LEAKY CHARACTERISTICS OF A NEW MILLIMETER WAVE ANTENNA BASED ON GROOVE GUIDE WITH AN ASYMMETRIC CONDUCTOR STRIP

A new millimeter wave leaky wave antenna is presented in this paper, which is a modification of the groove guide with an asymmetric conductor strip by introducing a dielectric slab into the conductor plane region of the groove guide antenna. The leakage property of the new antenna is carefully examined through calculations of an equivalent network, which is developed here with taking into account the coupling between different modes to guarantee the calculating accuracy. It has been found that the new leaky wave antenna is of larger leakage constant than that for the original groove guide antenna because of the introduction of the dielectric slab. Extensive numerical results of the leakage characteristics are given to establish useful guidelines for the design of the new type groove guide leaky wave antenna.     

Perturbation Analysis of Dielectric Grating Antenna with LHM Substrate

A dielectric grating leaky wave antenna with a substrate consisted of left handed material (LHM) is presented in this paper, the case where the n?=??1 space harmonic of TM mode radiating into the space is carefully investigated through the improved perturbation analysis, which tremendously simplifies the analysis procedure with good calculation accuracy and brings considerable physical insight into the overall behavior of the dielectric grating antenna. It has been found that the new leaky wave antenna is of larger leakage constant than that of the traditional antenna with substrate of the right handed material (RHM). As a result the dimension of the antenna could be largely reduced, which is of practical significance for some applications. Extensive numerical results of the radiation characteristics are given to establish useful guidelines for the design of the new grating antenna.     

一种基于左手介质的新型介质栅漏波天线的理论分析

提出了一种基于左手介质的新型介质栅漏波天线,并采用多模网络与严格模匹配相结合的方法,对该左手介质栅天线的辐射特性进行了仔细严格的分析.文中给出了漏波系数随天线结构参数变化的关系以显示该左手介质天线特有的性质.数值结果表明这种新型漏波天线比传统介质栅天线具有更强的辐射能力.讨论了产生这种现象的原因.     

A New Dielectric Grating Antenna with Large Leakage Constant for Millimeter-Wave Applications

The leakage properties of a new dielectric grating leaky wave antenna are carefully examined by an approach of combining the multimode network theory with the mode-matching method. A systematic comparison is given for the leaky characteristics of the n?=??1 space harmonic of TM mode polarization between the present antenna and the traditional one. It has been found that the former is not only of lower conductor loss, but also of larger leakage constant than the latter. As a result, the dimension of the antenna could be largely reduced, which is of practical significance for some applications. Extensive numerical results of the radiation characteristics are given to establish useful guidelines for the design of the new grating antenna. Furthermore, special features such as cancellation or resonance effects are high-lighted and discussed. Physical insights for the mathematical findings are also presented.     

Mode Matching Analysis for a New Millimeter Wave Omni-Directional Antenna Consisting of Circular Rod Corrugations Gloved with a Dielectric Shell

A new millimeter-wave omnidirectional antenna consisting of circular rod corrugations gloved with a dielectric shell is investigated. As an eigenvalue problem, the antenna is analyzed with the rigorous mode matching method. The radiation characteristics of the antenna are calculated in the Ka-band frequency range. A comparison of the leaky characteristics is made between the antennas with and without dielectric shell. It is found that the circular dielectric shell layer greatly affects the leaky characteristics of the antenna and the leakage constant increases considerably. In such a way, the length of the antenna can be reduced tremendously with higher radiation efficiency. This fact indicates that the proposed leaky wave antenna is of essentially practical significance for the case where the limitation in size and weight of system is strictly required. The effectiveness and reliability of the present analysis are verified by the calculated and experimental results given in the literature.     

新型NRD波导漏波天线特性分析

本文利用多模网络理论结合模匹配技术对任意横截面NRD波导漏波天线的辐射特性作了系统的分析,这些天线可以作为低成本的实用天线应用在毫米波系统中.文中着重研究了结构参数的变化对天线辐射特性的影响.这些计算结果对这类新型漏波天线的设计和确定NRD波导作为传输结构时的制作容差有重要的指导意义.     

