| 1. |
- Losenicky, Vit, et al.
(författare)
-
Dissipation Factors of Spherical Current Modes on Multiple Spherical Layers
- 2018
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 66:9, s. 4948-4952
-
Tidskriftsartikel (refereegranskat)abstract
- Radiation efficiencies of modal current densities distributed on a spherical shell are evaluated in terms of dissipation factor. The presented approach is rigorous, yet simple and straightforward, leading to closed-form expressions. The same approach is utilized for a two-layered shell and the results are compared with other models existing in the literature. Discrepancies in this comparison are reported and reasons are analyzed. Finally, it is demonstrated that radiation efficiency potentially benefits from the use of internal volume which contrasts with the case of the radiation Q-factor.
|
|
| 2. |
- Schab, Kurt, et al.
(författare)
-
Energy Stored by Radiating Systems
- 2018
-
Ingår i: IEEE Access. - 2169-3536. ; 6, s. 10553-10568
-
Tidskriftsartikel (refereegranskat)abstract
- Though commonly used to calculate Q-factor and fractional bandwidth, the energy stored by radiating systems (antennas) is a subtle and challenging concept that has perplexed researchers for over half a century. Here, the obstacles in defining and calculating stored energy in general electromagnetic systems are presented from first principles as well as using demonstrative examples from electrostatics, circuits, and radiating systems. Along the way, the concept of unobservable energy is introduced to formalize such challenges. Existing methods of defining stored energy in radiating systems are then reviewed in a framework based on technical commonalities rather than chronological order. Equivalences between some methods under common assumptions are highlighted, along with the strengths, weaknesses, and unique applications of certain techniques. Numerical examples are provided to compare the relative margin between methods on several radiating structures.
|
|
| 3. |
- Tayli, Doruk, et al.
(författare)
-
Accurate and Efficient Evaluation of Characteristic Modes
- 2018
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 66:12, s. 7066-7075
-
Tidskriftsartikel (refereegranskat)abstract
- A new method to improve the accuracy and efficiency of characteristic mode (CM) decomposition for perfectly conducting bodies is presented. The method uses the expansion of the Green dyadic in spherical vector waves. This expansion is utilized in the method of moments (MoM) solution of the electric field integral equation (EFIE) to factorize the real part of the impedance matrix. The factorization is then employed in the computation of CMs, which improves the accuracy as well as the computational speed. An additional benefit is a rapid computation of far fields. The method can easily be integrated into existing MoM solvers. Several structures are investigated illustrating the improved accuracy and performance of the new method.
|
|
