蘑菇型EBG微带天线电磁辐射特性分析

利用矩量法对探针馈电的蘑菇型EBG微带天线的电磁辐射特性进行了分析。首先建立了天线模型,采用细导线的带模型将馈电探针和EBG短路过孔等效为细带,并与EBG金属表面和微带贴片一样均采用平面三角面元剖分,RWG基函数作为电流展开函数,将线面连接问题转化为面面连接问题。然后给出了采用空域矩量法对天线辐射特性进行分析的全过程,并介绍了激励源的添加模型。最后对蘑菇型EBG微带天线的回路损耗、输入阻抗和方向图等特性进行了分析计算,相关结果与FEKO和文献吻合良好,验证了本文方法的正确性。     

Electric-field distribution near rectangular microstrip radiatorsfor hyperthermia heating: theory versus experiment in water

A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode-dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low (epsilon r = 10) and high (epsilon r = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios at 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power.     

FDTD法分析探针加载微带天线的简便方法

给出了一种FDTD法分析短路探针加载同轴馈电的微带天线.该方法利用一维传输线模型描述同轴线部分;而用细导线模型来分析探针.其优点是模型简单,易于编程,且程序的通用性好.数值和实测结果符合较好,表明该方法是有效的.     

准光腔单微带贴片输入阻抗的理论分析

本文利用并矢格林函数获得了准光腔中的电磁场积分方程。利用矩量法导出了被一个轴向电流源激励的单微带贴片腔的输入阻抗的计算公式。利用本方法对矩形微带贴片的输入阻抗进行了讨论。其结果与微带天线很类似。这对设计微带型准光振荡器有重要的参考价值。     

AN ANALYSIS ON INPUT IMPEDANCE OF A SINGLE MICROSTRIP PATCH IN THE QUASI-OPTICAL CAVITY

The electromagnetic field integral equation in the quasi-optical cavity is obtained using the dyadic Green's function. An expression is derived for the input impedance of a single microstrip patch cavity excited by a coaxial probe using moment method. The input impedance of a rectangular microstrip patch is discussed with this method. The result of this paper is similar to that of the microstrip antenna. This paper is of very important value for designing microstrip quasi-optical oscillator.     

An analysis of input impedance of a single microstrip patch in the quasi-optical cavity

The electromagnetic field integral equation in the quasi-optical cavity is obtained using the dyadic Green's function. An expression is derived for the input impedance of a single microstrip patch cavity excited by a coaxial probe using moment method. The input impedance of a rectangular microstrip patch is discussed with this method. The result of this paper is similar to that of the microstrip antenna. This paper is of very important value for designing microstrip quasi-optical oscillator. Supported by the National Science Foundation of China.     

一种基于基片集成波导技术的引线键合结构

当前微波毫米波芯片的引线键合主要是在芯片焊盘和微带线之间实施,当工作频率达到毫米波频段,引线键合的性能对键合线属性及微带线加工精度的敏感度越来越高,键合操作中键合线长度的差异或微带线加工的误差都可能导致键合性能的快速恶化。文章提出了一种基于基片集成波导(SIW)的引线键合结构,该结构直接使用SIW与芯片焊盘或其他电路进行键合,对比现有微带键合方案,使用本文提出的基于SIW的键合方案,可以显著减小加工精度的敏感度,同时减少对介质基片的限制等。文章分别设计了无源和有源SIW键合结构,仿真和测试结果表明:基于SIW的键合结构拥有良好的键合性能,相比微带键合结构,降低了传输损耗、降低了对结构尺寸的灵敏度、改善了键合性能。     

Comparison of models for the probe inductance for a parallel-plate waveguide and a microstrip patch

Four different models for the probe inductance of a circular probe in an infinite parallel plate waveguide are studied. These models include a uniform-current model, a cosine-current model, a gap-voltage source model, and a coaxial-frill model. These different models treat the vertical variation of the fields within the substrate and the field of the coaxial feed with varying degrees of rigor. Numerical high frequency structure simulator data are also compared with the results of these models in order to draw reliable conclusions about the accuracy of these models as a function of the substrate thickness. A simple computer-aided design formula for the probe inductance of a coaxial feed probe for a rectangular microstrip patch antenna is also introduced.     

