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无源雷达导引头一般采用宽带天线以满足对空间辐射源的探测和跟踪。圆锥等角螺旋天线具有宽频带和圆极化的辐射性能,因此它是一种合适的无源雷达导引头天线实现方案。为了满足实际项目的需要,本文开展了圆锥等角螺旋天线的设计和实验研究。设计了具体的天线结构和参数,采用微带粘结技术实现圆锥表面共形的等角螺旋天线臂的加工和焊接。设计了一种超宽带微带平衡-不平衡转换器(巴伦)以实现对设计天线的馈电。在微波暗室内对加工的天线进行了测量,给出了辐射方向图、增益、轴比等测试结果。实验结果表明,对于频带1GHz到5GHz工作频率范围,本文设计和加工的天线性能可以满足技术要求,其实验结果为本天线的实际应用奠定了基础。 相似文献
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《无线电通信技术》2017,(6)
微带阵列天线是实现通信、测控等系统小型化的关键设备之一。为了进一步降低天线高度,对应用深腔刻蚀、硅通孔等微电子机械微纳加工技术,实现Ka频段硅基阵列天线的方案进行了分析研究。对常用的各种微波基板材料特性进行分析,结合3D封装集成需求,最终采用背面开腔的高阻硅材料,设计了同轴背馈硅基线极化4×4阵列天线。对天线阵元、馈线等结构进行了理论分析计算,并通过电磁场仿真软件进行优化验证,仿真结果表明指标满足系统要求。同时也对阵列天线在制造过程中的关键工艺问题进行了分析,研究了在硅基材料上实现微带阵列天线制造可行性,为今后相控阵中天线与微波有源电路3D系统级封装集成进行了有益探索。 相似文献
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设计了一种中心频率为20 GHz的8单元微带光子天线阵列,利用微波光子技术解决了传统微波技术在高频、宽带等方面的问题。天线单元为矩形微带贴片天线,馈电网络采用具有λ/4阻抗匹配枝节设计的多级T型等分功分器。采用光子上变频技术产生20 GHz的微波信号,光载微波信号经光纤传输后由阵列天线发射。利用三维高频结构电磁场仿真对该天线阵模型的搭建和优化进行仿真,结果表明天线阵仿真阻抗带宽为1.15 GHz,在带宽内最大增益为13.6 dBi。将天线阵列应用到微波光子系统发射端,测量结果表明,最大增益可以达到6.92 dBi。该天线阵列性能良好,可广泛应用于未来移动通信网络覆盖领域。 相似文献
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用于整流天线的口径耦合圆极化微带天线的设计与实验 总被引:4,自引:0,他引:4
提出了一种用于整流天线的新型圆极化微带天线形式,此天线采用单端口径耦合馈电,易与整流电路集成和匹配。利用电磁场仿真软件分析了天线参数对天线性能的影响,设计并加工了一个圆极化天线单元。设计值和实验值较吻合,实验结果表明该天线在10.25GHz具有良好的圆极化特性:在最大方向上圆极化轴比为0.3dB,3dB圆极化带宽达到160MHz,驻波比小于2的带宽达到800MHz。 相似文献
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在信号处理中抑制水体传输中带来的后向散射噪声,是水下脉冲激光探测的关键技术之一。基于同一水域相邻2次探测后向散射的相关性,提出一种改进的归一化最小均方(NLMS)自适应滤波算法。根据后向散射的强度和滤波后目标信号大小控制步长因子,使其对不同距离、不同强度的目标信号均能取得良好的滤波效果。通过计算机仿真和水池实验对算法进行验证,结果表明,对不同距离、不同反射强度的目标,该滤波器算法均能以较低的阶数有效滤除后向散射噪声,保留目标回波信号。与现有的自适应滤波方法相比,大大减少了滤波所需的计算资源,在水下脉冲激光探测系统上具有一定的应用价值。 相似文献
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该文针对水下机器人在核电站水池中的位置估计问题,提出基于扫描声呐的概率迭代匹配定位算法进行机器人水下定位。首先分析了扫描声呐的信号特征,对声呐信号进行预处理的方法,通过阈值去噪、距离限定和减少采样来降低信号干扰和剔除多余数据,提高计算效率。然后针对声呐量测存在较大噪声的问题,提出基于概率迭代匹配的算法。利用马氏距离计算声呐扫描图与核电站水池环境地图之间的最近匹配点,同时通过置信度提高匹配的精度,以寻优迭代估计得到水下机器人的绝对位姿。与传统的最近点迭代算法的仿真比较表明该算法提高了水下机器人的估计精度。最后,通过水池实验验证了该算法的有效性。 相似文献
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A new type of fish-like underwater microrobot 总被引:6,自引:0,他引:6
Shuxiang Guo T. Fukuda K. Asaka 《Mechatronics, IEEE/ASME Transactions on》2003,8(1):136-141
This paper presents a new prototype model of an underwater fish-like microrobot utilizing ionic conducting polymer film (ICPF) actuator as the servo actuator to realize swimming motion with three degrees of freedom. A biomimetic fish-like microrobot using ICPF actuator as a propulsion tail fin and a buoyancy adjuster for the swimming structure in water or aqueous medium is developed. The overall size of the underwater prototype fish shaped microrobot is 45 mm in length, 10 mm in width, and 4 mm in thickness. It has two tails with a fin driven respectively, a body posture adjuster, and a buoyancy adjuster. The moving characteristic of the underwater microrobot is measured by changing the frequency of input voltage from 0.1-5 Hz in water and the amplitude of input voltage from 0.5-10 V. The experimental results indicate that changing the amplitude and frequency of input voltage can control the swimming speed of proposed underwater microrobot. 相似文献
