低频补偿TEM喇叭天线的仿真与测试

以超宽带窄脉冲辐射为应用背景,通过添加补偿回路并调整回路的大小,设计了一种具有低频补偿的超宽带TEM喇叭天线.利用FDTD方法对天线结构进行了仿真,分析了不同补偿回路大小时TEM喇叭天线的S11参数、相位特性、辐射带宽及前后向辐射场等参数,得到了在大于400 MHz频带范围内S11参数低于-10 dB的天线结构.制作天线原型,并进行了实际测试,频域S11参数测试结果与仿真结果基本吻合.通过对时域波形的分析可知,该天线具有较高的波形保真度.     

瞬时超宽带TEM加脊喇叭的时域特性研究

根据瞬时超宽带天线的时域特点,仿真设计了一款超宽带TEM加脊喇叭天线,并对其频域和时域特性进行了初步研究,在频域内实现了3 GHz～18 GHz的超大带宽。在时域内进行了单个喇叭天线的时域信号测试,包括辐射的时域波形和峰峰值方向图。对该类天线的时域特性有了一定的认识。     

超宽带馈源技术发展综述

反射面天线是最主要的高增益天线形式,在与无线电相关的各个领域具有广泛应用。随着科技的发展,对于超宽带(UWB)反射面天线的要求日益迫切。因此,作为反射面天线核心的馈源,如何在超宽的频带内具有良好的阻抗特性、恒定的辐射特性和稳定的相位中心,已成为当今天线技术的研究热点。给出了超宽带馈源的设计要点,总结了超宽带馈源的类型、特点和发展现状,并对超宽带馈源设计技术的未来提出了展望。     

一种双频喇叭馈源的相位中心分析

多模圆锥喇叭天线是一种应用较广的高效率喇叭天线,它被广泛应用于反射面初级馈源。双频多模圆锥喇叭天线在收发两个频率处的相位中心是不重合的,当其作为反射面馈源时,其相位中心及安放位置的确定对于反射面天线的性能有着不可忽视的影响。从天线相位中心的定义出发,计算了双频多模喇叭天线在收发频率处的相位中心,并对该天线在偏置反射面系统中的安放位置进行了分析,确定了馈源的最佳安放位置。     

天线的机电一体化分析方法

基于机电综合分析的思想,给出了变形反射面的变形函数描述,以及天线变形后的辐射场计算方法,并分析了变形反射面对天线辐射方向图的影响。最后,运用最优化方法计算出了馈源在最佳位置时天线的辐射方向图。     

超宽带超低副瓣相控阵天线时域远场辐射特性研究

本文首先研究了天线时域辐射远场的基本原理,建立了计算公式.在此基础之上,分析了相控阵天线工作在窄脉冲条件下的时域辐射场,发现其时域方向性(如:时域远场峰值方向图、时域远场平均功率方向图)与频域方向性(频域远场方向图)并不一致,这种不一致性随着天线口径的增大或脉冲宽度的变窄而愈加明显,并且在天线注满时间之内表现得尤为突出.文章由此指出:对于超宽带超低副瓣相控阵天线来说,其性能用时域指标去衡量胜于用频域指标去衡量的新观点.     

超宽带脉冲横电磁波喇叭的数值模拟

本文用时域有限差分方法分析和优化了前端是平行板传输线的横电磁波喇叭天线（其激励源是由同轴线馈入的超宽带电磁脉冲），优化了平行板传输线和横电磁波喇叭的尺寸，给出了天线的一些特性参数随频率的变化关系、天线的辐射场分布、天线辐射的能量方向图以及天线长度对增益的影响等。     

超宽带TEM喇叭天线的研究

研究一种超宽带TEM喇叭天线。提出一种无需加载的超宽带TEM喇叭天线的设计思路,理论推导该天线的远区场,由此得到特性阻抗变化与反射系数的关系。利用电磁仿真软件Ansoft HFSS模拟分析,在此基础上,设计一种视轴长度10cm的此类型TEM喇叭天线。测量得到在100～550MHz天线驻波比小于2.0,结果表明此天线在不加载情况下,通过对其结构进行合理的弯曲设计,也能使其具有良好超宽带特性。     

