miniaturized z-shaped uwb antenna

8/9/2019 Miniaturized Z-shaped UWB Antenna

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Miniaturized Z-shaped Micro-strip Ultra-wideband Antenna

Prepared By:

Sagar Kumar Dhar

ID: g201206700



Table of Contents

Abstract ........................................................................................................................................... 4

Introduction ..................................................................................................................................... 4

Literature Review............................................................................................................................ 6

UWB Antenna Technique ............................................................................................................. 10

Antenna Miniaturization Technique ............................................................................................. 11

Proposed Antenna Structure ......................................................................................................... 11

Miniaturization Using L shaped Slot ............................................................................................ 12

Scaled and Parametric Analysis .................................................................................................... 13

Future Works ................................................................................................................................ 15

Conclusion .................................................................................................................................... 15

References ..................................................................................................................................... 16



List of Figures

Figure 1 Possible UWB communication application ...................................................................... 5

Figure 2 Dual ring UWB antenna [8] ............................................................................................. 6

Figure 3 UWB Antenna: top view (left) and bottom view (right) [9] ............................................ 7

Figure 4 Square Ring UWB Antenna [10] ...................................................................................... 7

Figure 5 Reconfigurable UWB Antenna [11] ................................................................................. 8

Figure 6 UWB monopole antenna [12] ........................................................................................... 8

Figure 7 Z shaped compact narrow band antenna .......................................................................... 9

Figure 8 Z shaped UWB antenna structure [14] ............................................................................. 9

Figure 9 Multiband Z-shaped antenna [15] .................................................................................. 10

Figure 10 Proposed Antenna Structure ......................................................................................... 11

Figure 11 Return loss plot S11...................................................................................................... 12

Figure 12 Miniaturization Using L-shaped slot ............................................................................ 13

Figure 13 Return loss plot of miniaturized antenna ...................................................................... 13

Figure 14 Scaled structure for parametric analysis ....................................................................... 14

Figure 15 Parametric simulation of rectangular ring .................................................................... 14

List of Tables

Table 1 FCC Restrictions [2] .......................................................................................................... 5



Abstract

Micro-strip UWB antennas are highly desirable cause of their unique features such as low cost,

low weight, simple structure and small size where UWB antennas are required in the many

today’s wireless communication system cause of their advantages such as high data rate, spatial

resolution in radar and imaging technique. A miniaturized UWB antenna with high gain and

omnidirectional radiation pattern is required for all of these systems for seamless operation. In

this work, a miniaturized Z-shaped antenna is proposed in the range of 1.72 to 2.94 GHz which

covers the 2.4 GHz WLAN application having fractional bandwidth of 52% and of the size

18mm*25mm. 17% size reduction is observed using an L-shaped slot in the Z-shaped patch.

However, more fraction bandwidth and size reduction is possible and to cover the whole

3.1GHz-10.6GHz range is desirable.



Introduction

Ultra-wideband (UWB) systems are associated with larger bandwidth typically refer to the

systems having fractional bandwidth greater than or equal to 20% [1]. Due to its extremely wider

operating bandwidth, such systems are potential for high data rate communication, can provide

high spatial resolution and resistant to multipath fading. But there are Federal Communication

Commission (FCC) restrictions for UWB emission. According to FCC rules, UWB unlicensed

commercial application should follow the emission limits shown in Table I and according to this

rules, highest allowed UWB emission is in the range of 0.5-0.96GHz and 3.1-10.6GHz and the

maximum allowable emission is -41.3dBm/MHz [1]. This restriction in emission limits the range

of operation of UWB system which typically lies in the range of 10m or a few 10m. However,

within the range, portable and handheld devices have good opportunity to communicate with

higher data rate even in Gbps range. Figure 1 shows such possible applications of UWB system

in portable devices like laptop, mobile, projector, printer etc. as WLAN communication system.

Table 1 FCC Restrictions [2]

Frequency

(GHz)

Max.

Power in

dBm/MHz

Frequency

(GHz)

Max.

Power in

dBm/MHz

0.5-0.96 -41.3 1.99-3.1 -51.3

0.96-1.61 -75.3 3.1-10.6 -41.3

1.61-1.99 -53.3 10.6-50.6 -51.3

Figure 1 Possible UWB communication application

On the other hand, cause of high band width, UWB systems can provide high spatial resolution

and high resistant to multipath fading which are useful for low range wireless and wearable

biosensors, contactless remote healthcare system, imaging and radar systems [3], [4], [5], [6].

However, all these lucrative features of wireless communication system requires UWB antenna

at the same time for unaltered system performance.



