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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • circularly polarized (CP) antenna
  • Elliptical microstrip antenna (EPMA)
  • impedance bandwidth (IBW)
  • defected ground (DG) technique
  • multi-layered stacked structure
  • axial ratio bandwidth (ARBW)
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Bhagwant University, Ajmer, Rajasthan, India
  • Govt Mahila Engineering College, Ajmer, Rajasthan, India
97 条数据
?? 中文（中国） ▾

  • DESIGN AND REALIZATION OF CIRCULAR POLARIZED SIW SLOT ARRAY ANTENNA FOR CUBESAT INTERSATELLITE LINKS

    摘要： This paper presents the design and fabrication of an antenna based on Substrate Integrated Waveguide (SIW) for intersatellite crosslinks in C-band. The entire antenna consists of two elements of SIW slots array that is fed by a hybrid 3 dB directional coupler. The entire SIW slots array antenna is circularly polarized (CP), and each element has four longitudinal slots. The element’s e?ective ?eld matching is realized with a microstrip to SIW transition. The antenna design has been evaluated with its return loss, gain plot, and radiation pattern characteristics to validate the fabricated antenna. The fabricated prototype antenna radiates a left-handed circularly polarized (LHCP) electromagnetic wave with the peak gain of 5 dB and o?ers approximately 2% AR bandwidth around 5 GHz.

    关键词： circularly polarized (CP),intersatellite links,slot array antenna,CubeSat,Substrate Integrated Waveguide (SIW)

    更新于2025-09-23 15:21:01

  • NOVEL CIRCULARLY POLARIZED SIW CAVITY-BACKED ANTENNA WITH WIDE CP BEAMWIDTH BY USING DUAL ORTHOGONAL SLOT SPLIT RINGS

    摘要： A circularly polarized (CP) substrate integrated waveguide (SIW) cavity-backed antenna based on dual concentric, orthogonal slot split ring resonators is proposed and experimentally studied. The circularly polarized wave is generated by two split ring-slots etched in the upper metal layer of the SIW cavity resonator. These two slots are excited by a coaxial probe located in the gap of the external slot split ring to radiate the right-handed circularly polarized (RHCP) wave. By rotating the dual split slot ring resonators and the probe by 45 degrees relative to the backed cavity, a better match characteristic and a slightly higher radiation gain are obtained. Because of the concentricity of radiant split ring slots, the beamwidth of the circular polarization is obviously increased. From the experimental results, the impedance bandwidth was 10.8% for the re?ection coe?cient less than ?10 dB, the axial ratio (AR) bandwidth was 1.54% for the AR less than 3 dB, and the RHCP gain was 4.44 dBic. Moreover, the 3-dB axial ratio beamwidth at the centre frequency of 10.40 GHz has been extended to 142? in the angular range from ?78? to +64?.

    关键词： circularly polarized,wide CP beamwidth,SIW cavity-backed antenna,dual orthogonal slot split rings

    更新于2025-09-23 15:21:01

  • RCS REDUCTION USING A MINIATURIZED UNI-PLANAR ELECTROMAGNETIC BAND GAP STRUCTURE FOR CIRCULARLY POLARIZED MICROSTRIP ANTENNA ARRAY

    摘要： In this paper, a new method for radar cross section (RCS) reduction of circularly polarized (CP) microstrip antenna array with small element spacing is proposed. By employing the element rotation technique and loading EBG structures, the in-band and out-of-band RCSs are reduced simultaneously despite the extreme small space between array elements. The simulated results show that the proposed antenna has an average RCS reduction over 10 dB in the X-band for x-polarized and y-polarized incident waves impinging from normal direction compared to the original CP microstrip antenna array, indicating a fractional bandwidth of 40%. The maximum RCS reduction is over 25 dB. Meanwhile, the radiation performance of the proposed antenna array is kept.

