Gopinath Gampala - Academia.edu (original) (raw)

Papers by Gopinath Gampala

─ Advances in computational resources facilitate anechoic chamber modeling and analysis at VHF/UH... more ─ Advances in computational resources facilitate anechoic chamber modeling and analysis at VHF/UHF frequencies using full-wave solvers available in commercial software such as FEKO. The measurement community has a substantial and increasing interest in utilizing computational electromagnetic (CEM) tools to minimize the financial and real estate resources required to design and construct a custom anechoic chamber without sacrificing performance. A full-wave simulation analysis such as the finite element method (FEM) provides a more accurate solution than the approximations inherent to asymptotic ray-tracing techniques such as physical optics (PO), which have traditionally been exploited to overcome computational resource limitations. An anechoic chamber is simulated with a rectangular down-range cross-section (in contrast with the traditional square cross-section) to utilize the software’s capability to assess polarization performance. The absorber layout within the anechoic chamber ...

In this paper, design and analysis of Frequency Selective Surface (FSS) radomes are discussed. Pe... more In this paper, design and analysis of Frequency Selective Surface (FSS) radomes are discussed. Periodic Boundary Conditions (PBC) are employed for the analysis of planar radome wall configuration with frequency selective surface layer sandwiched between the dielectric layers. The transmission/reflection coefficients obtained from the PBC analysis can be transformed into frequency dependent impedance parameters, used to define an Impedance Sheet. The impedance sheet feature can be used to realize any arbitrary shaped radome, instead of explicitly modeling the dielectric layers with the FSS.

2016 IEEE International Symposium on Phased Array Systems and Technology (PAST), 2016

This paper investigates the applicability of various Computational Electromagnetic (CEM) Methods ... more This paper investigates the applicability of various Computational Electromagnetic (CEM) Methods for the design and analysis of phased array antennas. The full-wave methods like the Method of Moments (MoM), Finite Element Method (FEM), Finite-Difference Time-Domain (FDTD) and Multi-level Fast Multipole Method (MLFMM) are discussed in detail starting with simple arrays like a planar strip dipole to more complex Vivaldi antenna arrays. The usefulness of special features like the Periodic Boundary Conditions (PBCs) and the Domain Green's Function Method (DGFM) is also investigated.

2016 IEEE/ACES International Conference on Wireless Information Technology and Systems (ICWITS) and Applied Computational Electromagnetics (ACES), 2016

The technologies under development in the world of mobile broadband networks specifically focusin... more The technologies under development in the world of mobile broadband networks specifically focusing on the next generation of standards, namely 5G, are targeting the millimeter wave spectrum of 28 GHz and beyond. This paper discusses some of these futuristic technologies that are laying the foundation for the 5G standards, highlighting the concept of massive MIMO that employs antenna arrays and beamforming techniques to address the high data rate demands.

2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014

Mobile communications technology is constantly changing with the increasing demands of the consum... more Mobile communications technology is constantly changing with the increasing demands of the consumers and Long Term Evolution (LTE) is widely accepted as the technology that can meet these requirements. This paper presents an electrically small antenna designed for European LTE frequency band of 1800 MHz. A systematic design procedure is developed using characteristic mode analysis (CMA). The CMA design procedure provides needed insights for the antenna designers to quickly come up with an antenna design using an arbitrarily shared structure.

2013 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), 2013

Summary form only given. Long-Term Evolution (LTE) technology implements MIMO for higher data rat... more Summary form only given. Long-Term Evolution (LTE) technology implements MIMO for higher data rates that need multiple antennas on the mobile handset (G. Gampala, et al., Microwave Journal, March 2012). At the same time, there is also an increased pressure on the design engineers to come up with attractive thinner and slimmer phones, leaving very little space for the antenna engineers. This paper presents a novel electrically small antenna designed for the European LTE frequency band of 1800 MHz. The theory of characteristic modes (D. J Ludick, et al., ICEAA.2012, 208-211) used to come up with the presented design within the given limited space. Characteristic modes are real current modes that depend only on the shape and size of the geometry. Given the shape and size of the mobile handset, and the available space for the antenna, characteristic modes are computed for the geometry using commercial EM simulation tool, FEKO (www.feko.info). The antenna design is optimized by cutting out slots in the geometry with zero modal currents. Two antennas, orthogonally oriented to each other to provide the space and polarization diversity, are integrated into the mobile handset with the PCB acting as the ground plane, as shown in Fig.1. More results with the detailed process of the antenna design will be presented at the conference.

ABSTRACT Recent advances in computational electromagnetic tools have made antenna design possible... more ABSTRACT Recent advances in computational electromagnetic tools have made antenna design possible along with integration of antennas on various ground, sea and air platforms. Numerical computations can be performed to evaluate the effects of antenna placement, radiation hazard, EMC/EMI, etc. The typical numerical approaches 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). For many practical applications, sometimes it is necessary to study the electromagnetic behavior on a specific structure over a broad frequency band, and therefore it is important to have some benchmark data on computational resources needed for some commonly used numerical techniques. In this study, representative full-size air, ground and sea platforms are considered and the frequency limit is pushed at different bands using several numerical techniques. The accuracy and computational resources are compared.

2007 IEEE Antennas and Propagation International Symposium, 2007

... Gopinath Gampala* and Alexander B. Yakovlev Department of Electrical Engineering University o... more ... Gopinath Gampala* and Alexander B. Yakovlev Department of Electrical Engineering University of Mississippi, University, MS 38677-1848, USA ggampala@olemiss.edu, yakovlev@olemiss. edu ... 53, no. 1, pp. 70-81, Jan. 2005. [3] G. Goussetis, Y. Guo, AP Feresidis, and JC ...

