Download A DEVICE, A METHOD AND A SYSTEM FOR DETECTING

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A DEVICE, A METHOD AND A SYSTEM FOR DETECTING PROPERTIES OF
A MATERIAL
TECHNICAL FIELD
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Embodiments of the present invention relate to technologies for
detection of material properties and more particularly to a device, method and
system for detecting properties of a material. Further, the disclosed device and
system characterize the material in determining material properties and quality.
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BACKGROUND ART
Sensing or detecting material properties undergoing physical or
chemical changes is essential for numerous applications such as food industry,
quality control, bio-sensing, agriculture, medicine and pharmacy, and material
science. Material composition, moisture or water content in material under test
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(MUT) carry valuable information and electrical properties of these materials
depends on their properties. Thus, quality control in the material science, food
industry, bio-sensing can be conducted based on sensing electrical properties
of the materials.
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Microwave measurement is a potential technique for detecting and
characterizing materials due to its non-invasive characteristics and penetration
sensing capability. Numerous microwave methods have been proposed and
used for material characterization. These methods can be classified as
free-space transmission methods, near-field sensors methods, resonant cavity
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methods and planar resonator methods.
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In conventional free-space methods, the material under test (MUT) is
placed between a pair of spot-focusing lens antennas which required a large
space to process measurement for reflection and transmission coefficients. In
the near-field sensors methods, properties of the material can be extracted by
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measuring the reflection coefficient from an open end when the sample or
material under test is placed right at an opening. This method is called
open-ended coaxial probe and this exhibits high precision for material
characterization. This method can be used for extracting the properties of local
materials since it is not limited by diffraction limitation.
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In the resonant cavity methods, a cavity resonator is filled with an
adjusted material under test (MUT) and a shift in resonant frequency and
change in quality factor are measured. This method is considered as a most
precise characterization method because this is applicable over a narrow band.
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Further, in the planar resonator methods, the material under test (MUT) is
placed either on top of a resonator or inside a substrate which depends on
maximum electric field location (E-Field).
There have been a number of solutions provided for efficient methods
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for detection and characterization of materials and few of them have been
discussed below:
US20020175693A1 discloses a system and a method for detecting
properties of a material. A detection apparatus comprises a pair of reflecting
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surfaces which directs electromagnetic radiations into the detection apparatus.
This electromagnetic radiation is detected to determine characteristics of a
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sample under test.
WO2013072844A1 describes systems, tools and methods for
measuring a property of a solid body or a fluid. An electromagnetic
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measurement tool of the invention includes a transmitter, a receiver and a
metamaterial
element
comprising
a
negative
refractive
index.
The
electromagnetic measurement tool is placed adjacent to the solid body or the
fluid and electromagnetic energy is transmitted through the transmitter and
received by the receiver to measure the properties of solid body or the fluid.
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US20140250553A1 describes a sensor. The sensor comprises a
resonator, a probe and an encasement. The probe is attached to the resonator
and the encasement encases the resonator. The encasement includes and
opening through which the probe can protrude. Further, the sensor measures
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for example acceleration, changes in mass, viscosity of its environment.
The aforesaid documents and other similar solutions may strive to
provide efficient methods for detecting and characterizing materials; however,
they still have a number of limitations and shortcomings such as, but not limited
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to, requirement of highly sophisticated and bulky equipment with high
maintenance cost including antennas, lenses etc. Further, in the conventional
methods, modelling of measured reflection coefficient as a function of dielectric
properties remains a difficult task. Also, the resonant cavity method requires a
precise
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sample
preparation
and
its
effectiveness
is
limited
when
non-destructive measurements and preservation of original sample are required.
In addition, the planar resonator method suffers from low sensitivity and poor
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Quality factor (Q-factor) which restricts its use and limits range of materials and
its applications.
Accordingly, there remains a need in the prior art to have an improved
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system and method for detecting properties of a material which overcomes the
aforesaid problems and shortcomings.
However, there remains a need in the art for a device, a method and a
system which detects or measures properties of the materials. Further, the
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proposed device is useful in characterizing the materials particularly in
determining material properties and quality. Also, the device, method and
system are efficient and economical.
