© 2019 JETIR March 2019, Volume 6, Issue 3 www.jetir.

org (ISSN-2349-5162)

ANALYSIS OF ELECTROMAGNETIC
INTERFERENCE IN PRESSURE SENSOR USING
MICROSTRIP LOW PASS FILTER
Prof. Dola Sanjay S.1, Dr B S Sathish1, B. Madhu Sri2, P.Bangaraya2, D.B.S.Naveen2,
Ch.Bala Chandra2
1: Professor, Dept of ECE, Ramachandra College of Engineering Eluru, Andhra Pradesh
2: UG Scholars, Dept of ECE, Ramachandra College of Engineering Eluru, Andhra Pradesh
________________________________________________________________________________________________________

Abstract: In recent days the importance of “Vehicle Electronics” and the challenges in this area has been a subject of interest in
the core area of safety. The Tyre Pressure Monitoring System (TPMS) is used to monitor the level of pressure in the tyres of the
vehicles. The target of Tyre Pressure Monitoring System is to avoid accidents and increase tyre wear due to low tyre pressure,
through early recognition of hazardous state of tyres. The tyre pressure monitoring system reports real time tyre pressure
information to the driver via a simple low pressure warning light. The Brake Calliper, Control arm, large metal in the vehicle acts
as a source of Electromagnetic Interference .The Electromagnetic field produced around the large metal, brake calliper, control
arm interferes with the signal from the pressure sensor in Tyre Pressure Monitoring System. Resulting in false alarm to the dash
board. In order to protect from the electromagnetic signal which is interfering with the signal from pressure sensor a Microstrip
Low Pass Filter is designed using HFSS.

Keywords: Microstrip Low Pass Filter, ANSYS HFSS, Electromagnetic Interference, Pressure Sensor, Tyre Pressure Monitoring
System, EMI.
_______________________________________________________________________________________________________

I. Introduction
This paper investigates the Analysis of Electromagnetic Interference in Pressure sensor using Microstrip Low Pass Filter. Filter
represent a class of electronic filter designed to operate on signals in the medium frequency to extremely high frequency. The
frequency range is the range used by most wireless communication. Low Pass Filter allow frequencies below cut-off frequency.
Therefore the Microstrip Low Pass Filter removes the Electromagnetic Signal from the signal from pressure sensor. A Tyre
Pressure Monitoring System is an electronic system designed to monitor the air pressure inside the tyres on various types of
vehicles. TPMS report real time pressure information to driver via a simple low pressure warning light. The Brake Calliper, control
arm and large metal act as a source of electromagnetic field interferes with signal from pressure sensor. Electromagnetic
interference is an unwanted or undesired signal that influences the normal operation of the system, leading to the malfunction of the
system. It is also known as Radio frequency interference. It is a phenomenon where one electromagnetic field interferes with
another resulting in the distortion of both fields. This interference can be reduced by using Microstrip Low Pass Filter. Microstrip is
a type of electrical transmission line which can be fabricated using printed circuit board technology and is used to convey
microwave frequency signals. It consists of a conducting strip separated from a ground plane by a dielectric layer known as
substrate. A Microstrip filter represents a class of electronic filter designed to operate on signals in the megahertz to gigahertz
frequency ranges. This range is used by most wireless communication and thus most RF and microwave devices will include some
kind of filtering on the signals transmitted or received.

II. Existed System

As far back as 1970,the U.S.National Highway Traffic Safety administration looked into the benefits of low tyre pressure
warning equipment. In the 1970s,an Indian State University suggested that the Under-inflated tyres were the cause of 1.5% of all
motor vehicles crashes, because tires low on pressure hamper handling and braking on dry and wet roads. But the early 1980s,tyre
pressure sensor technology had advanced somewhat, but equipment was still not reliable or accurate enough for prime time. The
U.S. congress passed the Tire Recall Enhancement, accountability and Documentation Act of 2000.That act mandated that all the
passenger vehicles weighing under 10,000 pounds sold in the U.S. as of September 1,2007 be equipped with a tyre pressure
monitoring system that warns drives if any of the tyres on the vehicles are under flatted by 25% or more. In the present market the
Tyre Pressure Monitoring Systems are popular. For this systems there is a chance for low accuracy. To overcome this challenge we
need a highly accurate and securable system. The Tyre Pressure Monitoring System may get affected due to Electromagnetic
Interference. The brake calliper, control arm, large metal acts as a source of electromagnetic field. The constant rotation of the
wheel, the metallic wheel structure, electromagnetic interference are the factors that will negatively impact the performance of an
active TPMS using RF communication Technology. The electromagnetic field produced around the metallic wheel may interfere
with the signal from pressure sensor results in decreasing the efficiency of the system.

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© 2019 JETIR March 2019, Volume 6, Issue 3 www.jetir.org (ISSN-2349-5162)

III. Proposed System

The proposed system consists of a Microstrip Low Pass Filters. This filter is essential to reduce the influence of radiation. The
pressure sensor is protected using Microstrip Low Pass Filter. The Low pass filter allows the Low frequency signals through it and
blocks the high frequency signals. A Microstrip is a type of electrical transmission line which can be fabricated using printed circuit
board technology and is used to convey microwave frequency signals. It consists of a conducting strip separated from a ground
plane by a dielectric layer known as substrate. This Microstrip Low Pass Filter removes the electromagnetic signal from the signal
from pressure sensor.

