Design of Antenna for Real Time Breath Detection
Jemi Anugraha #1, Maria Sharon Sanjana *2
KCG College of Technology, Department o f Electronics and Communication, Karapakkam
Ms. B Thyla assistant professor (Sel. Grade)
ABSTRACT This paper presents 2 wearable models based on ISM antenna for real tim e breath detection.
It demonstrates a novel design of a compact fiber antenna which has been developed for medical
applications. The proposed antenna covers a frequency range from 2.4 GHz – 2.
5 GHz. A new generation
of wearable antenna is presented, and its potential use as a contactless and non -invasive sensor for human
breath detection is demonstrated. The antenna is made from multimaterial ?ber designed for short -range
wireless network applications at 2.4 GHz frequency. It this project various antenna shapes are analyzed
in using HFSS software/environment based on the return loss, gain & radiation pattern. The spiral
shaped fiber antenna is chosen as the optimum design on promising comfort or restricting movement of
the user due to their high ?exibility, and ef?ciently shield the antenna from the environmental
perturbation. Breathing rate (BR) is a vital sig n used to monitor the progres sion of illness and an
abnormal BR is an important indicator of serious illnes s.
Variation in BR can be used to predict potentially serious clinical events such as heart attack.
Keywords ISM (Industrial Scientific Medical) band, HFSS (High Frequency Struc ture Simulator) , wearable
antenna, BR (Breathing rate), Multimaterial fibre.
With t he exponential development of wireless communication technologies, researchers are now focusing on the study of
Wireless Body Area Network (WBAN), which allow the communication between wearable devices (on -body communications),
between body -worn devices a nd surrounding devices (o? body communications), and ?nally between implanted devices and
devices mounted on human body surface (in -body communications) .
Breathing (or respiration) is an important physiological task in living organisms. Breathing rate (B R) is a vital sign used to
monitor the progression of illness and an abnormal BR is an important indicator of serious illness. Variation in BR can be us ed
to predict potentially serious clinical events such as heart attack. For example, using changes in BR measurements, patients
could have been identi?ed as high risk up to 24 h before the event with 95.5% con?dence. BR monitoring devices are separated
into two categories: contact and non -contact sensors. In contact BR monitoring sensor, a direct physical contact with the body is
needed. Howe ver, in non -contact monitoring sensor, the BR is measured without making contact with the subjects body. The
most popular contact -based approach to derive the BR is from the ECG signal.
Several antenna designs have been proposed for medical applications i n the industrial, scienti?c and medical (ISM) and Ultra
High Frequency (UHF) bands fabricated a modi?ed inverted -F antenna inkjet printer directly on the fabric using silver
nanoparticle ink with a frequency radiating at 2.45 GHz. With the rapid progress o n the fabrication of conductive textile, silver
yarn was used to create a spiral antenna for a system that senses heart rate, fall detection and measures ambient temperature .
II. PROPOSED METHOD
A spiral ?ber antenna was integrated into a ?tted T -shirt at the mid -chest position, allowing the chest expansion to slightly
stretch the antenna. The operating frequency shift was continuously measured using a VNA connected to the antenna through an
Connector by mean of a coaxial cable, with this con?guration, performed a series of measurements to detect breathing of a
volunteer asked to take four breaths, followed by one minute of relaxed, shallow breathing, and four more deep breaths. A
frequency sh ift of 120 MHz was detected for deep breathing, while relaxing, shallow breathing led to smaller 4 15 MHz
frequency shifts. These measurements validate the proposed respiration sensor based on multimaterial ?ber in spiral shape
arrangement integrated into a standard T -shirt for breath detection. Although these measurements seem to be very promising,
the users comfort which is an important factor as discussed in the introduction needs to be addressed. Received signal stren gth
based breathing monitoring is e merging as an alternative non -contact technology. A wireless systems operating at a 2.4 -GHz
frequency to estimate the respiration rate has been presented recently, and showed limitation in term of detection accuracy a nd
heavy mathematical treatments.
