NEC-LIST: Re: Plasma Antennas

There is a report by the Naval Postgraduate School (Monterey, CA) about
Plasma Antennas: Survey of Techniques and the Current State of the
Art, Sept. 2003. The report is made public and can be found at this url:
http://www.nps.navy.mil/jenn/pubs/PlasmaReportFinal.pdf

Another interesting url is of the Plasma Research Lab at the Australian
National University:
http://wwwrsphysse.anu.edu.au/~ggb112/

Recapping I guess these are the most obvious aspects of plasma antennas
(please add/correct/delete& trying to get a complete picture of the
technology here!):

Plasma is simply a replacement for metal as a conductor. Plasma antennas
come in different shapes: reflectors, direct radiators, lenses.

Pros:
· Plasma is only required when using antenna, default could be off:
transparent tube (plasma container) remains with negligable conductivity.
· Possibly aerial is lighter than metal one.
· By tapering (or stepping) the cross-section of the plasma container,
the length of the antenna can be varied by increasing or decreasing the
plasma creating current. Combined with tapered helical or spiral
arrangement, this leads to varying beamwidth and/or bandwidth.
· Many forms of plasma container possible (even inflatable claimed).

Cons:
· Energised plasma creates wideband noise (which does not have to be a
problem for high power transmitters; and Markland claims there is
virtually no noise when gas is ionised).
· Energy required to establish and maintain plasma.
· Plasma has a very high temperature.
· Probably entire system is more expensive, more complex, more damage
prone and heavier than comparable metal antenna.
· Low radiating efficiency (order 50%-70%, although 1%-5% also claimed).

Active researchers/institutes:
· Jeffrey Harris, Gerard Borg, Noel Martin, The Australian National
University: patent on plasma antennas.
· Australian National University, Plasma Research Laboratory.
· Defense Science and Technology Organisation, Australian DoD. Blue
Skies research programme for future antennas in conjunction with ANU PRL.
· Theodore Anderson, ASI Technology Corp.: 12 patents on plasma
antennas, 8 more filed. Consultant to Markland Tech.
· Igor Alexeff, ASI Technology Corp.
· ASI (Anderson Science Inc.?) Technology Corp.: Research on plasma
antennas and other applications of plasma (plasma waveguides, plasma
FSS, plasma shield, plasma reflectors, plasma jet engine noise reduction
and plasma decomtamination), sponsored through Missile Defense Agencys
Small Business Innovation Research (SBIR) program.
· Markland Technology: Homeland security company, markets plasma
antennas. Linked to ASI and Anderson.
· US Navy: sponsors plasma research through SBIR programs. Interested in
reconfigurable wideband apertures (2003), plasma electronic-scan satcom
(1995), plasma phased array radar antennas (2002).
· Plasma Antennas Ltd., Oxford UK.

In all, very interesting, but not (as claimed in the Naval Postgraduate
School report) the ultimate answer in the search for the ideal antenna!

Regards,
Jasper

-- 
Jasper van der Graaff
Thales Naval Nederland B.V.
Environmental Competence Center
P.O. Box 42, 7550 GD Hengelo
The Netherlands
Tel.: +31 (0)74 - 248 3655
Fax : +31 (0)74 - 248 4037
E-mail : Jasper.vanderGraaff_at_nl.thalesgroup.com
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