Analysis and Implementation of Fractal Antenna

Transcription

1 Analysis and Implementation of Fractal Antenna Shahnil Noorani 1, Aliza Shaikh 2, Ruksar Shaikh 3, Abdul Sayeed 4 Electronics and Telecommunication Department, M.H. Saboo Siddik College Of Engineering, Mumbai. Abstract This paper presents the Sierpienski Carpet Fractal Antenna(SCFA) for multiband applications. Ansoft High Frequency Structural Simulator (HFSS) software is used for simulation purpose. The FR-4 epoxy with relative permittivity 4.4 and height 1.6 mm is taken as substrate material for the design of suggested antenna. This antenna is fed by a 50 ohm edge feed. The suggested antenna is simulated up to 2nd iteration. The hardware implementation of SCFA is also carried out. Return losses of suggested antenna are measured using Vector Network Analyzer (VNA). Experimental results show that suggested antenna works at three resonant frequencies having values (in GHz) , , , and exhibits the multiband behavior. The measured and simulated results are compared. Return Loss (RL), VSWR gain and radiation pattern are used to evaluate performance of this antenna. Keywords Fractal antenna, sierpinski carpet, multiband, edge feed; gain. return loss, multiband I. INTRODUCTION Light weight, low profile are the properties of Microstrip antenna due to which it has been significantly used for the applications in different fields such as radar navigation, WLAN, satellite etc [13]. The basic patch shaped microstrip antenna has drawbacks such as size, single band.modern communication systems need antennas with lesser dimensions and more bandwidth [9].The BW of antenna can be improved by decreasing dielectric constant of substrate material or increasing substrate height. Increase in substrate height makes it bulky which is unwanted as per particular application. To overcome these limitations, antenna with multiband feature is primarily required these days [3]. Fractal antenna is a fascinating advancement to overcome this problem. It has two main characteristics: self-similarity and space filling [10].The space-filling characteristic describes the reduced size of antenna and self-similarity characteristic depicts the multi-band behavior of antenna [8]. A Fractal is a recurring structure having a fractional dimension which provides broad - flexibility in antenna analysis and design [10]. Fractals are generally independent of scales [7].Fractal antennas are designed in different shapes, like Koch Island, Sierpinski Carpet, Minkowski Loop and Sierpinski Gasket [4]. Fractal designs are useful for purpose of multi-band and reduced size antenna [14]. II. ANTENNA DESIGN AND CONFIGURATION The geometries of suggested antenna are represented in fig. 1(a) to 1(c) respectively. FR-4 epoxy substrate material is used for the fabrication and simulation of suggested antenna with height 1.6 mm and dielectric constant 4.4. The resonant frequency is chosen 2.4 GHz. The equations 1-4 are used forcalculating the dimensions of patch and are in [6] [8]. a. b. c. Fig 1. Geometries of a. 0 th, b. 1 st, c. 2 nd iteration Where c is light velocity in free-space. IJRTI International Journal for Research Trends and Innovation ( 75

2 (2) The expression for extension of length as in [6] [8] is given by (3) Then actual length of patch is calculated using the expression as given in [6] [8]. The dimensions of ground plane are calculated by using formula as given in [6] [8]. (4) TABLE I. _ ANTENN A DESIGN SPECIFICATIONS OF SUGGESTED S. No. Antenna Parameters Dimensions 1 2 Length of substrate (L) Width of substrate (W) mm mm 3 Dielectric constant Thickness of substrate 1.6 mm 5 6 Ground plane length (L) Ground plane width (W) mm mm 7 Length of patch (L 1 ) mm 8 Width of patch (W 1 ) mm 9 Feed location (mm) 10 Length of edge feed mm 11 Length of feedline mm IJRTI International Journal for Research Trends and Innovation ( 76

3 Fig 2. Front view of fabricated antenna III. RESULTS AND DISCUSSIONS Simulation results of projected antenna such as return losses, radiation pattern and VSWR are calculated by using Ansoft HFSS software. A. Return Loss Fig 3. Return loss for 0 th iteration The return loss is dB at GHz Fig 4. Return loss for 1 st iteration The return loss is dB at GHz and dB at GHz. IJRTI International Journal for Research Trends and Innovation ( 77

4 Fig 5. Return loss for 2 nd iteration Return Loss at frequency GHz is dB, at GHz is , and at GHz is Return Loss (RL) graph or scattering parameters graph also known as S-Parameters graph is used to measure the reflection and transmission losses between the incident and reflection waves [12]. Fig. 3 shows the simulated results of different iterations from 0 th to 2nd. Each iteration result shows that the return losses are less than -10 db at each resonating frequency. Fig. 4, 5 and 6 shows the comparison of measured and simulated results of return loss of SCFA. The results for VSWR and RL are measured using VNA. B. VSWR Fig 6. VSWR of 0 th iteration At 2.4GHz the VSWR is IJRTI International Journal for Research Trends and Innovation ( 78

