JOURNAL OF CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 19, 2020 COMPARATIVE ANALYSIS ON BEAM STEERING TECHNIQUES OF PHASED ARRAY ON THE MOVE ANTENNA FOR SATCOM APPLICATIONS Dr. Sudha Arvind1, Dr. Devika SV2 , Dr.S.Arvind3 1Associate Professor in Department of ECE, CMR Technical Campus, Hyderabad, Telengana, India 2Professor in Department of ECE, Hyderabad Institute of Technology and Management, Hyderabad, Telengana, India 3Dean Academics, Hyderabad Institute of Technology and Management, Hyderabad, Telengana, India E-mail: [email protected], [email protected], [email protected] Received: 14 April 2020 Revised and Accepted: 8 August 2020 ABSTRACT: To achieve maximum gain and performance improvement phased array is preferred for SATCOM applications. Beam steering methodology is adopted in order to maintain the link between Satellite and antenna terminal. To Achieve continuous link between antenna terminal and satellite hybrid beam steering methodology is adopted that is both electronic beam steering and mechanical beam steering for continuous broadband data communication for various SATCOM applications. The comparative analysis for both steering methods is done and observed the gain and side lobe signal level of phased array antenna. This analysis is done in MATLAB and HFSS Softwares and results are recorded for analysis. This paper clearly presents the comparative analysis with results of the Hybrid beam steering method used for phased array with 100 micro strip elements. KEYWORDS: SATCOM, Phased array, Beam steering, Gain, side lobe level, On the Move. I. INTRODUCTION Antenna is a device which is used to radiate or receive electromagnetic energy [1]. Antenna array is used to increase directivity and beam width of an antenna. Usage of number of elements in the array depends on the desired application. There are various structures for placing micro strip elements in array. They are: Hexagonal structure Rectangular structure Honeycomb structure In hexagonal structure, all sides appear to be same and because of its structure all gaps will be filled between adjacent structures. In case of rectangular structure, distance between diagonal elements and adjacent elements are not equal and lot of space will be wasted compared to other two structures. Honey comb structure has appreciable advantage compared to that of other two. For array grid it has an advantage of space efficiency as extra element can be placed at the center. Fig 1: Sample Honey comb structure for phased array 6570 JOURNAL OF CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 19, 2020 In this paper, a Phased array of 100 micro strip elements structure is taken for comparative study. Phased array antenna with parabolic reflector radiates narrow beam width that fetches for satellite communication applications in current era. In case of On the Move antennas, continuous link to be established between satellite and antenna terminal where hybrid beam steering methodology is adopted. In hybrid beam steering both electronic and mechanical steering is implemented to track the satellite link and maintain the link between antenna terminal and satellite. Phased array antenna with 100 Micro strip elements is designed using MATLAB. Fig 2: Phased array antenna with 100 micro strip elements II. METHODOLOGY The combination of more than one element is called an array which may improve the directivity of the antenna and provide a narrower radiation pattern with high directivity [4]. To track the satellite link and to maintain the link between the satellite and antenna terminal for the vehicle moving with average speed, both electronic and mechanical steering is adopted. In Electronic beam steering, the radiation pattern of the main lobe is altered in various directions (checked with various steering angles) by changing θ and Ø values by the means of MATLAB. While steering the beam at different angles the radiation patterns are observed and examined. Spherical co-ordinate system is used for plotting resultant beam steering graphically with both corresponding E plane and H plane radiation patterns examined. Here 'phi' represents the angle made with positive X axis in anticlockwise direction and 'theta' denotes the angle made with positive Z axis in clockwise direction. Comparative Analysis at Different Steering Angles MATLAB is the tool that is used to execute both mechanical and electronic beam steering. Hence the conclusion can be drawn that with a change in relative phases of the antenna elements and the orientation of the plane for electronic and mechanical beam steering respectively hybrid beam steering can be achieved. Beam formation of Phased array antenna Fig 3. Beam formation for angle an array of 100 isotropic elements 6571 JOURNAL OF CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 19, 2020 The phased array antenna radiates broad beam but in order to fetch satellite communication applications, narrow beam is preferred. parabolic reflector