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Presents the introductory welcome message from the conference proceedings. May include the conference officers' congratulations to all involved with the conference event and publication of the proceedings record.
This work describes an efficient and powerful technique to obtain optimal currents with respect to the lower bounds of quality factor Q for an arbitrarily shaped electrically small antenna made of perfect conductor. The resulting optimal currents are expressed in terms of characteristic mode basis with the minimum always being obtained by either one mode tuned to the resonance, or, by properly combining...
This paper presents a two-notch antenna cut on a small ground plane excited out of phase to a radiate horizontally polarized omnidirectional pattern. The radiating modes of this antenna is evaluated by characteristic modes analysis to obtain omni-pattern. The second mode provides a loop current in horizontal plane, radiating omni-pattern with small ripples. To improve the uniformity of pattern, this...
A new definition is given for the reactive energy of a radiating device in time domain, leading to a clear physical insight also in frequency domain. In the new paradigm, the recently observed problem of so-called negative reactive energies is easily explained by causality: it takes a finite time for an electromagnetic wave to travel from one part of the device to another. The new definition of reactive...
The Theory of Characteristic Modes (TCM) is applied for the analysis of a slot etched in a metallic finite-sized ground plane, providing physical insight into the effect produced by the ground plane dimensions. The information yielded by the modal analysis reveals the close influence of the finite-sized plate on the radiation pattern of the slot antenna and its stability with frequency. Information...
Characteristic mode analysis has traditionally been constrained to problems which utilize only perfect electric conductors (PEC). Through forced symmetry of a method of moments surface integral equation and newly proposed post-processing, characteristic modes can be solved for any material in a computationally efficient manner. As an example, the characteristic modes are solved for a mobile terminal...
A compact ultra-wideband multi antenna system is presented in this paper. The concept is based on the simultaneous excitation of different Characteristic Modes on each antenna element by multiple decoupled ports. This enables a 484 port antenna with low port to port coupling having only 121 physical antenna elements.
Crossing avoidances in characteristic mode eigenvalues are discussed in the context of modal symmetry and inter-modal energies. Imperfect symmetry enforcement by coarse meshing is identified as a potential cause of spurious crossing avoidances. Inter-modal energy is discussed as a possible a priori analysis to guide fast, wideband modal tracking algorithms.
We introduce a design methodology for planar MIMO antennas, including both shape synthesis and feed placement. Using characteristic mode theory (CMT), the planar MIMO antenna aperture is first optimized to support multiple self-resonant and low Q modes. Iterative mesh refinement is employed to improve the convergence speed. Optimal feed positions for the multi-port aperture are then selected based...
In this paper, a printed monopole working at ultra-high frequency (UHF) is designed for TV white space (TVWS) applications. By employing U-shape radiator, tapered feeding and notched ground plane, impedance matching of the antenna is improved and its size is reduced. The proposed antenna achieves 414MHz bandwidth within a dimension as compact as 231mm × 35mm × 0.8mm. Furthermore, characteristic mode...
We present our recent results on efficient tuning of optical properties of a high refractive index subwavelength nanoparticle with a magnetic Mie-type resonance by means of femtosecond laser irradiation. This concept is based on ultrafast photo-injection of dense (> 1020 cm−3) electron-hole plasma within such nanoparticle, drastically changing its transient dielectric permittivity. This allows...
Superdirectivity has been a topic of active research in antennas at radio frequencies since it was first postulated almost a hundred years ago. Despite its potential use in solar cells and optical communications, the topic of superdirectivity on the nano-scale is a relatively new field of study. Examples of superdirective nano-antennas include phased arrays and notched dielectric spheres. In this...
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