双极变张角时域天线设计

传统的超宽带天线概念是在频域下定义的,有些不能作为时域脉冲天线使用。为实现时域天线的定向性、低剖面、小尺寸、可承受高功率等性能,结合领结天线的低剖面特性和TEM喇叭天线的定向辐射特性设计双极变张角时域天线,该天线是根据光导开关的时域响应设计天线激励源的低剖面定向时域超宽带天线,仿真结果表明．该天线是一种高性能的时域天线。     

双极变张角时域天线设计

传统的超宽带天线概念是在频域下定义的,有些不能作为时域脉冲天线使用.为实现时域天线的定向性、低剖面、小尺寸、可承受高功率等性能,结合领结天线的低剖面特性和TEM喇叭天线的定向辐射特性设计双极变张角时域天线,该天线是根据光导开关的时域响应设计天线激励源的低剖面定向时域超宽带天线,仿真结果表明,该天线是一种高性能的时域天线.     

A novel UWB feeding mechanism for the TEM horn antenna, reflector IRA, and the Vivaldi antenna

This work proposes a method for feeding a balanced IRA with an unbalanced transmission line. This method is based on the current distribution on the surface of the antenna. The method of moments (MoM) simulations show that for the IRAs, there are some areas with low current density in comparison to the current density of the feeding points, almost over the entire frequency range. The coaxial cable is attached to the antenna's body all the way from the feeding point to an area of low current density, and extends out of the antenna structure at that point. This tremendously reduces the current density on the body of the coaxial cable. As a result, the current balance between two parts of the antenna is not disturbed. This method is applied to the TEM horn antenna, the reflector IRA, and the Vivaldi antenna. The TEM horn antenna was simulated using the HEMI software, and was fed by an unbalanced coaxial cable, both directly at the feeding point and using this method. This method was also applied to the reflector impulse-radiating antenna. Also, the Vivaldi antenna was fed both by considering the low-current density area and direct feeding. The E-plane far-field pattern of the new feeding method had good agreement with the result generated by the HEMI software for the balanced-fed antenna.     

超宽带TEM喇叭天线阻抗加载的时域分析

基于时域有限差分法中的阶梯近似方法,分析了超宽带TEM喇叭天线辐射场的时域波形.为了改善宽带TEM喇叭天线拖尾效应,文中利用集总元件的时域有限差分法,详细分析了不同阻抗加载条件下TEM喇叭天线辐射场的时域波形.计算机模拟结果表明,加载吸收电阻可以有效地解决TEM喇叭天线由于低频反射引起的拖尾振荡,改善辐射电场的波形特性.     

On the characterization of a reflector impulse radiating antenna (IRA): full-wave analysis and measured results

There is a growing demand for impulse radiating antennas (IRAs) to receive and transmit short pulses. The basic concepts of IRA are reviewed and the far-field pattern versus frequency of an ideal IRA is characterized based on the fundamental properties of IRA. It is shown that the transmitted pulse is ideally in the form of a time derivative of the input pulse. The physical optics simulation results show that the far-field characteristics of a parabolic reflector are very close to an ideal IRA if it is fed properly. The reflector IRA was constructed, analyzed and measured at UCLA. The near-field and far-field characteristics of the reflector IRA are studied using both the method of moments (MoM) full-wave simulations and the frequency domain measurements. In this paper, the radiation mechanism of the reflector IRA is studied using a detailed current distribution on the parabolic reflector and the feeding structure at different frequencies. Applying either the calculated current distribution on the reflector IRA or the measured near-field results, it is seen that the aperture field intensity of the parabolic reflector is not the same in the two principle planes and as a result the beam-widths in the two principle planes are different. The far-field patterns of the antenna are measured and the calculated far-field patterns support the measured results. The calculated current distribution results provide a guideline on how to properly change the feeding structure to achieve a more uniform aperture field and increase the antenna radiation efficiency.     

恒阻抗TEM喇叭天线设计关键问题研究

恒阻抗TEM喇叭天线具有沿轴线方向特性阻抗为一恒定值的特点,所以喇叭内的反射损耗非常小,常用于超宽带电磁脉冲的辐射与接收。为了提高恒阻抗TEM喇叭天线远场主射方向脉冲峰峰值,通过数值仿真和实验测试研究了天线口径以及特性阻抗值与远场主射脉冲的关系。研究发现,天线沿主轴方向长度一定时,脉冲源通过50Ω同轴线直接向天线馈电,远场主射方向脉冲峰峰值先随天线口径增大而迅速增加,当口径达到某一值时,脉冲峰峰值达到最大值,如果继续增大口径,脉冲峰峰值开始缓慢下降。对于各个特性阻抗值不同的TEM喇叭天线,当它们分别选取上述峰峰值最大对应的口径时,280Ω的恒阻抗天线远场主射方向脉冲峰峰值最大。     

