共查询到19条相似文献,搜索用时 140 毫秒
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本文提出一种用双线背射螺旋作馈源的新式背射天线。这种天线具有结构简单,馈电方便,增益较高,易于产生圆极化波等优点。 相似文献
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一种新型平面阿基米德螺旋天线的分析与设计 总被引:1,自引:0,他引:1
对一种新型的平面阿基米德螺旋天线--锯齿状平面阿基米德螺旋天线进行了研究。首先给出了该天线的几何结构,介绍了其主要特点和应用领域,设计并制作了一个2.9~6.2GHz的锯齿状平面阿基米德螺旋天线。测试表明,与普通平面阿基米德螺旋天线相比,该天线能够缩小尺寸,展宽频带,很好地改善天线的低频特性。 相似文献
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机载螺旋天线辐射特性的研究 总被引:1,自引:0,他引:1
本文用螺旋的半圆近似法计算了阿基米德螺旋天线的辐射场。应用几何绕射理论(GTD)导出了机载螺旋天线辐射场的计算公式。计算结果与实测结果进行了比较,两者吻合较好。 相似文献
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文章主要论述了等角螺旋天线和阿基米德螺旋天线的特性以及各自的优缺点,并且对两种天线用基于FDTD的时域求解器进行了仿真,对其反射损耗和驻波比进行了对比,以便研究出性能更好的复合型天线。 相似文献
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一种L波段背射模螺旋馈源 总被引:1,自引:1,他引:0
螺旋天线具有较好的宽频带圆极化特性,在L或S波段体积和增益都很适中,加工制造公差要求较低,因此在该频段螺旋天线得到了广泛的应用。由背射模螺旋构成的L波段宽带馈源具有结构简单,馈电、调试方便,口面遮挡小,频带宽(大于25%),可以承受大功率等优点,可以满足L或S波段测控系统对天线的要求。用该背射模螺旋馈源研制的前馈天线的口径效率超过了53%,第一副瓣小于-20 dB,在工程中得到了很好的应用。 相似文献
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通信网络的可靠性评估 总被引:13,自引:1,他引:12
通信网络的可靠性评估是一个难题。目前人们只对环型网和树型网进行可靠性分析。本文首先定义了通信网络的可靠性,依据图论提出了网络生成树的计算方法,以及网络可靠度的估算公式。最后给出了一个栅格型网的可靠度估算示例。 相似文献
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本文叙述了背射模螺旋天线的频率响应理论。基于电流行波的假设,求解了远区场的近似解析解。结果与Nakano的数值解基本一致,笔者应用该理论研究了以背射模螺旋作为馈源,导体圆板作反射器的新型天线的辐射特性。取得了具有实用意义的结果。 相似文献
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轴向模螺旋天线的仿真研究 总被引:1,自引:0,他引:1
对轴向模螺旋天线的特性进行了理论分析,利用电磁仿真软件Ansoft HFSS12在1.615GHz对螺旋天线的特性进行了仿真,并通过改变导线接地板平面直径的尺寸,得到天线良好的背射方向图。 相似文献
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带小接地板锯齿形天线的背射特性 总被引:1,自引:0,他引:1
本文讨论了当锯齿天线接地板改为小于其宽度的小圆板时将呈现很有用的、显著的背射特性。文中给出测试结果。这种天线本身既可作收发天线,同时也可以作反射面天线的馈源。 相似文献
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Nakano H. Yamauchi J. Mimaki H. 《Antennas and Propagation, IEEE Transactions on》1988,36(10):1359-1364
Numerical analysis of a helical antenna is made in the presence of a finite-grid ground plane. It is found that the transition from forward-fire radiation to backfire radiation occurs as the ground-plane diameter is reduced to the order of the helix diameter. The investigation of the backfire helix with a small ground plane shows that a circularly polarized wave is radiated over a frequency range of more than 1 to 1.3. An application of the backfire helix to primary feed for a paraboloidal reflector is also described, in which the far-field pattern is evaluated by the physical-optics approximation 相似文献
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Quadrifilar loop antenna 总被引:2,自引:0,他引:2
A new quadrifilar antenna has been developed for generating circularly polarized backfire radiation. The antenna consists of two orthogonal rectangular conducting loops, each incorporating capacitive coupling and fed using either a single or two coaxial cables. Though the geometry is much simpler than a conventional quadrifilar helix antenna, the radiation pattern performance is very similar. Measured and simulated patterns are compared for two antennas with different feed arrangements. It is shown that the resonant structure can produce a cardioid pattern with a directivity of 4.5 dB (120/spl deg/ 3 dB beamwidth) and a front-to-back ratio of more than 20 dB at the center operating frequency. A 10% impedance bandwidth (VSWR<2) over which the axial ratio is less than 3 dB is demonstrated. 相似文献
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A backfire helical feed 总被引:1,自引:0,他引:1
A novel backfire helical feed for a paraboloidal reflector is described. The antenna requirements were a 20 percent bandwidth atL - band, right-hand circular polarization, a maximum voltage standing-wave ratio (VSWR) of 2.0, and a peak power capability of 200 kW unpressurized. The feed consists basically of a 3.5-turn helix wound around a1frac{5}{8} -in rigid coaxial transmission line. The50 Omega transmission line is coupled to the helix through a two-stage transformer within the coax followed by a half-wave coax to two-wire (unequal diameters) balun. 相似文献
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A long backfire antenna using an insular image waveguide feed compatible with microwave dielectric integrated circuit technology is presented. The antenna operates as a backfire component from 9.7 to 9.9 GHz and as an endfire antenna from 8.9 to 9.9 GHz, with symmetrical radiation patterns and low crosspolarisation. The important parameters of the antenna are experimentally optimised to give a maximum gain of 20 dB and 17 dB when working as a backfire and endfire antenna, respectively. This type of antenna can find extensive applications at millimetre-wave frequencies. 相似文献