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Multipole Radiations from Large Gold Nanospheres Excited by Evanescent Wave
摘要： We proposed the use of the evanescent wave generated in a total internal reflection configuration to excite large gold nanospheres and investigated the radiations of the high-order plasmon modes supported in gold nanospheres. It was revealed that the evanescent wave excitation is equivalent to the excitation by using both the incident and reflected light, offering us the opportunity to control the orientation of the electric field used to excite nanoparticles. In addition, it was found that the scattering light intensity is greatly enhanced and the background noise is considerably suppressed, making it possible to detect the radiations from high-order plasmon modes. Moreover, the influence of the mirror images on the scattering induced by a metal substrate is eliminated as compared with the surface plasmon polariton excitation. By exciting a gold nanosphere with s-polarized light and detecting the scattering light with a p-polarized analyzer, we were able to reveal the radiation from the electric quadrupole mode of the gold nanosphere in both the spatial and the frequency domains. Our findings are important for characterizing the radiations from the high-order modes of large nanoparticles and useful for designing nanoscale photonic devices.
关键词： scattering,plasmon mode,electric dipole,radiation pattern,gold nanosphere,evanescent wave,electric octupole,electric quadrupole
更新于2025-11-21 11:24:58
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Combined Wide-Angle Scanning by a Two-Dimensional Dipole Array
摘要： An analytical solution of an impedance synthesis problem for a two-dimensional dipole antenna array is obtained. The array consists of thin impedance electric dipoles whose centers are located at nodes of a planar rectangular grid with double periodicity. Radiation patterns of each dipole in the array does not differ from that of an isolated dipole. A new method for wide-angle scanning of the array radiation pattern, combining the simultaneous variation of phases of the excitation currents in the dipoles and of their surface impedances is proposed.
关键词： thin impedance dipole,flat two-dimensional antenna array,wide-angle scanning,radiation pattern,wave zone,impedance synthesis method
更新于2025-09-23 15:21:21
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[IEEE 2018 7th International Conference on Computer and Communication Engineering (ICCCE) - Kuala Lumpur, Malaysia (2018.9.19-2018.9.20)] 2018 7th International Conference on Computer and Communication Engineering (ICCCE) - CPW-Fed Patch Antenna with Reflecting Metasurface Covering for WLAN and WiMAX Applications
摘要： A coplanar waveguide (CPW)-fed multiband patch antenna with the integration reflecting metasurface covering has been designed and performance characteristics are critically analyzed. The proposed low profile antenna can offers the wireless communications services for WLAN and WiMAX applications. The rectangular shaped patch antenna consists of pair of C-, L- and splitted-T shape slotted radiator, and 2D reflective metasurface covering at the back of patch which is separated by dielectric layer of substrate. The details of the antenna design structure and performance criteria are discussed through numerical simulation using full-wave electromagnetic simulator. The simulation results shows that by employing the reflecting metasurface covering, the -10dB impedance bandwidth has considerably increased than the typical CPW-fed patch antenna: from 440 MHz to 570 MHz (29%), 390 MHz to 480 MHz (23%) and 900 MHz to 1060 MHz (18%) for three different operating bands centered at 2.5, 3.5 and 5.5 GHz respectively. The simulated result shows the antenna with RMC integration achieves peak gain of 6.56 dBi, 6.43 dBi and 6.97 dBi with average gain of 6.45 dBi, 6.27 dBi and 6.82 dBi at three operating bands respectively which are higher than the typical patch antenna.
关键词： patch antenna,low-profile,reflecting metasurface covering,CPW-fed,WiMAX/WLAN Applications,radiation pattern improvement
更新于2025-09-23 15:21:21
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Effect of LED Radiation Pattern on BER Performance in Indoor Multipath MIMO-VLC System
摘要： The present paper investigates the impact of three radiation patterns of LED namely Lambertian, Batwing, Elliptical on the BER performance of 4 × 4 indoor multiple-input multiple-output (MIMO) visible light communication (VLC) system. The BER simulation has been done using LOS and LOS plus first reflection (L-R1) signals for ceiling-mounted and wall-mounted LEDs. For the case of ceiling-mounted LEDs, impulse response and BER have been computed using those radiation patterns at the centre and corner of a room (5 m × 5 m × 3 m). It has been found that LED having Elliptical radiation profile is more suitable for LOS signal when receiver is placed at the centre position whereas, Batwing radiation is suitable for L-R1 signal, both at the centre and corner positions. In the case of wall-mounted LEDs, impulse response and BER have been determined at the centre of the room using LOS and L-R1 signals. The results show that Batwing has least BER using LOS signal due to its wide radiation beam, but for L-R1 signal, the Elliptical profile having its narrow radiation beam has provided better BER performance. The present study shows that the BER in MIMO-VLC system not only depends on the transmitter and receiver position but also on the radiation patterns of LED and higher order reflection signals.
