MM-wave microstrip patch and slot antennas on low cost large area panel MCM-D substrates-a feasibility and performance study

This paper analyzes the performance and feasibility of microstrip patch and slot antennas on low-cost thin film MCM-D in the MM-wave frequency range. The critical parameters of millimeter design such as losses, bandwidth, and radiation pattern are discussed based on EM modeling and design examples of microstrip patch and compact rectangular slot loop antennas in the frequency range of 40-85 GHz. Simple technology modifications are pointed out to overcome the basic limitations of the patch antennas on thin films such as low efficiency and low bandwidth. To perform this feasibility study, a finite element method (FEM) is used as a simulation tool and HP8510XF vector network analyzer (VNA) as measurement equipment.     

Modeling conformal antennas on metallic prolate spheroid surfaces using a hybrid finite element method

In this paper, the hybrid finite element-boundary integral (FE-BI) method appropriate for modeling conformal antennas on doubly curved surfaces is developed. The FE-BI method is extended to model doubly curved, convex surfaces by means of a specially formulated asymptotic dyadic Green's function. The FE-BI method will then be used to examine the effect of curvature variation on the resonant input impedance of a cavity-backed, conformal slot antenna and a conformal patch antenna recessed in a perfectly conducting, electrically large prolate spheroid surface. The prolate spheroid shape provides a canonical representation of a doubly curved mounting surface. The numerical results for conformal slot and patch antennas on the prolate spheroid are compared as a function of curvature and orientation.     

Printed antennas analysis by a Gabor frame-based method of moments

Gabor frame-based discretization is proposed for the first time as a fully rigorous and flexible tool in the context of antenna analysis. A rigorous discretization procedure based on frame theory is presented and applied to integral equations solution through a method of moments (MoM). In this approach, the unknown field or current is expanded in a set of spatially and spectrally translated elementary functions. The use of a Gaussian window function as basis element allows for the representation of radiated fields as a superposition of shifted and rotated Gaussian beams. By exploiting the well understood propagation and transformation features of Gaussian beams, the fields can be evaluated by summations of analytic terms, at any observation point. This method seems well suited to model antennas embedded in complex systems including arbitrary interfaces. Numerical results are presented for slot antennas at the interface between two dielectric half spaces and compared to a standard MoM to validate the approach and illustrate its attractive characteristics.     

Double higher order method of moments for surface integral equation modeling of metallic and dielectric antennas and scatterers

A novel double higher order Galerkin-type method of moments based on higher order geometrical modeling and higher order current modeling is proposed for surface integral equation analysis of combined metallic and dielectric antennas and scatterers of arbitrary shapes. The technique employs generalized curvilinear quadrilaterals of arbitrary geometrical orders for the approximation of geometry (metallic and dielectric surfaces) and hierarchical divergence-conforming polynomial vector basis functions of arbitrary orders for the approximation of electric and magnetic surface currents within the elements. The geometrical orders and current-approximation orders of the elements are entirely independent from each other, and can be combined independently for the best overall performance of the method in different applications. The results obtained by the higher order technique are validated against the analytical solutions and the numerical results obtained by low-order moment-method techniques from literature. The examples show excellent accuracy, flexibility, and efficiency of the new technique at modeling of both current variation and curvature, and demonstrate advantages of large-domain models using curved quadrilaterals of high geometrical orders with basis functions of high current-approximation orders over commonly used small-domain models and low-order techniques. The reduction in the number of unknowns is by an order of magnitude when compared to low-order solutions.     

Electromagnetic Scattering From Arbitrarily Shaped Dielectric Bodies Using Paired Pulse Vector Basis Functions and Method of Moments

A pair of orthogonal pulse vector basis functions is demonstrated for the calculation of electromagnetic scattering from arbitrarily-shaped material bodies. The basis functions are intended for use with triangular surface patch modeling applied to a method of moments (MoM) solution. For modeling the behavior of dielectric materials, several authors have used the same set of basis functions to represent equivalent electric and magnetic surface currents. This practice can result in zero-valued or very small diagonal terms in the moment matrix and an unstable numerical solution. To provide a more stable solution, we have developed orthogonally placed, pulse basis vectors: one for the electric surface current and one for the magnetic surface current. This combination ensures strongly diagonal moment matrices. The basis functions are suitable for electric field integral equation (EFIE), magnetic field integral equation (HFIE), and combined field formulations. In this work, we describe the implementations for EFIE and HFIE formulations and show example results for canonical figures.      