III. Design using HFSS
Two fibre antenna have been designed using HFSS and their parameters have been studied.
Table 1: Model specifications
Model Dimension Operating
Gain Return l oss
Half wave dipole
Length=61mm 2.45GHz 3.34dBi -32.5dB
Spiral Length=10cm 2.45GHz 3.34dBi -27.5dB
Half wave Dipole shape antenna
Materials involved – Polyamide, polystyrene, silver
Feed at the centre
Gain Ranges from -25dB to 5dB
Return loss at 2.45GHz = 0.00001dB
Fig 1: Dipole shaped antenna
Fig 2: A closer look at the dipole antenna
Gain of the antenna is to direct the input radiation in a particular direction producing the output of the radiated
antenna. The gain of the antenna is shown in figure 3.
Fig 3: Gain of the dipole antenna
Generally the gain value should be positive, i.e.>0dB. Here, the gain value is taken with respect to the theta value.
Outer radius of
Inner radius of 100
B. RADIATION PATTERN
Radiation pattern of the antenna is defined as a graphical representation of the radiation properties of the antenna
as a function of space coordinates which is shown in figure 4.
Fig 4: Radiation Patte rn
The parameter VSWR is a measure that numerically describes how well the antenna is impedance matched to the
radio or transmission line it is connected to. VSWR stands for Vo ltage Standing Wave Ratio.
Fig 5: The VSWR of the dipole antenna
Model 2 (Chosen model)
Half turn Archimedean spiral shape antenna
Materials involved – Polyamide, polystyrene, silver
Gain Ranges from 5 dB to -12.5 dB
Return loss at 2.45GHz = 0. 000 dB
Fig 6: S Shaped antenna
This fibre antenna is designed with the inner silver coating having the thickness of 150±30 nm. The measured electrical dc
resistivity of 3.8 ± 1 ?/cm for the inner silver conductor along with the geometry of the structure of the antenna provides a good
electrical matching to the standard 50 ? impedance of the RF components, while the external polyim ide coating provides long –
term protection against the heat/humidity in the environment. Using the conductive multimaterial ?ber, the simplest designed
antenna for 2.4 GHz operating frequency: a half -turn Archimedean spiral shape. Half -turn Archimedean spiral is a special case
of the dipole antenna with ?/2 at 2.4 GHz equals to 10 cm fabricated using two 50 mm long ?ber. As it is known from the
antenna theory, operating frequency of the dipole and loop antennas can be adjusted for p articular applications simply by
varying their length.
Fig 7: Gain of the S Shaped antenna in terms of Theta
B. RADIATION PATTERN
Fig 8: Radiation pattern of S Shaped antenna
Fig 9: VSW R of S Shaped antenna
A new generation of wearable antennas for healthcare monitoring was designed by integrating polymer -glass -metal
?ber composites into a well de?ned geometry. The mechanical properties of the ?ber enable an easy integr ation of the antenna
into textile using the classical weaving methods, thus leading to a development of new wireless communication platform. The
RF emissive performance of the textile -integrated ?ber loop, dipole and spiral antennas were characterized in t erms of return
loss, radiation pattern and gain, and found to be comparable to the commercial wireless router antennas, and suitable for sho rt
range wireless networks in the ISM band at 2.4 GHz.
The goal of this work was to demonstrate the capability of th e newly developed sensor to detect in real time the breathing
patterns of a human and communicate the data via a Bluetooth protocol at 2.4 GHz to a base station. For medical applications,
such as in situ diagnose of respiratory illnesses and monitor people suffering from asthma, or chronic obstructive pulmonary
disease, it is important to validate our system. This could be done by a head -to-head comparison with gold standard equipment
such as a spirometer or a pneumotograph, which is the subject of our futu re work.
I sincerely express my gratitude to all the authors who have published papers on medical application of antennas, I wold also
like to extend my thanks to all the professors for motivating us to carry out this project.
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