05575105

8/12/2019 05575105

1/5

Practical Novel Design Component of Microstrip Patch Slot

Antenna MSPSA for RFID Applications

Raied A. R. Ibrahim Student Member IEEE1, Mustapha C.E. Yagoub, Member IEEE2

1Carleton University, Ottawa, Ontario, 2University of Ottawa, Ottawa, Ontario, Canada,

[email protected]

Abstract---This paper presents and

demonstrates the necessity of microstrip

patch and slot antennas for RFID

applications. Various microstrip patch and

slot antennas fed by a feed line designed on a

2.2 permittivity Rogers Duriod substrate are

considerably studied and comprehensively

analyzed as new and authentic new design

approaches antennas. The antennas have been

designed using the 3D EM High Frequency

Structure Simulator (HFSS) V11. The

microstrip patch (MSPA) design 1 provides a

total antenna gain of 1.87 dBi, a return loss

(S11) of -5.5 dB. while the micro strip patch

slot antenna (MSPSA) design 2 have achieved

a total antenna gain of 6.017 dBi and a return

loss (S11) of -23.8 dB at 865 MHz for 60 mm

patch length. The other micro strip patch slot

antennas (MSPSA) designs have achieved a

total antenna gain of 5.92 dBi, 4.48 dBi and at

S11 12 dB, 6.87 dB respectively. Modeling and

optimization of the one slot MSPSA design 2have produced the most optimized results

hence the MSPSA design 2 is an attractive

antenna solution for RFID applications.

1. INTRODUCTION

Radio Frequency IDentitifation (RFID)

technology has been commercialized in areas of

mobile communications, logistics,manufacturing, transportation, and health care

[1]. RFID system generally uses frequencies

between 30 Hz and 5.8 GHz depending on itsapplications. Basically RFID system is a tag or

transponder and a transceiver or reader. The tag

consists of an antenna combined with anapplication-specific integrated circuit (ASIC)

chip. RFID system components can be seen in

Figure 1.

Microstrip patch and slot antennas are

increasing in recognition for use in wirelessapplications namely RFID applications

especially in UHF band due to their low-profile

structure. Antennas for communications ontelecom and military applications requires thin

and conformal structure and microstrip patch

antennas are the most suitable antennas to meetthese criterias. Another area where they have

been used successfully is in Satellite

Communications. Conventional microstrip patchantennas (MSPA) have a conducting patch

printed on grounded microwave substrate.

Microstrip patch slot antenna (MSPSA) by

utilizing slot techniques antenna design can be a

modified version of microstrip patch antenna by

enhancing bandwidth and reducing antenna size.

Backward Link Forward Link

Figure 1: RFID System Components

2. MODELING AND SIMULATION

It is vital to model and simulate the

microstrip patch antenna (MSPA) with thecombination of slot antennas technique for

optimized performance. The range of resonate

frequency of operation is 860 MHz to 960MHz.

The MSPA has been further optimized utilizing

slot antenna technique. This paper proposes threedifferent microstrip patch slot antennas

(MSPSA) that has been comparatively analyzed

and modeled using HFSS V11. The first designinitiates microstrip patch antenna with its

rectangular and square patches shape. It is

simulated using Rogers Duroid substrate. Themodeling occurs with the length of rectangular

are 50 mm 100mm, while the square part has its

length of equal measurements of 60mm. Figure 4shows the compact shape of new microstrip

patch antenna MSPA.

Reader

T

T

T

T

978-1-4244-5377-1/10/$26.00 2010 IEEE

8/12/2019 05575105

2/5

2.1 Design 1: MicroStrip Patch Antenna

MSPA

MSPA has been formed by integrating

square patch and rectangular patch. These twopatch combination form a microstrip patch

antenna (MSPA) on Rogers Duriod substratewith a coaxial port excitation feed in the square

patch area is shown in Figure 2. The modeling

and simulation results for the MSPA have beendone in HFSS. The MSPA antenna without

optimized impedance matching has reflection

coefficient RL (S11) -5.5 dB that is shown in

Figure 4.

