共查询到20条相似文献,搜索用时 31 毫秒
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Jianliang Yang Yunqi Liu Sweechuan Tjin Jianping Yao 《Journal of Infrared, Millimeter and Terahertz Waves》2002,23(8):1241-1250
A photonics true-time-delay system for phased array antenna beam steering employing a novel tunable chirped fiber grating delay line and a multi-wavelength erbium-doped fiber ring laser source based on a sampled grating filter is proposed. The tunable chirped fiber grating, which act as a continuous time-delay element, is achieved by bending a uniform fiber Bragg grating bonded at a slant onto the lateral surface of a simply supported beam. This technique allows the dynamic control of the chirp rate and spectral width of the grating without center wavelength shift. By adjusting the chirp rate of the fiber grating via bend strain, this kind of tunable chirped fiber grating could achieve very low and adjustable delay times, therefore provides higher angle resolution for scanning microwave beam, even the wavelengths of laser source are fixed and un-tunable. The true-time-delay system using proposed tunable chirped fiber grating delay element and sampled grating based laser source is constructed and demonstrated experimentally. 相似文献
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《Optical Fiber Technology》2000,6(2):91-108
Methods for wideband photonic signal processing using fiber delay lines and Bragg grating sampling elements are described. These processors provide new capabilities for the realization of high time-bandwidth operation and high resolution performance. Multiple wavelength techniques with discrete and chirped Bragg gratings are described, which have high capacity signal processing functions using dense parallel signal processing techniques. Both fixed and tunable or reconfigurable processors using wavelength control to change the sampling time are discussed. A range of grating-based signal processors, including high Q microwave filtering, frequency discriminators, widely tunable filters, fast and adaptive signal correlators, and true-time delay beamforming in phased array antennas are described. 相似文献
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LI Zheng 《半导体光子学与技术》2007,47(1):53-57
The system of a true-time delay line for X-band and 8-unit phased array antennas is introduced. Changing the length of a chirp grating with piezotranslator(PZT), the variable delay is obtained. The scheme is applied to X-band phased array radar whose searching data rate is 56/s. It is simulated that the beam squinting is influenced by the error of real time delay. The relation between the beamforming mode and its modifying volt is discussed. 相似文献
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Continuously tunable photonic microwave true-time delay based on tunable chirped fibre Bragg grating
A simple scheme for the photonic microwave true-time delay with high tunability based on a tunable chirped fibre Bragg grating without centre wavelength shift is experimentally demonstrated. A large dynamic range of true-time delay from 20 to 200 ps was achieved for a microwave signal carried over an optical signal. 相似文献
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Ortega B. Cruz J.L. Capmany J. Andres M.V. Pastor D. 《Microwave Theory and Techniques》2000,48(8):1352-1360
We present a theoretical and experimental analysis of the performance of phased-array antennas steered by a single chirped fiber grating. Two approaches consisting of conventional and single-sideband (SSB) modulation techniques of the optical signal are presented in order to compare their performance and suitability for beamforming applications in microwave antennas. By using a 40-cm-long chirped grating, we measure the phase and amplitude response and calculate the corresponding radiation patterns to demonstrate wide-band operation and continuous spatial scanning properties of both configurations. SSB modulation Is presented as a real alternative to the first one offering broader operation band (4-18 GHz) for a given chirped grating and being less demanding on the fiber grating characteristics 相似文献
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Chirped fibre Bragg gratings for phased-array antennas 总被引:1,自引:0,他引:1
Cruz J.L. Ortega B. Andres M.V. Gimeno B. Pastor D. Capmany J. Dong L. 《Electronics letters》1997,33(7):545-546
A variable delay line for phased-array antennas based on a chirped fibre Bragg grating is demonstrated. The time delay of a microwave modulating signal is modified by scanning in wavelength a chirped grating. In this initial experiment, time delay variations up to 556 ps have been achieved using a grating of 0.4 nm bandwidth and 6 cm length and modulating in the frequency range 390 MHz-5.20 GHz 相似文献
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《Optical Fiber Technology》2014,20(5):478-482
A high resolution optical true-time delay (OTTD) beamformer constructed by fiber Bragg grating (FBG) and highly dispersive fiber (HDF) is presented. It can produce the true time delay with the resolution of 1 ps. Besides the proposed system has compact structure and light weight even when a large number of antenna elements are present in a practical antenna array, this is because the used FBG fibers and HDFs are short and independent of the antenna element number. Theoretical analysis and numerical simulations are made. Proof-of-concept experiment results that demonstrate the feasibility of the system are presented. 相似文献
