The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Near-zero index metamaterials play an important role in wave-matter interactions, exhibiting several promising techniques to control and manipulate fields and waves. In this paper, we study the scattering properties of the epsilon-and-mu-near-zero metamaterials. By immersing a non-magnetic dielectric rod within the epsilon-near-zero host, we can imitate the far-field scattering pattern of epsilon-and-mu-near-zero...
Flower specialisation of angiosperms includes the occluded corollas of snapdragons (Antirrhinum and some relatives), which have been postulated to be one of the most efficient structures to physical limit access to pollinators. The Iberian Peninsula harbours the highest number of species (18 Iberian of the 20 species of Antirrhinum) that potentially share similar pollinator fauna.
Crossing experiments...
During recent years zero-index media have offered unique tools for the control and manipulation of electromagnetic waves. However, similar concepts and techniques could be transplanted to the manipulation of quantized fields. As a specific example, we demonstrate theoretically that supercoupling phenomena in a N-port epsilon-and-mu-near-zero (EMNZ) hub can be utilized in the generation of subradiant,...
This paper demonstrates the enhancement of the radiation performance of a slotted waveguide antenna (SWA) when it is covered with a metasurface. The design of this antenna is presented, along with the comparison with a dielectric covered SWA. This comparison shows that 3 dB gain improvement is achieved when the metasurface is used.
This paper studies several metasurface enhanced slot antenna. The metasurface is placed on top of the slots, which allows extending their radiating aperture, leading to narrower E-Plane radiation pattern and larger gain. An example is given in which a slotted waveguide antenna gain increases 8 dB with respect to the conventional slotted waveguide antenna.
Microsized carbon fibres exhibit strong resonant absorption at terahertz frequencies. Using near-field terahertz time-domain spectroscopy, we probe their conductivity by analysing the degree of field enhancement produced by plasmonic resonances. We demonstrate, theoretically and experimentally, the potential usability of carbon microfibres as terahertz absorbers with engineerable response.
An induction theorem-inspired approach is adopted for the design of a Huygens source nanoparticle laser. The proposed nanoparticle consists of a three-layer silicon-silver-silicon (Si-Ag-Si) concentric sphere, which enables the amplified and balanced excitation of the electric and magnetic dipole modes with scattering efficiencies in excess of 600. Moreover, with its dipolar modes designed to be in...
This contribution analyzes several multi-frequency antenna systems based on meta-surfaces. As it is demonstrated, there is a synergy between the frequency-domain behavior of the meta-surface and multi-frequency antenna architectures. Therefore, the use of the meta-surface is not restricted to enhance the radiation properties of the single-antenna element, but also contributes at system level aspects...
Quality control systems in industry can benefit from the new possibilities offered by THz frequency range. THz imaging systems can complement actual quality control systems and at the same time offer new information about products, improving quality and reducing costs. In this case we have implemented and imaging system to control the evolution of water content in leaves. THz frequencies are sensitive...
In this paper a broadband planar chessboard structure combining AMC structures is presented. Two Jerusalem crosses AMCs with different working frequencies have been selected to fill the cells of the chessboard. These AMC have been design to keep 180° of phase difference in a broadband.
An accurate analytical model for the scattering of a amorphous glass-coated ferromagnetic microwire is presented. The electromagnetic problems of both the scattering from a ferromagnetic microwire in free-space and inside a rectangular waveguide are solved and the results are experimentally verified with measurements inside a WR-90 waveguide.
The design and full-wave analysis of radio direction finders (RDFs) for ultra-wideband direction-of-arrival estimation is addressed. Conformal elliptically shaped dipoles are selected as antenna sensors by virtue of their good input impedance matching property, performance robustness and conformability. In order to achieve a full angular scanning coverage in the azimuthal direction, a uniform circular...
This contribution presents the design and full-wave analysis of a dual-frequency highly-directive planar antenna employing meta-surfaces composed of grids of cut and continuous wires. The designed antenna consists of a dual-band dipole placed between two meta-surfaces operating at two different frequencies. The result is a very low-profile antenna system with augmented directivity and radiating to...
Since the discovery of metamaterials, one of the potential applications of such structures has been the development of substrates and superstates for planar antennas. Recently, a meta-surface composed by grids of capacitively loaded and continuous wires has been implemented as superstate and substrate of a dipole antenna, with the consequent improvement of its radiations properties, The main advantages...
We present the design and full-wave analysis of conformal butterfly antennas for Ultra-Wideband (UWB) Radio Direction Finders (RDFs). The impact of the conformal deformation on the antenna performance is evaluated, a suitable antenna cover is designed, and single antenna elements for a RDF covering the band from 250MHz to 3.5GHz are optimized. Impact of coupling between antenna elements is evaluated,...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.