DESIGN AND IMPLEMENTATION OF MICROSTRIP SLOT ANTENNA FOR MEDICAL APPLICATIONS

Abstract

The titled invention "design and implementation of microstrip slot antenna for medical applications" involves optimizing their geometry, materials, and operating parameters to ensure efficient wireless communication in biomedical devices. This invention 10 typically includes a substrate (1), a ground plane (2), a slot (3), a feed line (4), a matching network (5), a radiating element (6), a shielding (7), a filter (8). This invention is used in medical applications such as wireless sensors, implantable devices, and medical imaging.to enable data transmission and communication.

Specification

FIELD OF INVENTION
5 The present invention is related to biomedical engineering domain. Particularly, the
present invention is relates to is to improve the radiation characteristics and bandwidth
of a microstrip patch antenna for various implantable medical applications. More
particularly, the present invention is relates to design and implementation of microstrip
slot antenna for medical applications. This invention offer advantages such as
10 compact size, low profile, ease of integration, and compatibility with various medical
devices, making them ideal for applications like wireless sensors, implantable,
imaging, and remote monitoring. This invention is used in various medical applications,
including wireless sensors, implantable devices, medical imaging, and remote patient
monitoring.
Prior Art:
This invention relates to design and implementation of microstrip slot antenna for
medical applications. Microstrip patch antennas (MPAs) are a popular choice in
modern wireless communication due to their compact size, low profile, and ease of
fabrication. The fundamental design involves a metallic patch on a grounded dielectric
substrate. Various designs and optimizations have beeh explored to enhance their
performance, particularly at the 2.4 GHz frequency, which is widely used in
applications such as Wi-Fi, Bluetooth, and other wireless communication systems.
The choice of substrate material significantly impacts the performance of MPAs.
Substrates with low dielectric constants are preferred for higher efficiency and broader
bandwidth. Common materials include: FR4 which is widely used and low-cost
material with a moderate dielectric constant.
One of prior art CN117117480A, titled "Miniaturized dual-band circularly polarized
antenna". The invention offers a compact dual-band circularly polarized antenna
comprising a dielectric substrate with a covering layer on top. The radiating surface is
printed on the top of the substrate, while the ground plane is on the bottom. These are connected via a short circuit probe and a coaxial feed point center probe. The radiating
surface features cross and L-shaped rectangular groove groups for central symmetry,
while the ground plane has a T -shaped rectangular groove group. This design benefits
from a simple structure, small size, low profile, low coupling, circular polarization, and
5 dual-band capabilities.
Another prior art CN107978849B, titled "Microstrip antenna structure and microwave
imaging system applying same". The invention proposes a -microstrip antenna
structure and a microwave imaging system that employs it. The antenna comprises a
10 substrate with a ring-shaped microstrip structure on one side and a signal transmission
port on the other. The ring-shaped structure generates a radiation frequency band,
while the port connects to it through the substrate. The antenna's electric field pattern
exhibits minimal variation between vertical planes, ensuring consistent signal·
reception in three-dimensional space. This leads to improved image restoration quality
15 and enhanced detection accuracy, addressing the issue of uneven signal reception in
conventional systems.
Another prior art RU2703604C 1, titled "Transient device comprising a contactless
transition or connection between siw ;md a waveguide or antenna". The invention
20 relates to a radio engineering device for transitions between substrate integrated
waveguide (SIW) and waveguide or antenna structures. It consists of two conductive
plates with an SIW on the first and an impedance matching structure on the second.
To switch between SIW and waveguide, an open protrusion with a length of }.g/4 is
added to the impedance matching structure for impedance inversion. This creates an
25 unclosed connection, allowing electromagnetic coupling between the SIW and the
matching structure. When the conductive plates are connected or assembled
contactless, the open protrusion is positioned above the SIW without galvanic contact,
enabling a flat, non-contact transfer.
30 Another prior art US20240175678A 1, titled "Method and Apparatus for Cooperative
Usage of Multiple Distance Meters". A method and apparatus for an angle meter
employs two or more non-contact distance meters to measure distances to a surface
along parallel lines. Measured distances are used to estimate or calculate the angle
> to the surface and the distance to it. Distance meters can use optical, acoustical, or electromagnetic means, with TOF, homodyne, or heterodyne phase detection
schemes for distance estimation. They may share components like correlators, signal
conditioning circuits, or sensors. Multiple angle meters can be used for measuring
angles between surfaces and estimating physical dimensions like length, area, or
5 volume.
