- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Wideband Monostatic Co-Polarized Co-Channel Simultaneous Transmit and Receive (C-STAR) Broadside Circular Array Antenna
摘要： A novel wideband monostatic circularly co-polarized co-channel simultaneously transmit and receive (C-STAR) broadside circular array antenna with a partially shared beam-forming network (BFN) is proposed. The configuration consists of four sequentially rotated two-arm Archimedean spiral antennas, backed by a finite ground plane and driven by a BFN. Every two diagonal antenna pairs are fed with differential phases to obtain similar co-polarized broadside transmitting (TX) and receiving (RX) beams. Each individual element has single feeding port and operates simultaneously as TX and RX over the same frequency. The proposed C-STAR approach utilizes antenna orientation, geometric symmetry, and partially shared BFN to overcome self-interference. In the absence of asymmetry and BFN imbalances, complete wideband self-interference cancellation is achieved without relying on frequency-, time-, space-, pattern-, antenna/port-, or polarization-multiplexing. The fabricated prototype has measured TX/RX isolation >38 dB, axial ratio <3.7 dB, and realized gain between 3 and 8.8 dBic over 1.25-2.5 GHz. The TX and RX radiation patterns are similar with envelope correlation coefficient >0.93.
关键词： transmit and receive (STAR),coupling,spiral,in-band full-duplex,Circular array,simultaneous self-interference cancellation,isolation
更新于2025-09-10 09:29:36
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First vibrational investigations of N <sub/>2</sub> O–H <sub/>2</sub> O, N <sub/>2</sub> O–(H <sub/>2</sub> O) <sub/>2</sub> , and (N <sub/>2</sub> O) <sub/>2</sub> –H <sub/>2</sub> O complexes from the far to the near-infrared spectral region by neon matrix isolation and <i>ab initio</i> calculations
摘要： We present for the first time the investigation of water molecules complexed with dinitrogen monoxide, two abundant molecules in atmosphere, in solid neon using Fourier transform infrared (IR) spectroscopy. We identify at least three complexes from concentration effects, N2O–H2O, N2O–(H2O)2, and (N2O)2–H2O, by observation of new absorption bands close to the monomer fundamental modes from the far to the near IR region. We highlight the presence of isomers for the N2O–H2O complex with the help of theoretical calculations at second order M?ller-Plesset (MP2) and coupled-cluster single double triple-F12a/aug-cc-pVTZ levels. The observed frequencies for the N2O–(H2O)2 and (N2O)2–H2O complexes are compared with MP2/aug-cc-pVTZ harmonic data. Anharmonic coupling constants have been derived from the observations of overtones and combination bands.
关键词： ab initio calculations,anharmonic coupling constants,neon matrix isolation,N2O–H2O complexes,Fourier transform infrared spectroscopy
更新于2025-09-09 09:28:46
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Total-internal-reflection elastic metasurfaces: Design and application to structural vibration isolation
摘要： This letter presents the concept of the Total Internal Reflection metasurface (TIR-MS) which supports the realization of structure-embedded subwavelength acoustic shields for elastic waves propagating in thin waveguides. The proposed metasurface design exploits extreme phase gradients, implemented via locally resonant elements, in order to achieve operating conditions that are largely beyond the critical angle. Such artificial discontinuity is capable of producing complete reflection of the incoming waves regardless of the specific angle of incidence. From a practical perspective, the TIR-MS behaves as a sound hard barrier that is impenetrable to long-wavelength modes at a selected frequency. The TIR metasurface concept is first conceived for a flat interface embedded in a rectangular waveguide and designed to block longitudinal S0-type guided modes. Then, it is extended to circular plates in order to show how enclosed areas can be effectively shielded by incoming waves. Given the same underlying physics, an equivalent dynamic behavior was also numerically and experimentally illustrated for flexural A0-type guided modes. This study shows numerical and experimental evidence that, when the metasurface is excited at the target frequency, significant vibration isolation can be achieved in the presence of waves having any arbitrary angle of incidence. These results open interesting paths to achieve vibration isolation and energy filtering in certain prototypical structures of interest for practical engineering applications.
关键词： elastic waves,TIR-MS,vibration isolation,Total Internal Reflection metasurface,subwavelength acoustic shields
更新于2025-09-09 09:28:46
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Reference Module in Materials Science and Materials Engineering || RF MEMS
摘要： RF MEMS switches are quickly becoming very popular with microwave engineers, and they have already been used in antennas, filters, phase shifters, oscillators, multiplexers, and other traditional (radio frequency) RF devices. Their popularity has grown because of their wider bandwidth, better isolation, lower loss at high frequencies, improved linearity, and lower power consumption compared with traditional switch devices.
关键词： filters,antennas,linearity,multiplexers,power consumption,RF MEMS,bandwidth,microwave,switches,isolation,radio frequency,oscillators,phase shifters
更新于2025-09-09 09:28:46
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[IEEE 2018 Conference on Emerging Devices and Smart Systems (ICEDSS) - Tiruchengode, India (2018.3.2-2018.3.3)] 2018 Conference on Emerging Devices and Smart Systems (ICEDSS) - Enhancement of Isolation in Dual-band Hemispherical DRA using DGS for MIMO Systems
摘要： A simple compact novel hemispherical DRA (HDRA) for isolation improvement with rectangular shaped slot Defected Ground Structure (DGS) is proposed. Length of the slot on the ground plane plays a vital role to enhance the isolation. An optimized length of the slot of b=4.5cm on PEC ground plane offers an isolation of -30dB and impedance bandwidth (S11< - 10dB) of 15.6% with return loss -42.5dB at 2.412GHz and - 23.3dB isolation with -18dB return loss at 4.216GHz. The proposed geometry resonates at two bands, primarily at ISM band and it is best suitable for Bluetooth, Wi-Fi, WiMax, WLAN and Satellite and radar applications in S-band.