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This paper has presented our interesting in wireless underwater communications for different ocean water types. Recent interest in ocean exploration has brought about a desire for developing wireless communication techniques in this challenging environment. Due to its high attenuation in water, a radio frequency (RF) carrier is not the optimum choice. Acoustic techniques have made tremendous progress in establishing wireless underwater links, but they are ultimately limited in bandwidth. In traditional communication systems, constructing a link budget is often relatively straight forward. In the case of underwater optical systems the variations in the optical properties of ocean water lead to interesting problems when considering the feasibility and reliability of underwater optical links. The main focus of this paper is to construct an underwater link budget which includes the effects of scattering and absorption of realistic ocean water. As well as we have developed the underwater optical wireless communication systems to have shorter ranges, that can provide higher bandwidth (up to several hundred Mbit/s) communications by the assistant of exciting high brightness blue LED sources, and laser diodes suggest that high speed optical links can be viable for short range application. The received signal power, signal to noise ratio, bit error rate, transmitted signal bandwidth, and transmission bit rates are the major interesting parameters for different ocean water mediums as a criteria of the best signal transmission characteristics of short wireless optical communications over wide range of the affecting parameters. 相似文献
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由于水体的吸收和散射作用,光束能量在传播的过程中会产生衰减,激光脉冲会被展宽,制约着水下激光雷达的探测范围和探测精度。文中以浑浊水体环境下水下弱小目标探测为应用背景,建立了水下光子传播的蒙特卡洛仿真模型,模拟了不同衰减系数和散射率的水体后向散射回波信号,并对相应的水体后向散射回波信号变化趋势进行了分析。仿真结果表明:随水体衰减系数的增加,近场水体激光回波信号接收光子数逐渐增多;随水体散射率的增加,回波信号光子消亡速度逐渐降低。开展了不同浊度下的激光雷达回波信号的测试实验,实验结果表明:随水体衰减系数的增加,水体激光后向散射回波幅度逐渐增高,脉冲宽度逐渐展宽。在进行浑浊水体水下弱小目标探测时,随水体衰减系数的增加,应通过逐渐减小激光器能量或接收系统增益来增强水体回波与目标回波之间的差异,以此提高浑浊水体水下弱小目标探测的信噪比。实验验证了理论与仿真结果,为浑浊水体环境下水下弱小目标激光探测系统在不同水质下的激光能量选取、接收系统增益设计等提供理论支撑。 相似文献
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水下光学成像是重要的水下探测方式。现有水下相机成像检测方法受到水体本身以及测量方法的影响,难以准确进行成像分辨率检测。提出了基于水下平行光管的水下相机成像分辨率检测技术,通过在水中产生平行光束,直接对水下相机成像分辨率进行检测。通过仿真得出:水下平行光管在水中可见光和空气中单波长的调制传递函数(Modulation Transfer Function, MTF)基本一致。利用这一结论,提出了水下平行光管空气中装调检测的方法。针对实验室所研制的一款水下相机开展实验测试,其在水中可见光与空气中635 m光源照明条件下的分辨率相同。实验结果表明,所提出的基于水下平行光管的水下相机成像分辨率检测方法可有效消除水体对分辨率测量的影响,实现水下相机成像分辨率的准确测量。 相似文献
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An approach is proposed and demonstrated to improve the measurement range and resolution of a microwave frequency measurement system. Two optical wavelengths are modulated by a microwave signal in a Mach-Zehnder modulator (MZM). The optical output from the MZM is sent to a dispersive element to introduce different chromatic dispersions, leading to different microwave power penalties. A fixed relationship between the microwave power ratio and the microwave frequency is established. The microwave frequency is estimated by measuring the microwave powers. A new measurement range is defined with an improved measurement range and resolution. Analysis is performed and confirmed by an experiment. 相似文献