On the other hand, commercial UWB systems require small low-cost antennas with

omnidirectional radiation patterns and large bandwidth. It is a well-known fact that planner

antennas present really appealing physical features, such as simple structure, small size and low

cost than any other antenna types. Due to all these interesting characteristics, micro-strip

antennas are extremely attractive to be used in emerging UWB applications and growing

research activity is being focused on them. In this work, a miniaturized Z-shaped UWB antenna

is presented for WLAN application in the range of 1.72 to 2.94 GHz which covers the 2.4 GHz

WLAN application having fractional bandwidth of 52% and of the size 18mm*25mm.

Literature Review

In literature, different UWB antennas can be found but for seamless operation throughout the

band, a UWB antenna should show high gain and linear phase at the operating band. Moreover,

for the portable and handheld devices, miniaturized UWB antennas are highly recommendable.

But reduction in size reduces the bandwidth and gain which causes the uttermost challenge in

UWB Antenna design. In this work, among different UWB antenna technique, slotted patch

geometry are chosen to be worked with and related literature review in this perspective is

presented.

[7] presents an annual ring UWB antenna in the range of 2.8 to 12.3GHz and also provide almost

omnidirectional radiation pattern. But the size of the antenna in this work presented is large

which is 44mm×44mm. [8] presents a dual ring UWB antenna in the range of 31 to 42.8GHz

with fractional bandwidth which used slotted patch technique for UWB realization. The

technique behind the structure presented in [8] is using two radiator rings radiate in adjacent

bands provides wideband together shown in Figure 2.

Figure 2 Dual ring UWB antenna [8]

[9] presents triple band UWB antenna at 3.5/5.5/7.2GHz which also used slotted technique for

UWB realization. In this work, pair of C shaped and one U shaped slot in the radiating patch are

used and dual I shaped slots are used in the ground plane as shown in the Figure 3. The size of

the antenna is larger which is 32mm×28mm : 0.384λ *0.336 λ at 3.5GHz.



Figure 3 UWB Antenna: top view (left) and bottom view (right) [9]

[10] presents band notched square ring UWB antenna in the range of 3-14.6GHz which has

fractional bandwidth of 130% using pairs of T shaped patch in the radiating element and π

shaped patch in the ground plane. This work also present relatively low sized structure of

12mm×18mm: 0.18λ *0.25 λ at 4.2 GHz and also provide omnidirectional radiation pattern.

Figure 4 Square Ring UWB Antenna [10]

[11] presents on the other hand a reconfigurable UWB antenna possible to tune within the range

3.7 to 4.2GHz and 5.15 to 5.825 GHz electronically. Low fractional bandwidth is offered by this

structure with larger size of 45mm×40mm: 0.55 λ *0.49 λ at 3.7GHz. This work also used slotted

technique for UWB realization needed to be improved with the size.



Figure 5 Reconfigurable UWB Antenna [11]

[12] presents a compact ring monopole UWB antenna in the range of 3.1-10.6GHz with the size

of 20mm×30mm can be reduced in dimensions.

Figure 6 UWB monopole antenna [12]

[13] presents a Z shaped antenna structure with the size of 10mm×11mm: 0.1λ×0.1λ which

works at around 2.4GHz but provides very narrow bandwidth and can be modified for UWB

applications.



Figure 7 Z shaped compact narrow band antenna

[14] presents another Z-shaped antenna oriented inversely for UWB realization provides

frequency of operation in the range of 2.9 to 5.6GHz which covers the 5GHz WLAN and

3.5GHz WiMax. Size of the antenna was 40mm*40mm: 0.47λ *0.47 λ at 3.5GHz which is larger

comparatively and needed to be improved for USB type devices or so on.

Figure 8 Z shaped UWB antenna structure [14]

[15] presents multiband Z-shaped antenna structure operate at 2.5 GHz, 3.5GHz and 5.7GHz

with the size of 33m×28mm: 0.28 λ *0.23 λ at 2.5GHz. However, the structure can be improved

for UWB systems with proper slotted technique.



Figure 9 Multiband Z-shaped antenna [15]

Among all of the works reviewed, it is evident that slotted patch technique can be a possible

solution for UWB antenna realization with excellent gain and omnidirectional radiation pattern.

In this work, a new miniaturized Z-shaped UWB antenna structure is designed and analyzed

which provides frequency of operation in the range of 1.72 to 2.94 GHz which covers the 2.4

GHz WLAN application having fractional bandwidth of 52% and of the size 18mm*25mm.