SUMMARY OF THE INVENTION
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Embodiments of the present invention aim to provide a device, method
and system for detecting properties of a material. The device has potential for
high accuracy in extracting local material properties and exhibits high Q-factor
as well as suppresses undesired spurious of a microwave resonator, thus, the
device is used as a microwave sensor due to high sensitivity. Further, the
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device is used in detecting properties of a wide variety of materials such as food
industry, quality control, medicine & pharmaceutical, biological materials,
composition and moisture of materials such as permittivity. Also, the disclosed
device, method and system are efficient and economical.
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In accordance with an embodiment of the present invention, the device
for detecting properties of a material comprising a substrate, a pair of feed-lines
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and a pair of concentric annular rings. The pair of concentric annular rings
includes an inner ring with a centered-connecting joint and an outer ring
wrapped around the inner ring. The inner ring is configured to have a first
plurality of splits at opposite points on the inner ring and is placed on a top
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portion of the substrate. The outer ring is configured to have a second plurality
of splits formed at different symmetric points on the outer ring from the opposite
points on the inner ring. Further, the outer ring is placed on the top portion of the
substrate. The inner ring and the outer ring are having a coupling gap between
them. The pair of feed-lines and the pair of concentric annular rings are having
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another coupling gap between them. Also, the device is excited to generate an
electric field and a magnetic field.
In accordance with an embodiment of the present invention, the device
further comprises a single spurline configuration on the pair of feed-lines.
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Further, the single spurline configuration is embedded by an L-shape slot into
the pair of feed-lines.
In accordance with an embodiment of the present invention, the device
further comprises a double spurline configuration on the pair of feed-lines.
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Further, the double spurline configuration is embedded by an L-shape slot into
the pair of feed-lines.
In accordance with an embodiment of the present invention, the inner
ring is configured to have the first plurality of splits at angles of, but not limited to,
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900 and -900.
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In accordance with an embodiment of the present invention, the outer
ring is configured to have the second plurality of splits at angles of, but not
limited to, 00 and 1800.
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In accordance with an embodiment of the present invention, the inner
ring and the outer ring are made up of, but not limited to, an electrically
conductive and non-magnetic material. Further, the electrically conductive and
non-magnetic material is, but not limited to, copper.
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In accordance with an embodiment of the present invention, the inner
ring and the outer ring are formed in, but not limited to, a circular, square and
triangular shape.
In accordance with an embodiment of the present invention, the
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substrate is made up of materials selected from, but not limited to, a group
consisting of Rogers, FR4, gold, plastic, graphite, porcelain and glass.
In accordance with an embodiment of the present invention, the
substrate is, but not limited to, a circuit board.
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In accordance with an embodiment of the present invention, the
substrate is formed from, but not limited to, a dielectric material. The substrate
is cladded with an electrically conductive material on the top portion and ground
at a bottom end. Further, the electrically conductive material is, but not limited to,
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copper and the substrate material is, but not limited to, Rogers material.
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In accordance with an embodiment of the present invention, the inner
ring has a radius of, but not limited to, 10.85 mm.
In accordance with an embodiment of the present invention, the outer
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ring has a radius of, but not limited to, 15.85 mm.
In accordance with an embodiment of the present invention, the first
plurality of splits and the second plurality of splits have gaps in the range of, but
not limited to, 0.25 mm to 0.37 mm.
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In accordance with an embodiment of the present invention, the pair of
feed-lines is having a length of, but not limited to, 34 mm and a width of, but not
limited to, 2.5 mm.
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In accordance with an embodiment of the present invention, the
excitation of the device is performed using, but not limited to, microstrip
feed-lines and coaxial probes.
In accordance with an embodiment of the present invention, the method
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for manufacturing the device for detecting properties of a material comprising
the steps of forming an inner ring configured to have a first plurality of splits at
opposite points on the inner ring, forming an outer ring wrapped around the
inner ring and configured to have a second plurality of splits formed at different
symmetric points on the outer ring from the opposite points on the inner ring,
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providing a gap between the inner ring and the outer ring, placing the inner ring
and the outer ring on the top portion of a substrate, providing a pair of feed-lines
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and allowing a coupling gap between the pair of feed-lines and the inner ring
and the outer ring.
