In this paper, the ‘Plasma antenna technology’ is introduced to solve the problems of radio antennas. On hearing the name ‘plasma antenna’ for the first time, we may get a wrong impression that it is something entirely different. But that is not the case. Plasma antenna is just another type of radio antenna which is currently under development. In this innovation, plasma is used as a replacement for the metal elements of the traditional antennas. It performs all the functions of the radio antennas. That is it can be used for transmission and reception of signals.

Plasma antenna is a special type of antenna in which the metal conducting elements of a conventional antenna are replaced by plasma. It employs an ionized gas enclosed in a tube as the conducting element of antenna. When gas is electrically charged or ionized to plasma, it becomes conductive and allowing radio frequency signals to be transmitted or received. When gas is not ionized the antenna element ceases to exit. When voltage is applied to antenna electric field is produced which causes current to flow in antenna. Due to current flow, magnetic field is produced. It is more advantageous than other antenna due to ionized gas. It has higher efficiency and enhanced bandwidth.

Plasma Antennas:

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, anEnglish 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 spacebetween 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. When the Plasma Antenna Research Laboratory at ANU investigated the feasibility of plasma antennas as low radar cross-section radiating elements, Red centre established a network between DSTO ANU researchers, CEA Technologies, Cantec Australasia and Neo lite Neon for further development and future commercialization of this technology .The plasma antenna R & D project has proceeded over the last year at the Australian National University in response to a DSTO (Defence Science and Technology Organisation) contract to develop a new antenna solution that minimizes antenna detectability by radar.

Since then, an investigation of the wider technical issues of existing antenna systems has revealed areas where plasma antennas might be useful. The project attracts the interest of the industrial groups involved in such diverse areas as fluorescent lighting, telecommunications and radar. Plasma antennas have a number of potential advantages for antenna design .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 ,which falls in the microwave region. Plasma elements can be energized and de–energized in seconds, which prevents signal degradation. When a particular plasma element is not energized, its radiation does not affect nearby elements. HF CDMA Plasma antennas will have low probability of intercept( LP) and low probability of detection( LPD ) in HF communications.

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 propagated 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 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 beam width. Plasma antenna technology will enable antennas to be designed that are efficient, low in weight and smaller in size than traditional solid wire antennas.