionized gas plasma antenna, a gas is ionized to create a plasma. Unlike gasses,
plasmas have very high electrical conductivity so it is possible for radio frequency signals to
travel through them so that they act as a driven element (such as a dipole antenna) to radiate
radio waves, or to receive them. Alternatively the plasma can be used as a reflector or a
lens to guide and focus radio waves from another source.
PUMPING :
1. The gas inside the antenna is turned into plasma by applying a "pump signal" of high
power RF energy.
2. The RF energy is applied to the plasma tube using a device called a "launcher" or a
"coupler".
LAUNCHER :
1. Launcher is a metallic collar that is wrapped around the plasma tube.
2. In conjunction with a ground plane, this provides the high electric field required to initiate
and maintain a plasma within the tube.
3. It uses RF power levels of around 100 W at 500 MHz for the antennas as the pump signal.
PRINCIPLE OF OPERATION :
Antenna generates concentration of plasma to form plasma mirror. A central field is located
at the focus of mirror which deflects RF beam. Ionized region is produced by electronically
controlled device(plasma when dense act as conductor).Plasma is moved by switching device
on and off. One reflector becomes active at a time and beams are steered without the need of
mechanical motion. SI disc act as lens to form reflector system that enable RF energy to be
collimated and when gas is not ionized element ceases to exist.
MARKET APPLICATIONS OF PLASMA TECHNOLOGY
Plasma antennas offer distinct advantages and can compete with most metal
antenna applications. The plasma antenna's advantages over conventional metal elements are
most obvious in military applications where stealth and electronic warfare are primary
concerns. Other important military factors are weight, size and the ability to reconfigure.
Potential military applications include:
1.Shipboard/submarine antenna replacements.
2. Unmanned air vehicle sensor antennas.
3. IFF ("identification friend or foe") land-based vehicle antennas.
4. Stealth aircraft antenna replacements.
5. Broad band jamming equipment including for spread-spectrum emitters.
6. ECM (electronic counter-measure) antennas.
7. Phased array element replacements.
8. Phased array element replacements.
9. EMI/ECI mitigation.
10. Detection and tracking of ballistic missiles.
11. Side and backlobe reduction.