共查询到16条相似文献,搜索用时 46 毫秒
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超低频拖曳磁场天线磁致伸缩噪声分析 总被引:1,自引:0,他引:1
研究了海水中超低频拖曳磁场接收天线机械振动在地磁场中产生磁致伸缩噪声的机理,导出了计算磁场拖曳天线磁致伸缩噪声功率谱的理论公式,分析了天线灵敏度、电缆特性、地磁场等因素对磁致伸缩噪声的影响,并总结了降低磁场天线磁致伸缩噪声的四种有效方法. 相似文献
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针对目前磁补偿大多集中于算法研究而少有仿真和数值计算方面的研究,利用一种电磁场有限元分析软件Ansoft Maxwell的参数化计算功能,在静态磁场仿真环境下得到了导弹体表面上各点磁感应强度的数值解。通过数值计算的方法定性、定量地研究了真实大小模型的补偿效果,可以为磁探测器安装位置和材料相对磁导率的选取提供依据,缩短研发时间并降低成本。 相似文献
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针对目前多数运动车辆检测与跟踪算法在雨雪等强噪声场景下抗噪能力较弱这一难点问题,提出应用运动模板方法解决强噪声场景下运动车辆的检测与跟踪问题。通过针对标准测试视频的对比实验,相对其他几种典型的目标检测与跟踪算法,运动模板的检测方法具有以下特点:抗强噪声的能力、多目标检测和方向检测。基于车辆的检测与跟踪实验验证了运动模板方法在强噪声场景下对运动目标的实时检测与跟踪能力。 相似文献
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This article investigates techniques to design noise‐matching networks for a class of multimodal antennas, specifically, the so‐called quad‐mode antenna. Such an antenna utilizes weighted combinations of four very dissimilar radiation patterns, and different modal input impedances, which vary across scan angle. The matching problem is therefore quite different from that of a classical array, where antenna elements are normally assumed to be similar. In addition to the standard techniques, a new, recursively averaged active impedance, is proposed and applied, as well one using a noise‐active impedance, and two optimization approaches. It is shown for the first time that the quad‐mode antenna displays excellent noise properties, with the simplest technique, namely that of matching to the self‐impedances, producing noise performances across all scan angles which are almost as good as the best solution found by all the techniques. 相似文献
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利用波长变换理论的ELF天线设计及仿真 总被引:1,自引:0,他引:1
为了克服超长波天线建设困难、发射效率低下这一大难点,根据电磁波在不同介质中的波长变换原理,提出了在变介质中构建超长波发射天线的方法,使得超长波在介质中的电长度大大缩短,从而大幅度降低发射天线的设计难度,使天线高效辐射极低频信号成为可能。通过理论分析,得出了该设计的正确性,并根据功能性仿真试验,验证了变介质超长波发射天线的辐射性能。 相似文献
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Satyajit Chakrabarti 《国际射频与微波计算机辅助工程杂志》2018,28(6)
In this study, we present a new technique for the development of a dual frequency microstrip antenna. Two identical polarizations at two far apart frequencies have been generated in a compact configuration which uses two elements fed by a single feed line. This design technique provides an independent control to the desired frequencies and reduces element size by 50% compared to the conventional design at the cost of a marginal decrease in gain. The proposed antenna produces dual resonances at 4.056 and 4.96 GHz. It yields impedance bandwidths of about 1.71% at the lower resonance and 1.41% at the higher resonance respectively. It exhibits 7.0 and 6.6 dBi gains at the lower and upper resonances respectively which are 0.3 and 0.7 dB lower than a conventional patch. The measured cross polar discriminations of the proposed antenna are also comparable to the conventional patch. The measured efficiencies are 81.3% and 78.1% respectively. 相似文献
