甚低频信号全向接收方法研究

本文基于机动载体广泛使用的磁性天性存在可靠接收甚低频信号的难题,分析了磁性天线的方向特性,提出了甚低频信号全向接收方法。该方法是对两副正交安装的磁性天线中的一副天线接收信号进行移相,然后与另一副天线接收信号进行合成作为收信机输入,合成信号与信号来波方向无关,实现了甚低频信号全向接收。使用该方法进行甚低频收信时,对机动载体运动方向无任何限制,不影响机动载体的机动能力和其它任务的执行。     

基于超材料馈电网络的全向双极化天线阵设计

为了减小对天线阵辐射特性的影响,提出并设计了一种平行平板传输线结构的超材料串联馈电网络,基于超材料传输线设计了零相移传输线,利用零相移传输线设计了串联馈电网络。基于该馈电网络设计了一种全向水平/垂直双极化4元天线阵。天线阵由4个全向双极化天线单元和2个超材料串联馈电网络组成。全向双极化天线单元由折顶偶极子天线和缝隙电容加载的零相移圆环天线构成。利用HFSS仿真软件对该天馈系统进行了仿真,结果表明,该天线阵的中心工作频率为3.5 GHz,最大增益为7 dB,交叉极化电平小于-35 dB,隔离度大于40 dB,不圆度小于±1.2 dB,满足5G通信对基站天线和多入多出天线的要求。     

四维多极化天线阵

针对通信感知一体化应用,利用四维天线阵技术实现了能够同时辐射多个极化波的新型天线阵。该天线阵列由四维天线阵馈电网络和4端口圆环阵列组成。四维天线阵特有的时间调制特性可以在不改变天线结构且不引入移相器的情况下,在中心频率产生垂直极化全向辐射波束,在第一边带产生左旋圆极化定向辐射波束,在负一边带产生右旋圆极化定向辐射波束。相比于传统极化可重构、波束可重构天线,四维天线阵结构简单,且三种极化状态和两种辐射波束可以同时实现,更好地满足多功能一体化系统需求。     

卫星导航复合多功能桅杆天线的研究

本文利用双寄生套筒的结构,采用双锥和粗振子结合的辐射体形式设计了一款可与卫导天线级联的全向宽带穿杆天线。采用这种特殊结构该天线解决了常规天线内部穿金属接地杆后驻波恶化的问题。仿真和实测结果表明天线在120-550MHz频带内电压驻波比小于2.5,且高低频端的方向图全向性良好。     

天线孔径共用技术研究

提出了一种新的天线孔径共用的方法。在低频单圆锥天线的辐射非敏感区上加载高频段微带天线阵,可以将两个不同频段和极化的天线集成为一个天线孔径,该天线的体积质量与原低频段天线相当,天线的两个馈电端口集成在原单圆锥天线的地板上。利用电磁仿真软件HFSS分析了该共用孔径天线的性能,在双频段0.7~1.3 GHz和4.1~4.2 GHz内反射系数均小于–10 dB,两个端口之间的隔离度大于31 dB,辐射方向图低频段为全向,高频段为定向,4.15 GHz增益达到11 dBi,仿真结果验证了该孔径共用方法的可行性。     

全向宽带多极化天线的设计

针对军民两用机场对不同极化方式电台天线的新需求,本文介绍了一种全向宽带多极化天线,该天线由多个倾斜天线阵元组成,具备宽频带、多极化及全向辐射等特点。文中分析了不同倾斜角度对天线 H 面水平极化增益与垂直极化增益的影响。仿真结果表明,天线在不同极化增益配比下具备良好的全向辐射特性。     

超低频机械天线通信模型及信号接收线圈研究

机械天线作为超低频通信技术,是当今国际瞩目的一个新兴研究领域,在远距离通信、水下通信等方面具有广泛的应用前景.为实现小型化和低功耗的超低频机械天线,提出旋转偶极子式机械天线结构和通信模型.针对提出的通信拓扑结构及通信信号辐射强度,研制三轴正交线圈作为信号接收单元.提出基于线圈热噪声电压与感应电压比值的灵敏度归一化表征方法.并对研制线圈的灵敏度及工况进行实验.实验结果表明:灵敏度理论模型可用于高灵敏度线圈设计,研制的空芯线圈可用于机械天线信号接收;铁制品的存在对线圈接收性能有影响.该实验研究为超低频机械天线接收线圈的优化设计提供理论参考.     