Theoretical modeling of cavity-backed patch antennas using a hybridtechnique

A hybrid technique that combines the method of moments (MoM) and the finite element method (FEM) to analyze cavity-backed patch antennas is presented. This technique features the use of FEM in solving the electromagnetic field distribution in the cavity and the use of MoM in solving integral equations outside the cavity. The results of MoM and FEM are combined through the continuity conditions on the boundary of the cavity. Due to the flexibility of FEM, complex cavities filled with inhomogeneous media can be analyzed by this technique. The results obtained by this hybrid technique are compared to the finite difference time domain (FDTD) results and good agreement is found     

MLFMA分析复杂载体平台上天线问题

该文分析了导体介质复合结构平台上线天线的辐射问题。利用等效原理建立EFIE-PMCHW表面积分方程组,定义线、面和连接基函数描述复杂结构上电流分布,分析了导体介质分界面处基函数的处理;利用多层快速多极子方法(MLFMA)加速迭代求解过程中的矩阵矢量相乘运算,并用于有耗媒质求解。MLFMA的运用极大地提高了求解实际电大问题的能力。数值计算结果验证了方法的正确性和高效性。     

Analysis of cavity-backed aperture antennas with a dielectricoverlay

A full-wave analysis of cavity-backed aperture antennas with a dielectric overlay is presented. The theoretical approach uses a closed-form dyadic Green's function in the spectral domain. The aperture equivalent magnetic currents are obtained using the surface equivalence theorem and an integral equation is obtained by matching the fields across the aperture. The moment method applied in spectral domain analysis is employed to solve the integral equation for the equivalent magnetic currents with proper combination of subdomain or entire domain expansion functions. Numerical results include the aperture field distribution and antenna parameters such as input impedance, bandwidth, and efficiency. A set of measurements data is compared with results based on the theoretical work     

Analysis of transient scattering from composite arbitrarily shapedcomplex structures

A time-domain surface integral equation approach based on the electric field formulation is utilized to calculate the transient scattering from both conducting and dielectric bodies consisting of arbitrarily shaped complex structures. The solution method is based on the method of moments (MoM) and involves the modeling of an arbitrarily shaped structure in conjunction with the triangular patch basis functions. An implicit method is described to solve the coupled integral equations derived utilizing the equivalence principle directly in the time domain. The usual late-time instabilities associated with the time-domain integral equations are avoided by using an implicit scheme. Detailed mathematical steps are included along with representative numerical results     

Propagation characteristics of coplanar-type transmission lineswith lossy media

Lossy coplanar-type transmission lines are analyzed based on the hybrid-mode formulation by combining the spectral-domain approach with the perturbation method. Introducing a finite thickness of metallization and choosing the proper basis functions for the thick conductor model prevent the integrals used for calculating the conductor losses from becoming singular when evaluated at the conductor edge. An orthogonality relation is used to reduce the double infinite or semi-infinite integral to a single integral, thus reducing the computation effort drastically. Numerical computations by new basis functions for the thick conductor show convergence rates as fast as those for the zero-thickness cases. Numerical results include the effective dielectric constants, characteristic impedances, and total losses (conductor and dielectric losses) for slot lines and symmetrical and asymmetrical coplanar waveguides     

Numerical solution of time domain integral equations for arbitrarily shaped conductor/dielectric composite bodies

In this work, we present a numerical solution of the coupled time domain integral equations to obtain induced currents and scattered far fields on a three-dimensional, arbitrary shaped conducting/dielectric composite body illuminated by a Gaussian electromagnetic plane wave pulse. The coupled integral equations are derived utilizing the equivalence principle. The solution method is based on the method of moments and involves the triangular patch modeling of the composite body, in conjunction with the patch basis functions. Detailed mathematical steps along with several numerical results are presented to illustrate the efficacy of this approach.     