Figure 2: MSPA in HFSS modeling

The feed point is positioned where the

input impedance is 50 ohms for the resonantfrequency where the RL is most negative below -

10 dB. Figure 3 shows the center of MSPA

approximately.

Figure 3: MSPA model in HFSS and port

excitation.

The initial design of MSPA without any

slotting has produced a reflection coefficient(S11) below the nominal value of -10 dB which

indicates that this design has caused return losses

to be increased and the antenna behave as a nongood resonator. This means increased level of

back radiation as the compact patch (MSPA) do

not radiate efficiently and below 10 dB returnloss bandwidth.

Figure 4: Return Loss S11 for MSPA design 1

modeled using HFSS environment

Another drawback of this antenna

MSPA design 1 is that total antenna gain has a

value of 1.87 dBi and this drop in gain is due to

an increased level of back radiation and thecompact MSPA is not behaving as a good

radiator. The total antenna gain is shown in the

smith chart in Figure 5 which represents the

radiation pattern of microstrip patch antenna(MSPA) design 1.

-19.00

-13.00

-7.00

-1.00

90

60

30

0

-30

-60

-90

-120

-150

-180

150

120

Ansoft Corporation HFSSDesign6Radiation Pattern 1

m1

Curve Info

dB(GainTotal)

Setup1 : LastAdaptive

Phi='0deg'

dB(GainTotal)


Phi='10deg'

dB(GainTotal)


Phi='20deg'

dB(GainTotal)


Phi='30deg'

dB(GainTotal)


Phi='40deg'

dB(GainTotal)


Phi='50deg'

dB(GainTotal)


Phi='60deg'

dB(GainTotal)


Phi='70deg'

dB(GainTotal)


Phi='80deg'

dB(GainTotal)

Setup1 : LastAdaptivePhi='90deg'

Na me Th et a A ng Ma g

m 1 0 .0 00 0 0 .0 00 0 1 . 8 77 3

Figure 5: Radiation Pattern with a total

Antenna Gain of MSPA design 1 modeled

using HFSS environment

8/12/2019 05575105

3/5

2.2 Design 2: MicroStrip Patch Slot Antenna

MSPSA

MicroStrip Patch Slot Antenna

(MSPSA) has been formed by integrating squarepatch and rectangular patch. These two patch

combination form a microstrip patch antenna

(MSPA) on Rogers Duriod substrate with acoaxial port excitation feed in the square patch

area and inserting a slot in the square patch area

is shown in Figure 6. The MSPSA has been

modeled by having one slot in the square part of

the antenna with a dimension of 6 mm width and47 mm length. This design is shown in Figure 6.

Figure 6: MSPSA with one slot in square

patch modeled in HFSS

The MSPSA design 2 has been

structured by inserting slot technique using one

slot in the square patch and leaving therectangular patch without any slotting technique.

The MSPSA design 2 structure has been

modeled using HFSS environment. This designhas produced a return loss (S11) of -23.8 dB at

865 MHz as shown in Figure 7. The slot in the

patch introduces an additional capacitive

reactance that compensates the inductive

reactance contributed by the shorting pin and the

probe thus improved S11 impedance matching[6]. In Figure 7 markers such as m1, m2, m3,m4,

m5 m6, m7, m8, m9, m10 and m11. For examplem1 reads -10.83 dB at the frequency 861 MHz,

m2 reads the highest and most optimized value

of -23.83 dB at the frequency of 865 MHz. M3

reads a flat value of zero dB at 990 MHZ whilem4 reads the same value of m2 the highest value

of S11 for the best return loss for this design.

m5, m9 and m11 have the lowest values of -0.42

dB, -0.47dB, -0.37 dB at 826 MHZ, 828MHz,and 928 MHz respectively. Like m1 the values of

m6, m7, m8 and m10 are -10.47 dB, 9.08 dB,-

10.83, and -13.14 dB at the frequencies 869

MHz, 860 MHZ, 861MHz & 862 MHz. Thesevalues apart from the peak value show that this

MSPSA design 2 has a good margin of being

above -10 dB in the negative of S11 in dBagainst its corresponding frequencies. It

indicated clearly that m2 and m4 of S11 reflects

that best value.

