AN APERTURE-COUPLED MICROSTRIP ANTENNA WITH RECONFIGURABLE RADIATION PATTERN

PREPARED BY:

DR. MOHD TARMIZI ALI DR. MOHD KHAIRUL MOHD SALLEH

PN. SUHAILA SUBAHRI PN SUZILAWATI MUHAMUD@KAYAT

JULY 2012

COPYRIGHT UiTM

Table of Contents

LETTER OF REPORT SUBMISSION i LETTER OF OFFER (RESEARCH GRANT) iii ACKNOWLEDGEMENTS iii PROPOSED EXECUTIVE SUMMARY iv CHAPTER REPORT

1. INTRODUCTION 1 2. LITERATURE REVIEW 2

2.1. Reconfigurable Microstrip Antennas 2 2.1.1. Frequency Reconfigurable Microstrip Antennas 2

2.2. Antenna Feeding Techniques 3 3. METHODOLOGY 4 4. ANTENNA STRUCTURE 5

4.1. Elliptical Microstrip Patch Antenna 5 4.2. E-Shaped Microstrip Patch Antenna 5 4.3. Rectangular Patch Antenna 6 4.4. Reconfigurable Microstrip Patch Antenna 7

5. RESULTS AND DISCUSSION 8 5.1 Effect on Aperture Slot 8 5.2 Effect on Patch Slot 10 5.3 Effect on Patch Shape 12 5.4 Effect on Orientations of Patch Slot. 13 5.5 Reconfigurable Single Patch Antenna 15

6. CONCLUSION AND RECOMMENDATION 17 7. RESEARCH OUTCOMES 18 8. REFERENCES 19 9. APPENDIX 21

i COPYRIGHT UiTM

LETTER OF REPORT SUBMISSION

Tarikh :

No. Fail Projek : 11 Junel2012

600-RMI/ST/DANA 5/3Dst (366/2011) Penolong Naib Canselor (Penyelidikan) Institut Penyelidikan, Pembangunan dan Pengkomersilan Universiti Teknologi MARA 40450 Shah Alam

Ybgh. Prof.,

LAPORAN AKHIR PENYELIDIKAN "AN APERTURE-COUPLED MICROSTRIP ANTENNA WITH RECONFIGURABLE RADIATION PATTERN"

Merujuk kepada perkara di atas, bersama-sama ini disertakan dua naskah Laporan Akhir Penyelidikan bertajuk "An Aperture-Coupled Microstr ip Antenna With Reconfigurable Radiation Pattern".

Sekian, terima kasih.

Yang benar,

DR. MOHD TARMIZI ALI

Ketua Projek Penyelidikan

DR MOHD KHAIRpL IVJ0flDxSALLEH

Ahli Projek

SUHAILASOlAHRI

Ahli Projek

LETTER OF OFFER (RESEARCH GRANT)

Surat Kami : 600-RMI/ST/DANA 5/3/Dst (SC& /2011) Tarikh ': J^Julai2011

UNIVERSITI TEKNOLOGI MARA

PEMENANG ^ ^ Anugerah Kuaiiti mm fk Peraana Menteri W kJ

2QQ8Vv Dr Mohd Tarmizi All Fakulti Kejuruteraan Eiektrik Universiti Teknologi MARA 40450 Shah Alam

Y. Brs. Profesor/Tuan/Puan

KELULUSAN PERMOHONAN DANA KECEMERLANGAN 07/2011

Tajuk Projek Kod Projek Kategori Projek Tempoh Jumlah Peruntukan Ketua Projek

An Aperture-Coupled Microstrip Antenna with Reconfigurable Radiation Pattern 600-RMI/ST/DANA 5/3/Dst (&&C /2011) Kategori G (2011) 01 Ogos 2011 - 31 Julai 2013 (24 bulan) RM 10,000.00 Dr Mohd Tarmizi Ali

Dengan hormatnya perkara di atas adalah dirujuk. 2. Sukacita dimaklumkan pihak Universiti telah meluluskan cadangan penyelidikan Y. Brs Profesor/tuan/puan untuk membiayai projek penyelidikan di bawah Dana Kecemerlangan UiTM.