Separation of Horizontal and Vertical Dependencies in a Surface/Volume Integral Equation Approach to Model Quasi 3-D Structures in Multilayered Media

A new and efficient integral equation approach is presented to model heterogeneous dielectric volumes in a multilayered environment. The dielectric volumes can be vertically large, they can cross dielectric interfaces and they should be "quasi 3-D," which means that the contour faces should be placed either horizontally or vertically in the multilayered environment. In this way, a perpendicular prismatic mesh can be fitted on the volumes and the 3-D displacement currents can be expanded in generalized rooftop functions with separated horizontal x, y- and vertical z-dependencies. This makes it possible to evaluate all z, z' reaction integrals fully analytically in the spectral domain and ensures an efficient implementation. The formulation of the source-field relations is adapted to the quasi 3-D geometries as a hybrid dyadic-mixed potential form. Additionally, the electromagnetic coupling between dielectric volumes and metal sheets is included using a coupled volume/surface formulation. This turns the implementation into a complete full wave solver for planar antennas containing both finite and infinite dielectric regions. In order to illustrate and validate the presented approach, two patch antennas with a local volumetric inhomogeneity under the patch are numerically analyzed in a multilayered environment. Eventually, a matrix fill time comparison is used to demonstrate the improvement in computation efficiency     

A hybrid finite element-boundary integral method for the analysisof cavity-backed antennas of arbitrary shape

An edge-based hybrid finite element-boundary integral (FE-BI) formulation using tetrahedral elements is described for scattering and radiation analysis of arbitrarily shaped cavity-backed patch antennas. By virtue of the finite element method (FEM), the cavity irregularities, the dielectric super/substrate inhomogeneities, and the diverse excitation schemes inside the cavity may be readily modeled when tetrahedral elements are used to discretize the cavity. On the aperture, the volume mesh reduces to a triangular grid allowing the modeling of nonrectangular patches. Without special handling of the boundary integral system, this formulation is typically applicable to cavity-backed antenna systems with moderate aperture size. To retain an O(N) memory requirement, storage of the full matrix due to the boundary integral equation is avoided by resorting to a structured triangular aperture grid and taking advantage of the integral's convolutional property. If necessary, this is achieved by overlaying a structured triangular grid on the unstructured triangular grid and relating the edge field coefficients between the two grids via two narrow banded transformation matrices. The combined linear system of equations is solved via the biconjugate gradient (BICG) method, and the FFT algorithm is incorporated to compute the matrix-vector product efficiently, with minimal storage requirements     

Triangular prisms for edge-based vector finite element analysis ofconformal antennas

This paper deals with the derivation of the edge-based shape functions for the distorted triangular prism and their applications for the analysis of doubly curved conformal antennas in the context of the finite element method (FEM). Although the tetrahedron is often the element of choice for volume tessellation, mesh generation using tetrahedra is cumbersome and the central processing unit (CPU) intensive. On the other hand, the distorted triangular prism allows for meshes which are unstructured in two dimensions and structured in the third dimension. This leads to substantial simplifications in the meshing algorithm, and many conformal printed antenna and microwave circuit geometries can be easily tessellated using such a mesh. The new edge-based shape functions are first validated by computing the eigenvalues of three different cavities (rectangular, cylindrical, and pie-shell). We then proceed with their application to computing the input impedance of conformal patch antennas on planar, spherical, conical, and other doubly curved (ogival) platforms, where the FEM mesh is terminated using an artificial absorber applied conformal to the platform. Use of artificial absorbers for mesh termination avoids introduction of Green's functions and, in contrast to absorbing boundary conditions, a knowledge of the principal radii of curvature of the closure's boundary is not required     

A hybrid finite element method for scattering and radiation bymicrostrip path antennas and arrays residing in a cavity