多层电厚微带天线的阻抗特性

本文提出了一种多层介质电厚微带天线的一种分析方法。从无界空间中的电并矢格林函数出发,导出了分层介质中任意一点具有任意取向的水平电偶极子场的表达式。以此为基础,利用Richmond反作用积分方程,建立了关于贴片上电流分布的积分方程。通过适当选取电流基函数,使本方法适用于电厚介质微带天线。应用Galerkin方法建立矩阵方程。借助于计算机求解该矩阵方程,可得到天线的各项特性。文中用实例进行了验证。     

A Metrology Application of Reverberation Chambers: The Current Probe Calibration

This paper presents how it is possible to characterize a current probe in terms of its transfer impedance inside a reverberation chamber. The probe catches a floating wire placed inside the working volume of the chamber. The current on the wire is calculated from the knowledge of the total measured average field along the wire in the working volume. The current is calculated by representing the field in terms of a summation of random plane waves, where a finite-difference time-domain (FDTD) code is used to compute the current induced by each plane wave along the wire caught by the probe under test. Results for the current distribution along the wire are reported for several frequencies. Finally, the transfer impedance of commercial probes is recovered from the knowledge of the current and compared to the values given by the manufacturers and by an external laboratory     

Resonance-suppressed magnetic field probe for EM field-mapping system

A novel rectangular magnetic field probe is proposed, and calculated and measured results are presented. The proposed probe effectively suppresses the emission/reception of electromagnetic fields from the edge of the ground plane and, as a result, the usable frequency range of the probe is enhanced compared with that of the conventional one. In order to verify the performance of the probe, measured magnitude and phase of the magnetic field with an H/sub xy/ probe are presented from 1 to 7 GHz for two different geometries: microstrip line and bandpass filter for ultrawide-band application. The measurement results agree very well with theoretically predicted field distributions, showing its excellent performances.     

A Field-Probing Approach and Its Application to a Power Distribution Network

This study presents a means to probe the electric-field distribution in a microstrip resonator using the existing power/ground pins. The strength of the electric-field could be correlated with the reflection coefficient. Physical mechanism for the position-depended reflection effect is interpreted from the perspective of probe coupling. An application of this method is demonstrated through three phases: determining the maximum field of a microstrip resonator, shaping the geometry at the field bulk, and detuning the resonant frequency of a power distribution network. The results reveal that this approach can be employed to achieve a resonance-free operating environment.     

End-correction network of a coaxial probe for microstrip patchantennas

A simple end-correction network for the constant current probe model of probe-fed microstrip patch antennas is derived. The parameters of the network are solved asymptotically and verified by the numerical solution of the integral equation formulation. Based on the analysis of a problem concerning a coaxial-fed microstrip patch, it is concluded that: (1) TEM (transverse electromagnetic) aperture field approximation can provide an accurate result to the input admittance, and there is no need to introduce a specific correction network for most applications; and (2) Constant current probe is valid only when both k₁ h≪1 and a/h≪1 are satisfied. An end-correction network consists of a series inductance and a shunt capacitance should be used in other ranges or for higher accuracy     

INPUT IMPEDANCE OF MICROSTRIP ANTENNA WITH THICK MULTILAYER SUBSTRATE

A method has been devised to analyze multilayer electrically thick circular mi-crostrip antenna excited by a probe.The current on the probe is taken to be uniform.Thismethod was verified by analysis and experiment of an electrically thick circular microstrip an-tenna with an air gap.Based on the free space electric dyadic Green's function,the field expressionof an horizontal electric dipole(HED),which is located at any point of the multilayer media andpoints in any direction,has been derived.By using this field expression and the Richmond re-action equation,an integral equation in terms of electric current on the patch is formulated.Byproperly choosing current expansion modes,this method can be used for an electrically thick mi-crostrip antenna.The theoretical results agree very well with experimental data for an electricallythick circular microstrip antenna with an air gap.     