3. Bagi pihak Universiti kami mengucapkan tahniah kepada Y. Brs. Profesor/tuan/puan kerana kejayaan ini dan seterusnya diharapkan berjaya menyiapkan projek ini dengan cemerlang.

4. Peruntukan kewangan akan disalurkan melalui tiga (3) peringkat berdasarkan kepada laporan kemajuan serta kewangan yang mencapai perbelanjaan lebih kurang 50% dari peruntukan yang diterima.

Peringkat Pertama Peringkat Kedua Peringkat Ketiga

20% 40% 40%

5. Untuk tujuan mengemaskini, pihak Y. Brs. Profesor/tuan/puan adalah diminta untuk melengkapkan semula kertas cadangan penyelidikan sekiranya perlu, mengisi borang setuju terima projek penyelidikan dan menyusun perancangan semula bajet yang baru seperti yang diluluskan. Sila lihat lampiran bagi tatacara tambahan untuk pengurusan projek. Sekian, harap maklum.

"SELAMAT MENJALANKAN PENYELIDIKAN DENGAN JAYANYA"

Yang benar

PROFESOR DRABU BAKAR ABDUL MAJEED Penolong Nailreanselor (Penyelidikan)

Penolong Naib d K t e l o r (Penyelidikan) .603- 5544 2094/2095 i Bahagian Penerbi tan 603 5544 1425/2785 Bahagian Penyelidikan :603 5544 2097/2091/2101/5521 1462 | Bahagian Sokongan ICT :603-5544 3097/2 104/5521 Bahagian Perundingan ;603-5544 2100/2787/2092/2093 j Bahagian Sains :603-5544 2098 /5521 1463 Bahagian Inovasi .603-5544 2750/2747/2748 ] Pejabat Am :603-5544 2559/2057/5521 1636

Penolong Pentadbiran .603-5544 2090 Fax ; 603 5544 2096/2767 Uni t Kewangan Zon 17 :603-5544 3404

:603-5521 1386

COPYRIGHT UiTM

ACKNOWLEDGEMENTS

In preparing this report, I have been in contact with many people, researchers, academicians, and practitioners who have contributed towards my understanding and thoughts. First of all, I wish to express my sincere appreciation to my project member, En Mohd Nor Md Tan, Pn Suhaila Subahri and Pn Suzilawati Muhamud@Kayat for their continuous effort, patience and guidance in providing invaluable ideas, encouragement and exceptional role they have played in making this project a reality. Besides, I would like to acknowledge research fund as our research was supported in part by them under 600-RMI/ST/DANA 5/3Dst (366/2011). I am most grateful to Research Management Institute (RMI) for giving me the help needed throughout my reserach period in Faculty of Electrical Engineering. I would also like to thank all the staffs of Center For Electronic Communication Engineering Studies for giving me the opportunity that made my research possible.

Last but not least, my warmest appreciation to all my friends for their invaluable friendship and encouragement all these years.

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PROPOSED EXECUTIVE SUMMARY

In recent years as the technology evolves rapidly, it gives a significant impact on the modern wireless communication systems. As the most important components in any communication systems, the antennas require operations in a number of frequency bands. A reconfigurable antenna offers a great advantage over a conventional antenna with the ability to operate at multiple frequencies.

A frequency reconfigurable microstrip antenna can be achieved by having one or more slots with various shapes on the patch. The introduction of slots on the radiating patch enables the antenna to have multi-frequency while maintaining the size of the radiating elements. Thus, size reduction can be obtained for lower frequencies and overall manufacturing costs can be reduced.

To achieve frequency ^configurability, a switch is inserted in the slot so that it becomes switchable. In this research, the reconfigurable antenna can be operated at two different frequencies by controlling the states of the PIN diode switches. On top of that, its radiation pattern remains the same regardless of the frequency of operation.

In this particular research the proposed slotted antenna can be operated at dual-frequency with the same patch size. The benefit of this design is that the overall size of an array antenna can be reduced while being able to operate at lower frequency which requires bigger patch size.

This research will focus on two different operating frequencies of 5.8 GHz and a lower frequency of 5.8GHz. The results from this research will be beneficial to the knowledge domain of wireless communication systems, particularly in the applications of WiMAX.