IV. Design of Microstrip Low Pass Filter

A Microstrip is a type of electrical transmission line which can be fabricated using printed circuit board technology and is used
to convey microwave frequency signals. A Microstrip filter represents a class of electronic filter designed to operate on the signals
in the range of megahertz to gigahertz. A Microstrip filter is designed in two steps. The first step is to select suitable low pass filter
prototype. The selection type of response will depend on required specification. It includes pass band ripple and scalar of reactive
elements. The element value of low pass filter, which are normalized to made a source impedance g0 =1 and a cutoff frequency
Ωc=1.0 are then converted to L-C elements for cutoff frequency and source impedance which we usually take as 50 ohms for
Microstrip Low Pass Filter. Second step is to gain an appropriate microstrip realization to the lumped element filter. The filter is
fabricated on substrate of dielectric constant ɛr and angular thickness h mm. The Microstrip Low Pass Filter is designed and
simulated using ANSYS HFSS. Design a ninth-order low pass filter with 0.1dB ripple and cutoff frequency of 1GHz.The
source/load impedance of the filter is 50ohms.
Design a ninth-order low pass filter with 0.1dB ripple and cutoff frequency of 1GHz.The source/load impedance of the filter is
50ohms.
Design characteristics of Low Pass Filter
Cut-off frequency=1GHz
Source impedance=50 Ohms
Dielectric constant of substrate=4.4
Substrate thickness=0.5mm
Pass band Ripple=0.1dB
TABLE 1: Element values for low pass filter prototype

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© 2019 JETIR March 2019, Volume 6, Issue 3 www.jetir.org (ISSN-2349-5162)
From the table prototype element values are
g1=0.3473
g2=1.0000
g3=1.5321
g4=1.8794
g5=2.0000
g6=1.8794
g7=1.5321
g8=1.0000
g9=0.3473
Inductor and Capacitor values can be calculated by using the following formulas
Li= (1)
Ci= (2)

TABLE2: calculated lumped element values

prototype element corresponding L and C
values values

g1 C1=1.1pF

g2 L2=7.9577nH

g3 C3=4.9pF

g4 L4=14.9nH

g5 C5=6.4pF

g6 L6=14.9nH

g7 C7=4.9pF

g8 L8=7.9577nH

g9 C9=1.1pF

Characteristic impedance of high impedance line value ZoH=90ohms

Characteristic impedance of low impedance line value ZoL=25ohms
We are going to use FR4 Epoxy as substrate which has 4.4 dielectric permittivity,thickness of substrate is h=0.5mm.Now we
have to calculate width and length for Microstrip filter.we can calculate width of microstrip line by equations.Equations for
calculation of width and length are as given below
If (3)

Where A= (4)
Guided wavelength λgl= (5)
For calculation of physical length
lL= (6)
lL= (7)

TABLE 3:Lengths and widths of the elements

Elements Length Width
Impedance 50ohms 10 0.5626
C1 4.4919 1.2560
L2 16.3217 0.1542
C3 22.7199 1.2560
L4 41.9236 0.1542
C5 36.8974 1.2560
L6 41.9236 0.1542
C7 22.7199 1.2560

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© 2019 JETIR March 2019, Volume 6, Issue 3 www.jetir.org (ISSN-2349-5162)
L8 16.3217 0.1542
C9 4.4919 1.2560
Impedance 50ohms 10 0.5626

Design of Microstrip Low Pass Filter

V. Result
The simulation result of Microstrip Low pass filter is designed using ANSYS HFSS. The filter allows frequency which is less
than 1GHz.Therefore it removes the unwanted electromagnetic signals.

VI. Conclusion
In this Paper a Microstrip Low pass Filter is designed. This Paper shows the design of Microstrip Low pass Filter using ANSYS
HFSS with FR4 Epoxy as substrate. The Low Pass Filter is of ninth order. Hence it removes the unwanted the electromagnetic
signal.

VII. References
[1] A book titled “EMI-EMC Analysis”published by S.Vardarajan and Dola Sanjay S.
[2]vikas kukshya,Hyok J.song, Hui p.Hsu,Richard W.Wiese,”Impact of Intravehicular Electromagnetic Interference on Tire
pressure Monitoring System”,published in IEEE International symposium on Electromagnetic 2007.
[3]Binal A. Patel, Falguni Raval,” Wearable Textile Microstrip Low Pass Filterusing Jeans as Subtrate”, International Journal of
Engineering & Technology Vol.4 Issue 04,April-2015
[4]Devendra k. misrea, “radio-frequency and microwave communicationcircuits, analysis and design”,student edition, A wiley-
intersciencepublication
[5]Ian C. Hunter, L. Billonet, B. Jarry, and P. Guillon,”Microwave filters-application and tecchnology”,IEEE transaction on
vol.50, issue 3,march2002.

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