Workshop on Ground, Aircraft and Satellite Antennas

Prabhakar H. Pathak
Prof. Emeritus, The Ohio State Univ.
Adjunct Prof., Univ. of South Florida

1. Introduction to the Theory and Analysis of Conformal Phased Array Antennas:

Phased array antennas generally consist of periodically or quasi periodically spaced antenna elements which are phased to electronically scan an electromagnetic(EM) beam in a highly agile fashion. Finite planar arrays are briefly introduced and first treated via an element by element(EBE) field summation method. The presence of unwanted grating lobes is discussed and conditions for avoiding them are given. A backward fast wave is seen to exist in an example of a frequency scanned leaky waveguide array; this is in contrast to a phase scanned array. A Floquet modal analysis of infinite periodic arrays is briefly described for the approximate analysis of mutual coupling in very large finite arrays. The topics of sub arrays, grating lobes, and scan blindness effects in phased arrays are briefly discussed. An analysis of electrically large finite planar and convex arrays, which are conformal to even larger platforms, is a challenge that needs to be addressed. A uniform geometrical theory of diffraction(UTD) for treating such arrays is seen to be an attractive ray approach that is not only highly efficient as compared to the EBE field summation method, but also probably the only one that provides a vivid physical picture for the array radiation mechanisms. An efficient hybrid method is proposed for combining UTD and numerical methods for analysis of large conformal phased arrays on large complex platforms.

 

Dr. C.J. Reddy

VP-Altair Engineering

2. Pushing the Boundaries of Computational Electromagnetics: Application to Airborne antennas and radomes

Abstract:

Advances in computational electromagnetic tools have made possible design and optimization of airborne antennas and radomes. Numerical approaches that include full-wave techniques such as Method of Moments (MoM), Multilevel Fast Multipole Method (MLFMM) and asymptotic techniques such as Physical Optics (PO) and Uniform Theory of Diffraction (UTD) are being utilized to solve many challenging problems that were not possible in the past. In this talk, an overview of various advanced numerical techniques that are useful for airborne antenna designs and placement studies will be presented. Keeping the present-day challenges in mind, a complete solution for the design and analysis of radomes, from characterizing the wall construction materials through transmission loss analysis, to the full 3D radome analysis for calculating the radome induced effects will be presented. We will also discuss the design and analysis of Frequency Selective Surface (FSS) radomes.

BIO: Dr. C.J. Reddy is the Vice President, Business Development-Electromagnetics for Americas at Altair Engineering, Inc.(www.altair.com). At Altair, he is leading the marketing and support of commercial 3D electromagnetic software, FEKO (http://www.altairhyperworks.com/product/FEKO) in Americas. Dr. Reddy is also the President of Applied EM Inc, a small company specializing in innovative antenna design and development. Dr. Reddy is a Senior Member of Institute of Electrical and Electronics Engineers (IEEE) and also a Senior Member of Antenna Measurement Techniques Association (AMTA). He has been elected Fellow of the Applied Computational Electromagnetic Society (ACES) in 2012. Dr. Reddy served on ACES Board of Directors from 2006 to 2012 and is currently serving as the Secretary of ACES. He published 37 journal papers, 77 conference papers and 18 NASA Technical Reports to date. Dr. Reddy is a co-author of the book, “Antenna Analysis and Design Using FEKO Electromagnetic Simulation Software,” published in June 2014 by SciTech Publishing (now part of IET). Dr. Reddy was the General Chair of ACES 2011 Conference held in Williamsburg, VA during March 27-31, 2011. And alsoACES 2013 conference, Monterey CA (March 24-28, 2013) as well as the General Chair of ACES 2015 conference held in Williamsburg, Virginia during March 22-26, 2015. He was the Co-General Chair of 2014 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting held during July 6-11, 2014 in Memphis, TN. Dr. Reddy is the General Chair for AMTA 2018 conference to be held in Williamsburg, Virginia during November 3-8, 2018.