Rectangular Microstrip Antenna Parameter Study with HFSS

RECTANGULAR FEED MICROSTRIPANTENNA
PARAMETER STUDY WITH HFSS SOFTWARE
School of Electrical Engineering
(Branch - ENTC)
Course: Antenna theory and design
Group-2 Batch-2 Block-1
Omkar Rane (TETB118) Exam Seat No: T187014
Chaitanya Deshpande (TETB119) Exam Seat No: T187001
Kaustubh Wankhade (TETB131) Exam Seat No: T187003

Rectangular Microstrip Feedline Antenna(MSA)
Microstrip antennas are low profile antennas and requires where size, weight, cost, performance and ease of installation and
aerodynamic profile are constraint such as in high-performance aircraft, spacecraft, satellite and missile applications.
Presently in some government and commercial applications such as in mobile radio and wireless communications that have
similar specifications, to meet these requirements, microstrip antennas can be used. These antennas are low profile,
conformable to planar and non-planar surfaces, simple and inexpensive to manufacture using modern printed circuit
technology . They are very versatile in terms of resonant frequency, polarization, pattern and impedance when a particular
patch shape and mode are selected. In addition by adding loads between the patch and the ground plane, such as pins and
varactor diodes, adaptive elements with variable resonant frequency, impedance polarization and pattern can be designed.
Major operational disadvantages of microstrip antennas are their low efficiency, low power, high Q, poor polarization purity,
poor scanning performance, spurious feed radiation and very narrow frequency bandwidth, which is typically only a fraction
of a percent or at most a few percent. In some government security systems narrow bandwidth are desirable; however, there
are methods such as increasing the height of the substrate that can be used to extend the efficiency (to as large as 90 % if
surface waves are not included) and bandwidth (up to 35%); however, as the height increases, surface waves are introduced
which usually are not desirable because they extract power from the total available for direct radiation (space waves). The
surface waves travel within the substrate and they are scattered at bends and surface discontinuities, such as the truncation of
the dielectric ground plane and degrade the antenna pattern and polarization characteristics. Surface waves can be eliminated,
while maintaining large bandwidths, by using cavities stacking as well as other methods of microstrip elements can also be
used to increase the bandwidth. In addition, microstrip antennas also exhibit large electromagnetic signatures at certain
frequencies outside the operating band are rather large physically at VHF and possibly UHF frequencies, and in large arrays
there is a tradeoff between bandwidth and scan volume. The next section describes the basic characteristics of antenna.

Ref: http://www.antenna-theory.com/antennas/patches/patch3.php

Design of MSA patch length and width
Step 1: Calculation of the
Width (W) -
Step 2: Calculation of the Effective Dielectric Constant. This
is based on the height, dielectric constant of the dielectric and
the calculated width of the patch antenna.
Step 3: Calculation of the Effective length
Step 4: Calculation of the length extension ΔL
Step 5: Calculation of actual length of the patch
Where the following parameters are used
f0 is the Resonance Frequency
W is the Width of the Patch
L is the Length of the Patch
h is the thickness
εr is the relative Permittivity of the dielectric substrate
c is the Speed of light: 3 x 108

Rectangular Microstrip Feedline formulae

Antenna dimensions and operating frequency
Ref: EM-TALK Patch and Line Calculator
Feedline Dimensions :
L=7.47245 mm
W=3.0589 mm
Z0 (impedance)=50 Ω
Dimension of Ground ,Substrate and Patch:
Overall dimension of antenna : 40 x 40 mm
Infinite Ground: 40x 40 mm
Substrate FR_4 Epoxy : height =1.6 mm and εr=4.4
Width of patch: 16.597 mm
Length of patch :12.438 mm
Operating Frequency of
MSA : f0 =5.5 GHz

mmL
LLeffL
L
hweffhweffhL
Leff
efffcLeff
eff
whrreff
mmw
rfocw
47.7
2
57.0
))8.0)/)((258.0/()264.0)/)((3.0(*412.0
01.0
)*0*2/(
2.7
)2/1()]^06.3/6.1(121[*)2/)14.4(()2/)14.4((
)2/1()]^/(121[*)2/)1(()2/)1((
06.3
))14.4/(2(*))9^10*5.5*2/()8^10*3((
)1/(2*)2/(
=
−=
=
+−++=
=
=
=
−+−++=
−+−++=
=
+=
+=

