共查询到19条相似文献,搜索用时 125 毫秒
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国际通用的无线电高度计频段在4.3GHz,高度计校准和相应的目标模拟一般都采用同轴电缆延迟线或声体波微波延迟线。通过方案的对比,介绍了一种利用声表面波高频延迟线进行程控级联,并采用电路上下变频使其工作在微波频段上的微波程控延迟线,经过理论与实验分析,给出了测试结果,为SAWDL的应用提供了新的思路。 相似文献
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采用中频磁控溅射法在z轴石英基片上制备了(002)择优取向的AlN薄膜。采用X线衍射仪(XRD)、扫描电镜(SEM)表征了AlN薄膜的择优取向和表面形貌。结果表明,溅射功率、氮气流量、氩等离子清洗对AlN薄膜的择优取向有显著影响。将该方法制备的AlN薄膜应用于声体波微波延迟线,研制出频率为4.2~4.4GHz的声体波微波延迟线,其延迟时间为361ns,插入损耗为-57.3~-60.4dB,3次渡越抑制为28.6dB,直通信号抑制为52.7dB。 相似文献
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叙述了超短延时声体波微波延迟线的设计和制作。制作了工作频率4.2GHz,延迟时间分别为50ns和70ns的器件。直通隔离度达80dB和三次抑制大于18d 相似文献
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Clutter cancellation of 65 dB and better is directly proportional to good radar stability, and since many hardware areas produce instabilities at various levels, the architecture of a radar requires special design considerations to support this high stability. The noise character and generation methods of these instabilities in the various hardware areas are described, and design solutions are given to eliminate them. Microwave delay line, a reliable, accurate method of measuring radar stability in L - and S -band radars, is described. The longest microwave delay line available for use at L -band and S -band frequencies is a 15-μs sapphire bulk acoustic wave (BAW) delay line. For higher-frequency radars, smaller delays must be used to keep the insertion loss down to a usable level. The question is raised as to the adequacy of this delay time to provide sufficient visibility for stability measurements of the stable noise. For transmitter measurements, it is adequate for the more common pulse widths, which are less than 15 μs. For LO measurements, the analysis shows that this delay does provide sufficient decorrelation for accurate LO noise measurements 相似文献
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Campbell C.K. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1989,77(10):1453-1484
Surface acoustic wave (SAW) device coverage includes delay lines and filters operating at selected frequencies in the range from about 10 MHz to 11 GHz; modeling with single-crystal piezoelectrics and layered structures; resonators and low-loss filters; comb filters and multiplexers; antenna duplexers; harmonic devices; chirp filters for pulse compression; coding with fixed and programmable transversal filters; Barker and quadraphase coding; adaptive filters; acoustic and acoustoelectric convolvers and correlators for radar, spread spectrum, and packet radio; acoustooptic processors for Bragg modulation and spectrum analysis; real-time Fourier-transform and cepstrum processors for radar and sonar; compressive receivers; Nyquist filters for microwave digital radio; clock-recovery filters for fiber communications; fixed-, tunable-, and multimode oscillators and frequency synthesizers; acoustic charge transport (ACT); and other SAW devices for signal processing on gallium arsenide. Shallow bulk acoustic wave (SBAW) device applications include gigahertz delay lines, surface-transverse-wave resonators employing energy-trapping gratings and oscillators with enhanced performance and capability 相似文献
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多层结构氧化锌薄膜制备 总被引:1,自引:0,他引:1
介绍了高频声体波微波延迟线用多层结构氧化锌薄膜的制作方法,并对这种交替排列不同结晶取向的多层氧化锌薄膜的微观结构、成膜机理进行了分析和阐述。用具有不同机电耦合系数、厚度为半波长的交替排列多层氧化锌薄膜制成了中心频率为8GHz的声体波微波延迟线。同时亦给出了这种新结构的氧化锌压电材料的生长条件及相应的实验结果 相似文献
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The basic principle, methodology, and experimental results for frequency-swept microwave imaging of continuous shape conducting and discrete line objects in a bistatic scattering arrangement are presented. The theoretical analysis is developed under the assumptions of plane wave illumination and physical optics approximation. The measurement system and calibration procedures are implemented based on plane wave spectrum analysis. Images of three different types of scattering objects reconstructed from the experimental data obtained in the frequency range 7.5-12.5 GHz are shown to be in good agreement with the scattering object geometries. The results demonstrate that this bistatic frequency-swept microwave imaging system has potential as a cost-effective tool for remote sensing, imaging radar, and nondestructive evaluation 相似文献