- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM) - Nagoya (2018.8.29-2018.8.31)] 2018 IEEE International Workshop on Electromagnetics:Applications and Student Innovation Competition (iWEM) - A Printed Inverted-F Antenna for Dual-Band Dual-Sense Circular Polarization
摘要： In this paper, a printed inverted-F antenna (Printed-IFA) for dual-band dual-sense circular polarization is proposed. The bandwidth of 10 dB-return loss with a 3 dB-axial ratio is 5.5% for 2.5GHz band, and the one for 3.5GHz band is 10.0%. Antenna performance and operation principles of the proposed antenna are analyzed and discussed in detail.
关键词： Dual-sense,Printed Inverted-F Antenna,Circular polarization,Dual-band operation
更新于2025-09-19 17:15:36
-
Gain enhancement and RCS reduction of CP patch antenna using partially reflecting and absorbing metasurface
摘要： This paper presents a novel partially reflecting and absorbing metasurface (PRAM) in order to reduce Radar Cross Section (RCS) and enhance the gain of the circularly polarized patch antenna. The unit cell of PRAM consists of two stacked substrates with metallic patterns, which is used to design absorbing surface (AS) and partial reflecting surface (PRS). The metallic pattern on the top of the two substrates acts as AS and absorbs most of the out of band incoming wave. The bottom surface of the PRAM is used as PRS to construct Fabry-Perot (F-P) resonance cavity with metamaterial ground plane (MGP) for gain enhancement. Simulated and measured results show that the peak gain of the proposed antenna is enhanced by 5.7 dB at 6.6 GHz. The results also show that the impedance bandwidth and 3-dB axial ratio bandwidth of the antenna are also improved by the employment of PRAM. Monostatic RCS of the proposed antenna is significantly reduced in the broad range of 7 to 18 GHz and proposed antenna achieves maximum RCS reduction of 15.6 dB at 14.3 GHz.
关键词： Gain enhancement,circular polarization,partially reflecting and absorbing metasurface (PRAM),radar cross section (RCS)
更新于2025-09-19 17:15:36
-
Experimental demonstration of imaging hidden objects in opaque liquid-based media by fusion of single-shot multiview polarized and unpolarized speckle images
摘要： Turbid water-based liquids are common scattering media within which imaging objects is challenging, since scattering particles of various origins and sizes may cause severe image degradation, resulting in poor object recovery and resolution. Therefore, counteracting the nontrivial effects of light scattering is a primary challenge, limiting the utility of optical imaging within liquid media. In this work, we sought to circumvent the optical degradation in turbid liquid media and to recover high-quality images of hidden objects by averaging polarized speckle images projected from several directions through a lens array. Inspired by astronomy imaging techniques, the averaging process utilized a Shift-and-Add (SAA) algorithm developed to reconstruct atmospherically-degraded solar images. Both linear and circular polarization strategies were then applied to further improve image reconstruction. Experiments were carried out using two targets, each having a distinct geometrical shape, embedded within turbid liquid media comprising a range of dilutions of commercially available cow’s milk in seawater. The media were irradiated with a polarized laser beam, after which multiple polarized speckled images were captured with a CCD camera. Offline, images were first shifted to a common center and then fused, using the SAA algorithm, to yield reconstructed images of each hidden object. Quantitative image quality metrics, including SNR, entropy, and sharpness were applied to evaluate quality of the reconstructed images. The reconstructed images obtained demonstrate successful adaptation of our methodology for the identification of hidden objects within turbid media. To the best of our knowledge, this is the first report to demonstrate successful imaging of hidden object images within turbid liquid media by averaging multiple polarized speckle projections.
关键词： Linear and circular polarization,Imaging through turbid water,Lens array,Multiple polarized speckle projections,Image processing
更新于2025-09-19 17:15:36
-
[IEEE 2019 Computing, Communications and IoT Applications (ComComAp) - Shenzhen, China (2019.10.26-2019.10.28)] 2019 Computing, Communications and IoT Applications (ComComAp) - Dual-Sense Proximity-Coupled Antenna for Satellite Terminal
摘要： A dual-band dual-sense circularly polarized antenna is designed for satellite application. Method of Stacked patches with reverse truncated corners is proposed. It has achieved low frequency ratio of 1.13 in S-band, with two opposite circular polarizations. Details of the proposed antenna design are discussed.