5 Fig 7. VSWR of 1 st iteration At GHz VSWR is , at GHz VSWR is Fig 8. VSWR of iteration 2 nd iteration At GHz is , at GHz is ,at GHz is VSWR results shows that the values are near unity circle. VSWR equal to unity is an ideal case in which all the power is reflected. Close to one indicates maximum power is reflected. The measured results using vna i.e vector network analyser are:- A. Return Loss Fig 9. Return loss measured using VNA. The values obtained are:- Three frequencies i.e GHz, GHZ, GHz with respective return losses of dB, dB, dB. B. VSWR Fig 10. VSWR measured using VNA. The values obtained are:- At GHz VSWR is 1.309, At GHz VSWR is 1.634, at GHz VSWR is IJRTI International Journal for Research Trends and Innovation ( 79

6 C. Smith Chart Fig 10. VSWR measured using VNA. At GHz impedance is 54.2 Ohms,at GHz impedance is 43.3 Ohms, and at GHz impedance is 69.6 Ohms.Using Fractal Geometry multiple Frequency bandsare obtained at frequencies GHz, GHZ, GHz with respective return losses of dB, dB, dB.These Results have been obtained by optimizing the antenna s calculated dimensions. Values of other parameters like gain, directivity, input impedance are also simulated. The value of gain is around 3.5dB which satisfies the criteria. The directivity is around 7dB and input impedance is around 50 Ohms plus minus the tolerance. IV.CONCLUSION This work describes the development of Sierpienski Carpet Fractal Antenna upto second iteration. The aim of the design was to reduce the physical dimensions of the antenna without degrading its perfomance. The proposed antenna resonates at three frequencies GHz, GHZ, GHz which meets the requirements of commercial bands such as Wi-Fi y (3.6GHz-3.7GHz) and Wi-Max (3.7GHz-4.2GHz). For further understanding of the proposed antenna 2D Radiation Patterns are presented. The Measured results have confirmed multiband behavior of the designed antenna. REFERENCES [1]_ G. A. Rajawat, D. Kumar, C. Jain, P. Tomar, and K. Kapur, Novel design of multiband coplanar patch antenna for X band application, IEEE Power, Communication and Information Technology Conference (PCITC), [2]_B. Roy, A. Bhattacharya, A.K. Bhattacharjee, and S. K. Chowdhury, UWB monopole antenna design in a different substrate using sierpinski carpet fractal geometry, IEEE International Conference on Electronics and Communication Systems (ICECS), pp , [3]_ D. Kumar, Manmohan, and S. Ahmed, Modified ring shaped sierpinski triangle fractal antenna for C-bandand X -band applications, International Conference on Computational Intelligence and Communication Networks (CICN), pp.78-82, [4]_ H. Oraizi, and S. Hedayati, Miniaturization of microstrip antennas by the novel application of the giuseppe peano fractal geometries, IEEE Transaction Antennas and Propagation, vol. 60, no. 8, pp , [5]_ I. Singh, and V.S. Tripathi, Micro strip patch antenna and its applications: a survey, International Journal of Computer Technology and Applications (IJCTA), vol. 2(5), pp , [6]_ J.S.Sivia, and S.S.Bhatia, Design of fractal based microstrip rectangular patch antenna for multiband applications, IEEE International Advance Computing Conference (IACC), pp , [7]_ J.S. Sivia, A.P. Singh, and T.S. Kamal, Design of sierpinski carpet fractal antenna using artificial neural networks, International Journal [8]_ J.S. Sivia, A.P. Singh, and T.S. Kamal, Analysis and design of circular fractal antenna using artificial neural networks, Progress In Electromagnetic Research, vol. 56, pp , [9]_ K. Ashok, D. Sunita, and S. Pushpendra, Fractal technology for multi-frequency antenna design in wireless communication, IEEE International Confeence on Electrical, Electronics, and Optimization Techniques (ICEEOT), [10]_ M.R. Jena, B.B. Mangaraj, and D. Mishra, Bandwidth and gain enhancement of multiband fractal antenna based on the sierpinski carpet geometry, ICTACT Journal on Communication Technology, vol. 04, pp , [11]_ P. P.Patel, S. Zafar, and S. Uvaid, Miniaturized compact patch antenna for multiband applications using combination of sierpinski carpet & giuseppe peano fractral geometries, International Journal of Innovative Technology and Exploring Engineering, vol. 2, pp , [12]_ R. Singh, A. S. Sappal, and A. S. Bhandari, Efficient design of sierpinski fractal antenna for high frequency applications, International Journal of Engineering Research and Applications, vol. 4, pp , [13]_ S.S.Bhatia, and J.S.Sivia, A novel design of circular monopole antenna for wireless applications, Wireless Pers Commun, Springer, [14]_ V. V. Reddy, and N. V. S. N. Sarma, Compact circularly polarized asymmetrical fractal boundary microstrip antenna for wireless applications, IEEE Antennas and Wireless Propagation Letters, vol. 13, pp , IJRTI International Journal for Research Trends and Innovation ( 80