.
Another prior art US 1139412982, "Multiple band antenna structures". Various antenna
designs, such as slot and patch, slot and inverted "F" (IFA), hybrid slot, external slot,
split ring, arid dielectrically loaded planar inverted "F" (PI FA), can be incorporated into
10 wearable electronic devices to support wireless communication across multiple
frequency bands. These designs offer compact and efficient solutions for providing
connectivity in a variety of applications.
Microstrip slot antennas, while offering several advantages, also have certain
15 drawbacks. One significant limitation is their potential for cross-polarization, which can
reduce antenna efficiency and introduce interference. Additionally, their bandwidth can
be relatively narrow, limiting their ability to operate across a wide range of frequencies.
Another drawback is their susceptibility to surface wave propagation, which can cause
energy leakage and reduce antenna gain. Finally, the design and fabrication of
20 microstrip slot antennas can be challenging, especially for complex geometries or
high-frequency applications.
Therefore, the present invention overcomes the drawbacks of the prior art by providing
a design and implementation of microstrip slot antenna for medical applications.
25 OBJECTIVE OF THE INVENTION
1. The principal object of this invention is fa design and implementation of
microstrip slot antenna for medical applications.
2. Another object of this invention is Identify and utilize substrates with low
dielectric constants and low loss tangents to minimize dielectric losses and
enhance radiation efficiency.
3. Yet another object of this invention is to explore and implement various patch
geometries, including fractal and custom shapes, to optimize antenna
performance and potentially achieve multi-band capabilities.4. Another object of this invention is to employ advanced simulation tools to model
antenna behaviour, optimize key parameters,.and predict performance metrics.
5. Another object of this invention is to fabricate prototypes using precise PCB
manufacturing techniques to ensure accuracy and high-fidelity performance.
5 6. Another object of this invention is to test prototypes using network analy~ers
and anechoic chambers to measure gain, return loss, radiation pattern, and
efficiency.
7. Another object of this invention is to continuously refining the design based on
test results to achieve the desired performance goals and address any
10 shortcomings.
8. Another object of this invention is to contribute to the advancement of medical
technology by providing high-performance, compact antennas for various
biomedical applications.
15 BRIEF SUMMARY OF THE INVENTION
This invention aims to enhance the radiation characteristics and bandwidth of a
microstrip patch antenna (MPSA) for implantable medical applications by
incorporating a slot within its structure. The MPSA utilizes an FR-4 substrate with a
20 dielectric constant of 4.4, measuring 36 mm by 50 mm by 2 ·mm. The patch
dimensions, 28 mm by 36 mm, determine the antenna's physical geometry and
operating frequency of 2.4 GHz. These specifications are crucial for ensuring optimal
performance in the targeted medical applications. The goal of the proposed work is to
improve the radiation characteristics and bandwidth of a microstrip patch antenna for
25 various implantable medical applications. This will be accomplished by inserting a slot
into the antenna structure
BRIEF DESCRIPTION OF THE RELATED ART
30 The embodiment of the present invention is illustrated with the help of accompanying
drawings.
Figure.1: show the Work Flow of the proposed MPSA.
Figure.2: illustrate the basic structure of MPSA
Figure.3: show the Front view of Stimulated MPSA.
Figure 4: illustrate the Bottom view of Stimulated MPSA.
Figure 5: Show the Front view of the Fabricated MPSA
Figure.6: illustrate the Bottom view of the Fabricated MPSA.
5 Figure.7. show the comparison of experimental and simulated MPSA Return Loss
Figure.8. illustrate the gain of the MPSA
Figure. 9: show the comparison of experimental and simulated MPSA VSWR
This invention focuses on optimizing the patch shape of a microstrip patch antenna
10 (MPA) to improve its performance. Traditional rectangular and circular patches are
evaluated, with rectangular patches offering simplicity and circular patches providing
better symmetry and potentially wider bandwidth. Electromagnetic simulation tools like
HFSS are used to model the antenna's behaviour and optimize parameters such as
substrate type, patch shape, and dimensions. The invention systematically explores
15 various patch shapes and substrate combinations to achieve maximum gain and
efficiency at 2.4 GHz. Prototypes are fabricated and tested to validate the simulated
performance. A key advantage of this approach is the use of low dielectric constant
and low loss tangent substrates like FR-4, which help minimize losses and enhance
radiation efficiency compared to traditional MPAs.