UWB Antenna Technique

Ultra-wideband antennas with high gain and omnidirectional radiation pattern are highly

desirable for WLAN application and other imaging and radar technology. Due to attractive

features of the micro-strip antenna, UWB antennas are highly desired to be built on micro-strip

structure. But micro-strip structures are by default single frequency structure which throws a big

challenge in UWB antenna realization in micro-strip structure. However, over the years some

techniques are applied for UWB antenna realization from narrow band micro strip antennas:

1. L shaped probe

2. Slotted patch

3. Electromagnetic band gap (EBG) structure loading

4. Fractal structure

Among all of these four techniques, slotted patch is mostly used and desirable cause of its cost

effectiveness and planar structure. In this work, this technique is adopted for transforming a

narrow band Z antenna to a UWB antenna structure.



Antenna Miniaturization Technique

Miniaturized antenna refers to the electrically small antenna i.e. the physical length is smaller

than the corresponding wavelength at operational frequency [16]. Miniaturized antennas are

highly desirable for modern wireless communication system. But, reduction in size reduces the

bandwidth and gain which is the uttermost challenge in the miniaturized UWB antenna design.

Several miniaturization techniques can be used such as:

1. Loading the antenna with high contrast materials (high permittivity material)

2. Modifying antenna geometry and shape

3. Loading the antenna with lumped element to compensate the large reactance part of

the antenna impedance when size is reduced.

4. Use of meta-materials

In this work, modification in antenna structure is chosen to be worked with since it’s the most

convenient and intelligent manner that will provide low cost as well as rugged and small design.

Proposed Antenna Structure

In this work, a miniaturized Z-shaped UWB antenna is presented for WLAN application in the

range of 1.72 to 2.94 GHz which covers the 2.4 GHz WLAN application having fractional

bandwidth of 52% and of the size 18mm*25mm, material used: FR4. Figure 10 and Figure 11

show the proposed antenna structure and its return loss S11 plot consecutively.

Figure 10 Proposed Antenna Structure



Figure 11 Return loss plot S11

The key features of the proposed antenna are listed below:

• Operating Frequency Band: 1.72GHz to 2.94GHz

• Fractional Bandwidth: 52%

• Size: 18mm*25mm: 0.13 λ *0.18 λ at 2.18GHz

•

Lowest size ever reported

• Can Cover WLAN at 2.4GHz band

Miniaturization Using L shaped Slot

Once the Z shaped antenna resonates at 2.18 GHz, introducing an L shaped slot in the Z shaped

patch, reduces the center frequency to the 2GHz instead of 2.18 GHz which provides

miniaturization and size of the antenna becomes 0.12λ×0.16λ which indicated 18% of size

reduction. So, L shaped slot provides 18% miniaturization which is attractive very much. In

Figure 12, L shaped slotted Z-shaped UWB antenna is shown and its return loss plot is shown inFigure 13.

0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00Freq [GHz]

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

d B ( S ( 1 , 1

) )

HFSSDesign1XY Plot 2 ANSOFT

MX2: 2.9400

MX1: 1.7201

m1

-10.0986 -10.0096

1.2199

Curve Info

dB(S(1,1))Setup1 : Sw eep

Name X Y

m1 2.1800 -26.6421



Figure 12 Miniaturization Using L-shaped slot

Figure 13 Return loss plot of miniaturized antenna

Scaled and Parametric Analysis

The Z-shaped structure is a narrowband structure by nature. In this work, the narrowband Z-

shaped structure is turned into a UWB antenna using rectangular ring. The optimum size of the

rectangular ring for better return loss and UWB feature is set by parametric analysis in HFSS

13.0. The parametric simulation is shown in Figure 14. In this simulation, the structure is also

scaled to : 14mm*18mm which provides the ultrawideband in the range of 2.3to 3.8GHz at the

center frequency of 2.9GHz.

0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00Freq [GHz]

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

d B ( S ( 1 , 1

) )


MX2: 2.6552

MX1: 1.6500

m1

-10.0011 -10.0049

1.0052

Curve Info

dB(S(1,1))Setup1 : Sw eep

Name X Y

m1 2.0600 -23.2432



Figure 14 Scaled structure for parametric analysis

Figure 15 Parametric simulation of rectangular ring

0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

Freq [GHz]

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

d B ( S ( 1 , 1 ) )


MX1: 2.3000

MX2: 3.8200

-10.6706 -10.6606-10.3293-10.1038-9.6702 -9.4223

-10.0191

-7.4977-6.2323

-5.4870 -5.3081-4.2690

1.5200

Curve Info

dB(S(1,1))Setup1 : Sweepk='10mm'








Future Works

In this work, a new Z-shaped UWB antenna is investigated with UWB and miniaturization

technique and successfully simulated. However, the structure can be improved for higher

features such as:

•

Can be optimized for larger bandwidth without changing its size so that same antenna can

cover the LTE, GSM, WLAN, WiMax as well as ISM band

• This antenna structure can be a good candidate for MIMO system: uncoupled behavior of

the antenna can be tested.

