Analysis Of Microstrip Antenna Research Articles

Analysis of microstrip antennas with complex and anisotropic substrate by a hybrid FEM/BEM approach

In this paper, a hybrid formulation based on the finite element method (FEM) and boundary element method (BEM) is presented for numerical analysis of the electromagnetic (EM) radiation and scattering from cavity-backed microstrip patch antennas. The cavity is recessed in a ground plane and may have arbitrary shape and contain inhomogeneous, anisotropic, and lossy dielectric materials. The formulation has been implemented using edge elements and the computer program has been tested by a number of numerical examples, proven to be valid and robust.

Green's function of the dielectric slab for fast analysis of microstrip antennas with a modified boundary-integral method

Recently a modified boundary-integral method was suggested allowing for fast analysis of microstrip antennas. In this paper a Green's function of the dielectric slab to be incorporated into this method is proposed. Some implementation issues regarding the numerical evaluation of Sommerfeld integrals are discussed.

Scattering and radiation analysis of microstrip antennas using discrete complex image method and reciprocity theorem

A simple and efficient method is presented to characterize the scattering and radiation properties of arbitrarily shaped microstrip patch antennas. The method employs the discrete complex image technique to circumvent the time-consuming evaluation of the doubly infinite integrals in the spectral domain method of moments. Furthermore, the method calculates the scattered/radiated fields using the reciprocity theorem, which is found to be more straightforward than the commonly used stationary phase method. Numerical results are presented for arbitrarily shaped microstrip antennas and arrays to demonstrate the accuracy and efficiency of the method. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 212–216, 1997

Analysis of microstrip antennas on finite ground planes

In this article an integral equation for a microstrip antenna on a finite ground plane is derived with the use of the reaction theory and the dyadic Green's function. The integral equation is solved with the use of the Galerkin method, and the current densities on the patch and the ground plane are obtained simultaneously. The far-field radiation pattern is evaluated from currents on the patch, on the ground plane, and on the polarization currents within the substrate. Results are presented for the case where the patch and ground plane are of same size. The results are compared with measured data and show very good agreement. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 204–207, 1997.

Analysis of microstrip antennas on finite ground planes

In this article an integral equation for a microstrip antenna on a finite ground plane is derived with the use of the reaction theory and the dyadic Green's function. The integral equation is solved with the use of the Galerkin method, and the current densities on the patch and the ground plane are obtained simultaneously. The far-field radiation pattern is evaluated from currents on the patch, on the ground plane, and on the polarization currents within the substrate. Results are presented for the case where the patch and ground plane are of same size. The results are compared with measured data and show very good agreement. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 204–207, 1997.

On symmetry in microstrip antenna analysis

AbstractAn application of the patch shape symmetry for the basis‐function selection for the Green's function/Galerkin's solution is reported. As a result many impedance matrix elements are equal to zero and the computation time is reduced. The symmetry properties of four commonly used microstrip patch antennas are described as examples. © 1994 John Wiley & Sons, Inc.

Analysis of microstrip antennas on a curved surface using the conformal grids FD-TD method

The need for small, portable antennas for mobile communications has spurred the study of microstrip antennas (MSA). MSA are quite flexible and have been used as conformal antennas on arbitrary curved surfaces. The characteristics of conformal MSA can be expected to differ from those of planar models. Dependable numerical analyses will obviate many of the costs and other inconveniences associated with experiments, but as antennas may be mounted on surfaces of arbitrary topological complexity, analysis methods must have a general applicability. The curvilinear finite-difference time-domain (FD-TD) method has shown excellent versatility. This method is applied to analyze microstrip antennas mounted on curved surfaces. The numerical predictions are compared with the experimental values. The results confirm the predictions within acceptable limits and appear to confirm the validity of the method. As a result, it was confirmed that the input impedance and directivity of MSA on curved surfaces are different from the flat MSA. >

Analysis of Microstrip Antenna Based on Fringing Capacitance

A new theory based on fringing capacitance is proposed for the analysis of microstrip antenna. The source responsible for the radiation is defined in terms of fringing capacitance which is related to the change in area of the patch due to fringing field. The radiation patterns calculated using the proposed method, for rectangular and triangular patches, are in good agreement with the existing theory. The proposed concept provides an alternative tool for the analysis of microstrip patch of any shape.

Analysis of microstrip antennas on a curved surface using the conformal grids fd‐td method

AbstractWith the development of mobile communication, active research is being done on the small‐sized antennas such as microstrip antennas (MSAs). Moreover, MSAs normally are placed on spherical or cylindrical surfaces as a conformal antenna.Conformal MSAs are expected to have different characteristics compared to planar structure. In this case, numerical analysis is needed before the actual experiment.The method of analysis which has wide applications may be considered as efficient for this purpose. One such method is the conformal grids finite‐different time‐domain method (FD‐TD method).In this paper, an MSA on a curved surface is analyzed using the conformal grids FD‐TD method. Moreover, comparison with the experimental values also is performed. The experimental results and the analytical results are in close agreement which shows the validity of the method of analysis. As a result, it is confirmed that in the range of this paper, the input impedance and radiation pattern varies from their values for the planar patch when the patch surface is curved.