对数周期偶极子天线在航向覆盖中的作用

对浦东机场使用的NORMAC公司生产的24单元航向天线阵的信号合成和信号覆盖进行分析与计算。通过不同的合成方法进行优化,获得了与对数周期偶极子天线(LPDA)场型分布高度吻合的分布函数。使用对数周期偶极子天线的水平方向的分布特征,来对比全向天线阵的信号合成与对数周期偶极子天线阵的信号合成的差别。分析结果表明:对数周期偶极子天线能够明显抑制大角度旁瓣信号的辐射,从而降低机场附近因信号折射造成的干扰,并能够有效提高航向覆盖区内的射频。     

一种单层贴片式双频双极化滤波天线

设计了一种单层式跨频段双频双极化滤波天线。该天线在同一平面上的高频低频辐射贴片共用一个馈电端口,且均可以在两个垂直方向馈电实现交叉方向的线极化辐射。该天线通过在馈电点与低频辐射贴片之间插入一个低通滤波器,明显提高了高频辐射贴片的交叉极化隔离度。研究结果表明,带滤波结构的天线在两个频率点的反射系数小于-20 dB,4.9 GHz的最大增益大于4.8 dBi,26 GHz的最大增益11.7 dBi,〖JP2〗两个辐射频率的辐射方向图均体现良好的线极化特性,且主极化比交叉极化大20 dBi。该天线可作为未来微波与毫米波共用的5G通信终端天线或5G通信基站的MIMO天线阵元,相关技术和结论对于研制一体化集成的双频交叉极化相控阵天线也有重要参考价值。     

双频段体表/体外双模式可穿戴天线设计

基于特征模理论分析方法,设计了一款2.45、5.8 GHz频段的体表/体外双模式可穿戴天线。在三角形的辐射贴片和接地面之间加载一段微带线,在2.45 GHz引入一个具有全向辐射特性的新模式,加上三角形贴片本身在5.8 GHz具有的定向辐射特性,组成了一个双频段双模式可穿戴天线。天线的仿真结果表明,在低频处实现全向辐射特性,阻抗带宽为1.6%(2.45～2.49 GHz),可用于体表通信模式;在高频处具有定向辐射特性,阻抗带宽为4.3%(5.67～5.92 GHz),可用于体外通信模式。     

ESPAR array design for the UHF RFID wireless sensor communication system

In this paper, in order to improve the received signal strength (RSS) and signal quality, three arrays of electronically steerable parasitic array radiator (ESPAR) antennas are suggested for the ultra-high frequency (UHF) radio frequency identification (RFID) communication and sensing system applications. Instead of the single antenna, the array antennas have recently been widely used in many communication systems because of their peak gains, better radiation patterns, and higher radiation efficiency. Also, there are some important issues to use the antenna array like high data rates in wireless communication systems and to better understand the many targets or sensors. In this article, a wireless sensor network (WSN) is being investigated to overcome multipath fading and interference by antenna nulling technology that can be achieved through beam control ESPAR array antennas. The proposed ESPAR array antennas exhibit higher gains like 9.63, 10.2, and 12 dBi and proper radiation patterns from one array to another. Moreover, we investigate the mutual coupling effect on the performance of array antennas with different spacing (0.5λ, 0.75λ, λ) and configurations. It is found that the worst mutual coupling reduced by −28 to −34 dB for 2 × 2 array, −3 to −43 dB for 2 × 3 array, and finally −42 dB to −51 dB due to the antenna spacing from 0.5λ to λ. Thus, these suggested antennas could effectively be applied in the WSN communication systems, internet of things (IoT) networks, and massive wireless and backscatter communication systems.     

Simultaneous Electromagnetic Measurement Using a Parallel Modulated Probe Array

A simultaneous measurement method using a parallel modulated probe array is proposed to measure the electromagnetic field radiated by antennas at different locations simultaneously. Each modulated probe is excited by a local signal with different frequency, so that the received intermediate frequency (IF) signal contains different frequency components which indicate the relative magnitude of the radio-frequency signal at positions of the probes, and all the IF components are measured simultaneously by a broadband microwave receiver. The effect of the local signal on the received IF signal and interaction effect between the probe array and the measured antenna are investigated. The accuracy of the method is shown by measuring the antenna radiation pattern. A 3D antenna radiation measurement system based on the present method is also developed. The performance of the system is demonstrated by measuring the radiation efficiency of antennas.     

分集阵列式水下激光通信光学接收天线设计

针对水下无线激光通信系统中对准困难的问题,提出了一种分集阵列式光学接收天线,在光学设计软件Zemax中分别设计出了复合光学接收天线和分集阵列式光学接收天线的光学结构,分析了复合光学接收天线和分集阵列式光学接收天线的视场角、聚光效率以及光源移动范围,并且通过实验和Matlab仿真给出两种光学接收天线的聚光效率随光源径向移动范围和光源入射角的关系,结果表明:当光源尺寸10 mm时,复合光学接收天线的聚光效率是0.06%,接收视场角是6,光源径向移动范围是6 mm;分集阵列式光学接收天线的聚光效率是0.06%,接收视场角是16,光源径向移动范围是22 mm。因此分集阵列式光学接收天线更适用于水下激光通信系统。     

双频基站天线中的反射板形状设计

蜂窝移动通信系统中的基站天线通常由直线阵列加反射板构成,而反射板的形状主要影响天线的前后比特性及水平面辐射方向图.该文对适合于基站天线的几种典型反射板形状进行优选,并采用矩量法线栅技术仿真计算了各种反射板形状对天线辐射性能的影响,根据仿真结果给出了满足基站天线双频辐射要求的反射板形状.     