• Further miniaturization can be offered by slow wave loading using passive or active

elements

Conclusion

In this work, a miniaturized Z-shaped UWB antenna is presented for WLAN application in the

range of 1.72 to 2.94 GHz which covers the 2.4 GHz WLAN application having fractional

bandwidth of 52% and of the size 18mm*25mm. Miniaturization using an L shaped slot in the

patch is realized which gives 17% reduction in size. Successful simulation results in the HFSS 13

ensure the feasibility of such structures for real time implementation. However, it is also possible

to improve the fractional bandwidth with proper slotted patch design without affecting size is

highly desirable.



References

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applications,” in 5th IFIP International Conference on Wireless and Optical

Communications Networks, 2008. WOCN ’08, 2008, pp. 1 – 5.[2] G. Breed, “A summary of FCC rules for ultra wideband communications,” High Freq.

Electron., vol. 4, no. 1, pp. 42 – 44, 2005.[3] F. Mohammad-Zadeh, F. Taghibakhsh, and B. Kaminska, “Contactless Heart Monitoring

(CHM),” in Canadian Conference on Electrical and Computer Engineering, 2007. CCECE

2007 , 2007, pp. 583 – 585.

[4] B. Gupta, E. Cianca, M. Ruggieri, and R. Prasad, “A novel FM-UWB system for vital signmonitoring and its comparison with IR-UWB,” in 2nd International Symposium on AppliedSciences in Biomedical and Communication Technologies, 2009. ISABEL 2009, 2009, pp. 1

– 4.

[5] M. Jelen and E. M. Biebl, “Multi-frequency sensor for remote measurement of breath andheartbeat,” Adv Radio Sci, vol. 4, pp. 79 – 83, Sep. 2006.

[6] A. Lazaro, D. Girbau, R. Villarino, and A. Ramos, “Vital signs monitoring using impulse

based UWB signal,” in Microwave Conference (EuMC), 2011 41st European, 2011, pp. 135 – 138.

[7] Y.-J. Ren and K . Chang, “An Annual Ring Antenna for UWB Communications,” Ieee

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[8] Y.-J. Ren and K. Chang, “An Ultrawideband Microstrip Dual-Ring Antenna for Millimeter-Wave Applications,” Ieee Antennas Wirel. Propag. Lett., vol. 6, pp. 457 – 459, 2007.

[9] C. Wang, Z.-H. Yan, P. Xu, and B. Li, “A triple band-notched UWB printed antenna with

various slots,” Microw. Opt. Technol. Lett., vol. 54, no. 9, pp. 2088 – 2091, 2012.[10] M. Ojaroudi, S. Yazdanifard, N. Ojaroudi, and R. A. Sadeghzadeh, “Band-Notched Small

Square-Ring Antenna With a Pair of T-Shaped Strips Protruded Inside the Square Ring for

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[11] A.-A. Kalteh, G. R. DadashZadeh, M. Naser-Moghadasi, and B. S. Virdee, “Ultra-wideband circular slot antenna with reconfigurable notch band function,” Iet Microwaves

Antennas Propag., vol. 6, no. 1, pp. 108 – 112, 2012.

[12] M. K. Yang, G. p. Gao, S. F. Niu, and J. S. Zhang, “Study of a compact ring monopoleUWB antenna with band-notched characteristic,” Microw. Opt. Technol. Lett., vol. 54, no.

10, pp. 2387 – 2392, 2012.

[13] S. Ashok Kumar and T. Shanmuganantham, “Implantable CPW fed Z-shaped antenna for

ISM band,” in 2013 National Conference on Communications (NCC), 2013, pp. 1 – 4.[14] P. Ranjan, N. Kishore, I. Singh, and V. S. Tripathi, “Inverted Z and circular slot patch

antenna for WLAN and WiMAX,” in 2012 2nd International Conference on Power, Control

and Embedded Systems (ICPCES), 2012, pp. 1 – 5.

[15] W. T. Li, Y. Hei, J. Yang, and X.-W. Shi, “Novel design of printed multiband antenna forwireless applications,” in 2012 International Conference on Microwave and Millimeter

Wave Technology (ICMMT), 2012, vol. 3, pp. 1 – 3.

[16] J. Volakis, C.-C. Chen, and K. Fujimoto, Small Antennas:Miniaturization Techniques & Applications, 1st ed. McGraw-Hill Professional, 2010.

miniaturized z-shaped uwb antenna

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