Hosted jointly by the IEEE Ottawa EMC Chapter, the IEEE Ottawa MTT/AP Chapter and IEEE Ottawa CPMT Chapter
Speaker: Dr. Arun. K. Bhattacharyya, Distinguished Engineer, Northrop Grumman, Redondo Beach, CA
Topics: (1) Floquet modal based Analysis of Finite and Infinite Phased Array Antennas; (2) Efficient Shaped Beam Synthesis in Phased Arrays and Reflectors; (3) Advanced Horn structures for Reflectors and Phased Arrays
Organizers: Dr. Syed Bokhari, Chariman, IEEE Ottawa EMC Chapter;
Dr. Qingsheng Zeng , Chairman, IEEE Ottawa MTT/AP Chapter
Date: Monday November 10, 2014
Time: 6pm to 9pm
Location: Fidus Systems Inc. 35 Fitzgerald Rd. Ottawa ON K2H 1E6
Parking: Free in marked ‘Fidus’
Floquet modal based Analysis of Finite and Infinite Phased Array Antennas
In this talk we present the Floquet modal analysis procedure for analyzing periodic array structures. The talk begins with a discussion on the relevance of Floquet analysis with regard to a scanned beam array design. Effects of mutual coupling on the performance of an array are discussed in details. It is shown how Floquet analysis can be employed to analyze a finite array with arbitrary amplitude taper including mutual coupling effects. A step-by-step procedure for aperture design is presented next. Method of analysis for an “array of subarrays” is also discussed. Design examples of patch and horn arrays are presented. A methodology for analyzing multilayered array structures with different periodicities is presented and applications of such structures in phased array antennas are discussed. In particular, characteristic features of a patch array loaded with a multilayered meander line polarizer are shown.
Efficient Shaped Beam Synthesis in Phased Arrays and Reflectors
Shaped beam array synthesis invites considerable attentions because arrays offer in-orbit reconfigurability, which is an attractive feature for communication and broadcasting satellites. In this talk, we present a brief overview of commonly used beam shaping algorithms. This is followed by the rojection Matrix Method of synthesis. The Projection Matrix method relies on orthogonal projection of the desired far field intensity vector onto the space spanned by the far field intensity vectors of the array elements. It is found that for a uniform convergence of the solution the far field sample space must be extended beyond the coverage region, otherwise the projection matrix becomes ill-conditioned. A general guideline for the far field sample space is provided. The method, with necessary amendments, is then employed successfully for a reflector surface synthesis. The method is found to be several times faster than the gradient search method commonly used for beam synthesis. Numerical results for array and shaped reflector syntheses are shown and the advantages are discussed.
Advanced Horn structures for Reflectors and Phased Arrays
In this talk we present an overview of various types of feed horns that are commonly used in single and multi-beam reflector systems and direct radiating arrays. The presentation begins with a discussion of smooth wall horns with single and multiple apertures, their operating principles, applications, advantages and their design procedures. In particular, the high aperture efficiency horns, both for rectangular and circular versions are discussed. The modal contents and generation of appropriate modes for achieving high aperture efficiency is presented. Potential applications of such horns in phased arrays and multi-beam reflectors are shown. Next, multiband horn structures using coaxial configuration and their applications are presented. This is followed by a presentation of various types of corrugated horns and their radiation characteristics. It is found that high Q resonances may occur in a corrugated horn within certain frequency bands where space wave and surface wave modes simultaneously propagate. A simple model is presented to demonstrate the resonance mechanism. Such resonances deteriorate the gain and cross-polar performances of a corrugated horn even if the return losses are acceptable at some resonant frequencies. Rectangular corrugated horns are more susceptible to these resonances than circular corrugated horns and the reasons are explained.
Arun K. Bhattacharyya received his B.Eng. degree in electronics and telecommunication engineering from Bengal Engineering College, University of Calcutta in 1980, and the M.Tech. and Ph.D. degrees from Indian Institute of Technology, Kharagpur, India, in 1982 and 1985, respectively.
From November 1985 to April 1987, he was with the University of Manitoba, Canada, as a Postdoctoral Fellow in the electrical engineering department. From May 1987 to October 1987, he worked for Til-Tek Limited, Kemptville, Ontario, Canada as a senior antenna engineer. In October 1987, he joined the University of Saskatchewan, Canada as an assistant professor of electrical engineering department and then promoted to the associate professor rank in 1990. In July 1991 he joined Boeing Satellite Systems (formerly Hughes Space and Communications), Los Angeles as a senior staff engineer, and then promoted to scientist and senior scientist ranks in 1994 and 1998, respectively. Dr. Bhattacharyya became a Technical Fellow of Boeing in 2002. In September 2003 he joined Northrop Grumman Space Technology group as a staff scientist, senior grade. He became a Distinguished Engineer which is a very rare and honorable recognition in Northrop Grumman. He is the author of “Electromagnetic Fields in Multilayered Structures-Theory and Applications”, Artech House, Norwood, MA, 1994 and “Phased Array Antennas, Floquet Analysis, Synthesis, BFNs and Active Array Systems”, Hoboken, Wiley, 2006. He authored over 95 technical papers and has 15 issued patents. His technical interests include electromagnetics, printed antennas, multilayered structures, active phased arrays and modeling of microwave components and circuits.
Dr. Bhattacharyya became a Fellow of IEEE in 2002. He is a recipient of numerous awards including the 1996 Hughes Technical Excellence Award, 2002 Boeing Special Invention Award for his invention of High Efficiency horns, 2003 Boeing Satellite Systems Patent Awards and 2005 Tim annemann Annual Quality Award, Northrop Grumman Space Technology.