共查询到16条相似文献,搜索用时 750 毫秒
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GSM1800移动通信用20级高温超导滤波器研究 总被引:1,自引:0,他引:1
本文研究设计了实用于GSM1800移动通信基站的接收机用20级高温超导滤波器,其中心频率为1750MHz,带宽78MHz。实验结果显示在低温60K时,超导滤波器的带内插入损耗小于0.35dB,带边陡度好于18dB/MHz,中心频率及带宽都和设计结果很好的吻合,验证了分析方法和制备工艺的准确可靠。为研制更高水平的超导滤波器打下了较好的基础。 相似文献
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本文设计并研制了一种GSM180 0移动通信基站接收机前端用高温超导滤波器 .滤波器选用集成度、性能均很好的前向耦合型微带结构 ,中心频率 1732 .5MHz ,通带带宽 4 5MHz .测试结果表明 :该滤波器具有很好的频率响应特性 ,与设计结果符合得很好 .在温度T =30K时 ,该滤波器的带内最大插损 <0 .5dB ,带内纹波 <0 .4dB ,反射损耗好于 10dB .文中也给出了不同温度下滤波器的频率响应特性 . 相似文献
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研制了用于CDMA移动通信基站接收机前端的14阶高温超导带通滤波器。该滤波器的设计带宽为10.9 MHz,中心频率为830MHz;仿真得到的回波损耗约为28 dB,带内波动小于0.008 dB,带外抑制大于90 dB;该滤波器由MgO衬底上的双面DyBa2Cu3O7超导薄膜加工而成。该滤波器在无后期调谐的情况下,72K温度的实测带宽为10.9MHz,回波损耗好于20dB,插入损耗0.001 dB,边带陡峭度高达80dB/16.3MHz,实测的中心频率等指标也与仿真设计结果吻合很好,各项指标均满足应用要求。 相似文献
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CDMA系统用高温超导滤波器的设计 总被引:1,自引:0,他引:1
本文根据CDMA(Code Division Multiple Access)移动通信系统的要求,采用Sapphire基片上的双面YBCO高温超导薄膜设计和制作了中心频率为830MHz,相对带宽为1.2%的16节高温超导滤波器,其谐振器采用了折叠型结构,能够显著地减小所用基片的尺寸.在68K的测试温度下实验结果与设计结果很好的吻合,带边陡峭度达到了50dB/MHz,带外抑制超过80dB,带内插损小于0.27dB,而尺寸限制在两英寸内. 相似文献
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设计了一种高选择性可调带通与带阻可切换微带滤波器。在微带谐振器及枝节末端加载变容二极管实现中心频率的可调;在输入与输出端口馈线之间,利用PIN二极管实现滤波器阻带和通带特性的切换。采用奇偶模的方法对滤波器结构进行分析,通过对奇偶模频率的调节实现了频率调节过程中的恒定绝对带宽。同时,在输入与输出馈线间引入源与负载耦合,使得频带两侧各有一个传输零点,且传输零点在整个频率调谐范围内相对位置几乎不变。因此,在整个频率调节范围内,滤波器实现了高选择性及良好的带外抑制能力。最终设计出的可调带阻滤波器的频率调谐范围为5.58~5.89 GHz,绝对带宽80 MHz±5 MHz,阻带衰减优于14 dB;可调带通滤波器的频率调谐范围为5.42~5.79 GHz,绝对带宽120 MHz±5 MHz,插入损耗1.69~2.25 dB,回波损耗优于13 dB。同时,该滤波器具有0.28λg×0.62λg(λg是可调频率范围中心频率的波长)的紧凑结构尺寸。实验和仿真结果一致性较好。 相似文献
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开发了一种基于模型的高温超导滤波器仿真设计方法和一种紧凑的组群式G型谐振器结构,研制出了用于WCDMA系统上的带宽为20MHz中心频率为1950MHz的8阶高温超导滤波器.该滤波器由Tl2Ba2CaCu2O8薄膜制作而成,制作在LaAlO_3衬底上,尺寸大小仅为26mm×18mm.实测结果显示滤波器的最小插入损耗为0.25dB,带外抑制大于70dB,回波损耗好于-16dB,实测的滤波器带宽、中心频率以及边带陡峭度也与仿真设计结果吻合很好,验证了设计方法和制作工艺的准确性. 相似文献
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Hervé Gouraud Laurent Billonnet Pierre Faugeras Bernard Jarry 《Optics Communications》2006,265(2):506-512
The analysis of the influence of dispersion properties of the dispersive line used in a microwave photonic slicing filter is presented. We establish a general relation between both chromatic dispersion value and slope, allowing the optimization of the frequency response of the filter. Experimental validations are presented in good agreement with theoretical and numerically simulated results. Narrow bandwidth bandpass filter (<100 MHz) is achieved at the central frequency of 6.48 GHz, corresponding to the limit value in reference to the used broadband light source and fiber dispersion. 相似文献
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Parameter optimization of pulse compression in ultrasound imaging systems with coded excitation 总被引:1,自引:0,他引:1
A linear array imaging system with coded excitation is considered, where the proposed excitation/compression scheme maximizes the signal-to-noise ratio (SNR) and minimizes sidelobes at the output of the compression filter. A pulse with linear frequency modulation (LFM) is used for coded excitation. The excitation/compression scheme is based on the fast digital mismatched filtering. The parameter optimization of the excitation/compression scheme includes (i) choice of an optimal filtering function for the mismatched filtering; (ii) choice of an optimal window function for tapering of the chirp amplitude; (iii) optimization of a chirp-to-transducer bandwidth ratio; (iv) choice of an appropriate n-bit quantizer. The simulation results show that the excitation/compression scheme can be implemented as a Dolph–Chebyshev filter including amplitude tapering of the chirp with a Lanczos window. An example of such an optimized system is given where the chirp bandwidth is chosen to be 2.5 times the transducer bandwidth and equals 6 MHz: The sidelobes are suppressed to −80 dB, for a central frequency of 4 MHz, and to −94 dB, for a central frequency of 8 MHz. The corresponding improvement of the SNR is 18 and 21 dB, respectively, when compared to a conventional short pulse imaging system. Simulation of B-mode images demonstrates the advantage of coded excitation systems of detecting regions with low contrast. 相似文献
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An analogue Hilbert transformer capable of performing complex envelope detection of ultrasonic waveforms is described and initial experimental results presented. The unit is based on a SAW programmable microprocessor controlled transversal filter, which accepts data at a 3 MHz clock rate and is thus capable of processing the input waveform in real-time. A squaring-summing network performs the required operation for envelope extraction. 相似文献
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Stephen A. Pappert Ching-Ten Chang Matthew N. McLandrich 《Fiber and Integrated Optics》2013,32(1):63-77
A wide-band electro-optic direction-finding (DF) processor employing a network of fiber optic delay lines is described. This DF filter offers a potential instantaneous bandwidth of 20 GHz and allows for multiple, simultaneous beam-angular responses with peaks that are independent of frequency. Preliminary results of an eight-laser feasibility test model DF device with two transversal filters show good agreement between predicted and measured angular responses. This experimental matched-delay filter operates in the 200–1,000 MHz frequency range and can simultaneously monitor two angles of arrival. The laboratory results obtained in this investigation suggest that the fiber optics matched-delay filter can be useful for wide-band direction finding. 相似文献