In accordance with an embodiment of the present invention, the method
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further comprises a step of embedding a single spurline configuration on the
pair of feed-lines. Further, the single spurline configuration is embedded by an
L-shape slot into the pair of feed-lines.
In accordance with an embodiment of the present invention, the method
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further comprises a step of embedding a double spurline configuration on the
pair of feed-lines. Further, the double spurline configuration is embedded by an
L-shape slot into the pair of feed-lines.
In accordance with an embodiment of the present invention, the first
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plurality of splits and the second plurality of splits are formed by, but not limited
to, etching.
In accordance with an embodiment of the present invention, the system
for detecting properties of a material comprising a material under test, a device,
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and a vector network analyzer having a power source. The device comprises a
substrate, a pair of feed-lines and a pair of concentric annular rings including an
inner ring with a centered-connecting joint and an outer ring wrapped around
the inner ring. The inner ring is configured to have a first plurality of splits at
opposite points on the inner ring. The outer ring is configured to have a second
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plurality of splits formed at different symmetric points on the outer ring from the
opposite points on the inner ring. The inner ring and the outer ring are placed on
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the top portion of the substrate. Further, the inner ring and the outer ring are
having a coupling gap between them. Also, the pair of feed-lines and the pair of
concentric annular rings are having another coupling gap between them. The
device is connected to the vector network analyzer. The device is excited to
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generate an electric field and a magnetic field and the material under test is
configured to be placed on the device for detection of properties.
In accordance with an embodiment of the present invention, the pair of
feed-lines is configured to have a plurality of ports at end of each feed-line.
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Further, the plurality of ports is connected to the vector network analyzer using
a coaxial cable.
In accordance with an embodiment of the present invention, the system
further comprises a computing device.
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In accordance with an embodiment of the present invention, the device
detects reflection coefficient and transmission coefficient of the material under
test. Further, the reflection coefficient and transmission coefficient are analyzed
by the computing device. Also, the material under test is having a thickness in
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the range of, but not limited to, 0.787 mm to 7.78 mm.
In accordance with an embodiment of the present invention, the device
is operated at a frequency of, but not limited to, 2.2 GHz.
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BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
So that the manner in which the above recited features of the present
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invention can be understood in detail, a more particular description of the
invention, briefly summarized above, may have been referred by embodiments,
some of which are illustrated in the appended drawings. It is to be noted,
however, that the appended drawing illustrates only typical embodiments of this
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invention and are therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
These and other features, benefits and advantages of the present
invention will become apparent by reference to the following text figure, with like
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reference numbers referring to like structures across the views, wherein:
Fig. 1 illustrates a device for detecting properties of a material in
accordance with an embodiment of the present invention.
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Fig. 2 illustrates a single spurline configuration embedded in a pair of
feed-lines of the device in accordance with an embodiment of the present
invention.
Fig. 3 illustrates a double spurline configuration embedded in the pair of
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feed-lines of the device in accordance with an embodiment of the present
invention.
Fig. 4 illustrates a pictorial presentation of the device in accordance
with an embodiment of the present invention.
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Fig. 5 is a flow chart illustrating a method for manufacturing the device
for detecting properties of the material in accordance with an embodiment of the
present invention.
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Fig. 6 illustrates a system for detecting properties of the material in
accordance with an embodiment of the present invention.
Fig. 7 illustrates a side view of the device with material under test in
accordance with an embodiment of the present invention.
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Fig. 8 is a graph showing difference between simulated and measured
transmission coefficients in accordance with an embodiment of the present
invention.
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Fig. 9 is a graph showing variability of resonance frequency and relative
shift of a symmetrical split ring resonator (SSRR) in accordance with an
embodiment of the present invention.
Fig. 10 is a graph showing variability of transmission coefficients (S21
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in dB) and quality factor of the symmetrical slit ring resonator (SSRR) in
accordance with an embodiment of the present invention.
Fig. 11 is a graph showing variability of thickness of tested samples and
the resonant frequency of the symmetrical split ring resonator (SSRR) in
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accordance with an embodiment of the present invention.
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Fig. 12 is a graph showing standard material under test (MUT) with
known permittivity to validate the device sensitivity in accordance with an
embodiment of the present invention.
