CIRCULAR SHAPED WEARABLE TEXTILE MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATION

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CIRCULAR SHAPED WEARABLE TEXTILE MICROSTRIP PATCH

ANTENNA FOR WLAN APPLICATION

Gaurav Varma¹, Ramesh Kumar Verma²

1PG Student, Department of Electronics & Communication Engineering

2Research Scholar, Department of Electronics & Communication Engineering Bundelkhand Institute of Engineering & Technology, Jhansi, UP, India

Email: [email protected]¹, [email protected]²

ABSTRACT

This paper is explained a circular shaped wearable slot loaded textile microstrip patch antenna. The WLAN application is suitable for this antenna due to operating frequency band 2.54GHz to 4.04GHz. The resonant frequency of this antenna design is 3.71GHz. In this frequency band, antenna resonates with return loss -17.29dB at resonant frequency 3.71GHz.

For this antenna design, jeans fabric is used as a textile substrate. The relative permittivity of jeans fabric is 1.6. The thickness of fabric is 1mm and the loss tangent (δ) is 0.025. The antenna shape, height of substrate and feeding techniques improve the bandwidth of microstrip antenna. The projected textile antenna gain is 5.56dB and antenna efficiency is 94.09%. Software IE3D is used for the design and simulation of circular shaped wearable textile antenna.

Keywords: Circular, Textile, Jeans fabric, IE3D, WLAN applications.

I. INTRODUCTION

With the remarkable & phenomenal growth and use of wide band wireless communication systems more and more people is taking about advantage of portable computing systems on daily basis. The use of textile antenna not only in medical line but it also use in military, these antenna fabricate on military clothes to detect the location of solders and communicate easily with them at the time of war. This antenna has low weight, small size and flexible due to these reasons. This is easily integrated on wearable textile and easily closed to human body. Textile antenna is a type of microstrip patch antenna but in which the textile use as a substrate so it is called textile antenna. There are many shapes [1]

of microstrip patch antenna like rectangular, triangular, circular and ring etc.

In following antenna design, a circular shaped wearable textile microstrip antenna is designed which contain a circular patch of radius 30mm.The radius of patch is calculated by predefine equations. All the dimensions are in mm. In this design the cut the slots of rectangular shape. One slot of the patch at which connector is connected by probe feeding and another patch work as parasitic patch. There are many types of feeding techniques use but in this antenna design, probe feeding is used for feeding the antenna which connect the ground

and patch. The IE3D software is used for simulation of this antenna for 2GHz to 5GHz. This antenna design achieves bandwidth about 45.59%. The antenna resonates from 2.54GHz to 4.04GHz. This range of frequency band is useful for WLAN application [4].

From the simulation result, we can see that the microstrip patch antenna with parasitic patch find better results.

II. DESIGN PROCEDURE OF ANTENNA

Width W of rectangular patch is calculated by [9]

W

=

^𝑐

2𝑓𝑟

√

_𝜀²

𝑟+1 (1) Where, c is speed of light (3x10⁸ m/s) in free space, εr is dielectric constant, ƒr is design frequency and εreff is effective dielectric constant given as [9]

𝜀𝑟𝑒𝑓𝑓=^𝜀^𝑟⁺¹

2 +^𝜀^𝑟⁻¹

2 (1 +^12h

W)⁻

1

2 (2) Extension length, ΔL is calculated by [9]

^∆𝐿

ℎ = 0.412^(𝜀^{𝑟𝑒𝑓𝑓}^+0.3)(

𝑊 ℎ+0.264) (𝜀_{𝑟𝑒𝑓𝑓}−0.258)(^𝑊

ℎ+0.8) (3) Actual length of patch is calculated as [9]

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©IJETIE 2019 𝐿 = ^𝑐

2𝑓_𝑟

√𝜀𝑟𝑒𝑓𝑓

− 2∆𝐿 (4) Length and width of rectangular ground plane are calculated as [9]

𝐿𝑔=6h+L (5) 𝑊𝑔=6h+𝑊 (6)

III. ANTENNA DESIGN SPECIFICATIONS The jeans fabric is used as a textile substrate for this antenna design. The dielectric constant of 1.6, height of the dielectric substrate h=1mm [5] and loss tangent (tan δ) =0.025 are selected for the fabrication of this antenna. The designing frequency (fr) is 3.71GHz. All the design parameters are given in table 1.

Table1:Design specifications of projected antenna

The length of ground is 60mm and width is 60mm of this antenna. The measurements of ground plane and patch are started from (0, 0) at center for designing the projected antenna in IE3D software tool. Projected geometry of antenna is obtained after various modifications such as slotting and notching inside the circular patch. A circular patch of radius 25mm is designed at centre of ground substrate as shown in figure 1(a). Then a square slot of length 30mm and width 30mm is cut at the centre of circular patch. Two vertical slot of length 10mm and width of 2mm are cut at the top and bottom of the patch that divides the patch in two parts. If feed is connected on one part of patch, then other part of patch works as a parasitic patch. The feed is connected at the co-ordinate (1.6, -17.7) from centre of patch. The projected textile antenna geometry is shown in figure 1(b).

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Figure.1 Geometry of projected circular patch antenna IV. RESULTS AND DISCUSSION

The projected circular patch antenna is analyzed through IE3D simulator [10]. Antenna is simulated between 2GHz to 5GHz. This designed antenna covers range of frequency between 2.54 GHz to 4.04 GHz as a lower cutoff to highest cutoff frequency respectively with return loss of -17.29dB. It displays maximum return loss of -17.29dB at 3.71GHz, illustrated in figure 2. According to analysis of return loss graph, it produced the bandwidth 45.59% with 3.71GHz resonant frequency.

S. No Parameters Value (mm) 1. h(height of substrate) 1 2. Lg (length of ground) 60 3. Wg (width of ground) 60 4. Rp (radius of patch) 25 5. R(Length of vertical slot) 10 6. S(Width of vertical slot) 2 7. Q(Length of square slot) 30 8. P(Width of square slot) 30 9. Feed location (1.6, -17.7)

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©IJETIE 2019 Figure.2. Bandwidth of projected textile antenna

Projected slotted textile antenna has VSWR of 1.316 at 3.71GHz. Gain and directivity of antenna is 5.56dB and 5.92dB respectively at resonant frequency 3.71GHz which is presented in figure 3, figure 4 and figure 5. This projected antenna has high antenna efficiency about 94.09% at 3.16GHz which shown in figure.6. Smith chart is a graphical representation of impedance as shown in figure 7. Stimulated 2D and 3D radiation pattern are displayed in figure 8 and figure 9. 2D radiation pattern is measured at phi equal 0º and 90º.

Figure.3. VSWR of projected textile antenna

Figure.4. Directivity of projected textile antenna

Figure.5. Gain of projected textile antenna

Figure.6. Antenna efficiency of projected textile antenna

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Figure.8. 2D Radiation pattern of projected textile antenna

Figure.9. 3D Radiation pattern of projected textile antenna

V. CONCLUSION

A slot loaded 50Ω microstrip fed line circular shape textile MPA has been simulated by IE3D and designed on jeans fabric substrate which produces a bandwidth of 45.59% and maximum antenna efficiency of about 94.09% at frequency 3.16GHz. This antenna is designed to cover frequency band of 2.54GHz to 4.04GHz suitable for S band applications.

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