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1. INTRODUCTION

The development of reconfigurable microstrip antennas (RMAs) has received significant attention in wireless communication systems in recent years. RMAs provide numerous applications and offer more versatility as compared to conventional antennas. Reconfigurable antennas have attractive features such as the ability to reconfigure themselves independently to adapt to the changes or with the system to perform entirely different functions. The reconfigurable antenna is also capable of providing a single antenna for use with multiple systems.

In modern wireless communication systems, different wireless standards are available for mobile communication. Therefore, it is not possible to equip a device with many antennas of different frequency band. Multi frequency band antennas which can provide the feature of multi-band reception would be highly demanded by the end-users. Thus, an antenna with the ability to reconfigure its operating frequency is required.

The rapid advances in technology have also significantly resulted in high demand for thin and compact devices including the antennas. To cope with this demand, small and compact antennas can be considered to be the one of the key advances in future wireless communications technology. However, the development of these antennas poses significant challenges to antenna designers particularly. Therefore, the design of an antenna must not only be focused on its functionality such as the capability to reconfigure but also the overall size of the antenna structure without compromising its good characteristics performance.

In modern wireless communication systems, a reconfigurable microstrip antenna has the flexibility for use in multiple applications by integrating appropriate switches into the design. There are a few types of RF switches that can be integrated with the antenna to achieve its reconfigurability. The most popular types that have been used in previous researches are the PIN diodes [1]-[3] and micro-electro-mechanical system (MEMS) [4],[5] switches.

In this research, the proposed antenna design would be have the capability to reconfigure its operating frequency with a broad bandwidth in a compact size without compromising its overall performance including the reduction of back lobe.

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2. LITERATURE REVIEW

2.1 Reconfigurable Antennas

Ideally, a reconfigurable microstrip antenna (RMA) is able to change its operating frequency, radiation pattern and polarization independently to accommodate changing operating requirements [6]. Reconfigurable antennas can provide diversity functions in operating frequency, radiation pattern and polarization to mobile communication. A reconfigurable antenna that concentrated on changing its radiation patterns while maintaining its other characteristics is referred to as a radiation pattern reconfigurable antenna [7]. Radiation pattern reconfigurable antennas can be classified into two categories in which the overall performance of wireless communication systems can be improved. The first category involves in varying the beam shape [8]; while the other involves in controlling beam direction pattern [9].

2.1,1 Frequency Reconfigurable Antenna

Most reconfigurable systems concentrate on changing operating frequency while maintaining radiation characteristics [19-21]. However, Manipulation of an antenna's radiation pattern can be used to avoid noise sources or intentional jamming, improve security by directing signals only toward intended users, serve as a switched diversity system, and expand the beamsteering capabilities of large phased arrays. Researches on both pattern and frequency reconfigurable antennas have been done to further enhance the reconfigurable systems.

A novel ring antenna with pattern and frequency reconfigurability was proposed by [10]. Three switches are used in the antenna to achieve different radiation patterns at two different frequencies at 2.0 GHz and 2.4 GHz. However, other antenna characteristics performance such as gain and return loss were not mentioned in the paper. Another related study was done by [24], with a design of a single turn square spiral microstrip antenna. However, the results seem to illustrate that the antenna is capable in both pattern and frequency reconfigurabilities but not in simultaneous manner.

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2.2 Antenna Feeding Technique

The antenna feeding technique can be categorized into four : (a) coxial probe; (b) Microstrip line; (c) aperture coupler and (d) proximity coupler.

/ a) Coaxial Probe \ f c) Aperture Coupler

S*~ b) Microstrip line \ f d) Proximity Coupler

Figure 1. Types of feeding technique (a) Coaxial Probe; (b) Microstrip Line; (c) Aperture Coupler and (d) Proximity Coupler

Aperture coupler technique was first introduced by D.M Pozar [11],[12]. It can be considered the best feeding technique, isolating the spurious feed radiation from antenna element by a common ground plane with ease of input impedance matching. Figure 1 shows an overview of a microstrip patch antenna design with aperture coupler technique. The antenna is formed on a dielectric substrate above the ground plane. The feed which consists of an open-ended microstrip line is located on a separate dielectric substrate below the ground plane. These two structures are electromagnetically coupled through an electrical small aperture in the ground plane between them [13].