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Fig. 13 is a graph showing differences between reference materials
with standard permittivity with measured result using the symmetrical split ring
resonator (SSRR) in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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While the present invention is described herein by way of example
using embodiments and illustrative drawings, those skilled in the art will
recognize that the invention is not limited to the embodiments of drawing or
drawings described, and are not intended to represent the scale of the various
components. Further, some components that may form a part of the invention
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may not be illustrated in certain figures, for ease of illustration, and such
omissions do not limit the embodiments outlined in any way. It should be
understood that the drawings and detailed description thereto are not intended
to limit the invention to the particular form disclosed, but on the contrary, the
invention is to cover all modifications, equivalents and alternatives falling within
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the scope of the present invention as defined by the appended claim. As used
throughout this description, the word "may" is used in a permissive sense (i.e.
meaning having the potential to), rather than the mandatory sense (i.e. meaning
must). Further, the words "a" or "an" mean "at least one” and the word “plurality”
means “one or more” unless otherwise mentioned. Furthermore, the
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terminology and phraseology used herein is solely used for descriptive
purposes and should not be construed as limiting in scope. Language such as
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"including," "comprising," "having," "containing," or "involving," and variations
thereof, is intended to be broad and encompass the subject matter listed
thereafter, equivalents, and additional subject matter not recited, and is not
intended to exclude other additives, components, integers or steps. Likewise,
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the term "comprising" is considered synonymous with the terms "including" or
"containing" for applicable legal purposes. Any discussion of documents, acts,
materials, devices, articles and the like is included in the specification solely for
the purpose of providing a context for the present invention. It is not suggested
or represented that any or all of these matters form part of the prior art base or
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were common general knowledge in the field relevant to the present invention.
In this disclosure, whenever a composition or an element or a group of
elements is preceded with the transitional phrase “comprising”, it is understood
that we also contemplate the same composition, element or group of elements
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with transitional phrases “consisting of”, “consisting”, “selected from the group
of consisting of, “including”, or “is” preceding the recitation of the composition,
element or group of elements and vice versa.
The present invention is described hereinafter by various embodiments
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with reference to the accompanying drawing, wherein reference numerals used
in the accompanying drawing correspond to the like elements throughout the
description. This invention may, however, be embodied in many different forms
and should not be construed as limited to the embodiment set forth herein.
Rather, the embodiment is provided so that this disclosure will be thorough and
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complete and will fully convey the scope of the invention to those skilled in the
art. In the following detailed description, numeric values and ranges are
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provided for various aspects of the implementations described. These values
and ranges are to be treated as examples only, and are not intended to limit the
scope of the claims. In addition, a number of materials are identified as suitable
for various facets of the implementations. These materials are to be treated as
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exemplary, and are not intended to limit the scope of the invention.
Referring to the drawings, the invention will now be described in more
detail. In accordance with an embodiment of the present invention, a device
(100) for detecting properties of a material, as shown in figure 1, comprises a
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substrate (102), a pair of feed-lines (104) and a pair of concentric annular rings.
The pair of concentric annular rings includes an inner ring (106) and an outer
ring (108) wrapped around the inner ring (106). Further, the device (100) is a
symmetrical split-ring resonator (SSRR).
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In accordance with an embodiment of the present invention, the inner
ring (106) is configured to have a first plurality of splits (110) at opposite points
on the inner ring (106). The inner ring (106) is placed on a top portion of the
substrate (102). Further, the inner ring (106) is having a centered-connecting
joint. The inner ring (106) is configured to have the first plurality of splits (110) at
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angles of, but not limited to, 900 and -900. Also, the inner ring (106) has a radius
of, but not limited to, 10.85 mm.
In accordance with an embodiment of the present invention, the outer
ring (108) is configured to have a second plurality of splits (112) formed at
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different symmetric points on the outer ring (108) from the opposite points on
the inner ring (106). The outer ring (108) is placed on the top portion of the
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substrate (102). Further, the outer ring (108) is configured to have the second
plurality of splits (112) at angles of, but not limited to, 00 and 1800. Also, the
outer ring (108) has a radius of, but not limited to, 15.85 mm.
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In accordance with an embodiment of the present invention, the inner
ring (106) and the outer ring (108) are having a coupling gap between them.
