ANTENTOP- 03- 2003, # 004

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. In these applications, metal antennas are often accompanied by sophisticated computer signal processing. By reducing ringing and noise, we believe our plasma antenna provides increased accuracy and reduces computer signal processing requirements. These advantages are important in cutting edge applications for impulse radar and high-speed digital communications.

Based on the results of development to date, plasma antenna technology has the following additional attributes:

No antenna ringing provides an improved signal to noise ratio and reduces multipath signal distortion.
-Reduced radar cross section provides stealth due to the non-metallic elements.
-Changes in the ion density can result in instantaneous changes in bandwidth over wide dynamic ranges.
-After the gas is ionized, the plasma antenna has virtually no noise floor.
-While in operation, a plasma antenna with a low ionization level can be decoupled from an adjacent high-frequency transmitter.
-A circular scan can be performed electronically with no moving parts at a higher speed than traditional mechanical antenna structures.
-It has been mathematically illustrated that by selecting the gases and changing ion density that the electrical aperture (or apparent footprint) of a plasma antenna can be made to perform on par with a metal counterpart having a larger physical size.
-Our plasma antenna can transmit and receive from the same aperture provided the frequencies are widely separated.
-Plasma resonance, impedance and electron charge density are all dynamically reconfigurable. Ionized gas antenna elements can be constructed and configured into an array that is dynamically reconfigurable for frequency, beamwidth, power, gain, polarization and directionality - on the fly.

-A single dynamic antenna structure can use time multiplexing so that many RF subsystems can share one antenna resource reducing the number and size of antenna structures.

Sponsored Work

To date, plasma antenna technology has been studied and characterized by ASI Technology Corporation revealing favorable attributes in connection with antenna applications. Government sponsored work has included:

-ONR contract N66001-97-M-1153 May 1997 - The major objective of this program was to determine the noise levels associated with the use of gas plasma as a conductor for a transmitting and receiving antenna. Both laboratory and field-test measurements were conducted.

-ONR contract N00014-98-C-0045 November 1997 - The major objective of this effort was to characterize the GP antenna for conductivity, ionization breakdowns, upper frequency limits, excitation and relaxation times, ignition mechanisms, temperatures and thermionic noise emissions and compare these results to a reference folded copper wire monopole. The measured radiation patterns of the plasma antenna compared very well with copper wire antennas.

-MDA Phase I SBIR Contract DASG60-01-P-0063 May 2001 - This six month work (expanded for an additional three months by MDA) focused on using plasma rather than solid metal as the current medium for an antenna. We illustrated the use of controllable apertures (open plasma windows) for far field antenna radiation. Experiments verified our plasma windowing concept.

-MDA Phase II SBIR Contract DASG60-02-C-0055 April 2002 - This 24 month contract is focusing on developing a feasibility prototype high power antenna based on our windowing concept and to design and develop a high power phased array using plasma phase shifters to steer the beam. Malibu Research Associates is our subcontractor on this project.

-MDA Phase I SBIR Contract DASG60-02-P-0033 April 2002 - This 6 month contract focused on using plasma as a replacement for metal in a frequency selective surface (FSS) used to filter electromagnetic waves. A tunable FSS can absorb frequencies above the resonant frequency and reflect those above to reduce radar vulnerability to countermeasures. Plasma is an excellent shield and filter for antenna systems.

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