Performance Comparison of Microstrip Array Antenna with Single Microstrip Antenna

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1 e-issn Volume 2 Issue 4, April 2016 pp Scientific Journal Impact Factor : Performance Comparison of Microstrip Array Antenna with Single Microstrip Antenna Dharmesh Koria 1, Kiran Rathod 2, Abhijit Khandagale 3, Jesal Kosambi 4, Hins Jain 5 1,2,3,4,5 Electronics and Telecommunication Engineering, kjsieit, Sion Abstract In this paper our aim is to compare single patch antenna with 1x2 array antenna on FR4. The main focus will be on optimizing the dimensions of patch antenna also maintained high gain in ISM band (2.4 GHz to GHz) at center frequency 2.45 GHz. Different parameters of antenna like VSWR, return loss, gain and radiation pattern are simulated using Ansoft HFSS software v13. Microstrip patch antenna in wireless communication is gaining importance as a most powerful technological trend. Its immense potential promises significant change in near term future of wireless application fields. Current technological trend has focused much more attention towards microstrip patch antenna. Single microstrip patch antenna has some advantages (low cost, light weight, conformal & low profile), but it has little disadvantages too- like low gain, low efficiency, low directivity and narrow bandwidth. These disadvantages can be overcome by implementation of many patch antennas in array configuration. Here term array stands for geometrical and electrical arrangements of patch elements. As we increase number of patch elements to form an array, improvement in performance is observed. In this paper, performance for 1x1, 1x2 arrays has been analyzed and compared. It has been concluded that 1x2 patch array shows better result than single patch antenna. Keywords Microstrip Patch Antenna, Microstrip Array antenna, Impedance Matching, Return Loss, Radiation Patterns, Gain, Directivity. I. INTRODUCTION To demonstrate the implementation of the digital beam forming, array is to be built for 2.4 GHz Transmission in order to allow testing and demonstrational use of the array in the unrestricted Industrial, Scientific and Medical (ISM) band. The demonstrated technique, however, can be implemented at any frequency and with minor changes for a transmitting array as well. Microstrip antenna is printed type of antenna consisting of a dielectric substrate sandwiched in between a ground plane and a patch.the concept of Micro strip antenna was first proposed in 1953, twenty years before the practical antennas were produced [1]. Since the first practical antennas were developed in early 1970s, interest in this kind of antennas was held in New Mexico. Some of the main advantages of the microstrip antennas are that it has low fabrication cost, its lightweight, low volume, and low profile configurations that it can be made conformal, it can be easily be mounted on rockets, missiles and satellites without major modifications with the ever-increasing need for mobile communication and the emergence of many systems, it is important to design broadband antennas to cover a wide frequency range [4]. The design of an efficient wide band small size antenna, for recent wireless applications, is a major challenge. Microstrip patch antennas have found extensive application in wireless communication system owing to their advantages such as low profile, conformability, low-cost fabrication and ease of integration with feed networks [3].However, these antennas are generally fabricated on thicker substrates. The gain of single patch antenna is also increase by increasing the arrays elements. Each array element improves the gain of antenna. The proposed single patch and 1x2 are designed and compare their different parameter. It has been concluded that 1x2 array shows better performance than single patch antenna. Multiple arrays improve the gain of antenna as well bandwidth of All rights Reserved 349