Further, a coupling gap (114) is also provided between the pair of feed-lines
(104) and the inner ring (106) and the outer ring (108). The first plurality of splits
(110) of the inner ring (106) and the second plurality of splits (112) of the outer
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ring (108) have gaps in the range of, but not limited to, 0.25 mm to 0.37 mm.
Also, the pair of feed-lines (104) is having a length of, but not limited to, 34 mm
and a width of, but not limited to, 2.5 mm.
In accordance with an embodiment of the present invention, the inner
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ring (106) and the outer ring (108) are made up of, but not limited to, an
electrically conductive and non-magnetic material. The electrically conductive
and non-magnetic material is, but not limited to, copper. Further, the inner ring
(106) and the outer ring (108) are formed in, but not limited to, a circular, square
and triangular shape.
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In accordance with an embodiment of the present invention, the
substrate (102) is made up of materials selected from, but not limited to, a
group consisting of Rogers, FR4, gold, plastic, graphite, porcelain and glass.
Further, the substrate (102) is, but not limited to, a circuit board. The substrate
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(102) is formed from a dielectric material. Also, the substrate (102) is cladded
with an electrically conductive material (122) on the top portion and ground
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(124) at a bottom end. The electrically conductive material (122) is, but not
limited to, copper and the substrate (102) material is, but not limited to, Rogers
material.
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In accordance with an embodiment of the present invention, the
substrate (102) supports a periodic, or a number of symmetrical split-ring
resonators (SSRR) formed in parallel with each other and connected by the pair
of feed-lines (104).
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In accordance with an embodiment of the present invention, the device
(100) is excited to generate an electric field and a magnetic field. Further, the
device (100) is excited using, but not limited to, microstrip feed-lines, coaxial
probes or any other relevant excitations.
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In accordance with an embodiment of the present invention, the device
(100) further comprises with a single spurline configuration on the pair of
feed-lines (104) and a double spurline configuration on the pair of feed-lines
(104).
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Figure 2 illustrates the single spurline configuration embedded in the
pair of feed-lines (104) of the device (100) in accordance with an embodiment
of the present invention.
As shown in figure 2, the single spurline configuration is embedded by
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an L-shape slot with a length and a width into the pair of feed-lines (104) of the
device (100). The width of the L- shape slot exhibits an effect of capacitance
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while the microstrip line or the length of the L- shape slot provides an effect of
inductance. The length and the width of the L- shape slot are formed without
any stubs or etching process on microstrip feedlines. Further, the device (100)
with the single spurline configuration is a small structure.
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Figure 3 illustrates the double spurline configuration embedded in the
pair of feed-lines (104) of the device (100) in accordance with an embodiment
of the present invention.
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As shown in figure 3, the double spurline configuration is embedded by
the L-shape slot with a length and a width into the pair of feed-lines (104) of the
device (100). The length and the width of the L-shape slot are formed without
any stubs or etching process on microstrip feedlines. Further, the device (100)
with the double spurline configuration is a small structure. Also, the double
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spurline configuration is applied on the pair of feed-lines (104) without
increasing overall circuit size of the substrate (102).
Figure 4 illustrates a pictorial presentation of the device (100) in
accordance with an embodiment of the present invention.
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Figure 5 is a flow chart illustrating a method (200) for manufacturing the
device (100) for detecting properties of the material in accordance with an
embodiment of the present invention.
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At step 202, the inner ring (106) is formed which is configured to have
the first plurality of splits (110) at opposite points on the inner ring (106). Further,
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the inner ring (106) is having the centered-connecting joint.
In accordance with an embodiment of the present invention, the first
plurality of splits (110) of the inner ring (106) are formed by, but not limited to,
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etching.
At step 204, the outer ring (108) is formed which is wrapped around the
inner ring (106). Further, the outer ring (108) is configured to have the second
plurality of splits (112) formed at different symmetric points on the outer ring
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(108) from the opposite points on the inner ring (106).
In accordance with an embodiment of the present invention, the second
plurality of splits (112) of the outer ring (108) are formed by, but not limited to,
etching.
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At step 206, a gap between the inner ring (106) and the outer ring (108)
is provided.