水平全向共形微带天线的设计

设计了两种水平全向共形微带天线,采用电磁仿真软件CST MWS（CST MICROWAVE STUDIO）进行仿真,给出了天线的回波损耗和水平面方向图。天线采用了结构上对称的形式,利用微带贴片天线单向辐射的机理,实现了水平方向全向辐射。分析了天线的结构及仿真图,研究了阵列天线参数对全向性不圆度指标的影响,对于设计水平全向共形微 带天线有重要的价值。     

宽带无线Mesh网络中的多扇区天线阵列设计

在宽带无线Mesh网络中,为了扩展传输距离和提升链路速率,天线的性能至关重要。提出了一种多扇区天线阵列,每个扇区天线为带反射板的微带偶极子阵列天线,工作频段为5.1～5.9 GHz,其水平主瓣张角为45°,增益为18 dbi。多扇区天线阵列共包括8个扇区,信号在各扇区天线间进行动态切换,从而实现水平360°全向覆盖。通过采用HFSS三维电磁场仿真工具进行仿真及实际生产并在微波暗室中进行测试,结果表明和传统无线Mesh网络所采用的全向天线相比,在满足全向覆盖的同时,天线的方向性有了很大的改善。     

Applications of antenna arrays to mobile communications. I.Performance improvement, feasibility, and system considerations

The demand for wireless mobile communications services is growing at an explosive rate, with the anticipation that communication to a mobile device anywhere on the globe at all times will be available in the near future. An array of antennas mounted on vehicles, ships, aircraft, satellites, and base stations is expected to play an important role in fulfilling the increased demand of channel requirement for these services, as well as for the realization of the dream that a portable communications device the size of a wristwatch be available at an affordable cost for such services. This paper is the first of a two-part study. It provides a comprehensive treatment, at a level appropriate to nonspecialists, of the use of an antenna array to enhance the efficiency of mobile communications systems. It presents an overview of mobile communications as well as details of how an array may be used in various mobile communications systems, including land-mobile, indoor-radio, and satellite-based systems. It discusses advantages of an array of antennas in a mobile communications system, highlights improvements that are possible by using multiple antennas compared to a single antenna in a system, and provides details on the feasibility of antenna arrays for mobile communications applications     

Dielectric resonator antenna for dual-band PCS/IMT-2000

A novel broadband and small dielectric resonator antenna has been investigated experimentally and numerically. A bandwidth of 25% has been achieved, and an omni-directional radiation pattern obtained. These features make such antennas highly suitable for application to mobile handsets     

Phased array antennas for mobile communications

An antenna system including antenna elements and a tracking method is considered a key technology in mobile communication systems. A phased array antenna has been considered the most favorite candidate because of many attractive characteristics such as a low and compact profile, high-speed tracking and potentially low cost performance for vehicle antennas in mobile communications. On the other hand, it has several such disadvantages as beam steering error, loss in feed lines and an increase of noise level in a receiving frequency band. Some of phased array antennas have already been used in satellite communications, and some of them are under development. This paper overviewed basic performance and some examples of phased array antennas for especially satellite mobile communications.     

A distributed-feedback antenna oscillator

In this paper, a new design of the active transmitting antenna array, called the distributed-feedback antenna oscillator, is proposed. The active array is formed by serially connecting several unit cells to a closed loop. Each unit cell contains an amplifier and a two-port antenna, with an overall insertion gain larger than 0 dB and a phase delay equal to a multiple of 360°. The signal traveling on the loop is amplified and radiated in each unit cell. The radiation fields from all the antennas are then combined in free space. A four-element feedback antenna oscillator operating at 10 GHz is demonstrated by using two-port aperture-coupled microstrip antennas. Simulation results show that multiple oscillation modes with different frequencies and different radiation beams may be excited in the antenna oscillator. By experiment, it is found that each oscillation mode can be built by tuning the biases of the oscillator. The measured radiation pattern for each mode agrees very well with the predicted one. For a single-mode operation with a broadside pattern, bandstop filters of a simple geometry are designed and embedded in the oscillator to suppress the unwanted oscillation modes. Finally, the influence of the bias condition on the radiation power of the single-mode oscillator is investigated