Figure 7: Design 2 MSPSA S11 Return Loss

The MSPSA design 2 with one slot has a totalantenna gain of 6.17 dBi as shown in Figure 8. In

this figure it is apparent that the values of total

antenna gain have ranged from 5.9 dBi to 6.017

dBi with different angles from 0- 360 degree.This reflects that this design (MSPSA design 2)

with one slot in the square patch behave like a

good resonator and the rectangular patch play the

role of reflecting the radiated power in the main

area of excitation near the wave port. Figure 8presents the radiation pattern of microstrip patch

slot antenna (MSPSA) design 2 with a total

antenna gain of 6.017 dBi.

Figure 8: Radiation Pattern with a total

Antenna (MSPSA) Design modeled using

HFSS environment

8/12/2019 05575105

4/5


MSPSA with two slots

MicroStrip Patch Slot Antenna

(MSPSA) has been formed by integrating squarepatch and rectangular patch. These two patch

combination form a microstrip patch antenna

(MSPA) on Rogers Duriod substrate with acoaxial port excitation feed in the square patch

area and inserting two slots in the square patch

and rectangular patch areas as shown in Figure 9.

In this design the two slots have been initiated on

square with a dimension of 6 mm width and 60mm both sides and rectangular with a dimension

of 6 mm width and 47 mm length patches and

can be seen in Figure 9.

Figure 9: Design 3 MSPSA with 2 slots

modeled in HFSS

The MSPSA design 3 has been

structured with two slots in the square patch and

the rectangular patch. The MSPSA design 3

compact structure has been modeled using HFSSenvironment. This design has produced a return

loss (S11) of -12.11 dB at 954 MHz as shown in

Figure 10. The slot dimensions were of 6 mmwidth and 47 mm length for the square patch and

a dimension of 6 mm width and 47 mm length,

50 mm width for rectangular patches

820.00 840.00 860.00 880.00 900.00 920.00 940.00 960.00 980.00 1000.00Freq [MHz]

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

dB(S(WavePort1,W

avePort1))

Ansoft Corporation HFSSDesign8XY Plot 5

m2

CurveInfo

dB(S(WavePort1,WavePort1))

Setup1:Sweep1

Name X Y

m2 953.0000 -12.1145

Figure 10: MSPSA Design 3 (S11) Return

Loss modeled using HFSS environment

The impedance matching known as -10 dB return

loss bandwidth is a function of electricalthickness of substrate the thicker substrate

material, the greater the gain of the design 3

MSPSA antenna. The gain of design 3 MSPSAhas a value of 5.92 dBi as shown in Figure 11.

Figure 11: Radiation Pattern (MSPSA)

Design 3 with a total antenna gain modeled


As can be noticed from figure 11, MSPSA

design 3 has a fairly large collecting area and

therefore larger gain from design 1 MSPAantenna. The gain increases due to the volume of

the antenna is large [7, 8].


MSPSA with four slots.

MicroStrip Patch Slot Antenna (MSPSA) has

been formed by integrating square patch and

rectangular patch. These two patch combination

form a microstrip patch antenna (MSPA) onRogers Duriod substrate with a coaxial port

excitation feed in the square patch area and

inserting two slots in the square patch andrectangular patch areas as shown in Figure 9.

In design 4 of MSPSA the slots have been

initiated as one slot on square patch and 3 slots

on rectangular patch with a dimension of 6 mm

width and 60 mm length for both sides and

rectangular with a dimension of 6 mm slot width

and 47 mm length, 6 mm width 50 mm width forboth sides patches and can be seen in Figure 12.