2020 14th European Conference on Antennas and Propagation (EuCAP)

Design exploration using numerical field simulation is a valuable approach to analyze antenna per... more Design exploration using numerical field simulation is a valuable approach to analyze antenna performance parameters. In such a process many data describing a mapping from design variables to response functions are generated. In this work different machine learning (ML) techniques are applied on these data to analyze and optimize antenna performance. This data driven simulation approach can speed up antenna optimization tremendously. Also, the benefit of dimensionality reduction algorithms and evolutionary learning in antenna performance analysis is described.

2015 31st International Review of Progress in Applied Computational Electromagnetics (ACES), 2015

The applicability of Computational Electromagnetic (CEM) Methods, specifically the full-wave meth... more The applicability of Computational Electromagnetic (CEM) Methods, specifically the full-wave methods like the Method of Moments (MoM), Finite Element Method (FEM), Finite Difference Time Domain (FDTD) and Multi-level Fast Multipole Method (MLFMM) for the design and analysis of wideband Vivaldi antenna arrays of various sizes is discussed.

2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021

Bluetooth, Wi-Fi, LTE and ZigBee are some of the common technologies used in the household electr... more Bluetooth, Wi-Fi, LTE and ZigBee are some of the common technologies used in the household electronic devices. The most common factor among these technologies is the use of the extremely popular 2.4 GHz frequency band. Some of these technologies coexist within the same device leading to interference. This paper focuses on identifying the interference issues in the early design stage and mitigating them through virtual prototyping.

2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021

Recently, applications that use millimeter (mm) wave frequencies (30–300 GHz) have increased sign... more Recently, applications that use millimeter (mm) wave frequencies (30–300 GHz) have increased significantly to facilitate very high data rates and wide operational bandwidth. However, designing circuits and antennas at mm wave frequencies pose a challenge of its own. One such factor is surface roughness, which affects the conductivity of the metals used in the design and leads to degradation of performance. Surface roughness can be controlled using advanced and precise manufacturing techniques; however, they can be expensive. So, it is important to study the effect of surface roughness while designing mm wave circuits and antennas to avoid expensive modifications later in the design stages. In this paper, we consider one such application of automotive cruise control (ACC) radar that operates at 76.5 GHz and study how various values of surface roughness affect different performance parameters of the design.

Radomes protect antennas from structural damage due to wind, precipitation, and bird strikes. In ... more Radomes protect antennas from structural damage due to wind, precipitation, and bird strikes. In aerospace applications, radomes often double as a nose cone and thus have a significant impact on the aerodynamics of the aircraft. While radomes should be designed not to affect the performance of the underlying antennas, they also must satisfy structural and aerodynamic requirements. In this paper, we demonstrate a multiphysics approach to analysis of airborne radomes not only for electromagnetic (EM) performance, but also for structural, aerodynamic, and bird strike performances, as depicted in figure 1. We consider a radome constructed using composite fiberglass plies and a foam core, and coated with an anti-static coating, paint, and primer. A slotted waveguide array is designed at X-band to represent a weather radar antenna. The transmission loss of the radome walls is analyzed using a planar Green's function approach. An asymptotic technique, Ray-Launching Geometric Optics (RL...

Low emissivity (low-E) windows have thin layers of metallic oxides for extra thermal insulation. ... more Low emissivity (low-E) windows have thin layers of metallic oxides for extra thermal insulation. These metallic layers not only block infrared and ultraviolet waves but also attenuate cellular signals. Cellular coverage can be improved by using Frequency Selective Surface (FSS) layers that will act as bandpass filters, instead of solid layers. This paper discusses the type of FSS structures that can be integrated into the window glass. A workflow process is demonstrated for efficient design and analysis of such structures using Periodic Boundary Conditions (PBC), Characterised Surfaces in conjunction with Ray-Launching Geometrical Optics (RL-GO) method.

Long-term evolution (LTE) is one of the 4th generation (4G) mobile communication technologies dev... more Long-term evolution (LTE) is one of the 4th generation (4G) mobile communication technologies developed at different frequencies ranging from 400 MHz to 4 GHz with bandwidths up to 20 MHz [1]. LTE technology facilitates multiple antennas performing both transmit and receive operations (i.e. multiple-input-multiple-output (MIMO)) to

2018 International Applied Computational Electromagnetics Society Symposium (ACES)

Applied Computational Electromagnetics Society

Traditional antenna optimization solves the modified version of the original antenna design for e... more Traditional antenna optimization solves the modified version of the original antenna design for each iteration. Thus, the total time required to optimize a given antenna design is highly dependent on the convergence criteria of the selected algorithm and the time taken for each iteration. The use of machine learning enables the antenna designer to generate trained mathematical model that replicates the original antenna design and then apply optimization on the trained model. Use of trained model allows to run thousands of optimization iterations in a span of few seconds.

IEEE Antennas and Propagation Magazine, 2015

—The technologies under development in the world of mobile broadband networks specifically focusi... more —The technologies under development in the world of mobile broadband networks specifically focusing on the next generation of standards, namely 5G, are targeting the millimeter wave spectrum of 28 GHz and beyond. This paper discusses some of these futuristic technologies that are laying the foundation for the 5G standards, highlighting the concept of massive MIMO that employs antenna arrays and beamforming techniques to address the high data rate demands.