A Double-Beam Radiation Leaky Wave Antenna Based on Left-Handed Material Slab with Metallic Strips Periodically Loaded

A new leaky-wave antenna structure is carefully investigated in the paper, which is based on a grounded Left-Handed material (LHM) slab periodically loaded with metal strips. A rigorous formulation similar to the spectral domain method for planar circuits is deduced to analyze the radiation characteristics of the antenna. Theoretical analysis results reveal that at specific frequency region or with proper geometrical parameters chosen, the present structure supports simultaneously two leaky modes corresponding to the forward and backward radiations. The principle of the antenna is due to the peculiar propagation properties of the unperturbed LHM grounded slab waveguide, which is totally different from the phenomenon of double or even more space harmonic mode radiations in normal periodic structures. Extensive numerical results of the leakage characteristics are given to establish useful guidelines for the design of the new type leaky wave antenna.     

Investigation on a Novel Leaky Wave Antenna with Double Radiation Beam Composed of Left-handed Slab Loaded Hybrid Waveguide using Planar Technology

A novel leaky wave antenna with double radiation beam composed of left-handed slab loaded hybrid waveguide using planar technology is proposed in this paper and its leaky characteristics are investigated with a method that the multimode network theory is combined with mode-matching method. The study of dispersion curves reveals that the proposed antenna structure supports two leaky modes corresponding to the forward and the backward radiations respectively. It demonstrates that the proposed antenna is of desirable property that can radiate both forward and backward directions simultaneously with quite simple and flexible configuration. Extensive numerical results of leaky characteristics with different structural parameters of the antenna are given to provide useful guidelines for the design of the new antenna.     

A new leaky wave antenna for millimeter waves using an asymmetric strip in groove guide, Part I: Theory

Traveling wave antennas for the millimeter wave range face two main problems: higher metal loss at the higher frequencies, and fabrication difficulties due to the smaller wavelengths. These two problems are addressed here by a new type of leaky wave antenna, in which the fabrication problem is minimized by employing a longitudinally continuous aperture, and the higher loss reduced by basing the antenna on a low-loss waveguide, the groove guide. A longitudinally continuous asymmetric metal strip provides the mechanism that transforms the initially bound mode into a leaky mode. An accurate analysis, based on a transverse equivalent network, is presented here for the properties of this leaky structure that takes into account the mode conversion from the bound mode to the leaky mode. All the constituents of this transverse equivalent network are obtained in closed form, thus yielding a dispersion relation in closed form. Part I of these two companion papers describes the new antenna and its principle of operation, and then derives the parameters of the complete transverse equivalent network. Part II is concerned with the properties of the leaky mode and their relations to leaky wave antenna performance; design considerations together with a variety of numerical results are contained in Part II.     

A new leaky wave antenna for millimeter waves using an asymmetric strip in groove guide, Part II: Design considerations

part I of this pair of companion papers describes a new type of leaky wave antenna for millimeter wavelengths and presents derivations of the parameters of the transverse equivalent network that accurately characterizes its leaky wave behavior. From a resonance of this transverse equivalent network, one obtains a dispersion relation in closed form from which numerical values of the leaky wave behavior have been obtained. Part II begins with this dispersion relation and a brief discussion of the numerical procedure employed. The relations between these leaky wave properties and the design of leaky wave antennas form the main concern of Part II. In this context, design aspects are discussed, including optimization considerations and the fact that they are frequency independent, and then a variety of numerical results are presented, together with their relevance to leaky wave antenna performance. It is seen that this antenna is capable of systematic design and is versatile with respect to the scan angle and beamwidth of the radiation.     

An Improved Perturbation Analysis of a New Omnidirectional Circular Rod Antenna with Double Dielectric Gratings for Millimeterwave Application

The leakage characteristics of a new millimeter-wave omnidirectional circular rod antenna with double dielectric gratings are analyzed by an improved perturbation method. The electromagnetic fields are described in terms of a radial transmission-line network, which brings considerable physical insight into the overall behaviour of the leaky wave antenna. The analysis yields expression for the leakage constant in a closed form so that the design procedure of the antenna becomes very convenient. It is found that under the condition of the same radiation intensity, the double dielectric-grating antenna has relatively smaller dimension than that of the single one. The results obtained by the present analysis are compared with the exact solution based on the mode matching method; it is found that the improved perturbation analysis yields as accurate results as the rigorous method with extreme simplicity of the analysis and calculations.     