    关键词： RCS reduction,EBG structures,circularly polarized microstrip antenna array,element rotation technique

    更新于2025-09-23 15:21:01

  • Rays via Single-Shot Laser-Electron Interaction

    摘要： Generation of circularly polarized (CP) and linearly polarized (LP) γ rays via the single-shot interaction of an ultraintense laser pulse with a spin-polarized counterpropagating ultrarelativistic electron beam has been investigated in nonlinear Compton scattering in the quantum radiation-dominated regime. For the process simulation, a Monte Carlo method is developed which employs the electron-spin-resolved probabilities for polarized photon emissions. We show efficient ways for the transfer of the electron polarization to the high-energy photon polarization. In particular, multi-GeV CP (LP) γ rays with polarization of up to about 95% can be generated by a longitudinally (transversely) spin-polarized electron beam, with a photon flux meeting the requirements of recent proposals for the vacuum birefringence measurement in ultrastrong laser fields. Such high-energy, high-brilliance, high-polarization γ rays are also beneficial for other applications in high-energy physics, and laboratory astrophysics.

    关键词： nonlinear Compton scattering,electron-spin-resolved probabilities,high-energy physics,Monte Carlo method,circularly polarized γ rays,vacuum birefringence,quantum radiation-dominated regime,laboratory astrophysics,linearly polarized γ rays

    更新于2025-09-23 15:19:57

  • Asymmetric photoelectron emission from chiral molecules using a high repetition rate laser

    摘要： In the chiro-optical phenomenon known as photoelectron circular dichroism, the angular distribution of electrons ionized from chiral molecules by circularly polarized light pulses has been found to be anti-symmetric with respect to the direction of the light propagation. To study this phenomenon, chiral molecules were multiphoton ionized with a femtosecond laser in our laboratory. Using a simple stereo-detection setup, direct measurements of the asymmetry for the exemplar aromatic chiral molecule 1-phenylethanol were made using 260 nm pulses produced at a rate of 1 MHz. It was found that the asymmetry had a linear dependence on Stokes’ S3 parameter indicating that the photoelectron circular dichroism is due to a single photon process from the excited state of the molecule. This is in contrast to previous and new results for camphor where a more complex dependence on S3 suggested that selective excitation of molecules with certain orientations was influential.

    关键词： photoelectron circular dichroism,circularly polarized light,asymmetry,Stokes’ S3 parameter,chiral molecules

    更新于2025-09-23 15:19:57

  • Design and Characterization of Wideband Aperture-Coupled Circularly Polarized Antenna for Gigabits Per Second Wireless Communication System

    摘要： In this paper, design and characterization of an aperture-coupled circularly polarized (CP) rectangular patch antenna suitable for Gigabit per second wireless communications system is presented. The proposed antenna exhibits a large bandwidth of 2.77 GHz at centre frequency fc = 19.5 GHz (about 15% of fractional bandwidth (FBW)). It also has a gain of about 7.25 dBi at 18 GHz with good stable gain and radiation characteristics in the frequency band of interest. For indoor wireless channel measurements, two developed prototypes are employed as single input single output transmit receive (TX–RX) antennas with a robust and versatile channel modeling system. We demonstrate a measurement campaign to investigate the dynamic range of the system by calculating path loss. The pulse dispersion effect is quantified by pulse fidelity factor (PFF). The measurements are performed in laboratory environment using Gaussian pulse based sounding signal modulated at 19.3 GHz carrier frequency. The design and characterization of compact size antennas with pertinent bandwidth and excellent radiation characteristics is one of our initiatives towards developing a millimeter wave (MMW) test bed system for channel modeling and measurement, since 5G wireless communication is supposed to operate in MMW band.

    关键词： Aperture-coupled antenna,Gigabits per second wireless system,Circularly polarized antenna

    更新于2025-09-23 15:19:57

  • DUAL-BAND CIRCULAR POLARIZED SLOT ARRAY ANTENNA IN SUBSTRATE INTEGRATED WAVEGUIDE USING TWO PROPAGATION MODES FOR COMMUNICATION SATELLITES TRANSCEIVERS

    摘要： A novel dual-band circularly-polarized slot array antenna aimed at LEO satellites communications where up-link and down-link operate at di?erent frequencies is introduced. By using higher order modes, the slots can be placed at points where current distributions are null for the fundamental mode. According to this idea, at the receiver frequency band the slots are placed to be excited by mode T E10 currents distribution, and at the transmitting band slots are forced to radiate according to mode T E20 currents distribution. A matching load termination is used to generate the required travelling wave to obtain the circular polarization, introducing low dissipation losses. Additionally, in this investigation an antenna feeder is also designed. Both the feeder and the slot antenna array are designed using Substrate Integrated Waveguide (SIW). The use of SIW makes easier the design of the transitions from the array to the microstrip input lines and the grounded-coplanar termination as well, relaxing fabrication constraints and tolerance.