2 II. ANTENNA DESIGN The Single patch antenna is designed using transmission line model [1].The Steps to design single patch element using transmission line model is explained as follows: Step 1: Calculation of the Width (W) Figure 1. Microstrip patch antenna [1] The width of the Microstrip patch antenna is given as: W=c/ (2 f 0 (ɛ r +1)/2.. (1) Where,c is velocity of light,fo is Resonant Frequency & εr is Relative Dielectric Constant Of course other widths may be chosen but for widths smaller than those selected according width equation, radiator efficiency is lower while for larger widths, the efficiency are greater but for higher modes may result, causing field distortion. Step 2: Calculating the Length (L) Effective dielectric constant: Ɛre = (ɛ r+1/2) + ( ɛ r-1/2)[1+12(h/w)] -1/2. (2) Once W is known, the next step is the calculation of the length which involves several other computations; the first would be the effective dielectric constant. The dielectric constant of the substrate is much greater than the unity; the effective value of εeff will be closer to the value of the actual dielectric constant εr of the substrate. The effective dielectric constant is also a function of frequency. The effective length is: which is found to be: L=1/2f c ɛ 0 ɛ r µ 0.. (3) Because of fringing effects, electrically the micro strip antenna looks larger than its actual physical dimensions. For the principle E plane (x-y plane), where the dimensions of the path along its length have been extended on each by a distance, ΔL, which is a function of the effective dielectric constant and the width-to-height ratio (W/h).The length extension is: ΔL=0.42h*[(ɛ re+0.3) (w/h+0.264)/( ɛ re0.28)(w/h+0.8 )]... (4) Calculation of actual length of patch All rights Reserved 350

3 Because of inherent narrow bandwidth of the resonant element, the length is a critical parameter and the above equations are used to obtain an accurate value for the patch length L. The actual length is obtained by: Leff L 2 L.. (5) Step 3: Feed Point Location It is observed that the change in feed location gives rise to a change in the input impedance and hence provides a simple method for impedance matching. Z in =jx f +R/1+j2Q (f/f 0-1). (6) From the equation we see that if the feed is located at x = xf and 0 yf W, the input resistance at resonance for the dominant TM10 mode can be expressed as: R in = R r cos 2 ( x f /L) (7) Where, Rr Rin, xf is the inset distance from the radiating edge and Rr is the radiation resistance at resonance when the patch is fed at a radiating edge. The inset distance xf is selected such that Rin is equal to the feed line impedance, usually taken to be 50Ω. The feed point can be selected anywhere along the patch width. It is approximately given by Xf=L/2 ɛ re (L).. (8) Array Antenna: An antenna array is a set of individual antennas used for transmitting and/or receiving radio waves, connected together in such a way that their individual currents are in specified amplitude and phase relationship. The interactions of the different phases enhance the signal in one desired direction at the expense of other directions. This allows the array to act as a single antenna, generally with improved directional characteristics (thus higher antenna gain) than would be obtained from the individual elements. The resulting array in fact is often referred to and treated as "an antenna," particularly when the elements are in rigid arrangement with respect to each other, and when the ratio of currents (and their phase relationships) are fixed. On the other hand, a steerable array may be fixed physically but has electronic control over the relationship between those currents, allowing for adjustment of the antenna's directionality without requiring physical motion. The spacing between the two patches in array design should be λ/2 s λ/3 so that the antenna will give the better performance. Design of Patch: Parameters Single Patch (in mm) 1x2 Patch (in mm) Substrate Length Substrate width Substrate height Patch length Patch width Inset distance Inset Gap Feed width Feed length Table 1. Parameters of All rights Reserved 351

4 MY1: db(st(50ohm_t1,50ohm_t1)) MY1: db(st(patch_t1,patch_t1)) International Journal of Current Trends in Engineering & Research (IJCTER) III. ANTENNA MODELLING Figure 2. Single Patch Model Figure 3. 1x2 Patch Model 1) Return Loss vs. frequency: IV. RESULTS XY Plot 1 db(st(patch_t1,patch_t1)) MX2: MX1: Figure 4. Frequency vs. Return loss of single patch XY Plot 1 db(st(50ohm_t1,50ohm_t1)) MX2: MX1: Figure 5. Frequency vs. Return loss of 1x2 patch The impedance bandwidth of single patch is MHz calculated from fig. 4 and for 1x2 patch antenna is 130 MHz. This results shows that in terms of impedance bandwidth 1x2 patch array antenna is excellent than single patch antenna. 2) VSWR vs. All rights Reserved 352