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3. METHODOLOGY

The main emphasis of this research is to design, and develop a reconfigurable microstrip patch antenna. In order to achieve that, the research is divided into two; software and hardware parts. The software part includes the antenna design process and its simulations and also the switching circuit network design. Meanwhile, the hardware part includes the fabrication of the proposed antenna. In this research, the designs are based on aperture coupler feeding technique and the concept of PIN diodes has been used in the switching circuit.

To start, a comprehensive review is required to obtain knowledge on antenna design. The proposed antenna will be designed and simulated using CST Microwave Studio 2009. On the other hand, switching circuit network will be designed using AWR. The design parameters of both designs will be optimized to achieve optimal results. Finally, a prototype antenna will be fabricated and a comparison will be made between simulation and measurement results. Measurement results will be in terms of return loss and radiation pattern at different modes of switch configurations.

The flow chart of the research methodology is shown in Figure 3.

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D e s i g n - s i m u l a t i o n , f a b r i c a t i o n a n d m e a s u r e m e n t o f s i n g l e p a t c h a n t e n n a

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" I S l e e t t h e N O

YES

Figure 3.0: Flow chart of the research

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4. ANTENNA STRUCTURE 4.1 Elliptical Microstrip Patch Antenna

The slotted elliptical patch antenna for wideband communications proposed in this paper is shown in Figure 4.1(a). The elliptical patch is designed with a major axis a=27mm, and a minor axis b= 18mm (ellipticity ratio a/b=1.5), from which a rectangular region is carved out. The prototype of the design is shown in Figure 4.1(b).

W t u b 45.0

Ellipse patch

Front View Side View

Fig. 4.1(a) The structure of slotted elliptical antenna

m '

(a i From View

Switch it

\ HHB (b) Front View

'^ uH^^HSr

fc) Back View

Fig. 4.1(b) The prototype of the antenna structure

4.2 E-Shaped Microstrip Patch Antenna

The design geometry of the E-shaped patch antenna is shown in Figure 4.2. The antenna is fed by a SMA connector positioned at (Wc/2,Lf)- The patch and ground are separated by closed-cell low loss foam named PF-2 of thickness 3.2 mm.

,Vb 21.7 nun Pafcft

I Sub ' t t f i tH* C

&o\.mtil JL+ TGfkm ( t 4 .0B)

Fig. 4.2. The geometry of an E-shaped microstrip antenna.

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4.3 Rectangular Patch Antenna

The schematic diagram of the initial design is shown in Fig. 4.3(a) and the optimized design parameters are tabulated in Table I. Next, a rectangular slot is inserted on to the microstrip patch in two different orientations, horizontal and vertical as shown in Fig.4.3 (b).

w

\

wf

Va

-n\

4. 1J

jt

4

Fig.4.3(a). The geometry ofinitial design of ACMSA

TABLE I. DESIGN PARAMETERS FOR INITIAL DESIGN OF ACMSA Parameters

Patch (W, L) Substrate (Wg, Lg)

Aperture Slot (Wa, La) Feed Line (Wf, Lt)

Width (mm) 37.4

60 15.3 3.86

Length (mm) 22.3 60 3.9 31.5

immJL jjS ! 1 4 w

n * w

1 K

!

I 1 I >:

H-slot

V-slot, Vs1

V-slot, Vs2

Parameter

Width

Length

x-axis

y-axis

Width

Length

x-axis

y-axis

Width

Length

x-axis

y-axis

Label

WsH

LsH

X

y

WsV1

LsV1

X

y

WsV2

LsV2

X

y

Dimension (mm)

7

2

11.7

2

2

14.5

2

1

1

16

2

0

Fig. 4.3 (b) The orientations of a rectangular patch slot with different slot dimensions.

