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.     

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。     

Input impedance of microstrip patch in the quasi-optical cavity resonator

The dyadic Green's function in an active loaded quasi-optical oscillator is presented. An expression is derived for the input impedance of a single microstrip patch cavity excited by a coaxial probe using the method of moment. Using the present formulation the input impedance of a rectangular microstrip patch is determined.     

Theoretical Investigation of the Input Impedance of Gap-Coupled Circular Microstrip Patch Antennas

In this paper, we have explored a simple theoretical input impedance computation technique for the two gap-coupled circular microstrip patch antennas by using circuit theory approach. The frequency characteristics of the input impedance of the two gap-coupled circular microstrip patch antennas with the gap-distance between the feed patch and parasitic patch is analyzed and simulated. The effect of feed location in the feed patch on the input impedance of proposed antenna is also studied. The theoretical results are compared with the simulated results as well as other reported literature. The simulation has been performed by using a method-of-moment based commercially available simulator IE3D.     

Analysis of Aperture Coupled Microstrip Antenna with Circular Polarization Diversity

The circular polarization diversity with the square patch microstrip antenna was obtained by the implantation of the quadrature hybrid as a microstrip feed line. The small size antenna is achieved by using the aperture coupled structure. The analysis of an aperture-coupled microstrip antenna (ACMSA) based on the cavity model theory is presented in this paper. The cavity model has been used to design an ACMSA and determine the relationship between the input impedance of the ACMSA and the position of the aperture. The matlab and the Advanced Design Software have been used for designing and simulating the ACMSA. There is a good agreement between the simulated and the experimental results.     

高温超导体非线性特性对微带天线性能的影响

主要研究了高温超导(HTS)薄膜非线性特性对微带天线性能的影响。首先介绍了高温超导薄膜的非线性特性现象，以及产生该现象的可能的机理，在此基础上以矩形微带贴片天线为例，采用谱域矩量法对微带天线的辐射效率和输入阻抗进行了计算。结果表明输入功率增大到一定值时，将使天线的辐射效率下降，而且输入功率对输入阻抗也有一定的影响。     

Full-wave analysis of the annular-ring loaded spherical-circularmicrostrip antenna

In this paper, an annular-ring loaded (ARL) spherical-circular microstrip antenna is studied theoretically. The antenna is excited by a coaxial probe. The theoretical formulation is based on full-wave analysis in the spectral domain by using the vector Legendre transform and Galerkin's moment method is used for numerical calculation. Numerical results of the resonance frequencies, input impedance, voltage standing wave ratio (VSWR), and radiation characteristics are presented. It is shown that the impedance bandwidth of the spherical-circular microstrip antenna can be broadened by adding an annular-ring parasitic patch. By comparing to the single circular-patch case the spherical-circular microstrip antenna with an annular-ring parasitic patch has larger minor lobes and larger cross-polarization radiation     

腔基微带天线的矢量有限元--边界积分方法分析

该文将矢量有限元——边界积分(Edge-Based FE-BI)混合方法用于腔基微带贴片线的辐射特性分析。分别计算了在无阻抗负载和加有阻抗负载两种情况下的输入阻抗，以此验证了该混合方法的正确性；然后计算了贴片天线表面缝隙部分的场分布，验证微带天线分析模型——传输线模型的合理性；最后计算了E面、H面方向图以及相应的交叉极化方向图。     

Analysis of a probe-fed short-circuited microstrip antenna

The input impedance of a probe-fed short-circuited microstrip antenna (SCMSA) is presented. The electric field expression under the microstrip patch by using the Wiener-Hopf technique is used and the electromotive force (EMF) method is applied. Analytical and experimental results for the impedance show the dependence on the dimensions and frequency     

矩形微带贴片天线的简化多端口网络模型

提出了矩形微带贴片天线的简化多端口网络模型，并运用该模型和二维平面电路的分析方法计算了一矩形微带贴片天线的输入阻抗，所得结果与一些文献的计算结果和实验结果相一致，证明了所用方法是有效的。     

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.     

