1,721,022 research outputs found
Single layer Multimodal OAM Reflectarray
Full text linkIn this work, the procedure for the design of innovative reflectarray (RA) antennas able to radiate multiple Orbital Angular Momentum (OAM) modes is introduced. Extending the concepts at the base of multifocal lenses, the RA is designed in such a way that, depending on the direction of arrival of the incident field, it radiates a broadside beam carrying an OAM with different index. As a proof of concept, a circular RA with diameter D = 20λ at the the frequency f0 = 30 GHz, able to radiate OAMs with l = 2 and l = 4 has been designed. The results obtained through its full-wave simulation, confirm the effectiveness of the proposed solution
Space-fed antenna based on dielectric-only transmitarray
Full text linkIn this work, preliminary results on the design of a dielectric transmitarray (TA) antenna are presented. The unit-cell consists in two circular cylinders located on the two sides of a thin square slab, with size 0.3λ at the central frequency, realized with the same dielectric material of the cylinders. The amplitude and phase of the transmission coefficient are controlled varying the diameter of the cylinders, while their height is kept constant. In order to minimize the unit-cell thickness, but at the same time assuming that 3D printing techniques will be used for the TA manufacturing, a dielectric material with εr=10 is considered. The results obtained from the simulation of a transmitarray working in Ka-band with size 15λ×15λ are presented and discussed
Single-Layer, Multi-Mode OAM Reflectarray Antennas
Full text linkIn this letter, an innovative ReflectArray (RA) antenna able to radiate in the same direction multiple Orbital Angular Momentum (OAM) modes, is presented: depending on the direction of arrival of the impinging field, the RA radiates a broadside beam carrying on an OAM mode with different index. Two circular RAs with diameter D = 19.8λ at the the frequency f0 = 30 GHz, able to radiate two or four OAMs, have been designed and simulated, while a prototype of the dual-mode configuration has also been manufactured and experimentally characterised. The obtained results prove that vortex beams are successfully generated in the range of frequencies from 28 to 32 GHz, confirming the effectiveness of the proposed design
Preliminary Results on the Feasibility of Flexible Space-Fed Antennas
Full text linkIn this communication, the feasibility of space-fed antennas as Transmitarrays or Reflectarrays, where the focusing transmitting/reflecting surface is flexible, is investigated, with the aim of obtaining configurations providing almost the same radiating features even when they are conformal to cylinders with different radii of curvature. Preliminary numerical results on both a reflectarray and a transmitarray confirm the possibility to realize such antennas
MmCn-BBO schemes for electromagnetic problem optimization
No full textIn this communication some variations of the Biogeography Based Optimization, named MmCn-BBO are introduced. They present new features with respect to the standard BBO, aimed to improve the performances of this last algorithm. The comparison among the different schemes, when applied to both benchmark functions and real-world electromagnetic problems, shows the improvement of the here introduced BBO variations and serves to define the most performing among the different proposed variatio
Multi-Resonant Unit Cell for Efficient Smart Electromagnetic Skins
Full text linkRecently, passive Smart Electromagnetic Skins (SESs) have gained popularity for their capability to enhance the performance of a communication system without increasing its complexity. Since the focus was initially on the design of the structure at the whole, less attention was paid to the effects that the unit cell used for discretizing the surface itself has on the SES performance, just making a distinction between the use of resonant or sub-wavelength elements. Conversely, in this communication a multi-resonant unit cell is introduced and some preliminary numerical results on its application to the design of a smart skin are shown: they confirm its effectiveness and capability to improve the performance of the SES in comparison with other unit cells
Metaswarm: Enhanced evolutionary algorithms for electromagnetic optimization
No full textHere some variations of the basic Particle Swarm algorithm (a relatively novel approach for global stochastic optimisation) are proposed in order to increase the efficiency of the search over the solution space with a negligible overhead in the algorithm complexity and speed. The resulting algorithms have been first compared in terms of capability and speed of convergence by their application to a test function, then the resulting best technique has been used for the design of a microwave filter
Transparent Smart Electromagnetic Skins for Outdoor to Indoor Communications
Full text linkIn this communication, preliminary results on the design of a passive, transparent, Smart Electromagnetic Skin (SES) for outdoor-to-indoor (O21) communications are presented. Contrary to what is already available in literature, here a dielectric-only configuration is proposed, in order to avoid the presence of metallizations that can reduce the transparency. Moreover, a glass layer is directly introduced in the unit cell, to take into account the presence of the window. Different configurations have been designed and numerically analyzed: the obtained results demonstrate the feasibility of the proposed solution and its effectiveness
Reflectarray with mechanically steerable beam for DTH application
No full textIn this paper, the possibility of designing a Direct-To-Home (DTH) system using as receiving antenna a planar Reflectarray (RA) with mechanical beam steering capabilities is discussed: the preliminary results on the numerical analysis and experimental characterization of the designed prototype are promising, confirming the feasibility of proposed antenna configuration
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