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This paper describes a new device called an optical commutator. It is shown that this device can provide the time delays needed for true-time steering of an antenna array. The optical commutator consists of a rotatable folded lens comprising a set of fiber-optic coils arranged on a rotor and other fiber optics arranged on a stator. The beam steering is achieved by simply rotating the lens. The design theory of the commutator is described and equations are derived that allow the fiber-optic coil lengths of the windings to be determined for a given antenna performance specification. It is shown that the commutator can be designed to steer either flat, circular, or cylindrical arrays. The bandwidth of this concept is predicted to be significantly broader than any existing phased-array systems and that due to the simplicity of this system, considerable savings in both cost and weight should be possible when compared to present phased-array steering approaches. An optical commutator has been constructed to verify the design concept, and timing measurements have been made that validate the design 相似文献
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提出并实验验证了一个四通道的基于啁啾光栅的连续可调光控延时系统,该系统适合于频率达10 GHz的相控阵天线的波束形成及扫描,使用一种基于啁啾光栅的延时网络和一种新型的波长等间隔增大或减小的多波长可调谐线性腔光纤激光器.光纤激光器的等波长间隔,通过相等增量的作用力挤压或拉伸激光谐振器中固定在一个有机塑料盘上成一定的角度相邻的布拉格光栅来调谐.光控延时是通过被调制光在一个线性啁啾光栅的不同位置反射而实现,波长等间隔激光可获得等间隔的延时. 相似文献
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Lee S. Khosravani R. Peng J. Grubsky V. Starodubov D.S. Willner A.E. Feinberg J. 《Photonics Technology Letters, IEEE》1999,11(10):1277-1279
We demonstrate an adjustable polarization-mode-dispersion (PMD) compensator. The device uses a nonlinearly chirped fiber Bragg grating written into a high-birefringence photosensitive fiber. By mechanically stretching the grating, the device generates a time delay between different polarizations that is adjustable from 100 to 320 ps and is tunable over 2.3 nm. We demonstrate tunable PMD compensation of a 10-Gb/s signal that has an initial delay between the two polarization states of 127 or 302 ps 相似文献
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光实时延时技术与相控阵技术的融合,解决了传统相控阵雷达的瞬时大带宽受限和波束偏斜问题.文中给出了光实时延时技术的思想,讨论了光实时延时技术出现的背景.分析了应用于光实时延时技术中的光纤光栅的原理,着重讨论了均匀光纤光栅和线性啁啾光栅,分别给出了基于两种光纤光栅的光实时延时的技术方案,在此基础上,讨论了受控于应变和温度的光纤光栅在光实时延时技术中的应用.最后讨论了一些技术上存在的问题.Abstract: Optical true time delay technology (OTTD) is the key technology for phase array antennas (PAA).By using OTTD,the beam squint and the restriction of instantaneous bandwidth are resolved.The principles of OTTD are given,the emergence background of OTTD is discussed.The theory of fiber Bragg grating(FBG) used in OTTD is analyzed,especially on uniform fiber bragg grating and linear chirped fiber Bragg grating.Two OTTD schemes based on FBG is presented,then some new kinds of FBG used in OTTD are discussed.Some technique hurdles are analyzed as well. 相似文献
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A photonic true-time delay beamforming system for phased array antennas based on superstructured fiber Bragg gratings (SFBGs) with linearly increasing equivalent chirps is proposed and demonstrated. The theory behind SFBGs with equivalent chirps is detailed and a closed-form equation for the equivalent dispersion is presented for the first time. Array factors, calculated based on the experimentally measured time delays are shown for different wavelengths of the photonic beamformer. An analysis of the errors present in the group delay responses of the fabricated SFBGs is also presented. 相似文献
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Zhang W. Williams J.A.R. Bennion I. 《Microwave and Wireless Components Letters, IEEE》2001,11(5):217-219
For a practical optical fiber recirculating delay line the maximum notch depth and tunable free spectral range are difficult to achieve because of fixed coupling coefficient and loop length. We present here an optical fiber recirculating delay line incorporating a fiber grating array. In this work, the effect of insertion loss in the delay loop is investigated and used to maximize the notch depth of the frequency response. The tunable free spectral range is obtained from the wavelength dependent loop length introduced by the fiber grating array 相似文献
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A photonic microwave true-time delay using a tapered chirped fibre Bragg grating is proposed and fabricated. A resistive heating electrode coated on the tapered fibre and a single-wavelength light was incorporated to control the time delay continuously without any mechanical perturbation and moving. It was achieved by adjusting the reflection positions of the optical signal carrying the microwave signal from within the tapered grating via the thermo-optic effect. The measured time delay was /spl sim/120 ps with electrical power consumption of 250 mW. 相似文献
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微环作为一种典型的平面光波导回路,具有结构紧凑、性能可靠等特点,而用其制成的波导延时芯片集成度高、体积小,与其他光延时器件相比,更适合于贴近阵面安装。因此提出了一种基于阵元级微环延时、子阵级光纤延时的宽带相控阵天线系统,并在均匀线阵的情况下,对所提天线系统进行了数学建模和性能仿真。由仿真结果可知,与一般的阵元级移相、子阵级光纤延时的相控阵系统相比,所提系统能够更有效地满足电子对抗宽带宽角扫描的需求。 相似文献