Long rectangular patch antenna with a single feed

Radiation characteristics of a long rectangular patch antenna excited by a single feed are investigated. The equivalent circuit of the patch including the feed line section is developed. It is found theoretically that a single feed long rectangular patch supports a leaky traveling wave along the length of the patch. The complex propagation constant of the traveling wave is estimated by solving the wave equation with impedance boundary conditions. Radiation patterns of the antenna are obtained using the principle of equivalence. Various radiation characteristics of center-fed and end-fed long patch antennas are presented     

Design of Dielectric Grating Antennas for Millimeter-Wave Applications

At theoretical procedure well suited for generating design data on dielectric grating antennas for the millimeter-wave region is presented. The procedure utilizes the effective dielectric constant (EDC) method to determine the phase constant of the leaky modes supported by the antenna structure of finite lateral width. The radiation or leakage constant of these modes is obtained from the relatively simple boundary value problem of dielectric grating antennas of infinite width. For single-beam radiation, the practicably interesting case, the phase and leakage constants completely determine the field distribution in the antenna aperture, from which the directivity gain and radiation pattern are then calculated. The dependence of the antenna characteristics on the dimensions of the radiating structure is presented and discussed for epsilon = 12, the dielectric constant of typical millimeter-wave materials, such as silicon and GaAs.     

基于FDTD的微带缝隙漏波天线分析

应用时域有限差分法(FDTD)对微带缝隙漏波天线进行分析,直观地得到了微带缝隙漏波天线内部的电场分布。提出了一条有效的经验公式,成功地计算了微带缝隙漏波天线的漏波传播系数,与实验数据吻合较好。比较了不同缝隙宽度和微带宽度对微带缝隙漏波天线性能的影响。证明了在微带漏波天线上开缝可以有效地减少天线尺寸及降低天线的工作频率。     

A leaky-wave analysis of the high-gain printed antennaconfiguration

A leaky-wave analysis is used to explain the narrow-beam resonance-gain phenomenon in which narrow beams may be produced from a printed antenna element in a substrate-superstrate geometry. It is demonstrated that the phenomenon is attributable to the presence of both transverse electric and transverse magnetic-mode leaky waves, that are excited on the structure. Asymptotic formulas for the leaky wave are compared with the exact patterns to demonstrate the dominant role of the leaky waves in determining the pattern. Results are presented as a function of frequency, the scan angle, and the permittivity of the superstrate     

一种新型多层介质悬置微带线漏波特性的分析

提出了一种多层介质悬置微带线天线结构,以改善天线的频扫特性.分析表明:该结构不仅可以确保天线工作在效率较高的天线模工作区,而且它的泄漏常数在相当宽的范围内随频率都能平坦地变化.对频率扫描天线能保证当波束扫描时,可以保持一个相对稳定不畸变的辐射方向图.     

Aperture-coupled microstrip line leaky wave antenna with broadsidemainbeam

A microstrip first higher order leaky wave antenna (LWA), centre-fed by an aperture-coupled microstrip with a broadside mainbeam, is presented. The measured bandwidth (23% for VSWR<2:1) is in agreement with the leaky radiation band predicted. The experimental gain patterns, compared with those of a patch antenna fed by the same type of structure, reveal the difference between these two kinds of antenna. With increasing frequency, the radiation field of the LWA spreads into the H-plane, forming a flatter broadside pattern, which can be applied to long rectangular area communication     

毫米波介质栅漏波天线的改进微扰法分析

本文用改进的微扰法分析了毫米波介质栅漏波天线的辐射特性。文中通过横向谐振法确定漏波天线的相位常数,而漏波常数的计算归结为对有源传输线方程的求解。所得数据和用场匹配方法得到的精确值进行了比较,结果表明,本文方法在保持相同精度的情况下,简化了分析和计算过程。     

基于不同等效面的漏波天线辐射特性研究

基于等效原理计算了一款分别使用线电流源与线磁流源激励的一维无限长漏波天线的总场辐射方向图和漏波辐射方向图.应用等效原理,两种辐射方向图均分别使用了等效面电流和等效面磁流两种不同的等效方法推导.使用谱域法推导出天线总场与漏波辐射场方向图的解析解并使用互易性原理推导出总场的辐射方向图以作对比.对比结果显示不同等效面得出的漏波场辐射方向图不同.     

基于复合左右手材料的圆柱共形漏波天线设计

提出了一种基于复合左右手材料的平衡式圆柱共形漏波天线。天线单元由圆柱共形介质波导构成,通过在波导上表面蚀刻矩形缝隙槽结构,在引入串联电容的同时实现电磁波能量的连续泄漏,从而得到所需要的辐射特性。同时在波导结构中采用金属化通孔,引入并联电感, 实现了电磁波的左手传输特性。所设计的天线在平衡频点 15.6 GHz 处具有良好的边射特性。所提出的复合左右手漏波天线的阻抗带宽为 4.3 GHz(13.5~17.8 GHz),在天线阻抗带宽范围内天线主波束可以从-57°连续扫描到+30°。