关键词： DGS,DRA,Dual band,Isolation
更新于2025-09-09 09:28:46
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COMPACT 1×2 AND 2×2 MIMO ANTENNAS WITH ENHANCED ISOLATION FOR ULTRAWIDEBAND APPLICATION
摘要： Two small size multiple-input–multiple-out (MIMO) antennas with high isolation for ultrawideband (UWB) applications are presented. A two-element MIMO antenna, which is mounted on an FR4 substrate with a compact size of 24 mm × 33 mm, consists of two symmetric circular monopole elements and a modi?ed ground. The protruded ground provides a way to improve isolation and impedance matching. Such a wide band from 2.75 to 11 GHz is achieved by using modi?ed ground technology, and high isolation more than 20 dB is also accomplished. Meanwhile, moderate gain and omnidirectional radiation patterns can be obtained. Based on the circular monopole with modi?ed ground, a four-element antenna array is also constructed and studied. The size of the four-element antenna with orthogonal arrangement is 44 mm × 44 mm. Measured results show that the antenna also exhibits good impedance matching as well as low envelope correlation coe?cient over the entire UWB spectrum.
关键词： high isolation,ultrawideband (UWB),circular monopole,MIMO antennas,modified ground
更新于2025-09-09 09:28:46
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POWER DIVIDER BASED ON STEPPED-IMPEDANCE SLOTLINE
摘要： A novel 180? out-of-phase power divider based on stepped-impedance slotline is presented in this article. This power divider employs one T-junction formed by microstrip line and slotline to obtain two out-of-phase dividing signals. Stepped-impedance slotline and lumped resistor are introduced to improve the isolation between output ports. The experimental data show that the proposed power divider has good performance on insertion loss, return losses, isolation, phase balance, as well as group delay over the wide band 5 GHz–10 GHz.
关键词： slotline,isolation,group delay,microstrip line,insertion loss,power divider,phase balance,stepped-impedance slotline,return losses
更新于2025-09-09 09:28:46
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[Institution of Engineering and Technology 7th International Conference on Imaging for Crime Detection and Prevention (ICDP 2016) - Madrid, Spain (23-25 Nov. 2016)] 7th International Conference on Imaging for Crime Detection and Prevention (ICDP 2016) - Attack Detection in an Autonomous Entrance System using Optical Flow
摘要： Unstaffed access control portals are becoming more common in high security areas. Existing systems require expensive hardware, or are sensitive to changing environmental conditions. We present a single camera system for a mantrap which is able to verify that only one individual is in the designated transit area. Our novel approach combines optical flow and machine-learning classification. A database was created that consists of images of attempted attacks and regular verification. The results show that our approach provides competitive results and outperforms detection rates in several attack scenarios.
关键词： Scene Analysis,Isolation Detection,Computer Vision,Optical Flow,People Counting
更新于2025-09-09 09:28:46
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COMPACT ULTRAWIDEBAND MIMO ANTENNA WITH WLAN/UWB BANDS COVERAGE
摘要： A compact multiple-input-multiple-output (MIMO) antenna that covers the WLAN (2.4 GHz) and UWB (3.1–10.6 GHz) bands for wireless device applications is presented. The proposed antenna consists of two open L-shaped slot (LS) antenna elements and a narrow slot on the ground plane. The antenna elements are placed perpendicularly to each other to obtain a high isolation, and the narrow slot is added to reduce the mutual coupling between antenna elements at the WLAN band (2.4 GHz). The presented MIMO antenna has a small size of 40×40 mm2, and the prototypes of antenna is fabricated and measured. The measured results show that the antenna has an impedance bandwidth of larger than 2.4–10.6 GHz with the mutual coupling less than 20 dB in WLAN band and 18 dB in 3.1–10.6 GHz, making the antenna a good candidate for portable applications.
关键词： mutual coupling,MIMO antenna,WLAN,isolation,UWB,compact
更新于2025-09-09 09:28:46
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[Lecture Notes in Electrical Engineering] Recent Trends in Communication, Computing, and Electronics Volume 524 (Select Proceedings of IC3E 2018) || Design of An Improved Micro-Electro-Mechanical-Systems Switch for RF Communication System
摘要： This paper presents the design of improved MEMS shunt switch for RF communication applications. The switch was designed to provide a better performance in 10–100 GHz range. The switch was optimized in terms of width of the beam and air gap between the fixed type beam and dielectric layer to improve the isolation, insertion, and return loss. This study concludes that materials with high k-dielectrics and high Young’s modulus are desirable for better performance in high-frequency range. The isolation, insertion, and return loss for the designed switch are obtained as –12 dB, –0.05 dB, and –45 dB, respectively.
关键词： RF,Switch,Isolation,Insertion,MEMS
更新于2025-09-09 09:28:46