A hybrid numerical technique is presented for a characterization of the scattering and radiation properties of microstrip patch antennas and arrays residing in a cavity recessed in a ground plane. The technique combines the finite-element and boundary integral methods to formulate a system for the solution of the fields at the aperture and those inside the cavity via the biconjugate gradient method in conjunction with the fast Fourier transform (FFT). By virtue of the finite-element method, the proposed technique is applicable to patch antennas and arrays residing on or embedded in a layered dielectric substrate and is also capable of treating various feed configurations and impedance loads. Several numerical results are presented, demonstrating the validity, efficiency, and capability of the technique     

Polygonal patch antennas for wireless communications

An effective design of polygonal patch antennas with multifrequency or broad-band operation modes for wireless communications is presented in this paper. It is shown how polygonal patches with suitable features may be obtained after a proper perturbation of conventional rectangular geometries, which inherently present poor bandwidth performances. These perturbed irregular geometries may support multiple resonances and, thus, may present a broad-band or multifrequency operation mode, even employing conventional patch antennas with a single dielectric substrate. These polygonal patches are efficiently analyzed through a numerical code based on the method of moments, with entire domain basis functions that accurately describe the radiation mechanism. After the presentation of the analysis and design techniques, some antenna layouts for modern wireless communication systems will be proposed. Such antennas are designed for both universal mobile telecommunication system and wireless local area network portable equipment with real-life finite ground planes.     

Self and mutual admittance of slot antennas on a dielectric half-space

In this paper, an efficient implementation of the spectral domain moment technique is presented for computing the self and mutual coupling between slot antennas on a dielectric half-space. It is demonstrated that by the proper selection of the weighting functions in the method of moments, the analytic evaluation or simplification of the transverse moment integrals is enabled. This results into a significant reduction of the required computational labor. The method is then utilized in order to provide design data for the self and mutual admittances between two slot antennas on a dielectric substrate lens in the case of fused quartz (∈ _r =3.80), crystal quartz (∈ _r =4.53), silicon (∈ _r =11.9) and GaAs (∈ _r =12.8). The presented technique and associated results are useful when designing twin slot quasi-optical receivers, imaging arrays, phased arrays or power-combining arrays of slot elements at millimeter-wave frequencies.     

Analyse de structures tridimensionnelles inhomogenes quelconques

This paper illustrates the capability of SR3D software to rigorously analyze 3D radiating structures including wires (thin or thick), dielectric parts and finite ground planes. The analysis method is within the class of bound ary element method (bem) and use integral equation formulation (combined field integral equation cfie) to solve electromagnetic scattering problems. It includes a variational approach based on Rumsey reaction concept. The problem is numerically solved with a surface finite element method : surfaces of 3D conducting object and interfaces between dielectric domains are meshed using surface triangular patches. We discuss on the numerical options chosen, the basis functions used, discretization density, and treatment of wires. The last sections emphasize the accuracy of the method on examples for which computed and measured reflection coefficient and radiation patterns are compared.     

A time domain theoretical method for the analysis of microstrip antennas composed by slots

In this paper, a time domain method is introduced for analyzing microstrip antennas having thin slots. The present method is based on a resolution of Maxwel?s. equtions using the finite difffreence time domain method. A particular investigation has been made for taking thin slots into account, this avoids a prohibitive grid to represent the slots. Two kinds of antennas have been analyzed by this method: the slot antennas and the radiatins patch fed by a line through a slot.     

用时域有限差分法对缝隙渐变天线的瞬态电磁场分析

本文用时域有限差分（ＦＤＴＤ）法分析缝隙渐变天线，分析中对天线缝隙边缘场和薄天线衬底采取了特殊的处理方法，求天线的远区辐射场采用了ＦＤＴＤ中近场到远场的变换方法。本文计算出的缝隙渐变天线的辐射方向图和远区辐射场与实验结果比较一致。本文给出了超短电磁脉冲在天线上传播和辐射过程的瞬态直观图象，同时还研究了这种天线衬底厚度、几何尺寸及介电常数对其辐射特性及频带的影响。