关键词： dual-band,circular polarization,Dual-sense
更新于2025-09-19 17:13:59
-
A Wideband Terahertz Transmissive Polarization Manipulator Based on Metasurfaces
摘要： Wideband and multifunction operation for THz polarization manipulating devices has been desired for a wide range of applications. In this paper, a novel wideband transmissive type polarization manipulator based on metasurfaces is proposed in the THz region. The designed metasurface acts as a multifunctional polarization manipulator, performing linear to circular polarization conversion (LCPC) for relative bandwidth 43.9% (0.94 THz to 1.47 THz) for incident x/y polarizations and a wideband bandpass filter with relative bandwidth 67% (0.713 THz to 1.4346 THz) for incident slant (xy) polarizations. Wideband LCPC operation is achieved using a unique diagonal symmetric structure based on a bilayered metasurface. In order to confirm the validation of proposed results, electromagnetic simulation was carried out in two industry-standard software packages, HFSS and CST, using frequency domain and time domain solvers, respectively. Close agreement between numerical results depicts the validity and reliability of the proposed design. Polarized wave trajectory, equivalent microscopic circuit, physical mechanisms, and impact of different geometrical parameters on the performance is investigated. To the best of our knowledge, this is the first polarization manipulator based on bilayered metasurfaces. The same structure can be used as for LCPC and the transmit reject filter for THz wireless communication, including THz satellite communications, the future of communication. Moreover, they can be used in THz imaging and biomolecular control devices.
关键词： polarization manipulation,receive filter,linear to circular polarization conversion,terahertz
更新于2025-09-16 10:30:52
-
[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Tri-band Linear to Circular Polarization Converter based on Transmissive Metasurfaces
摘要： Multi-band operation for terahertz wireless systems is a challenging problem. We propose a tri-band linear to circular polarization converter in the terahertz regime using metasurfaces in transmission modes. The converter is composed of bi-layered metasurfaces separated by a dielectric spacer. Three bands (0.54-0.804, 1.904-2.476, and 2.96-3.884 THz) of linear to circular polarization conversion (LCPC) are achieved due to the superposition of the two transmitted components with a near 90° phase difference. Idea is verified by HFSS and paves a way to the design of multi-band transmissive linear to circular polarization converter.
关键词： linear to circular polarization converter,transmission modes,metasurfaces,terahertz,Multi-band operation
更新于2025-09-16 10:30:52
-
Circularly Polarized T-Shaped Slot Waveguide Array Antenna for Satellite Communications
摘要： A novel circularly polarized (CP) waveguide slot array for satellite communications is proposed. The antenna features a unique feeding network and a unit cell that consists of a pair of simple T-shaped waveguide slots. The proposed configuration not only eliminates grating lobes, which are often seen in conventional waveguide slot arrays, but also simplifies the fabrication process without any sacrifice in the performance, while also allowing scalability. A prototype 6×8 array antenna is designed at 29.5 GHz, and fabricated by dip brazing. A high gain of 21.9 dBi and a -10 dB impedance bandwidth of 1 GHz are achieved, with an axial ratio of 1.3 dB without any grating lobes. The measured results are in very good agreement with the simulated results.
关键词： circular polarization,antenna arrays,Slot antennas,waveguide antennas,planar arrays
更新于2025-09-16 10:30:52
-
Single-Layer Series-Fed Planar Array with Controlled Aperture Distribution for Circularly Polarized Radiation
摘要： We propose a compact circularly polarized series-fed patch array with enhanced radiation performance at S-band. To our best knowledge, no similar single-layer structure has been designed, measured and reported in the literature with equivalent radiation performances in terms of reduced sidelobe-level (SLL) and aperture efficiency as well as compactness and simplicity. The planar array consists of a 50-? microstrip single feed point, offering uniform and efficient excitation of all its elements that enables a broadside beam with high-gain and low sidelobes. A feed network for such aperture control is designed and optimized to provide good impedance matching with a two-point excitation per radiating element, which is based on 0? and 90? meander lines to enable circularly polarized radiation. A structure made by a 4×1 arrangement of square patches is simulated, optimized, and manufactured, providing a realized gain of about 10 dBic and a SLL below ?15 dB. Very good axial ratios and high efficiencies are obtained. The proposed antenna may be of interest for next-generation far-field wireless power transmission systems and other applications including target tracking, radar and internet of things technologies requiring efficient circularly polarized radiation.