Improved feeding structures to enhance the performance of the reflector impulse radiating antenna (IRA)

This paper considers the improvement of the feeding structure of the reflector impulse radiating antenna (IRA). Full-wave analysis and measured results of the orthogonal cross-coplanar plate reflector IRA shows that the aperture fields are not uniform. The arm angle is varied as an optimization factor and it is shown that the arm angle of 70/spl deg/ has the maximum radiation efficiency. The termination load and the arm tapering effects are studied using simulation and measurement results. Furthermore, the effect of radius of circle of symmetry is studied and it is shown that a greater circle provides higher gain. A combination of transverse electromagnetic (TEM) horn antenna and the conical coplanar TEM transmission line is investigated to avoid tiny structure at the focal point and make the connection between the coaxial cable and the feeding arms more convenient. It is shown that a small triangle does not degrade the antenna performance but helps to excite the antenna by a coaxial cable. Finally a combination of the Vivaldi antenna and the coplanar transmission line is introduced to improve the antenna performance. The simulation results for the new antenna show that the antenna efficiency is improved to 45% at the frequency band between 2 GHz to 6 GHz in comparison to the 20.9% for the traditional design and 29.7% for the tapered design. The calculated far-field results of all these antennas are used to radiate a 0.5 ns impulse. The radiated impulse from the Vivaldi fed reflector IRA is 3.55, 2.41, and 2.12 dB higher than the same radiated impulses from the reflector IRA fed by a 45/spl deg/ traditional feeding arms, 70/spl deg/ traditional feeding arms, and 70/spl deg/ tapered feeding arms, respectively.     

超宽带（UWB）短脉冲天线性能改善方法研究

分析了各种超宽带短脉冲天线的性能 ,针对各天线存在的不同特点采取不同的措施进行改进。改变对数周期天线的馈电方式可以避免滞后失真 ;根据 WU- KING偶极子理论 ,对圆柱单极子天线、单圆锥天线和 TEM喇叭天线等进行加载可以有效减小反射 ,改善了天线辐射短脉冲的性能 ,但同时也导致了辐射效率的降低     

A High-Power Reflector Impulse Antenna with Dual-Tem Source

There are different demands on radiation efficiency and direction pattern according to various ultra-wideband (UWB) antennas and high power applications. To obtain more radiating gain on bore-sight of paraboloidal reflector and centralized radiating direction, a novel feeding structure called dual-TEM source has been designed and applied in half-paraboloidal reflector impulse radiating antenna (IRA) applications. Simulation results proved that this proposed half-paraboloidal reflector IRA with dual-TEM source provided greater radiation performance on bore-sight as a result of the synthesized power in the aperture space of paraboloid. Moreover, lots of simulation work and comparison have been done in different feeding models to summarize a relative optimal feeding structure.     

UWB TEM HORN ANTENNA FOR THE ASPHALT PAVEMENT INVESTIGATION简

A simple Ultra-WideBand （UWB） exponentially-tapered Transverse ElectroMagnetic （TEM） horn antenna is presented for the asphalt detection based on Ground Penetrating Radar （GPR） In order to reduce the reflections from the antenna aperture, some absorbing material is loaded on the outer surface of the conductor. Comparing with the traditional TEM horn antenna, the proposed antenna has a small size and a large impedance bandwidth. Simulated and measured results show that the proposed TEM horn antenna has a low Voltage Standing Wave Ratio （VSWR） below 2 over the whole band from 0.35 GHz to 12 GHz, good radiation characteristics, and small late-time ringing, which can perfectly meet the requirements of the GPR application.     

一种新型超宽带喇叭天线的研究

提出一种基于H波导的新型超宽带喇叭天线以减小一般的超宽带天线如TEM喇叭天线侧向泄漏较大的问题.先在理论上研究了H波导用作超宽带天线的可行性以及参数选择的依据,然后利用FDTD方法研究了同轴探针激励的H波导的时域传输特性和截断的H波导及喇叭的辐射特性,得出该天线可用于超宽带天线,尤其是该天线具有较小的侧向泄漏,使其可以用作天线阵的单元的结论.