8/12/2019 05575105

5/5

Figure 12: Design 4 of MSPSA with 4 slots

modeled in HFSS environment

The MSPSA design 4 with four slots with the

one slot on square patch and 3 slots on

rectangular patch with a dimension of 6 mmwidth and 60 mm length for both sides andrectangular with a dimension of 6 mm slot width

and 47 mm length, 6 mm width 50 mm width

patches has a return loss (S11) of -8.7 dB asshown in Figure 13.

82 0.00 840.0 0 860 .00 8 80.00 9 00.00 920 .00 940.00 9 60.00 98 0.00 1 000.00Freq [MHz]

-9.00

-8.00

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

dB(S(WavePort1,W

avePort1))

Ansoft Corporation HFSSDesign7XY Plot 5

m2

CurveInfo

dB(S(WavePort1,WavePort1))

Setup1: Sweep1

Name X Y

m2 943.0000 -8 .6948

Figure 13: MSPSA Design 4 S11 Return Loss

The radiation pattern of MSPSA design 4 has

produced a total antenna gain of a value of 4.48

dBi as shown in Figure 14.

90

60

30

0

-30

-60

-90

-120

-150

-180

150

120

Ansoft Corporation HFSSDesign7Radiation Pattern 1

m1

m1:totalantennagain =4.48 dBi

CurveInfo

dB(GainTotal)

Setup1: LastAdaptive

Na me T he ta A ng Ma g

m1 0.0000 0.0000 4.6840

Figure 14: Radiation Pattern of MSPSA

Design 4 with a total antenna gain modeled


3. DISCUSSIONS AND CONCLUSION

The microstrip patch (MSPA) design 1

provides a gain of 1.87 dBi, a return loss (S11)

of -5.7 dB while the microstrip patch slotantenna (MSPSA) design 2 have achieved a total

antenna gain of 6.017 dBi and a return loss(S11) of -23.8 dB at 865 MHz for 120 mm patch

length. Thus introducing one slot technique, as in

design 2 improves both return loss and antennagain S11 respectively. MSPSA Design 3 has

achieved a total antenna gain of 5.92 dBi and areturn loss (S11) of -12 dB. MSPSA Design 4

has achieved a total antenna gain of 4.68 dBi and

a return loss (S11) of -8.7 dB. The other microstrip patch slot antennas (MSPSA) designs have

achieved a total antenna gain of 5.92 dBi, 4.68

dBi and at S11 12 dB, 6.87 dB respectively.Therefore antenna design 2 MicroStrip Patch

Slot Antenna (MSPSA) has produced the most

optimized results and is suitable for RFIDapplications.

4. References

[1] MD. Shamim Shahriar Hossain, and Dr

Nemai Karmakar, An Overview on RFID

Frequency Regulations and Antennas. 4th

International Conference on Electrical and

Computer Engineering, ICECE 2006, 19-21December 2006.

[2] R.B..Waterhouse, Microstrip PatchAntennas A Designers Guide, Kluwer

Academic Publishers, 2003.

[3] R.A.R. Ibrahim, M.C.E. Yagoub, R.W.Y.Habash Microstrip Patch Antenna for RFID

Applications 3-6 May 2009.

[4] C. A. Balanis, Antenna theory: analysis anddesign, John Wiley and Sons, New York, 1996.

[5] Kin-Lu Wong, Compact and Broadband

Microstrip Antennas, John Wiley & Sons, NewYork, 2002.

[6] Jean-Francois Zurcher, Fred E. Gardiol,

Broadband Patch Antennas, Artech House,

Boston, London, 1995.[7] Budak, E.; Catay, B.; Tekin, I.;

Yenigun, H.; Abbak, M.; Drannikov, S.;,

Microstrip Patch Antenna for RFIDApplications 2007.[8] Lorean I. Basilio, Michael A. Khayat, Jeffery

T. Willianms, and Stuart A. Long, TheDependence of the Input Impedance on Feed

Position of Probe and Microstrip Line-Fed PatchAntennas IEEE Trans. Antennas Propagation

,VOL.49,NO.1,January 2001.

Documents

05575105