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[IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Va?ster?s (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Monopole Design for Superdirectivity with Pattern Radiation Reconfigurable
摘要： This paper presents a global study for superdirectivity of an array of 2 monopoles antennas. It is principally based on Uzkov’s theory, who define the possibility to obtain a high directivity in order of N 2 in a desired direction by linearly associating a large number N of radiators closely spaced. A first study is made by exciting monopoles by specific currents excitation in magnitude and phase to obtain a superdirectivity reconfigurable in a desired direction. Secondly, to reduce until eliminate mutual coupling between monopoles, we excite one of monopole by a unit current and loaded the other one by an impedance Zload determined from uzkov’s theory. Simulator Ansys HFSS is used to calculated impedance matrix Hmn of monopoles antennas array and then currents excitation coefficients a0n used after to determine impedance Zload. Simulations show approximately similar results in the 2 cases with a reconfigurable directivity a least in around of 8.5dB in a desired direction.
关键词： impedance active,end-fire,Superdirectivity,impedance-matched
更新于2025-09-23 15:23:52
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Multiple scattering enabled superdirectivity from a subwavelength ensemble of resonators
摘要： An ensemble of resonators arranged on a subwavelength scale is usually considered as a bulk effective medium, known as a metamaterial, and can offer unusual macroscopic properties. Here, we take a different approach and limit ourselves to the study of only a few number of such elementary components and demonstrate that they still offer uncommon opportunities. Typically, owing to the multiple scattering and the phase shift that the resonances offer, we observe ?elds that vary at scales completely independent of the wavelength in free space. By smartly tuning the resonance frequencies, we can design at will the complex current distribution in those resonators. This way, we design a superdirective antenna, i.e., an antenna that is surprisingly more directive than its size would foreshadow. This approach is veri?ed numerically and experimentally in the context of microwaves, but this applies to any wave ?eld where subwavelength resonators exist.
关键词： metamaterials,superdirectivity,microwaves,subwavelength resonators,multiple scattering
更新于2025-09-16 10:30:52
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Planar Directivity of a Dipole Array
摘要： We develop a technique for fast evaluation of superdirective performance of coupled meta-atoms. Traditionally, the directivity of a small antenna is obtained from measurements of the far-field radiated power over a spherical surface. We propose an alternative method of finding the directivity from a faster polar scan over a circular path, by introducing the “planar directivity” (D2D) for dipole arrays. We derive analytical expressions for maximum achievable values of directivity and D2D, establish the correlation between them, and identify the range of parameters (inter-element distance, coupling constant, quality factor) for which the conversion of D2D to D for superdirective dimers is possible.
关键词： dipole arrays,planar directivity,far-field measurements,metamaterials,superdirectivity
更新于2025-09-10 09:29:36