08-16-2017, 09:58 PM
the new world of Plasma Antennas
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Antenna technology
Physically, an antenna is an arrangement
of one or more conductors, usually
called elements. In transmission,
an alternating current is created in the
elements by applying a voltage at the
antenna terminals, causing the elements
to radiate an electromagnetic field. In
reception, the inverse occurs. An electromagnetic
field from another source
induces an alternating current in the elements
and a corresponding voltage at
the antenna s terminals. Some receiving
antennas (such as parabolic and horn
types) incorporate shaped reflective surfaces
to collect the radio waves striking
them, and direct these waves onto the
actual conductive elements.
Plasma antennas
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 per cent of the
visible universe and perhaps most of
what is not visible.
Development progress
Initial investigations were related
to the feasibility of plasma antennas
as low-radar cross-section radiating
elements with further development
and future commercialisation of this
technology. The plasma antenna R&D
project has proceeded to develop a
new antenna solution that minimises
antenna-detectability by radar at the
first instance. But since then an investigation
of the wider technical issues of
existing antenna systems has revealed
areas where plasma antennas might
be useful.
Advantages of plasma antennas
1. An important advantage of plasma
antenna over a conventional antenna is
that the former is much lighter. Based
on a set of patented beam-forming
technologies, these high-performance
electronically-steerable antennas are
extremely lightweight and compact.
2. Free from mechanical parts, these
maintenance-free plasma antennas
are ideally suited for a wide range of
wireless communications and sensing
applications.
3. Plasma antennas have a number
of potential advantages for antenna
design. These are reconfigurable. When
one plasma antenna is de-energised,
the antenna reverts to a dielectric tube,
and a second antenna can transmit
through it. This allows using several
large antennas stacked over each
other instead of several small antennas
placed next to each other. This results
in better sensitivity and directivity.
Limitations
1. The current hardware uses a wider
range of frequencies so it s impractically
massive to be used for mobile
environments.
2. Plasma antennas are expensive
and hard to manufacture.
3. High-frequency signals mean
that antennas operating at higher frequencies
couldn t penetrate walls like
conventional Wi-Fi, so signals would
have to be reflected throughout the
buildings.