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4.4 Reconfigurable Microstrip Patch Antenna

The design of the proposed antenna was based on basic design of an aperture

coupled microstrip antenna (ACMSA). A comparison between two vertical slot lengths, Ls1 and Ls2 was done in three conditions: Ls1>Ls2, Ls1=Ls2 and Ls1

5. RESULTS AND DISCUSSION 5.1 Parametric Study on Single Patch Antenna

A comprehensive parametric studies have been done to investigate the effects of certain properties on the antenna. The studies include the effects on its aperture slot, patch slot and patch shape.

5.1.1 Effect on Aperture Slot

A Return Loss, Sn

Fig. 5.1 shows the return losses (Sn) of a microstrip patch antenna with aperture coupler technique in dB during optimization. Return loss is a convenient way to characterize the input and output signal sources. S11 represents how much power is reflected from the antenna. If Sn=0 dB, it shows that all power is reflected from the antenna and nothing is radiated. The final design chosen from the optimization is indicated in purple (no.4) as the return loss illustrates the largest value, -20.5743dB. Larger return loss indicates higher power being radiated by the antenna which eventually increases the gain. In other word, the increase in Sn shows that the antenna has a better reflection coefficient and power reaches the load with minimal losses [25].

.-> i-y. rrt# ttMrbjfo n A

% U 1* U [VI1

Fig. 5.1. Return losses from optimization process

B. Voltage Standing Wave Ratio, VSWR

The simulation result of Voltage Standing Wave Ratio, VSWR is shown in Fig.5.2 below. VSWR is an important specification for all microwave devices. It measures how well an antenna is matched to the cable impedance where the reflection, |T| = 0. This means that all power is transmitted to the antenna and there is no reflection [26]. The optimal VSWR is 1. By referring to Fig. 5.2, at operating frequency 5.8GHz, the VSWR value obtained is 1.2065. It shows that the antenna is near to perfect matching.

I

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E~B^

Fig. 5.2. Return losses from optimization process

C. Radiation Patterns

Fig. 5.3 illustrates the simulated radiation pattern in terms of gain of 3.846dB. Gain is another measure to describe the performance of an antenna [27]. Aperture coupled microstrip antenna is a special class of microstrip antennas with high gain and wide bandwidth [25]. However, the result in Fig. 5.3 indicates that the gain obtained can be considered as low. This may be because the substrate used is FR-4 which has high tangent loss that will eventually results in lower gain [28]. The antenna gain may also be related to the dimension of the patch [25]. Fig. 5.3 depicts the simulated radiation pattern of a microstrip patch antenna with aperture coupler technique. The simulation result shows the major lobe directed the signal at 0 with beamwidth (HPBW) of 118.2. Meanwhile, the front-to-back ratio is the difference in dB between the level of the maximum radiation in the forward direction and the level of radiation at 180 degrees which by referring to the figure, the value is 6.9dB.

Farfield ' farf ield (f=5.8) [1] ' Gain_Abs(Theta)

Type Approximation Monitor Component Output Frequency Rad . effic. Tot- eFFic. Gain

Farfield enabled (kit >> 1) farfield CF-5.8) [1 Abs Gain 5.B -1.53J* dB -1-572 dB 3.846 dB

180 Frequency = 5.8 Main lobe magnitude = 3.8 dB Main lobe direction = 0.8 deg. Angular width (3 dB] = 1 1 8.2 deg. Side lobe level = -11.3 dB

(a) Radiation pattern in 3-D plot (b) Radiation pattern in polar plot Fig. 5.3. Simulation results on the effects of the aperture slot.

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5.1.2 Effect on Patch Slot

A Return Loss, Sn Numerical simulations and measurements are conducted on the slotted elliptical

patch antenna with and without a switch. The simulation and optimization of the design is done by commercial simulation software, CST Microwave Studio and Rohde & Schwarz ZVA40 vector network analyzer is used for the impedance measurements.

The position of the slot is changed in order to see the antenna performance. The slot is placed on the top, center and the bottom of the ellipse patch and the results are depicted in Fig.5.4. Due to the fact that the current is mostly concentrated on the periphery of ellipse patch and the current is lower at the center, hence the best position for the slot is at the center of the patch as shown in Fig. 5.4(b). The performance of the antenna is not improved even though the position of the slot is changed.

