Design and Simulation of wideband Microstrip U-T slot Patch Antenna for Wireless Application
Parsuram Pradhan, Manoj Kumar Das
Abstract— In this paper, microstrip antenna designed for wide band application by cutting a U-T slot in the patch .The patch antenna with U-T slot is used for wide band application with very low return loss .The coplanner waveguide feeding is used to increase the bandwidth with better vector impedance matching.The patch antenna has been designed and simulated using IE3D software .The wide band antenna resonates at 4.2 GHz and 5.5 GHz .For U-T slot wide band antenna the bandwidth is 2.11 GHz covers some of the band used for WLAN and WiMAX .So the proposed antenna can be used for WLAN and WiMAX.
Index Terms Bandwidth, WLAN,WiMAX, Resonant Frequency, VSWR, CPW Feed.IE3D
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1 INTRODUCTION Here is huge demand of microstrip antennas Which can operate over multiple bands due their virtual role played in wireless communication system .The IEEE 802.11
standard was proposed in 1997 WLANs , operating on 2.4 GHz ISM band (2.4-2.484 GHz) and IEEE 802.11a standard was provide the 5 GHz ISM band (5.15-5.35 GHz and 5.725-5.825 GHz) .Microstrip patch antenna has tremendous scope in WLAN and WiMAX application due to their low profile plat-form design ,small size, low cost of fabrication process , light in wight and ease of installation process [1].The general mi-crostrip antenna s have disadvantage that narrow band width and low gain [2].The probe feed antenna required a large size of ground plane which is printed on the different side of the sub-strate from the radiating patch subjected to manufacturing diffi-culty and high cost[3].The coplanar Wave Guide fed antenna have been widely used for wireless communication owing to their attractive features such as wide bandwidth ,simplest struc-ture of a single metallic layer ,no soldering points and easy in-tegration with MMICs,etc.The rapid devlopement of wireless communication systems, specially the WLAN and WiMAX ap-plication ,which cover most of the bands of have aroused much intrest in the broadband. In this paper ,a proposed antenna de-sign with CPW fed has been used for Wireless applications. The prposed antenna consist of U-T shaped patch element .Details of the antenna design are described and simulated return loss and antenna gain results are presented. 2. Antenna Design The proposed antenna geometry is shown in fig.1where a coplaner Waveguide (CPW) fed is used .The proposed anten-na was designed on FR4 (Flame Retradant and type 4)with dielectric constant rε of 4.4 and thickness h of 1.6 mm and loss tangent of 0.0012. To meet the actual design requirements i.e operating frequency ,bandwidth, and radiation pattern some approximation are considered .The calculation are based on the transmission line model [1].
The width of the antenna at resonant frequency is rf
)1(..1
22
−−−−−−−−−−−−−−−−−−+
=rrf
cwε
C=speed of the light Length of the patch is
)2(2
−−−−−−−−−−−−−−−−−−−−=effrf
cLε
Where effε is the effective dielectric constant of the substrate .to measure for the fringing effects ,the lengthe of the patch needs correction factor .The actual lengt is
)3(22
−−−−−−−−−−−−−−−−∆−= Lf
cLeffr
eff ε And the correction factor found using equation (4)
)4()8.0)(258.0(
)264.0)(3.0(42.0 −−−−−−−−−
+−
++=∆
hw
hw
hLeff
eff
ε
ε
Where h is the height of the substrate .The effective dielectric constant
)5()121(2
12
1 21
−−−−−−−−−−−+−
++
=−
whrr
effεεε
The final optimized dimension of proposed antenna are listed below (all in mm)
2. SIMULATION RESULTS AND DISCUSSION In this section simulations and results for the return loss ,vswr radiation pattern, gain of the designed antenna are measured and presented. The frequency Range of 2 to 7 GHz is used for simulations as the WiMAX and WLAN frequency bands lies in this range The simulated return loss of the proposed antenna shown in figure 2.The antenna operates in broad band fre-quency from 3.6 GHz to 5.97GHz covering some of the WLAN and WiMAX band.
The parametric study have critical influence on antenna per-formance.This parametric study is carried out by simulating the antenna with one geometry parameter slightly changed from the reference design while all the other parameter are fixed. For this the effect of gap- distance “d” on the perfor-mance of the antenna is studied and presented in figure. 3 At distance d= 1mm the antenna has better return loss
The variation of return loss due to the change of the width (w) of the antenna is given in figure .4.Hence it is shown that the variation of width doesn’t show significant effect on band-width.
The variation of return loss due to the change of the ground plane width (wg) of the antenna is given in figure.5.From the simulation it is clear that there is less effect of return loss due to variation in the ground plane width of the patch.
Figure-2 return loss of proposed antenna
Figure 3 Effect of variation of gap distance (d) between the feed –line and the ground plane on return loss
. Figure 5 . Effect of variation wg on return loss
Figure. 4 Effect of variation w on return loss
Figure.1
Geometry of the proposed CPW fed microstrip antenna
Figure 7 shows the gain of the antenna the maximum gain of the antenna at 5.8GHz is 4.8 dBi, at 5.2GHz is 4.2 dBi and 5.5 is 4.6dBi.
Simulated result shows that the maximum antenna efficiency is approximately 100% at 5.4887 GHz and 4.0904 GHz.
The radiation charecterstic are presented in fig 8(a),(b) (c),(d),(e),(f),(g) and (h). The measured two dimensional (2-D) patterns at various resonant frequencies with respect to total power in azimuthal plane (x-y planes) and elevation and ele-vation angle (y-z plane) are shown. It observed that radiation pattern are nearly good omnidirectional patterns at all fre-quency E-plane (x-y planes) and H plane (y-z plane).So this pattern is suitable for most wireless applications.
The 3-d radiation pattern are shown in figure 9 represent the total radiation power,While the 2-d radiation pattern demon-strates the E and E components separately .radiation prop-erty include power flux density, radiationintensity, field strength and directivity of the antenna.
4. Conclusion A U-T slot microstrip antenna operating in wideband has been proposed and investigated.The antenna has bandwidth of 2.11GHz(3.859-5.971GHz).The designed microstrip patch an-tenna with CPW fed technology for WLAN and WiMAX oper-ating frequencies has been presented and discussed. We con-clude that when the spacing between the ground planes and the feed line is 1mm has a better returnloss with a higher gain.The simulated results of return loss and VSWR have been presented and discussed .Obtained results shows that the an-tenna operates effectively over the some of WLAN and Wi-MAX communication bands.
ACKNOWLEDGMENT The authors wish to thank C V Raman College of engineering, Bhubaneswar for assistantce to Design and Simulate the pro-posed antenna in their R&D Lab and also thanks to Dr.(Prof) P. Kanungo for providing facilities in their research Lab.
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