At step 208, the inner ring (106) and the outer ring (108) are placed on
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the top portion of the substrate (102).
At step 210, the pair of feed-lines (104) is provided.
In accordance with an embodiment of the present invention, the step
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210 further comprises a step of embedding the single spurline configuration on
the pair of feed-lines (104). Further, the single spurline configuration is
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embedded by the L-shape slot into the pair of feed-lines (104).
In accordance with an embodiment of the present invention, the step
210 further comprises a step of embedding the double spurline configuration on
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the pair of feed-lines (104). Further, the double spurline configuration is
embedded by the L-shape slot into the pair of feed-lines (104).
At step 212, the coupling gap (114) is allowed between the pair of
feed-lines (104) and the inner ring (106) and the outer ring (108). The coupling
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gap (114) between the rings (106), (108) and the pair of feed-lines (104)
produce large capacitance values which lower resonance frequency.
Figure 6 illustrates a system (300) for detecting properties of the
material in accordance with an embodiment of the present invention.
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In accordance with an embodiment of the present invention, the system
(300) as shown in figure 6, comprises a material under test (MUT) (302), a
vector network analyzer (VNA) (306) and the device (100). Further, the vector
network analyzer (VNA) (306) has a power source (304).
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In accordance with an embodiment of the present invention, the
resonance is produced when mean circumference of the ring resonator is equal
to an integral of guided wavelength
2πr = nλg
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Where n= 1, 2, 3, 4… and so on.
Resonant frequency can be calculated for n modes by using
(1)
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𝜆𝑔 =
𝜆
(2)
√ɛeff
Where;
𝜆=
𝑐
𝑓
So, by considering equations (1) and (2), the resonant frequency is
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found as:
𝑛𝑐
𝑓0 = 2𝜋𝑟
(3)
√ɛeff
Where; r: main radius of the ring element
λg: the guided wave length
n: the mode number, 1, 2, 3, ...
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fo: the resonant frequency
ɛeff: the effective of dielectric constant
C: the speed of the light (3 x 10^8)
For 50 Ω characteristic impedance Zo, w/d ratio can be found using this
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formula:
8e𝐴
𝑤
= e2𝐴−2
𝑑
(4)
Where:
Z
ɛr+1 ɛr−1
𝐴 = 600 √
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ɛeff =
2
+ɛr+1 (0.23 +
ɛr+1
2
+
ɛr−1
2
0.11
ɛr
)
1
𝑑
𝑤
(5)
(6)
√1+12( )
For the main radius, it can be calculated using this formula:
𝑟=
𝑛𝜆𝑔
2𝜋
(7)
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For the spurline bandpass filter, the desired rejected wavelength can be
calculated using the follow equation.
𝑎=
5
𝜆𝑔
(8)
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Where a= length of the spurline, and λg = desired rejected wavelength
in the substrate.
Equation (8) can be derived into the frequency domain as follows:
𝑓𝑠𝑡𝑜𝑝 = 4𝑎
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𝑐
√ɛeff
(9)
In accordance with an embodiment of the present invention, the
material under test (MUT) (302) is configured to be placed on the device (100)
for detection of properties as illustrated in figure 7 below.
As shown in figure 7, the substrate (102) is cladded with an electrically
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conductive material (122) on the top portion and ground (124) at a bottom end.
The substrate (102) is also cladded with the electrically conductive material
(122) at the bottom end. The electrically conductive material (122) is, but not
limited to, copper and the substrate (102) material is, but not limited to, Rogers
material. The material under test (MUT) (302) is placed on a top portion of the
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device (100) in maximum electric field region. The electric field and magnetic
field is demonstrated in figure 7 as (E) and (H), respectively. The magnetic field
(H) penetrates the inner ring (106) and the outer ring (108) which induces
current in both the rings (106), (108) to enhance incident field (E) and it
depends on resonant properties of symmetrical split-ring resonator (SSRR). As
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shown in figure 7, the inner ring (106) and the outer ring (108) included with the
pair of feed-lines (104) are patched on the top portion of the substrate (102)
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where the bottom end of the substrate (102) is electrically conductive, such as
but not limited to, copper. Further, the material under test (302) is having a
thickness in the range of, but not limited to, 0.787 mm to 7.78 mm. Also, the
device (100) is excited to generate the electric field (E) and the magnetic field
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(H). The device (100) is excited using, but not limited to, the microstrip
feed-lines and coaxial probes.