关键词： BER,MIMO,LED radiation pattern,VLC,Impulse response
更新于2025-09-23 15:21:01
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ELECTRICALLY RECONFIGURABLE RADIATION PATTERNS OF SLOT ANTENNA ARRAY USING AGILE PLASMA WALL
摘要： In this paper, an antenna with recon?gurable radiation pattern in the H-plane at 2.45 GHz for high power applications is presented. It is based on a 3-slot array in the E-plane covered partially with a wall of plasma in order to reduce the length of the slots and consequently ensure electrically a modi?cation of the radiation pattern in the H-plane. The power distribution of the array is ensured with a power splitter.
关键词： recon?gurable radiation pattern,high power applications,slot antenna array,plasma wall
更新于2025-09-23 15:21:01
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Inset-fed rectangular MICROSTRIP patch antenna bandwidth enhancement
摘要： Bandwidth enhancement of the traditional inset-fed rectangular microstrip patch antenna is numerically analyzed using degraded ground plane technique. Input impedance calculation based on the electromagnetic theory in traveling-wave in conjunction with field distribution in quasi-TEM mode approximation is carried out. Radiated electric field properties are performed using Ampere’s law of the magneto-static. Some antenna performances such as ?10 dB return loss bandwidth of 36.7%, beam-width of about 94(cid:1), and stable gain of 3.4 dB have been achieved.
关键词： degraded GND inset-patch,traditional inset-patch,return loss,quasi-TEM mode,radiation pattern
更新于2025-09-23 15:21:01
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Analysis of the beam waist on spatial emission characteristics from an electron driven by intense linearly polarized laser pulses
摘要： This paper establishes a low-energy single-electron acceleration model based on the Lorentz equation and an energy equation, simulates the trajectories of electrons in laser pulses with different beam waist radii with the help of MATLAB software and analyzes the influence of linearly polarized laser intensity on the dynamic law of high-energy electrons. With the beam waist radius increasing, we find that the longitude drifting distance and the maximum transverse quivering amplitude are growing differently at each part at first (when the beam waist radius <4λ0) and then decreasing differently as well. Furthermore, when the beam waist radius is small enough, the ramifications are found first; increasing the radius of the beam will make the radiated power go up by orders of magnitude and the ramification of the location and number found in the asymmetric bifoliate radiation pattern change throughout.
关键词： relativistic motion,beam waist radius,radiation pattern,spatial distribution of emission,linearly polarized femtosecond Gaussian laser pulse,ramification
更新于2025-09-23 15:19:57
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A NOVEL COMPACT THREE-PORT DIELECTRIC RESONATOR ANTENNA WITH RECONFIGURABLE PATTERN FOR WLAN SYSTEMS
摘要： Splitting a cylinder dielectric resonator into four uniform quarters generates a new dielectric resonator antenna (DRA) shape, which is named a quarter volume of cylinder dielectric resonator antenna (QVCDRA) in the paper. On the basis, a novel compact three-port dielectric resonator antenna with recon?gurable radiation pattern is presented for WLAN systems at 5.2 GHz. A ?10 dB impedance bandwidth of 16.20%, covering the frequency range from 4.75 GHz to 5.54 GHz, is obtained with an isolation of lower than ?19 dB. The structure consists of three QVCDRAs that arrange evenly around Z axis, and as a result possesses the advantage of compact structure, wide impendence band and recon?gurable radiation patterns. The volume of the proposed three-port DRA without ground plane is only 0.0216λ3 d (λd is the dielectric wave length at the central operation frequency). The proposed antenna is analyzed in detail. Antenna prototype is fabricated and tested. The simulation and test results are in good agreement.
关键词： wide impendence band,dielectric resonator antenna,WLAN systems,compact structure,recon?gurable radiation pattern
更新于2025-09-23 15:19:57
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A Low-profile Wide Band “S” Shaped Rectangular Dielectric Resonator Antenna for “X” Band Application
摘要： The main goal of this article is to design a low-profile wide band Rectangular Dielectric Resonator Antenna (RDRA). The proposed “S” shaped rectangular DRA is excited by means of a popular microstrip line feeding. By using “S” shaped design, our proposed DRA yields an impedance bandwidth of 32% from 9.2 to 12.48 GHz, covering “X” band frequency. The proposed antenna has a wide impedance bandwidth, extremely low profile with the volume of 447 mm3, and a thickness equal to 2.5 mm. This design provides stable radiation patterns and high radiation efficiency. The proposed design is compared with some other designs in the literature in order to emphasize its significance. The proposed RDRA was fabricated and its characteristics were tested. Excellent agreement between simulated and measured ones was obtained.
关键词： Radiation pattern,Rectangular dielectric resonator antenna (RDRA),Low profile,X band,Impedance bandwidth
更新于2025-09-23 15:19:57
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GaAs-Based Laser Diode with InGaAs Waveguide Quantum Wells
摘要： The results of studying a GaAs-based laser with InGaAs waveguide quantum wells, which operates at room temperature in the electric-pumping mode, are presented. The minimal generation threshold is 15 A. Stable lasing at a wavelength of 1010 nm is attained, and the width of the radiation pattern in the plane perpendicular to the structure layers is (10 ± 2)°.
关键词： GaAs,laser diode,quantum well,radiation pattern,waveguide
更新于2025-09-19 17:13:59