    关键词： dual-band,Substrate Integrated Waveguide,slot array antenna,circularly-polarized,communication satellites transceivers

    更新于2025-09-23 15:19:57

  • Gap plasmons inducing strong plasmonic chirality in planar metallic nanostructures

    摘要： In this paper, an observation of chiral gap plasmons that induce strong optical chirality, spectroscopic circular dichroism (CD), and near-field enhancement in a planar metallic nanostructure is reported. The resulting chiral nanostructure consists of artificial gold nanoscale elements which are periodically fabricated on a glass substrate. The measured extinctions of the structure under linearly polarized light illumination are in good agreement with numerical calculations of extinction cross-sections. The dissymmetry of the extinctions under left- and right-handed circular polarization is correlated to the far-field CD of the chiral nanostructure that yields a strong CD of up to 0.02. Near-field enhancement of up to 20 times and a large local optical chirality is numerically found at a plane 5 nm above the chiral nanostructure. The finding of chiral gap plasmons that induce strong optical chirality is experimentally demonstrated to enhance interaction between achiral dye molecule and chiral gap plasmon, emitting circularly polarized luminescence with a dissymmetry factor of up to 0.15.

    关键词： optical chirality,chiral nanostructures,circularly polarized luminescence,circular dichroism,gap plasmon

    更新于2025-09-23 15:19:57

  • Size- and Composition-Dependent Exciton Spin Relaxation in Lead Halide Perovskite Quantum Dots

    摘要： The strong spin-orbital coupling in lead halide perovskites allows for facile spin injection for spintronics applications, but on the other hand also limits the lifetime of the injected spins. Full-dimensional confinement of the carriers using quantum dots (QDs) has been envisioned as an effective means to prolong the spin relaxation lifetime and has been explored for II-VI and III-V group QDs. Here we applied this idea to colloidal lead halide perovskite QDs and measured the exciton spin dynamics of QDs of varying sizes and compositions using circularly polarized transient absorption spectroscopy at room temperature. Interestingly, the spin lifetimes of CsPbI3 and CsPbBr3 QDs were prolonged and shortened, respectively, as compared to their bulk counterparts. Both CsPbI3 and CsPbBr3 QDs showed decreasing spin lifetime with decreasing QD size. Possible spin relaxation mechanisms, including those that are unique to these quantum-confined systems, were proposed, with important ramifications for the use of these perovskite QDs in spin-related applications.

    关键词： lead halide perovskites,spin-orbital coupling,exciton spin dynamics,circularly polarized transient absorption spectroscopy,quantum dots

    更新于2025-09-23 15:19:57

  • High-Gain Circularly Polarized Fabry–Pérot Patch Array Antenna with Wideband Low-Radar-Cross-Section Property

    摘要： In this paper, we explore the adoption of a chessboard polarization conversion metasurface (CPCM) for constructing a low-radar-cross-section (RCS), high-gain circularly polarized (CP) patch array antenna. The proposed CPCM is used as the polarization conversion metasurfaces’ chessboard configuration, which consists of adjacent two-layer substrates that have three metallic models. Low RCS is achieved by 180° (±30°) reflection phase variations of two adjoining PCMSs. Gain enhancement is achieved by adopting a Fabry–Pérot cavity constituted by a PCM and the antenna’s ground. The antenna with a CPCM that operates at X/Ku band, excited by the feeding network that is rotated sequentially, is measured and fabricated. The patch array antenna impedance bandwidth based on PCM was measured as 3.3 GHz (9.5–12.8 GHz) with a 3-dB axial ratio bandwidth of 11.6% and a high gain of 13.4 dBiC (9.5–12 GHz), more than 2.5 dB higher compared with a patch antenna without a PCM. In addition, the patch array antenna produced a useful wideband RCS decrease in the operational bandwidth from 9 to 13 GHz.

    关键词： low radar cross-section,dual patch,polarization conversion metasurface,circularly polarized

    更新于2025-09-19 17:15:36