共查询到17条相似文献,搜索用时 96 毫秒
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本文对Nakano简化的曲线天线积分方程核做了更便于数值计算的处理;运用矩量法分析,计算了谐振式四臂螺旋天线的圆极化方向图、增益、轴比、前后比及赋形特性等,并研究了馈电方法和导电板对天线性能的影响。 相似文献
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本文介绍了一种小尺寸多层平面式螺旋天线,通过近场耦合实现在频率范围10~300MHz之间的短距离数据通信。这种平面式结构采用PCB工艺,通过圆形螺旋绕组,由过孔连通每层线圈,并将不同螺旋圈数、不同层间距、收发天线之间不同距离等对天线特性的影响进行仿真研究。仿真结果表明,随着天线圈数的增加,天线的谐振频率减小,电场减弱,而磁场增强。 相似文献
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在卫星通信和定位设备中,为了迅速完成定位和通信功能,一般要求天线具有较大的波瓣宽度和较好的低仰角增益。设计了一种谐振式四臂螺旋天线,采用等幅馈电、相位依次相差90°的方案,实现了宽波束和圆极化,天线在上半空间的增益分布十分均匀。最后采用有限元方法对其辐射特性进行分析,计算结果与测试数据的一致性好。 相似文献
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A ring arrangement of four wires near to the excitation point of a quadrifilar helix antenna can be used to achieve an impedance match. The matching technique is applicable to resonant, fractional turn antennas, and to shaped conical beam backfire mode antennas 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 compact printed quadrifilar resonant helix antenna with integrated feeding system is presented. This antenna displays small size, low cost, hemispherical radiation coverage, large bandwidth, good efficiency and good axial ratio 相似文献
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Sainati R. Groppelli J. Olesen R. Stanland A. 《Antennas and Propagation, IEEE Transactions on》1982,30(5):1010-1013
A technique is presented that can be used to multiple tune a resonant quadrifilar helix. An example of a design is given with an antenna that covers two frequency ranges: 250-270 MHz and 290-310 MHz. 相似文献
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易力 《电子科学学刊(英文版)》1990,7(1):30-36
An efficient measure is taken to rearrange Nakano's kernels of integral equationsfor an antenna system composed of arbitrarily bent wires.By means of the moment method,great efforts are made to analyze and compute the circularly polarized patterns,directivity,axialratio,front-to-back ratio and beam-shaping characteristics of resonant quadrifilar helical antennasas well as the feeding technique and the effect of an electrically large conducting body on theperformance of the antennas. 相似文献
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It is shown that shaped-conical radiation patterns can be realized by extending the resonant fractional-turn quadrifilar helix to an integral number of turns, i.e., the radiated energy can be concentrated into a cone with the gain decreasing from a maximum at the edge of the cone to a local minimum at the center. This pattern shape is near optimum for many spacecraft communications and navigation applications, providing approximately 3 dB improvement over cardioid shaped patterns. 相似文献