High Fidelity Electromagnetic Design, Prediction and Optimization of Airborne Radomes

Navy SBIR 20.2 - Topic N202-114

Naval Air Systems Command (NAVAIR) - Ms. Donna Attick [email protected]

Opens: June 3, 2020 - Closes: July 2, 2020 (12:00 pm ET)

 

 

N202-114       TITLE: High Fidelity Electromagnetic Design, Prediction and Optimization of Airborne Radomes

 

RT&L FOCUS AREA(S): General Warfighting Requirements (GWR)

TECHNOLOGY AREA(S): Air Platform

 

OBJECTIVE: Define and develop a methodology by which high fidelity computation of antenna performance parameters of an installed system is utilized, and then apply that methodology to optimize the design of a radome covering an antenna.

 

DESCRIPTION: Currently, the computational tools used to design advanced airborne radomes are limited in their ability to predict and achieve installed performance over the full range of operating conditions [Ref 1]. The design and/or analysis of complex radomes with locally varying curvature and thickness, that incorporate metamaterials or frequency-selective surfaces (FSSs), is especially complex. Only full-wave electromagnetic analysis of the antenna cavity and radome structure can provide the required accuracy in predicting the variations in performance measures such as power transmission and reflection, boresight error, and sidelobe levels over the field of view. Such analyses can also reveal the levels of cross-polarization, grating lobes, and modifications of currents on the antenna structure resulting from electromagnetic coupling among the various structures in the antenna cavity. Providing that they can generate timely and accurate results, high fidelity predictions play a key role in extending the scope and accuracy of the design process for multilayer radome designs having complex internal structure, such as A-sandwich, C-sandwich, Prepreg, honeycomb/foam core, and Rohacell.

 

The Navy is interested in improving and optimizing the performance of radar systems already installed on Navy aircraft. The design of radomes currently covering such systems are to maximize transparency and beam quality at all viewing angles for in-band operation, and to minimize sidelobe levels. Structural, aerodynamic, and material-property considerations impose constraints that limit the design optimization process. Moreover, the optimization is performed using computational electromagnetics (CEM) tools with inherent approximations of the physical electromagnetic behaviors. Thus, the end-result is a less than optimal system that introduces uncertainties in the radar�s modes.

 

Recent progress in the development of full-wave electromagnetic solvers provides an opportunity to apply the detailed predictions to optimize actual radome designs [Ref 2]. The goal of this SBIR topic is to establish one or more methodologies based on full-wave solvers that will have the following characteristics:

 

1.     High fidelity in predicting all operational characteristics of radome-enclosed antenna arrays as installed on Navy aircraft including effects due to interaction with aircraft structures external to the antenna cavity. This entails precise descriptions of the elements and layers comprising the radome, as well as auxiliary structures such as lightning strips and pitot tubes inside the cavity.

2.     Modelling of electrically large radomes that will require advancements in high-order, full-wave solvers in the following areas:

a.     high order curved meshing;

b.     cell sizes larger than a wavelength to fill the volume domain with fewer cells

c.     high-order absorbing boundary conditions (ABC) that can bring the outer boundary very close to the target extruded prism and mixed cells to model very thin radome structures.

3.     Effective software support of volumetric grid generation from detailed computer-aided design (CAD) models of all relevant structures. These grids will typically be multi-resolution to model critical details according to the accuracy requirements of the solver.

4.     Fast execution of the solver and post-processing algorithms on massively parallel computer platforms. This capability is a high priority, as the time and resources available to perform the repeated runs required for optimization are limited.

5.     Development of a highly intuitive and intelligent Graphical User Interface (GUI) to assist the user in all phases of the CEM model development, import, export, preprocessing and post-processing.

6.     Flexibility in supporting a wide variety of optimization strategies, including genetic algorithms, particle swarms, and surrogates based upon the original design tools [Ref 3].

 

PHASE I: Design, develop and demonstrate the feasibility of a methodology to exercise a full-wave CEM code on an approved radome. Evaluate the potential of this software to adjust key details in radome design to improve actual performance metrics for the installed radar system. Demonstrate that the method is able to model various structural and material features of a complex radome. Demonstrate that the code fulfills the requirements 1-6 stated above. If not, make persuasive arguments as to how modification of the code could fulfill these requirements. The Phase I effort will include plans to be developed under Phase II.

 

PHASE II: Validate and mature the approach from Phase I. Develop optimization and design approaches to improve radome performance with installed antennas and interaction with neighboring structures.� Develop a GUI that encompasses the entire computational process, including: preprocessing tools for geometry import and generation of high order curved elements, high order processing tools, and a comprehensive set of post processing tools for data output and visualization.

 

PHASE III DUAL USE APPLICATIONS: Complete the development of the CEM software application. Perform final testing and transition into use on applicable platforms. The CEM software application will have a widespread use in the DoD, industry and academia for the design, optimization, and/or analysis of highly complex radomes and electromagnetic problems.� The aerospace industry as well as universities such as Massachusetts Institute of Technology (MIT), The Ohio State University (OSU) and California Poly-Technical Institute (Cal Tech) could all benefit from, or be interested in, the resulting technology.

 

REFERENCES:

1. Nair, R. & Jha, R. �Electromagnetic Design and Performance Analysis of Airborne Radomes: Trends and Perspectives [Antenna Applications Corner].� IEEE Antennas and Propagation Magazine, Volume 56, Issue 4, 2014, pp. 276-298. https://ieeexplore.ieee.org/document/6931715

 

2. Vukovic, A., Sewell, P. & Benson, T. �Holistic Appraisal of Modeling Installed Antennas for Aerospace Applications.� IEEE Transactions on Antennas and Propagation, 2019, pp. 1396-1409. https://ieeexplore.ieee.org/document/8558592

 

3. Massa, A. & Salucci, M. �Dealing with Complexity in Electromagnetics Through the System-by-Design Paradigm - New Strategies and Applications to the Design of Airborne Radomes.� 2018 IEEE Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, Boston MA, pp. 529-530). https://ieeexplore.ieee.org/document/8609182

 

KEYWORDS: Computational Electromagnetics, Radomes, Frequency Selective Surfaces, Curved Surfaces, Software Application, Aerospace.