5 VSWRt(patch_T1) VSWRt(patch_T1) International Journal of Current Trends in Engineering & Research (IJCTER) XY Plot 3 VSWRt(patch_T1) Figure 6. Frequency vs. VSWR of single patch XY Plot 3 VSWRt(patch_T1) Figure 7. Frequency vs. VSWR of 1x2 patch The VSWR of single patch is 1.24 and for 1x2 patch antenna it is 1.54 at 2.45 GHz.From results it has been concluded that this antennas are practically acceptable for wireless application. 3) Smith Chart: Name Freq Ang Mag RX i Smith Chart St(patch_T1,patch_T1) Figure 8. Smith Chart of single patch Name Freq Ang Mag RX i Smith Chart St(50ohm_T1,50ohm_T1) Figure 9. Smith Chart of 1x2 patch The Smith Chart of single patch is Ω and for 1x2 patch antenna it is Ω at 2.45 GHz. The results of both graph shows the perfect impedance matching. 4) All rights Reserved 353

6 db(gaintotal) db(gaintotal) ANSOFT International Journal of Current Trends in Engineering & Research (IJCTER) XY Plot 2 db(gaintotal) Figure 10. Frequency v/s Gain for single patch XY Plot 3 db(gaintotal) Figure 11. Frequency vs. Gain for 1x2 patch The gain of single patch is 6.35 db and for 1x2 patch array it is 8.75 db. This result indicates that as we increase the number of array elements the gain of the antenna increases and which can be used for longer distances. 5) Directivity XY Plot Figure 12. Frequency vs. Directivity for single patch XY Plot 2 Patch_Antenna_ADKv Figure 13. Frequency vs. Directivity for 1x2 patch The directivity of single patch is 6.60dB and for 1x2 patch antenna it is 8.83dB. As directivity of antenna is increase the efficiency of antenna also All rights Reserved 354

7 Parameter Single patch 1x2 array Gain 6.35 db 8.75dB VSWR Directivity 6.60dB 8.83dB Bandwidth MHz 130 MHz Impedance Matching Ω Ω Table 2. Results of antenna V. CONCLUSION A Single patch and 1x2 microstrip patch array antenna of rectangular shape was successfully designed and implemented using FR4 Epoxy substrate. It is observed that, Antenna is tuning in ISM band frequency at 2.45 GHz simulated by Ansoft HFSS software. The gain of array antenna is 8.27dB which is more than single patch. Due to small size and small weight, this array antenna is useful in many telecommunication applications such as Real Time Location System of small fishing boats. This antenna can also be applicable for monitoring position of Soldiers for Security of soldiers and Nation. ACKNOWLEDGEMENT Authors would like to thank reviewers for their careful review and helpful comment. Authors are also grateful to Dr. Milind Nemade for their continuous support and guidance. REFERENCES [1] Balanis, Constantine A., Antenna Theory, Analysis and Design (3 rd Edition), John Willey & Son, inc, (2010) pp [2] I. J. Bahl and P. Bharti, Micro-strip Antennas, Dedhum, MA; Artech house, 1980 [3] Ei Thae Aye, Chaw Myat New, Rectangular Microstrip Patch Antenna Array for RFID Application Using 2.45 Frequency Range Department of Electronic Engineering, Mandalay Technological University, Myanmar [4] K.R.Rathod,B.K.Mishra,"Performance evaluation of linearly polarized circularly polarized cornerscut square using coaxial feed and rectangular slot textile antenna using CPWfeedat 2.4 GHz"Mr. Patil Sarang,Dr.Bombale U.L. Design, Analysis and Study of 2x1 Rectangular Microstrip Antenna Array At 2.45 GHz for Beam Steering, [5] Kuldeep Kumar Singh, Dr. S.C.Gupta, Review and Analysis of Microstrip Patch Array Antenna with different configurations [6] Pradeep Kumar 1, Neha Thakur *2, Aman Sangh, Micro strip Patch Antenna for 2.4 GHz Wireless Applications Department of ECE, Ditmr, Faridabad 2 Mtech Student,Department of ECE, NGF College of Engg. & Tech, Palwal, Department of ECE, NGF College of Engg. & Tech, Palwal New Delhi, India. [7] Urvi Dhandha 1, Prof. Vivek. R, Design and Simulation of 4x1 Probe Feed Rectangular Patch Array Antenna for ISM Band Application. Electronics and Communication Department) MEFGI, Rajkot, All rights Reserved 355