Results (main antenna- f =5.5 GHz )
VSWR S11 Rectangular plot
2D polar plot 3D polar plot

Parametric study for Rectangular Microstrip Antenna
a) Varying L and W more than original value and observe results
b) Varying L and W less than original value and observe results
c) Changing height of substrate (h>1.6 mm)
d) Changing height of substrate (h<1.6 mm)
e) Changing Material of substrate (ℰr )

a) Varying L and W more than original value and observe
Calculations
L=9.8794 mm
W=3.0589 mm
Width of patch: 14 mm
Length of patch :17 mm
MSA : f0 =4.16 GHz

rfocw
mmL
LLeffL
L
hweffhweffhL
Leff
efffcLeff
eff
whrreff
mmw
rfocw
mmL
LLeffL
L
)1/(2*)2/(
87.9
2
57.0
))8.0)/)((258.0/()264.0)/)((3.0(*412.0
007.0
)*0*2/(
2.7
)2/1()]^05.3/6.1(121[*)2/)14.4(()2/)14.4((
)2/1()]^/(121[*)2/)1(()2/)1((
05.3
))14.4/(2(*))9^10*16.4*2/()8^10*3((
)1/(2*)2/(
47.7
2
57.0
+=
=
−=
=
+−++=
=
=
=
−+−++=
−+−++=
=
+=
+=
=
−=
=

Results (f=4.16GHz)
2D polar plot
3D polar plot

Calculations
L=6.737 mm
W=3.0589 mm
Width of patch: 11.130 mm
Length of patch :14.965 mm
MSA : f0 =6.1 GHz
b) Varying L and W less than original value and observe

mmL
LLeffL
L
hweffhweffhL
Leff
efffcLeff
eff
whrreff
mmw
rfocw
mmL
LLeffL
73.6
2
57.0
))8.0)/)((258.0/()264.0)/)((3.0(*412.0
01.0
)*0*2/(
2.7
)2/1()]^06.3/6.1(121[*)2/)14.4(()2/)14.4((
)2/1()]^/(121[*)2/)1(()2/)1((
05.3
))14.4/(2(*))9^10*1.6*2/()8^10*3((
)1/(2*)2/(
87.9
2
=
−=
=
+−++=
=
=
=
−+−++=
−+−++=
=
+=
+=
=
−=

Results (f=6.1 GHz)

HFSS design
c) Changing height of substrate (h>1.6mm)

Results (h>1.6mm)
VSWR Rectangular plot

HFSS design
d) Changing height of substrate (h<1.6mm)

Results (h<1.6mm)
2D polar plot
3D polar plot

e) Changing material of substrate
Previously the dielectric material was FR_4 Epoxy which is now Changed to RT_Duroid
ℰ r =4.4 for FR_4 Epoxy substrate material and ℰ r=2.2 for RT_Duroid
Radiation pattern

2D polar plot
3D polar plot

Applications of MSA
1) Mobile and satellite communication application:
Mobile communication requires small, low-cost, low profile
antennas. Microstrip patch antenna meets all requirements and
various types of microstrip antennas have been designed for use
in mobile communication systems. In case of satellite
communication circularly polarized radiation patterns are
required and can be realized using either square or circular
patch with one or two feed points.

2) Global Positioning System applications:
Nowadays microstrip patch antennas with substrate having high permittivity
sintered material are used for global positioning system. These antennas are
circularly polarized, very compact and quite expensive due to its positioning. It
is expected that millions of GPS receivers will be used by the general
population for land vehicles, aircraft and maritime vessels to find there position
accurately Єr2 Єr1 Patch Antenna Transmission Line Ground plane with
aperture Patch Microstrip feed line Antenna dielectric Feed substrate .