20 The main components of design and implementation of microstrip slot antenna for
medical applications, typically include:
1. Substrate
2. Ground Plane
3 . Slot
4. Feed Line
5. Matching Network
6. Radiating Elements
7. Shielding
8 . Filters
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWING
1. Substrate:
This is a dielectric material that supports the antenna elements. Common
substrates for medical applications include FR-4, Rogers RT/Duroid, and
Teflon.
10 2. Ground Plane:
15
20
25
A conductive layer beneath the substrate that provides a return path for the
antenna's current.
3. Slot:
A rectangular or circular aperture cut into the ground plane that serves as the
radiating element of the antenna.
4. Feed Line:
A transmission line that connects the antenna to the source of RF power. This
can be a microstrip line, coplanar waveguide, or other suitable transmission
line.
5. Matching Network:
A circuit that is used to match the impedance of the antenna to the impedance·
of the feed line, ensuring efficient power transfer.
6. Radiating Elements:
In some cases,·additional radiating elements may be added to the antenna to
improve its performance, such as parasitic elements or slot extensions.
7. Shielding:
A conductive enclosure that can be used to protect the antenna from
interference and to reduce electromagnetic emissions.
B. Filters:
Filters may be used to select specific frequency bands or to reject unwanted
signals.
5 Generally, this invention involve selecting suitable substrates, optimizing slot
dimensions and feed points, ensuring impedance matching, and incorporating
additional elements like radiating elements, shielding, or filters as needed. These
antennas are typically designed to operate at specific frequencies and provide efficient
radiation characteristics for wireless communication in biomedical devices.
10
15
DETAILED DESCRIPTION OF THE INVENTION:
The substrate (1) serves as the foundation for the microstrip slot antenna, supporting
the ground plane (2), slot (3), and feed line (4). Its electrical properties, such as
dielectric constant and loss tangent, significantly influence the antenna's performance.
A common substrate material is FR-4, known for its low cost and availability. The
ground plane .(2) serves as a conductive layer beneath the substrate (1), providing a
reference potential for the antenna and allowing for the flow of current and
electromagnetic fields. It is typically connected to the ground of the system and is often
20 made of copper due to its high conductivity.
The slot (3), a crucial component of the microstrip antenna, is the primary radiating
element where electromagnetic energy is transformed into radio waves. Its dimensions
and shape, such as rectangular, circular, or elliptical, significantly influence the
25 antenna's operating frequency, radiation pattern, and overall efficiency. The feed line·
(4), connects the antenna to the source of RF power, delivering the signal to the
radiating element. Typically fabricated on the same substrate as the antenna, the feed
line is often a microstrip line, a transmission line consisting of a narrow strip of
conductor separated from the ground plane by a dielectric layer.
The matching network (5) optimizes power transfer between the feed line and the
antenna by transforming their impedances to match. It typically consists of a series or
parallel combination of inductors and capacitors. A common matching network is the quarter-wave transformer, which is ideal for matching high-impedance antennas to
low-impedance feed lines.
The radiating element (6) is an optional component that can be added to the microstrip
slot antenna to improve its performance. By modifying the radiation pattern or
5 increasing the gain, the radiating element can enhance the antenna's efficiency and
coverage. Parasitic elements, like stubs or patches, are common examples of
radiating elements that can be placed on the slot or ground plane to achieve desired
effects such as broader bandwidth or specific radiation patterns.
10 Shielding (7) is to provide protection from external interference and reducing
electromagnetic emissions. It typically consists of a conductive enclosure that
surrounds the antenna, isolating it from external electromagnetic fields and ensuring
reliable operation in noisy environments. A metal can or box is commonly used as a
shielding material.