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在介绍罗兰C全向磁天线设计方法和接收特性的基础上,针对全向磁天线信号合成中的数字移相环节,设计了一种高精度数字移相算法,该算法突破了传统数字移相算法移相精度受信号采样率限制的缺陷,实现了信号的高精度数字移相。利用罗兰C标准脉冲信号对移相算法进行了仿真计算,并用实际采集的罗兰C信号进行了验证,结果均表明了算法的正确性和优越性。该算法具有计算过程简单,易于采用高性能硬件逻辑可编程芯片FPGA/CPLD来实现,在罗兰C全向磁天线设计中获得了较好的应用效果。 相似文献
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Izni Husna Idris Mohamad Rijal Hamid Kamilia Kamardin Mohamad Kamal A. Rahim 《国际射频与微波计算机辅助工程杂志》2018,28(4)
A frequency reconfigurable antenna with a simple design structure and biasing circuit is presented. The antenna is able to configure its frequencies to operate either in multiband or wideband modes. The antenna is fed by a coplanar waveguide transmission line. The reconfiguration characteristics of the antenna is achieved by using PIN diode switches. The operating frequencies of the multiband mode are designed within the wideband mode operating range, from 2 to 6 GHz. Both simulated and measured results of S11, radiation pattern and realized gains are verified. The antenna allows a degree of freedom in providing the frequency reconfiguration from multiband to wideband mode and vice versa. 相似文献
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矿井无线通信和矿用5G移动通信技术是煤矿智能化关键技术之一。为提高煤矿井下无线传输距离、绕射能力及无线通信系统的稳定性和可靠性,减少基站用量、组网成本和维护工作量,研究了矿用5G工作频段和基站天线位置对无线传输损耗和传输距离的影响。主要结论如下:①煤矿井下无线发射功率受本质安全防爆限制,接收灵敏度受电磁噪声限制,天线增益受本质安全防爆和巷道空间限制。在煤矿井下无线发射功率、接收灵敏度、天线增益受限的情况下,应通过优选无线工作频段和优化天线设置位置,提高矿井无线传输距离和绕射能力,提高系统稳定性和可靠性,减少基站用量、组网成本和维护工作量。②矿用5G工作频段应优选700 MHz。煤矿井下700 MHz频段与现有5G其他工作频段2.6,3.5,4.9 GHz相比,具有无线传输损耗小、无线传输距离远、绕射能力强、基站用量少、组网成本低和维护工作量小等优点。③提出的传输损耗/位置变化率分析方法便于分析巷道横向不同区域位置变化引起的无线传输损耗变化情况。④无线基站天线应靠近巷帮设置,距巷帮不小于0.01 m,垂向位于巷道高度约2/5处。这样既不影响行人和行车、便于安装维护,也可以满足无线传输损耗较小、无线传输距离较远的要求。⑤矿用手机、人员定位卡、便携式无线甲烷检测报警仪、多功能无线矿灯、便携式无线摄像机、便携式无线仪器设备、可穿戴无线设备、车辆定位卡、车载无线设备、无线摄像机、无线传感器、物联网设备等无线终端,在不影响使用的条件下应尽量靠近巷道中心,以提高无线传输距离。 相似文献
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A frequency‐reconfigurable antenna is presented for multiband (GSM850/900/GLONASS1616/DCS1800/PCS 1900/UMTS/LTE2300/2500/WLAN) mobile handset applications. It mainly consists of radiating elements with two PIN diodes. By switching the ON/OFF states of the PIN diodes, the proposed structure can operate in three states: OFF–ON, ON–OFF, and ON–ON. When PIN diodes are in the OFF–ON states, the proposed antenna can cover the GSM850/900, PCS1900, and UMTS2100 bands by operating in Invented‐F antenna (IFA) mode. When PIN diodes are in the ON–OFF states, the antenna can cover the LTE2300/2500 and WLAN2400 bands in monopole mode. Moreover, when PIN diodes are switched to the ON–ON states, the designed antenna works in loop mode and its resonant frequencies include the GLONASS1616, DCS1800/1900, and LTE2500 bands. With the reconfigurable technique, the proposed antenna achieves a compact size of 15 × 28.5 mm2 with high efficiency from 34% to 84.86% in the total frequency range. 相似文献