关键词： radar,series-fed array,Controlled aperture distribution,wireless power transfer,circular polarization
更新于2025-09-16 10:30:52
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Direct Observation of Topological Edge States in Silicon Photonic Crystals
摘要： The concept of topology has proven immensely powerful in physics, describing new phases of matter with unique properties. There has been a recent surge in attempts to implement topological protection in the photonic domain, owing to the application potential of robust transport immune to scattering at disorder. A famous class of electronic topological insulators relies on the quantum spin-Hall effect (QSHE). Photonic analogues of QSHE were recently predicted to occur in photonic crystals with special symmetries [1, 2]. Interestingly, topological photonic crystals employing QSHE offer the possibility to access their properties via far-field radiation [3]. Here we directly observe topological photonic states at telecom wavelengths in photonic crystals in silicon-on-insulator (SOI) technology, and characterize their inherent spin, dispersion, and propagation. We reveal that the radiation of the topological states carries a signature of their origin in photonic spin-orbit coupling, linking unidirectional propagation to circular polarization (see Fig. 1a). The employed photonic crystals (inset of Fig. 1a) employ higher-order symmetry breaking to open bandgaps of different topological order at the Γ point [1, 2]. The edge between two domains supports topological states of differing pseudospin. We analyze these states by dispersing normal-incidence reflected intensity in both frequency and angle, mapping the edge state dispersion (in Fig. 1b). It displays the characteristic linear dispersion of edge states, with measured group velocity ～ c/6 and quality factor ～ 450. The positive and negative group velocity modes can be selectively excited with opposite circular polarization. Conversely, the states’ pseudospin can be probed directly in the far field through the S3 Stokes parameter obtained from polarimetry (Fig. 1c). Our Fourier spectroscopic measurements moreover reveal a small gap at the edge state crossing that is related to spin-spin scattering. This coupling is inherent to the symmetry breaking at the edge, and a defining difference between photonic and electronic topological insulators. Through the far-field spin-orbit link, we selectively excite edge states in opposite directions, and image their propagation in real-space microscopy. Figure 1d shows the routing of the edge state at a sharp waveguide junction. Interestingly, we observe an absence of backscattering or forward scattering, demonstrating the topological protection of unidirectional propagation. In fact, the states closely follow the photonic crystal edge — defined by the junction’s chiral structure of sub-unit cell size — even though their transverse extent is significantly larger. In conclusion, we observe the unique nature of topologically protected light transport in photonic crystals, through a technique that holds great promise for developing novel topological systems for various applications, including integrated photonic components, quantum optical interfaces, enantiomeric sensing, and nanoscale lasing.
关键词： photonic spin-orbit coupling,topological photonic states,unidirectional propagation,silicon-on-insulator,circular polarization
更新于2025-09-16 10:30:52
-
Polarization-Dependent Lateral Optical Force of Subwavelength-Diameter Optical Fibers
摘要： It is highly desirable to design optical devices with diverse optomechanical functions. Here, we investigate lateral optical force exerted on subwavelength-diameter (SD) optical fibers harnessed by input light modes with different polarizations. It is interesting to find that input light modes of circular or elliptical polarizations would bring about lateral optical force in new directions, which has not been observed in previous studies. By means of finite-difference time-domain (FDTD) simulations, detailed spatial distributions of the asymmetric transverse force density are revealed, meanwhile dependence of optical force on input light polarizations, fiber diameters, and inclination angles of fiber endfaces are all carefully discussed. It is believed that polarization-sensitive reflection, refraction, and diffraction of optical fields occur at the interface, i.e., fiber oblique endfaces, resulting in asymmetrically distributed optical fields and thereafter non-zero transverse optical force. We believe our new findings could be helpful for constructing future steerable optomechanical devices with more flexibility.
关键词： circular polarization,elliptical polarization,optical force,subwavelength-diameter optical fiber
更新于2025-09-12 10:27:22