In accordance with an embodiment of the present invention, the device
(100) is connected to the vector network analyzer (VNA) (306) having the
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power source (304), as shown in figure 6. The vector network analyzer (VNA)
(306) supplies the power source (304) and monitors the results. The pair of
feed-lines (104) of the device (100) is configured to have a plurality of ports
(116) at end of each feed-line with, but not limited to, SMA (SubMiniature
version A) connectors. These plurality of ports (116) are connected to the vector
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network analyzer (VNA) (306) using coaxial cables (118).
In accordance with an embodiment of the present invention, the system
(300) further comprises a computing device (120). The device (100) detects
reflection coefficient and transmission coefficient of the material under test
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(MUT) (302) and also detects the reflection coefficient and transmission
coefficient when no overlay material under test (MUT) (302) is placed on the
device (100). The device (100) is operated at, but not limited to, microwave
frequencies such as, but not limited to, 2.2 GHz frequency. Further, recorded
results are analyzed by using the computing device (120) for characterizing and
25
detecting the properties of the materials.
23
Figure 8 is a graph showing the difference between simulated and
measured transmission coefficients (S21 in dB) in accordance with an
embodiment of the present invention. As shown in figure 8, the results
demonstrate some small deviations between the simulated and measured
5
transmission coefficients.
Figure 9 is a graph showing variability of resonance frequency and
relative shift of the symmetrical split ring resonator (SSRR) as a function of real
permittivity (ɛr) of the material under test (302) (MUT) in accordance with an
10
embodiment of the present invention. As shown in figure 9, the change in the
resonance frequency is dependent on interaction between the material under
test (302) (MUT) and the electric field of the device (100) (sensor) which causes
a reduction in the resonant frequency as well as reduction in Q-factor. The
resonant frequency is decreased when the value of the material under test
15
(302) (MUT) permittivity is increased. Further, the relative shift is around 0.21
for permittivity with ɛr = 10 which is required to achieve high sensitivity with
capability of detecting various materials at narrow band of frequencies.
Figure 10 is a graph showing variability of the transmission coefficients
20
(S21 in dB) and the quality factor of the symmetrical slit ring resonator (SSRR)
as a function of loss tangent (tanδ) in accordance with an embodiment of the
present invention. Figure 10 demonstrates the quality factor corresponding to
the change in loss tangent of the material under test (302) (MUT) (from 0 to 0.1)
by considering the real permittivity to ɛr = 2. The transmission coefficient S21
25
(dB) was also plotted in the same figure. It was noted that the quality factor is
dependent on the tangential loss of the material under test (302) (MUT) which
24
basically means that an increase in value of the tangent loss would lead to
decrease in the quality factor. However, the transmission coefficients would be
increased as well as the tangent loss was increased.
5
Figure 11 is a graph showing variability of thickness of tested samples
and the resonant frequency of the symmetrical split ring resonator (SSRR) as a
function of the real permittivity (ɛr) of the material under test (MUT) (302) in
accordance with an embodiment of the present invention. Further, the figure 11
illustrates the real permittivity (ɛr) of the material under test (MUT) (302)
10
corresponding to the resonant frequency which is extracted from the simulated
transmission coefficient data. It was observed that the slope of the plotted curve
is dependent on the thickness of the material under test (MUT) (302). However,
the slope of the curve remained constant when the sample thickness is greater
than, and not limited to 5 mm. The shift in the resonance frequency is increased
15
when increasing the thickness of the overlay material under test (MUT). The
reason behind this was that the overlay material under test (MUT) size
increased, the field perturbation was also increased due to the more fringing
fields which were getting concentrated into overlay material under test (MUT).
As a result of increasing fringing field capacitance, the resonance frequency
20
was decreased. Even though there was a shift in the resonance frequency,
which was significant within a certain thickness, but was limited to lower range
only, its effect was not important. Therefore, further increase in sample
thickness would not affect the resonance frequency. This is due to the fact that
all of the electric field was confined into the overlay sample and substrate which
25
interprets the effective permittivity was increased with the height of the overlay
until it reached asymptotic value.