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 Maxwelľs. 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.

Use of a combined expansion scheme to analyze microstrip antennas with the method of moments

A new expansion scheme is introduced to solve the integral equations describing a microstrip antenna with the method of moments. The scheme offers both flexibility and a low number of expansion functions and thus an acceptable calculation time. The basic idea consists of constructing secondary entire domain expansion functions as fixed combinations of primary expansion functions. This special concept allows the solution of several problems concerning rapid variations of the currents on the patches in an efficient way without having to deal with an unacceptable number of expansion functions to describe the mutual coupling between the patches. The efficiency of the combined scheme is illustrated by a comparison of measured and calculated results for a linear eight‐element microstrip array antenna.

Transmission line analysis of nonlinear slot coupled microstrip antenna

The transmission line method is used for the analysis of microstrip antennas fed by several nonlinear slots with ‘H’ shapes [see ref. 1] or new geometries ‘└┘’, ‘└┐’ and ‘└─’ types. This analysis allows the input impedance of nonlinear slot coupled microstrip antennas to be calculated for the four different structures. The theoretical results are in good agreement with experiments.

Microstrip antenna on a conical surface

A theoretical analysis of microstrip antennas on conical conducting surfaces is presented. The resonant frequency, input impedance, radiation pattern, quality factor, and efficiency are obtained for a general geometry. Numerical results for a patch antenna with a cone angle theta /sub 0/=33.88 degrees operating in the fundamental TM/sub 01/ mode are shown.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Feeding structure contribution to radiation by patch antennas with rectangular boundaries

A combination of piecewise sinusoidal-pulse functions and semi-infinite microstrip current expansion functions is used in the full-wave spectral-domain method to analyze microstrip antennas with arbitrary rectangular boundaries. Radiation properties are formulated in the spectral domain to achieve high numerical efficiency. Two types of microstrip antennas, edge-fed rectangular and inset fed patches, have been analyzed and measured. A line-reflect-line de-embedding algorithm has been implemented to measure the input impedance of both antennas. The results show good agreement between measurement and calculated data. The radiation patterns from the edge-fed rectangular patch are measured and are compared with the theoretical data. Results show that the current on the feed line can disturb the antenna radiation pattern. >

Simple high-frequency diffraction analysis of microstrip antenna on large cylinder

The aim of this Letter is to investigate the electromagnetic field surrounding an electrically large convex cylinder on which a microstrip antenna is mounted. Being capable of calculating the various types of field, i.e. directly incident field, reflected field and diffracted field on the plane perpendicular to the cylinder axis, the selfconsistent GTD formulation is employed. In accordance with such a formulation, a two-magnetic-line-current radiation model for the patch is given. Measurement is also performed in a microwave anechoic chamber for the purpose of validation of the proposed theory.

Spectral domain analysis of microstrip antennas with an airgap

AbstractThe circular disk microstrip antenna with an airgap between the dielectric substrate and the ground plane is formulated using the spectral domain method. The complex resonant frequencies of the structure is determined using Galerkin's procedure. Some available experimental data are compared with the present method.

On slot-coupled microstrip antennas and their applications to CP operation-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.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Scalar green function method for microstrip antenna analysis based on the exact image theory

Exact image theory, applicable to the analysis of plane-stratified structures, is reviewed in general form and expressions corresponding to the microstrip geometry are given. It is seen that essential in this method is the calculation of two scalar Green functions, responsible for the effect of the geometry for the field. Exact expressions for these Green functions are found for the microstrip in terms of integrals of special functions. The Green functions are needed in the formulation of electric field integral equations for the surface currents of the microstrip. The Green functions are shown to possess the same type of singularity as the free-space Green function and also a similar limit when the distance grows larger, with the exception of a waveguide-mode term, which can be easily evaluated separately. Simple approximate expressions for the Green functions are evaluated, suitable for practical analysis of microstrip structures.

Spectral analysis of microstrip antennas with CG-FFT: two-dimensional results

Theoretical expressions for the currents excited on the top and bottom surfaces of a coaxial-probe-fed patch antenna are derived. Exact expressions for the far-zone field in terms of the total current on the patch are found. The analysis is specialized to a two-dimensional case. Detailed results for current, far-zone fields, and radiating-aperture admittance have been computed for this two-dimensional antenna model using the conjugate-gradient-fast Fourier transform (CG-FFT) technique. For a thick-substrate antenna it is found that the upper surface current on the patch is significant. Under this condition the traditional approximation of the total current by the bottom surface current alone may be in considerable error.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Vertical monopoles embedded in a dielectric substrate

Vertical monopoles over an infinite ground plane that are embedded in a dielectric slab are studied using a mixed potential integral equation formulation. The method of moments is used to solve for the induced currents from which impedance parameters are calculated. The vector and scalar potentials are written in terms of Sommerfeld integrals that are evaluated using efficient techniques developed for the analysis of microstrip antennas. A magnetic current frill is used to model the coaxial aperture in the ground plane that excites the monopole. Measured and calculated input impedance and mutual coupling data are compared and a study of the effect of the dielectric inhomogeneity is performed.