serves this purpose. The above figure represents radiation pattern of phased array antenna with 100 isotropic elements using MATLAB. Fig 4. Beam steering for angle an array of 100 isotropic elements of 300 in Ө and Φ directions. The power gain of the main lobe formed without steering is 20dB when considered an isotropic antenna element in the phased array. The 1st side lobe level is observed at 13 dB. The beam width in E-plane and H-plane are calculated and they are 520 and 260 respectively. Mechanical Beam Steering Methodology Mechanical beam steering is applied for vehicle on the move in order to avoid pointing error with the satellite. When there is inertial movement in the vehicle during communication there occurs interference with adjacent satellites which reduces the efficiency of communication in SATCOM applications. To avoid this, the antenna is accurately pointed to the desired satellite using both electronic and mechanical beam steering methods. Fig 5. Mechanically rotated beam at 300for an array of 100 isotropic elements. 6572 JOURNAL OF CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 19, 2020 Fig 6. Mechanical rotated array of 100 isotropic elements at 300 along x axis We performed mechanical beam steering by changing the relative position of array plane with respect to the coordinate axis by using MATLAB. Here, it is observed that irrespective of the value of azimuthal and elevation angles, the main lobe level is constant – there is no distortion for any values of Ø and θ. With a raise in the elevation and azimuthal angle in electronic beam steering: An increase in gain of the radiation pattern and width of E-plane beam is witnessed, also there is an increase in the width of H-plane beam but a decrease in Side lobe level. The only changes that can be seen in the mechanical beam steering is the orientation of the plane while there is no alteration in the radiation characteristics. With the rise in the frequency along with hike in the gain, the beam becomes narrower. Table 1: Observation of various electronic beam steering angles S. No Beam steering Gain(dB) Side lobe Level (dB) 1 Өo = 0o and Φo 40 -14.35 = 0o 2 Өo = 45o and 37.27 -11.6 Φo = 45o 3 Өo = 35o and 38.38 -12.67 Φo = 35o 4 Өo = 15o and 39.7 -13.98 Φo = 15o 5 Өo = -15o and 39.7 -14.3 Φo = -15o 6 Өo = -35o and 38.38 -12.91 Φo = -35o 7 Өo = -45o and 37.27 -11.75 Φo = -45o The comparison analysis is done at various steering angles from -45 degrees to +45 degrees and variation of gain is observed to be increased. The Gain without beam steering is observed as 40 and 37.27 at -45 degrees steering 6573 JOURNAL OF CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 19, 2020 angle. But in mechanical steering, gain is not altered only relative phase change is observed. III. CONCLUSION This paper concludes that in Electrical beam steering as observed showed effect on gain, side lobe levels and also beam width. The beam formed in phased array of 100 isotropic elements has a wide beam width. But, to fetch satellite communication applications, the beam width a narrow beam width is required. Hence a parabolic reflector is chosen to sharpen the beam. In mechanical beam steering, there is no significant change in the gain of the antenna only relative phase of the major lobe is changed. Acknowledgements Authors want to thank Hyderabad Institute of Technology and Management, Hyderabad and CMR Technical campus, Hyderabad for providing necessary infrastructure to carry out the research work. IV. REFERENCES [1] C. A. Balanis, Antenna theory: analysis and design, 3rd ed. Hoboken, NJ: Wiley Interscience, 2005. [2] Devika, S., Karki, K., Kotamraju, S. K., Kavya, K., & Rahman, M. Z. (2017). A New Computation Method for Pointing Accuracy Of Cassegrain Antenna In Satellite Communication. Journal of Theoretical & Applied Information Technology, 95(13) [3] Devika, S. V., Kotamraju, S. K., Kavya, K. C. S., Kumar, V. S., Suhas, K., Vinu, K., & Anudeep, B. (2016). A circularly polarized Ka-band antenna for continuous link reception from GSAT-14. Indian J Sci Technol, 9, 38 [4] Malek, N., Khalifa, O. O., Abidin, Z. Z., Mohamad, S. Y., & Rahman, N. (2018). Beam steering using the active element pattern of antenna array. TELKOMNIKA (Telecommunication Computing Electronics and Control), 16(4), 1542-1550 [5] Jung, Y. B., Shishlov, A. V., & Park, S. O. (2009). Cassegrain antenna with hybrid beam steering scheme for mobile satellite communications. IEEE Transactions on Antennas and Propagation, 57(5), 1367- 1372. AUTHORS PROFILE Dr. Sudha Arvind, B.Tech from VNEC Bellary, M.Tech from BMS Bangalore and PhD from JNTUH is currently working as an Associate Professor in the Department of Electronics and Communication Engineering at CMR Technical Campus, Hyderabad,Telangana. She has teaching experience of 18 years and one year of Industry experience. Dr. Sudha has presented 17 papers in National & International Conferences, and published 15 papers in International Journals.