09-07-2012, 12:15 PM
MICRO ELECTRO MECHANICAL SYSTEMS INTEGRATED FREQUENCY
RECONFIGURABLE ANTENNAS FOR PUBLIC SAFETY APPLICATIONS
[attachment=27243]
Introduction
This age of rapid technological development demands an ever-increasing speed of infor-
mation transfer over the wireless communication systems for the sake of ease and speed of
access of useful information. The existing wireless communication systems need a massive
update both in the communication aspect and Radio Frequency (RF) perspective because
with today’s advent of smart phones, i-touch, i-pad, etc., the demand on efficient use of
Bandwidth (BW) in the wireless communication scenario has increased many a times. Sev-
eral coding and multiplexing schemes [1] have evolved in the signal processing domain for
this purpose but these require multiple antennas at the RF end for better performance.
Multiple Input Multiple Output (MIMO) systems [2–7] make the best use of such intelli-
gent coding schemes provided they can be benefitted from the adaptability in the antenna
design - a single antenna capable of performing multiple functions of several antennas by
dynamically changing its geometrical properties, i.e., Multi-functional Reconfigurable An-
tenna (MRA).
Broadband and Compact PIFA
Introduction
During natural or man-made catastrophes, there is a need for a robust wireless commu-
nication system with broad BW to support wireless communication needs (voice, data, and
video) of the US PS community. The broad bandwidth is also needed to accommodate the
interoperable communications among a large number of emergency responders of various
agencies trying to jointly handle the situation. Mobile devices require compact antennas
and the Planar Inverted F Antenna (PIFA) presented here suits this purpose well.
Patch Tapering
Given the limited volume available for antenna elements in wireless communication
devices, this BW enhancement technique [32] employs a linear tapering of the radiation
patch by simple geometrical modification of the original design, as opposed to common
techniques that use additional elements or increase the volume of the antenna.
Capacitive Coupling
This type of feeding is used to compensate for the inductance of the coaxial feed line
by means of terminating it with a capacitor patch [34]. The result is a better match in
a wider frequency range. Also, the use of capacitor feeding helps in easy fabrication and
there is no need to connect the coaxial feed directly to the top patch. As explained in the
T-shaped ground plane sub section, instead of using air as a dielectric for the capacitive
feed, a substrate (d 0.8mm, with r close to 1) is sandwiched by the bottom conductive
plate of the capacitive feed and top patch metal of the PIFA.
Fabrication and Measurements
A PIFA with the above dimensions was fabricated and its radiation and impedance
behaviour have been characterised. The fabrication involves copper layer removal by me-
chanical etching to define the planar geometrical features of different parts of the antenna.
The bottom metal plate of the capacitive feed was etched on one side of the substrate, and
the tapered patch layer is formed on the other side, which also contains the top metallisa-
tion of the feed.
RECONFIGURABLE ANTENNAS FOR PUBLIC SAFETY APPLICATIONS
[attachment=27243]
Introduction
This age of rapid technological development demands an ever-increasing speed of infor-
mation transfer over the wireless communication systems for the sake of ease and speed of
access of useful information. The existing wireless communication systems need a massive
update both in the communication aspect and Radio Frequency (RF) perspective because
with today’s advent of smart phones, i-touch, i-pad, etc., the demand on efficient use of
Bandwidth (BW) in the wireless communication scenario has increased many a times. Sev-
eral coding and multiplexing schemes [1] have evolved in the signal processing domain for
this purpose but these require multiple antennas at the RF end for better performance.
Multiple Input Multiple Output (MIMO) systems [2–7] make the best use of such intelli-
gent coding schemes provided they can be benefitted from the adaptability in the antenna
design - a single antenna capable of performing multiple functions of several antennas by
dynamically changing its geometrical properties, i.e., Multi-functional Reconfigurable An-
tenna (MRA).
Broadband and Compact PIFA
Introduction
During natural or man-made catastrophes, there is a need for a robust wireless commu-
nication system with broad BW to support wireless communication needs (voice, data, and
video) of the US PS community. The broad bandwidth is also needed to accommodate the
interoperable communications among a large number of emergency responders of various
agencies trying to jointly handle the situation. Mobile devices require compact antennas
and the Planar Inverted F Antenna (PIFA) presented here suits this purpose well.
Patch Tapering
Given the limited volume available for antenna elements in wireless communication
devices, this BW enhancement technique [32] employs a linear tapering of the radiation
patch by simple geometrical modification of the original design, as opposed to common
techniques that use additional elements or increase the volume of the antenna.
Capacitive Coupling
This type of feeding is used to compensate for the inductance of the coaxial feed line
by means of terminating it with a capacitor patch [34]. The result is a better match in
a wider frequency range. Also, the use of capacitor feeding helps in easy fabrication and
there is no need to connect the coaxial feed directly to the top patch. As explained in the
T-shaped ground plane sub section, instead of using air as a dielectric for the capacitive
feed, a substrate (d 0.8mm, with r close to 1) is sandwiched by the bottom conductive
plate of the capacitive feed and top patch metal of the PIFA.
Fabrication and Measurements
A PIFA with the above dimensions was fabricated and its radiation and impedance
behaviour have been characterised. The fabrication involves copper layer removal by me-
chanical etching to define the planar geometrical features of different parts of the antenna.
The bottom metal plate of the capacitive feed was etched on one side of the substrate, and
the tapered patch layer is formed on the other side, which also contains the top metallisa-
tion of the feed.