(a.} Antenna Structure

Fig. 5.4: The optimization of slot position

Hence, a modification for the slot has to be carried out in order to improve the performance of the antenna. A switch is integrated into the slot and the position of the switch is tuned (Fig.5.5) until the best results are determined. The simulation results from tuning the switch position are illustrated in Fig.5.5(b). From the results it is observed that the best position is when the switch is at 5mm from the right side of the slot. For comparison, the slotted elliptical antenna without a switch is also shown. It is observed from the figure that when a switch is introduced to the slot, the performance of return loss characteristic is better and the bandwidth is wider. The simulation result of slotted elliptical antenna without a switch shows that it has an impedance bandwidth for return loss less than -10 dB from 2.5 to 6.45 GHz. The value of return loss is -28.75 dB as illustrated in Fig.5.5(b). Meanwhile, the slotted elliptical antenna with a switch shows that the impedance bandwidth is 2.4 to 6.85 GHz. The return loss for this patch is value is -31.11 dB at resonance frequency of 3.97 GHz, which is lower than of the slotted antenna without a switch.

ib) Simulated Result

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(a) Antenna Structure i& * *&>* tf u-w. r*S* of-elm $ w $*m * t h e ?i?jtii til BI>:>I (b'| Simulated Result

Fig. 5.5: The optimization of switches position along the slot

Fig.5.6 depicts the return loss characteristics of both simulated and measured results for slotted elliptical antenna with a switch. The return loss for measured result is slightly lower as compared to the simulated result. On the other hand, the bandwidth of the measured results is greater than simulated results. However, there is a slight discrepancy between the measured and simulated return loss results in terms of frequency. The return loss for measured result is slightly lower compared to simulation result in which value at 3.4 GHz is -39.09 dB and -38.03 dB at 5.44 GHz. There is also a disagreement between the measured and simulated return loss results in terms of frequency. The inconsistency between simulation and measured results are due to some factors that would affect the results such as inappropriate handling during measurement process, soldering process and improper fabrication process.

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5

^/^

6 6 45 6 .65

Frequency (GH^)

(a) (b) Fig. 5.6: Comparison Su characteristic of simulation and measured results, (a) without a

switch (b) with a switch

B. Radiation Patterns The simulated results of the radiation patterns of the slotted elliptical antenna without

a switch are presented in Fig. 5.7. The results include polarization in the E(yz)-plane and the H(xz)-plane. The lobes cover 360 directions at the first resonance frequency of 3.97 GHz. A donut shape with an approximately omnidirectional in the H-plane pattern is also shown in Fig.5.7. The deformations appear due to the induced currents, causing in inclining the beam away from the broadside direction in the E-plane. The radiation pattern is inclined at 45

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elevation angle. In addition, the radiation pattern of the antenna is affected by the ground plane whereby the omnidirectional pattern is degraded significantly at frequencies and the radiation pattern of the antenna becomes more directional as the frequency increases beyond 5.0 GHz. This is due to the fact that as the frequency increases, more and more of higher order current modes are excited. The value of radiation efficiency is 93.2% at 3.97 GHz and 91.2% at 5.5 GHz.

im Palm plot [immm ib) Polar plot (fMtaffft) m 3 *** ^ , o t

(a)

Fig. 5.7: Simulated farfield radiation pattern in 3D at (a) 3.97 GHz (b) 5.5 GHz

4.1.3 Effect on Patch Shape

A. Return Loss, Sn

Figure 5.8 shows Sn parameters for the original air gap substrate, the original foam substrate, and the optimized wideband antenna. The frequency band for the optimized wideband antenna ranges from 8.35 GHz up to 14.07 GHz, which improves the bandwidth from 4.99 GHz to 5.72 GHz. The antenna operates at 1st resonant frequency (8.73 GHz), 2nd resonant (11.43 GHz) and 3rd resonant (13.1 GHz). The gain measured for default design at 11.355 GHz is 8.698 dB. There is 9.14% of gain improvement when comparing the gain of foam substrate at 8.73 GHz, which is 9.078 dB. In air gap substrate, at 9.15 GHz, Sn is measured to be 0.0847 (linear) while in foam substrate, Sn is 0.0058 at 8.73 GHz, which indicates smaller amount of signal is reflected back at port 1.

