| 1. |
- Capek, Miloslav, et al.
(författare)
-
Characteristic Mode Decomposition Using the Scattering Dyadic in Arbitrary Full-Wave Solvers
- 2023
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 71:1, s. 830-839
-
Tidskriftsartikel (refereegranskat)abstract
- Characteristic modes are formulated using the scattering dyadic, which maps incident plane waves to scattered far fields generated by an object of arbitrary material composition. Numerical construction of the scattering dyadic using arbitrary full-wave electromagnetic solvers is demonstrated in examples involving a variety of dielectric and magnetic materials. Wrapper functions for computing characteristic modes in method-of-moments, finite-difference time domain, and finite element solvers are provided as supplementary material.
|
|
| 2. |
- Capek, Miloslav, et al.
(författare)
-
Optimal Inverse Design Based on Memetic Algorithms - Part 1 : Theory and Implementation
- 2023
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 71:11, s. 8806-8816
-
Tidskriftsartikel (refereegranskat)abstract
- A memetic framework for optimal inverse design is proposed by combining a local gradient-based procedure and a robust global scheme. The procedure is based on method-of-moments matrices and does not demand full inversion of a system matrix. Fundamental bounds are evaluated for all optimized metrics in the same manner, providing natural stopping criteria and quality measures for realized devices. Compared to density-based topology optimization, the proposed routine does not require filtering or thresholding. Compared to commonly used heuristics, the technique is significantly faster, still preserving a high level of versatility and robustness. This is a two-part paper in which the first part is devoted to the theoretical background and properties, and the second part applies the method to examples of varying complexity.
|
|
| 3. |
- Capek, Miloslav, et al.
(författare)
-
Optimal Inverse Design Based on Memetic Algorithms - Part II : Examples and Properties
- 2023
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 71:11, s. 8817-8829
-
Tidskriftsartikel (refereegranskat)abstract
- Optimal inverse design, including topology optimization and evaluation of fundamental bounds on performance, which was introduced in Part 1, is applied to various antenna design problems. A memetic scheme for topology optimization combines local and global techniques to accelerate convergence and maintain robustness. Method-of-moments (MoMs) matrices are used to evaluate objective functions and allow determination of fundamental bounds on performance. By applying the Shermann-Morrison-Woodbury identity, the repetitively performed structural update is inversion-free yet full-wave. The technique can easily be combined with additional features often required in practice, e.g., only a part of the structure is controllable, or evaluation of an objective function is required in a subdomain only. The memetic framework supports multifrequency and multiport optimization and offers many other advantages, such as an actual shape being known at every moment of the optimization. The performance of the method is assessed, including its convergence and computational cost.
|
|
| 4. |
|
|
| 5. |
- Lundgren, Johan, et al.
(författare)
-
Iterative Calculation of Characteristic Modes Using Arbitrary Full-Wave Solvers
- 2023
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225. ; 22:4, s. 799-803
-
Tidskriftsartikel (refereegranskat)abstract
- An iterative algorithm is adopted to construct approximate representations of matrices describing the scattering properties of arbitrary objects. The method is based on the implicit evaluation of scattering responses from iteratively generated excitations. The method does not require explicit knowledge of any system matrices (e.g., stiffness or impedance matrices) and is well-suited for use with matrix-free and iterative full-wave solvers, such as FDTD (Finite-difference time-domain method), FEM (Finite element method), and MLFMA (Multilevel Fast Multipole Algorithm). The proposed method allows for significant speed-up compared to the direct construction of a full transition matrix or scattering dyadic. The method is applied to the characteristic mode decomposition of arbitrarily shaped obstacles of arbitrary material distribution. Examples demonstrating the speed-up and complexity of the algorithm are studied with several commercial software packages.
|
|
| 6. |
- Schab, Kurt, et al.
(författare)
-
Characteristic Modes of Frequency-Selective Surfaces and Metasurfaces from S-Parameter Data
- 2023
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 71:12, s. 9696-9706
-
Tidskriftsartikel (refereegranskat)abstract
- Characteristic modes of arbitrary 2-D periodic systems are analyzed using scattering parameter data. This approach bypasses the need for periodic integral equations and allows for characteristic modes to be computed from generic simulation or measurement data. Example calculations demonstrate the efficacy of the method through comparison against a periodic method of moments (MoM) formulation for a simple, single-layer conducting unit cell. The effect of vertical structure and electrical size on the number of modes is studied, and its discrete nature is verified with example calculations. A multiband polarization-selective surface and a beamsteering metasurface are presented as additional examples.
|
|