15
The. filter (8), placed between the feed line and the antenna, is used to select specific
frequency bands or reject unwanted signals, thereby enhancing the antenna's
selectivity and reducing interference. Examples of filters include cavity filters and
surface-mount filters, which can be employed to select specific frequency bands for
20 medical applications.
METHOD OF PERFORMING THE INVENTION
The antenna must be connected to a su!table power source, such as a battery or
25 external power supply, ensuring that the voltage and current levels are appropriate for
its operation. The desired RF signal is generated using a signal generator or
microcontroller. This signal serves as the carrier wave for transmitting medical data. If
necessary, the RF signal is modulated with medical data, such as patient vital signs
or sensor readings. This process encodes the medical information onto the carrier
30 wave for transmission.
The modulated RF signal is connected to the feed line (4) of the microstrip slot
antenna, ensuring proper impedance matching to optimize power transfer and
minimize signal reflection. The antenna radiates the RF signal into the surrounding
environment, allowing it to be received by a nearby receiver. The transmitted signal is received by a receiver, such as a medical device or a base station. The receiver
captures the RF signal and decodes the embedded medical data.
The medical data is extracted from the received signal using appropriate demodulation
techniques, which reverse the modulation process to recover the original information.
5 The extracted medi.cal data is processed and analysed to obtain meaningful
information, such as patient vital signs or diagnostic results. This information can be
used for medical decision-making. and treatment.
If required, feedback or control signals can be sent back to the medical device or
system using the same antenna or a separate communication channel. This allows for
10 remote monitoring and control of medical devices. Efficient power management
techniques are implemented to optimize battery life and ensure reliable operation of
the antenna and associated circuitry. This is particularly important for implantable
medical devices where power consumption is a critical factor.
ADVANTAGES:
}> Their low profile and small footprint make them ideal for integration into
wearable devices and implantable medical devices.
}> They can be easily fabricated using standard printed circuit board (PCB)
· manufacturing techniques, reducing production costs.
}> Microstrip slot antennas can be designed to operate at various frequencies and
with different radiation patterns, making them suitable for a wide range of
medical applications.
}> They exhibit good radiation efficiency, ensuring reliable wireless
communication and data transfer.
}> Compared to other antenna technologies, microstrip slot antennas are
generally more cost-effective to produce and integrate into medical devices.
}> They are known for their reliability and robustness, making them suitable for
long-term use in medical environments.
Claim(s):
1. A system for a design and implementation of microstrip slot antenna for
medical applications, comprising:
a substrate (1) to supports the antenna elements;
a ground plane (2) to provide a return path for the antenna's current;
a slot (3) to serve as the radiating element of the antenna;
a feed line (4) to connect the antenna to the source of rf power;
a matching network (5) to match the impedance of the antenna to the
impedance of the feed line, ensuring efficient power transfer;
a radiating element (6) to improve its performance, such as parasitic
elements or slot extensions;
a shielding (7) to protect the antenna from interference and to reduce
electromagnetic emissions;
a filter (8) to to select specific frequency bands or to reject unwanted
signals.
2. The method of claim 1, wherein the substrate is selected from the group
consisting of FR-4, Rogers RT/Duroid, and Teflon.
3. The method of claim 1, wherein the feed line {4) is a microstrip line, coplanar
waveguide, or other suitable transmission line.
4. The method of claim 1, wherein the matching network (5) is used to match the
impedance of the antenna to the impedance of the feed line.
5. The method of claim 1, wherein the at least one radiating element (6) is selected
from the group consisting of parasitic elements and slot extensions.
6. The method of claim 1, wherein the shielding (7) is a conductive enclosure.
7. A method of designing a microstrip slot antenna for medical applications
comprising the steps of:
a. selecting sad substrate (1 );
b. designing a slot in said ground plane (2);
c. designing said feed line (3);
d. designing said matching network (5);
e. optionally adding said radiating elements (6) , said shielding (7), and said
filters (8);
f. fabricating the microstrip slot antenna; and
g. testing the m. icrostrip slot antenna.
8. A method for operating a microstrip slot antenna for medical applications
15 comprising the steps of:
a. providing an rf signal to the said feed line (4) of the microstrip slot
antenna;
b. transmitting the rf signal from ttie microstrip slot antenna; and
c. receiving a response signal from a medical device.

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