Input impedance of a probe-fed circular microstrip antenna with thick substrate

A method of computing the input impedance for the probe fed circular microstrip antenna with thick dielectric substrate is presented. Utilizing the framework of the cavity model, the fields under the microstrip patch are expanded in a set of modes satisfying the boundary conditions on the eccentrically located probe, as well as on the cavity magnetic wall. A mode-matching technique is used to solve for the electric field at the junction between the cavity and the coaxial feed cable. The reflection coefficient of the transverse electromagnetic (TEM) mode incident in the coaxial cable is determined, from which the input impedance of the antenna is computed. Measured data are presented to verify the theoretical calculations. Results of the computation of various losses for the circular printed antenna as a function of substrate thickness are also included.     

适用于移动通信的宽频带微带天线

该文研究新型的宽频带微带天线,采用一种具有双层贴片结构的微带天线的形式,并用在探针顶端加电容性金属圆片来抵消探针感性的方法,增加了天线的工作带宽。制作适用于第二代和第三代移动通信的宽频带微带天线,测试结果显示天线具有良好的带宽特性,能够满足移动通信系统对天线的带宽要求。     

Numerical analysis of arbitrarily shaped probe-excited single-armprinted wire antennas

A general integral equation technique is described for analysis of an arbitrarily shaped single-arm printed wire antenna excited through a vertical probe. A unified current integral equation is formulated on the basis of dyadic Green's functions and the reciprocity theorem. The current distribution is obtained by using a parametric moment method in which parameter segments are adopted for the printed wire instead of the commonly employed wire length segments. The radiation field solution involving both the printed antenna and vertical probe is also presented. The validity of the formulation is verified by comparing the numerically obtained input impedance and radiation patterns for a linear antenna and a meander antenna with measured data. A circular open loop and an Archimedian spiral are investigated to illustrate the applicability of the present technique     

Radiation modes of open microstrip with applications

The well known bound modes of open microstrip do not constitute a complete spectrum, for, continuous radiation and localized (reactive) modes are excited at discontinuities in microstrip circuits and antennas. This part of the spectrum has not been investigated before so that, up to date, radiation problems in microstrip are being investigated by nonmodal methods, such as the moment method. We derive here for the first time the complete spectrum of open microstrip, including one or more bound modes and a continuum, and demonstrate its straightforward application to a practical problem such as the excitation by a cylindrical probe of finite radius. Application of Lorentz's reciprocity principle is now possible in complete analogy to the problem of excitation of a close waveguide by a probe. Mode patterns, the equivalent circuit of a via-hole and its radiation pattern are characterized as a practical application of the foregoing theory     

Excitation of an Infinite Microstrip Line With a Vertical Coaxial Feed

An efficient method is presented for the analysis of a vertical coaxial probe excitation of an infinite microstrip line. The novel feature of the method is that it uses a semianalytical Green's function that is derived for current sources in the presence of the infinite microstrip line. Hence, in a method of moments approach, unknown currents need only be placed on the conducting probe feed and not on the infinite strip surface. The method also utilizes an attachment mode at the contact point between the probe and line so that the correct Kirchhoff condition is automatically satisfied. Once the surface current density on the probe is known, the surface current density on the strip conductor can be readily obtained using the Green's function of the background grounded substrate. The method is valid even at high frequency, where simple transmission line theory fails to account for effects such as the continuous-spectrum current that is excited on the line. After validating the method with various commercial software simulation packages, results are presented to study the fundamental behavior of the input impedance, probe current, and current launched on the microstrip line, and to examine the high-frequency behavior of these currents.      

Center-fed microstrip patch antenna

A novel feeding scheme for microstrip patch antennas is presented, which consists of a coaxial probe and shorting pin separated by a narrow slot centrally cut at the radiating patch. The impedance and radiation characteristics of a conventional probe-fed microstrip patch antenna and the proposed microstrip patch antenna are experimentally examined and compared. The effects of the slot length on the antenna operation are also discussed.