25
Figure 12 is a graph showing standard material under test (MUT) with
known permittivity to validate the device (100) sensitivity in accordance with an
embodiment
of
the
present
invention.
For
experimental
validation,
measurements were made for standard materials under test (MUT) with known
5
permittivity (εr) to estimate their potential of dielectric detecting and sensing.
These materials were Air, Roger Duriod RT 5880, Roger RO4350B, and FR4
and they were placed on the maximum electric field area of the device (sensor)
(100). The electric field interacts with the dielectric materials under test (MUT)
and energy was coupled into these materials which caused shifting in the
10
resonant frequency. For the conducted experiment, the resonance frequency
was shifted to lower frequency as indicated in figure 12. It is clearly shown in
figure 12 that the resonant frequency was changed for each material under test
(MUT) with known dielectric constant. Thus, the materials with unknown
permittivity can be extracted. For each tested material, the resonant frequency
15
was slightly shifted to lower frequency which depends on the permittivity of
material under test (MUT). This makes the device (sensor) (100) detect and
characterize materials with small variations of materials permittivity.
Figure 13 is a graph showing differences between reference materials
20
with standard permittivity with the measured result using symmetrical split ring
resonator (SSRR) in accordance with an embodiment of the present invention.
As shown in figure 13, measurement of the resonant frequency was fitted
corresponding to the permittivity of material under test (MUT) for obtaining the
numerical model, as indicated in figure 13. It was demonstrated that the
25
measured permittivity of the standard materials using the SSRR sensor was in
a very good agreement to the reference or standards permittivity of the same
26
materials. This indicates that the SSRR sensor has high sensitivity and
accuracy which can detect and characterize a small variation of the materials
properties.
5
The above-mentioned device, method and system for detecting
properties of the material overcomes the problems and shortcomings of the
existing methods for detecting and characterizing materials and provides a
number of advantages over them. The device for detecting properties of the
material is suitable for use in industrial applications due to many advantages
10
such as, but not limited to, high sensitivity, easy to fabricate, inexpensive to
build, and compact size. The device and system are useful in applications such
as, but not limited to, food industry, agriculture, food processing, dairy products,
fruits and vegetables, geo-science, bio-engineering, quality control, bio-sensing,
medicine and pharmacy and especially for applications that require
15
non-destructiveness. The device includes metamaterials that have electric or
magnetic properties which are not found in natural materials. The
metamaterials include symmetrical split ring resonator (SSRR), symmetrical
split ring resonators with spurlines (SSRR), or variety of other electrically-small
resonators made of conducting wires or conducting flat surfaces. The device
20
with single spurline configuration provides excellent band stop and band pass
characteristics and moderate rejection bandwidth with its compact size. Further,
the device with single spurline configuration suppresses harmonic resonant and
undesired rejected wavelength. Also, the device with double spurline
configuration suppresses the harmonic resonant and undesired rejected
25
wavelength with a wider rejection bandwidth with higher performance. In
addition, the device uses the concept of reflected and transmitted coefficients
27
for detecting and characterizing the properties of, but not limited to, materials,
moisture and composition materials.
The exemplary implementation described above is illustrated with
5
specific shapes, dimensions, and other characteristics, but the scope of the
invention includes various other shapes, dimensions, and characteristics. Also,
the device, method and system for detecting properties of the material as
described above could be fabricated in various other ways and could include
various other materials, including various other metals, substrates etc.
10
Similarly, the exemplary implementations described above include
specific examples of metals, substrates etc., but a wide variety of other such
steps of fabrication could be used within the scope of the invention, including
additional steps, omission of some steps, or performing process in a different
15
order.
Various modifications to these embodiments are apparent to those
skilled in the art from the description and the accompanying drawings. The
principles associated with the various embodiments described herein may be
20
applied to other embodiments. Therefore, the description is not intended to be
limited to the embodiments shown along with the accompanying drawings but is
to be providing broadest scope of consistent with the principles and the novel
and inventive features disclosed or suggested herein. Accordingly, the invention
is anticipated to hold on to all other such alternatives, modifications, and
25
variations that fall within the scope of the present invention and appended
claim.