3) Radio Frequency Identification (RFID):
RFID uses in different areas like mobile communication,
logistics, manufacturing, transportation and health care [2].
RFID system generally uses frequencies between 30 Hz and 5.8
GHz depending on its applications. Basically RFID system is a
tag or transponder and a transceiver or reader. Worldwide
Interoperability for Microwave Access (WiMax): The IEEE
802.16 standard is known as WiMax. It can reach upto 30 mile
radius theoretically and data rate 70 Mbps. MPA generates three
resonant modes at 2.7, 3.3 and 5.3 GHz and can, therefore, be
used in WiMax compliant communication equipment.

4) Radar Application:
Radar can be used for detecting moving targets such as people
and vehicles. It demands a low profile, light weight antenna
subsystem, the microstrip antennas are an ideal choice. The
fabrication technology based on photolithography enables the
bulk production of microstrip antenna with repeatable
performance at a lower cost in a lesser time frame as compared
to the conventional antennas. Rectenna Application: Rectenna is
a rectifying antenna, a special type of antenna that is used to
directly convert microwave energy into DC power. Rectenna is
a combination of four subsystems i.e. Antenna, ore rectification
filter, rectifier, post rectification filter. in rectenna application, it
is necessary to design antennas with very high directive
characteristics to meet the demands of long-distance links. Since
the aim is to use the rectenna to transfer DC power through
wireless links for a long distance, this can only be accomplished
by increasing the electrical size of the antenna.
Ref:
https://www.drdo.gov.in/drdo/pub/techf
ocus/aug05/antena.htm

5) Telemedicine Application:
In telemedicine application antenna is operating at 2.45 GHz. Wearable
microstrip antenna is suitable for Wireless Body Area Network (WBAN).
The proposed antenna achieved a higher gain and front to back ratio
compared to the other antennas, in addition to the semi directional radiation
pattern which is preferred over the omni-directional pattern to overcome
unnecessary radiation to the user's body and satisfies the requirement for on-
body and off-body applications. A antenna having gain of 6.7 dB and a F/B
ratio of 11.7 dB and resonates at 2.45GHz is suitable for telemedicine
applications. Medicinal applications of patch: It is found that in the treatment
of malignant tumours the microwave energy is said to be the most effective
way of inducing hyperthermia. The design of the particular radiator which is
to be used for this purpose should posses light weight, easy in handling and
to be rugged. Only the patch radiator fulfils these requirements. The initial
designs for the Microstrip radiator for inducing hyperthermia was based on
the printed dipoles and annular rings which were designed on S-band. And
later on the design was based on the circular microstrip disk at L-band. There
is a simple operation that goes on with the instrument; two coupled
Microstrip lines are separated with a flexible separation which is used to
measure the temperature inside the human body. A flexible patch applicator
can be seen in the figure below which operates at 430 MHz

Conclusion
1) With increase in width, aperture area, (dielectric constant)εr and fringing fields increase, hence frequency
decreases and input impedance plot shifts towards lower impedance values. BW αWand Gain αW.
2) As height of substrate increases, fringing fields and probe inductance increase, frequency decreases and input
impedance plot shifts upward.
3) With decrease in εr, both Length and Width of patch Increase, which increases fringing fields and aperture area,
hence both Bandwidth and Gain increase.
4) With increase in εr , size of the antenna decreases for same resonance frequency. Hence, gain decreases and
HPBW increases.
5) Width of microstrip feedline plays important role in impedance matching.

References
[1] http://www.antenna-theory.com/antennas/patches/patch3.php
[2] EM-TALK Patch and Line Calculator
[3] https://www.pasternack.com/t-calculator-microstrip.aspx
[4] https://chemandy.com/calculators/microstrip-transmission-line-calculator.html

Rectangular Microstrip Antenna Parameter Study with HFSS

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Rectangular Microstrip Antenna Parameter Study with HFSS