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\ V j* \ /Cr ^S5^%^^

Return loss or Sn represents how much incident signal at port 1 being reflected at port 1. If Sn =0dB, it indicates that all signals are reflected and nothing is radiated. As depicted in fig. 5.12, the value of Sn is measured to be -17.378 dB for Hs at its resonant frequency of 2.4GHz. Meanwhile, the magnitude of Sn for Vs1 and Vs2 are -30.353dB and -43.638dB at their respective resonant frequencies.

0 *

-5

40

< s ;-- L..

(a) (b) (c)

Fig. 5.14. Radiation patterns for (a) H-slot at 2.4GHz in polar plot, (b) V-slot at 4.6GHz in polar plot; (c) V-slot at 5.7GHz in polar plot

The values of radiation parameters for each frequency are tabulated in Table I. From the table, it shows that the vertical slot, Vs2 which operates at 5.7GHz has the highest gain and the widest bandwidth, as compared to the results of the other two slots. The gain obtained from Vs1 is the lowest while the bandwidth of Hs is the narrowest among the three slots.

TABLE I. RADIATION PARAMETERS

Type of Slot

Frequency (GHz) Gain (dB) Beamwidth at -3dB () Bandwidth (MHz)

Hs

2.4

3.916

87.7

68.39

Vs1

4.6

1.473

66.9

116.4

Vs2

5.7

5.023

62.7

276.85

4.2 Reconfigurable Single Patch Antenna The switch configurations for the horizontal slot tabulated in Table II below.

TABLE II. SWITCH CONFIGURATIONS FOR HORIZONTAL SLOT

Case No SW1 SW2 SW3

1 ON OFF OFF

2 OFF ON OFF

3 OFF OFF ON

4 ON OFF ON

5 OFF ON ON

6 ON ON OFF

7 ON ON ON

8 OFF OFF OFF

Fig 5.15 clearly indicates that there are two resonant frequencies for all cases except for case 1 whereby only one switch, SW1 is ON. For the first frequency, f1 it yields at approximately 2.356 GHz, and at 5.6 GHz for the second frequency, f2. For case 1, there is only one resonant frequency available which is approximately 2.356 GHz when only SW1 is

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ON. This shows one of the properties of a reconfigurable antenna, which is the capability to change operating frequency independently [8].

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6. CONCLUSION AND RECOMMENDATION

In this project, several antenna structures have been proposed and those structures have been designed, simulated, optimized and analyzed using CST 2009 software. A parametric study for an E-shaped wideband microstrip patch antenna using C-Foam PF-2 shows that the antenna can be operated at 8.34 GHz up to 13.86 GHz frequency band. This result is an improvement to the original specification which saw the bandwidth is expanded from 4.99 GHz to 5.72 GHz. Other parameters such as gain, S

7. RESEARCH OUTCOMES

Publications

Number of articles/ manuscripts/ books (Please attach the paper)

Conference Proceeding (Please attach the paper)

List of published journal/article/proceeding (APA/IEEfromat)

Indexed Journal

International

3

Non-Indexed Journal

National

S. Muhamud @ Kayat, M. T. AN and M. K. M. Salleh , A Reconfigurable Microstrip Antenna with a Slotted Patch at Dual Frequency, IEEE 8th International Symposium on Wireless Communication Systems (ISWCS), Aachen, Germany, 2011

S. Muhamud @ Kayat, M. T. Ali, M. H. M. Zaharuddin, M. N. Md Tan and A. L. Yusof, Wideband Microstrip Single Patch Antenna, Proceeding of International Symposium on Antennas and Propagation (ISAP), Jeju, Korea, 2011

S. Muhamud @ Kayat, M.T Ali, E. Adznina and M. K. M. Salleh, A Slotted Elliptical Antenna for Wideband Applications, Proceeding of International Symposium on Antennas and Propagation (ISAP), Jeju, Korea, 2011

Human Capital Development

Human Capital

Citizen

PhD Students Master Students Undergraduate Students

Total

Number On-going

Malaysian

2

2

4

Non Malaysian

Graduated

Malaysian Non Malaysian

Others (please specify)

18 COPYRIGHT UiTM