On slot-coupled microstrip antennas and their applications to CPoperation-theory and experiment

A simple theory based on the cavity model is developed to analyze microstrip antennas excited by a slot in the ground plane. By using an equivalent magnetic current source at the feed, the electric field under the patch is obtained in terms of a set of cavity modes. In particular, the loci of the slot feed location for achieving the circular polarization and the input impedance are computed and found to be in excellent agreement with the experimentally measured results. Simple but surprisingly accurate formulas for slot-fed circularly polarized microstrip antennas are derived and compared with those for probe-fed counterparts     

有源集成天线的谐波平衡法分析

本文首先利用矩量法计算平面馈电型微带贴片天线的输入阻抗,并对其进行实验测量;其次,使用谐波平衡法分析了以Ｃｕｎｎ管为振荡源的有源微带天线电路。在求解谐波平衡方程时采用Ｐｏｗｅｌｌ优化法,得出整体电路的振荡频率和振荡电压;再次,仍使用谐波平衡法对肖特基二极管与微带贴片天线集成的接收型有源天线进行大信号的小信号分析,同样经过优化,得出其在本振电压作用下,非线性部分的谐波电压以及在小信号电压作用下的变频     

Novel design of broad-band stacked patch antenna

A novel broadband stacked E-shaped patch antenna is proposed in this paper. The proposed antenna has an input impedance bandwidth of about 38.41%, better than the conventional E-shaped microstrip patch antenna, which has an input impedance bandwidth of 33.8%. Through the use of the washer on the probe of the stacked patch antenna, the input impedance bandwidth is improved further to 44.9%. The radiation patterns are found to be relatively constant throughout the whole band. Comparisons of these antennas are presented in this paper.     

人体中心网络微带缝隙天线设计和研究

设计了一款小型微带缝隙天线.通过电磁仿真软件CST的参数优化功能,对微带缝隙天线缝隙的长度、宽度、馈电点等参数进行优化,得到了工作频率为2.45GHz,带宽100 MHz、阻抗匹配良好、辐射效率较高的用于人体中心网络的微带缝隙小型天线,根据仿真设计,制作了天线,测试结果和仿真结果吻合较好.     

A study on wideband gap-coupled microstrip antenna arrays

A method for increasing the bandwidth of microstrip antenna arrays by using gap-coupled patches is described. The input impedance properties of gap-coupled patches are analyzed by the use of the spectral dyadic Green's function for a grounded dielectric slab and the moment method. The dependence of different parameters such as s, L and ϵr on the impedance characteristics is investigated. In considering the effect of feed network, the impedance bandwidth for a VSWR<2 of two-element gap-coupled patch array is as large as 2.5 times that of an ordinary array. The radiation patterns over this bandwidth are measured and discussed. All the microstrip antenna arrays are fabricated on a substrate with ϵr=2.86, h=1.5 mm. A comparison of theoretical and experimental results for both input impedance and radiation patterns are given     

Analysis of arbitrarily shaped microstrip patch antennas using segmentation technique and cavity model

Arbitrarily shaped microstrip patch antennas have been analyzed for resonant frequency, input impedance, and radiation patterns. The segmentation technique and the cavity model have been used for this purpose. The usefulness and the accuracy of the method are shown through comparison with experimental results for a rectangular ring antenna. The agreement is seen to be very good. Ihe method appears to be more efficient compared to those reported so far for arbitrary shapes. Moreover, feed reactance is built into the analysis. The method presented here can also be used to analyze microstrip antennas with various types of loadings, e.g., shorting pins, matched loads, etc.     

Characteristics of the cylindrical-circular patch antenna

An analysis of a thin cylindrical-circular microstrip patch antenna is presented. Using the cavity model as a base, formulas are obtained for the far-zone electric field and the input impedance of a coax-fed patch. Numerical and graphical results are given to illustrate the effects of curvature on the characteristics of the TM₁₁ mode     

Analysis of the cylindrical-rectangular patch antenna

An analysis is presented of a thin cylindrical-rectangular microstrip patch antenna. After obtaining the electric field under the curved patch and the resonant frequencies using the cavity model, the far-field is found by considering the equivalent magnetic current radiating in the presence of a cylindrical surface. The input impedance and the total Q-factor are then calculated. Numerical and graphical results are presented to illustrate the effect of curvature on the characteristics of the TM₁₀ and TM₀₁ modes     

Input impedance of rectangular microstrip patch antenna withiso/anisotropic substrate-superstrate

The modified Wolff model (MWM), which is an improved version of the cavity model, is presented to compute the resonance frequency and input impedance of a rectangular microstrip patch antenna under the isotropic/anisotropic substrate-superstrate configuration. The model has accuracy better than 1.5% for both the resonance frequency and resonant resistance, as compared against the results of the method of moments (MOM) and experimental results