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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Multi-Frequency GNSS Dielectric Resonator Antenna with In-Band Filtering
摘要： This paper presents a novel multi-frequency GNSS antenna based on a dielectric resonator (DR) with in-band filtering. The antenna is based on a conventional hollow cylinder DR with four feeding ports. It introduces a novel concept so called "decoupling network". The "decoupling network" is an engineered surface conformal to the inner wall of the DR and it contributes to the antenna realized gain, impedance bandwidth and provides narrow-band notch-filter like suppression of antenna radiation between 1.34 and 1.41 GHz. In case of the GNSS antennas, the radiation suppression between 1.3 and 1.56 GHz is desirable to reject in-band interference from the L-band satellite and terrestrial communication signals. The "decoupling network" also contributes to the coupling reduction between the feeding ports.
关键词： GNSS antenna,compact antenna,broadband antenna,circular polarization,engineered surface,dielectric resonator,EBG
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - A Circularly Polarized Metasurface Antenna
摘要： The concept of metasurface antennas based on electrically small resonators was recently introduced and has opened a new window into the design of high gain antennas. In the earlier work, a linearly polarized metasurface antenna was designed and fabricated. In this work, we present the design of a circularly polarized metasurface antenna. An array of 8 × 8 cross-shaped resonators was designed to operate at 3 GHz with an overall array size of 12 cm × 12 cm (1.2 (cid:540) × 12 (cid:540)). By feeding the resonators with appropriate phases, we achieved circular polarization with a high gain of approximately 12 dBi.
关键词： feed network,Antenna array,circular polarization,metasurface
更新于2025-09-04 15:30:14
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A Reflectarray for Generating Wideband Circularly Polarized Orbital Angular Momentum Vortex Wave
摘要： A reflectarray for generating wideband circularly polarized (CP) orbital angular momentum (OAM) vortex wave in X band is proposed. First, a dual-linearly-polarized element consisting of two rhombus-shaped metal patches etched on two dielectric substrates is designed. The element has high isolations between two polarizations and preferable linear phase responses in wide frequency band. Then, the phase distribution of the reflectarray carrying the OAM vortex wave with mode l=1 is designed, and dimensions of the elements are determined by their reflective phases. The far-field radiation patterns and near-field phase distributions are simulated to verify the proposed design. Finally, prototype of a 313-element reflectarray with a linearly polarized (LP) Vivaldi feed, which converts an incident LP wave into a reflective CP wave, is fabricated and measured. The results of measurement indicate that the reflectarray can generate CP OAM vortex wave with mode l=1 in 9-11 GHz band (a fractional bandwidth of 20%). The reflectarray also achieves 20% 1-dB gain bandwidth, and its peak gain is 19.9 dB at 11 GHz. Except for a very narrow band (10.9-11.1 GHz), its measured 3-dB axial ratio (AR) bandwidth is about 40%.
关键词： reflectarray,Wideband,orbital angular momentum,circular polarization
更新于2025-09-04 15:30:14
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-Point Splitting
摘要： We investigate points of circular polarization in the far field of elliptically polarized dipoles and establish a relation between the angular position and helicity of these C points and the dipole moment. In the case of highly eccentric dipoles, the C points of opposite handedness exhibit only a small angular separation and occur in the low intensity region of the emission pattern. In this regard, we introduce an optical weak measurement approach that utilizes the transverse electric (azimuthal) and transverse magnetic (radial) far-field polarization basis. Projecting the far field onto a spatially varying postselected polarization state reveals the angular separation and the helicity of the C points. We demonstrate the applicability of this approach and determine the elliptical dipole moment of a particle sitting on an interface by measuring the C points in its far field.
关键词： C points,dipole moment,far field,circular polarization,weak measurement
更新于2025-09-04 15:30:14
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Efficient spectral domain MoM for the design of circularly polarized reflectarray antennas made of split rings
摘要： The Method of Moments (MoM) in the spectral domain is used for the analysis of the scattering of a plane wave by a multilayered periodic structure containing conducting concentric split rings in the unit cell. Basis functions accounting for edge singularities are used in the approximation of the current density on the split rings, which makes it possible a fast convergence of MoM with respect to the number of basis functions. Since the 2-D Fourier transforms of the basis functions cannot be obtained in closed-form, judicious tricks (controlled truncation of in?nite summations, interpolations, etc.) are used for the e?cient numerical determination of these Fourier transforms. The implemented spectral domain MoM software has been used in the design of a circularly polarized re?ectarray antenna based on split rings under the local periodicity condition. The antenna has been analyzed with our spectral domain MoM software, with CST and with HFSS, and good agreement has been found among all sets of results. Our software has proven to be around 27 times faster than CST and HFSS.
关键词： re?ectarrays,periodic structures,circular polarization,moment methods,Multilayered media
更新于2025-09-04 15:30:14
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Analysis of circular polarization antenna design trade‐offs using low‐cost EM‐driven multiobjective optimization
摘要： Circular polarization (CP) antennas are vital components of modern communication systems. Their design involves handling several requirements such as low reflection and axial ratio (AR) within the frequency range of interest. Small size is an important criterion for antenna mobility which is normally achieved as a by-product of performance-oriented modifications of the structure topology. In this work, multiobjective optimization is used in order to identify and analyze design trade-offs for miniaturized CP antenna including the antenna capability for maintaining small size while retaining acceptable levels of other performance figures. We use a population-based metaheuristic algorithm to obtain a set of designs which represent the best attainable compromise between the imposed requirements. To maintain a low optimization cost, the algorithm is executed on a cheap approximation model and the results are further corrected to bring them to the EM model accuracy level. Here, the analysis is carried out for a planar CP antenna. Achievable size reduction of the considered structure—while maintaining acceptable performance—is around 11%. Antenna performance in terms of in-band reflection and AR varies from ?14 to ?10 dB and from 1.3 to 3 dB, respectively. The numerical results are validated by measurements of fabricated antenna prototypes.
关键词： design trade-offs,design optimization,circular polarization antennas,compact antennas,EM-driven design,multiobjective optimization,axial ratio
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Metallic Metasurface Antennas for Space
摘要： In metasurface (MTS) antennas, a surface-wave (SW) is gradually radiated by modulating an equivalent reactance tensor in the aperture plane. Such modulation results in the (-1) indexed Floquet mode entering the visible region, thus becoming a leaky-wave (LW) mode with curvilinear phase-contour. This paper explores the use of a class of metallic MTS in the synthesis of the reactance tensor required to obtain the objective radiation patterns. The absence of dielectric is useful to survive harsh environments in space exploration. The proposed element consists of a metallic cylinder with elliptical cross-section, placed on a ground plane and arranged in a square lattice with sub-wavelength unit-cell side. We have applied this structure in the design of a right-handed circularly polarized antenna, with a broadside pencil beam in the Ka band. The obtained performance has been veri?ed by full-wave simulations. A prototype has been manufactured and measurements will be available at the time of the conference.
关键词： surface waves,leaky waves,metasurfaces,circular polarization,millimeter waves,Ka band
更新于2025-09-04 15:30:14