Proceedings Article

# Advanced modal techniques for microstrip patch antenna analysis

01 Sep 2010-pp 1-6
TL;DR: In this article, the Theory of Characteristic Modes (TCM) is developed starting from the Electric Field Integral Equation and formulating proper functional equation for stored and radiated power.
Abstract: This paper shows the advantage of modal methods utilization in the area of microstrip patch antennas design. Namely, the Theory of Characteristic Modes (TCM) is developed starting from the Electric Field Integral Equation and formulating proper functional equation for stored and radiated power. Developed in-house TCM analyzer is presented and employed to investigate properties of the linearly and circularly polarized rectangular patch antenna.
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Journal ArticleDOI
TL;DR: In this article, the modal current distribution on an antenna from the radiated far field and general knowledge about the modes involved is reconstructed with good results if the radiation mechanism of the antenna can be approximated by the current distribution of a simplified structure.
Abstract: In this paper, we present a method to reconstruct the modal current distribution on an antenna from the radiated far field and general knowledge about the modes involved. The method leads to good results if the radiation mechanism of the antenna can be approximated by the current distribution on a simplified structure. The current distribution of the simplified structure is decomposed into its characteristic modes and the related modal far field is calculated. Assuming that the far field of the actual antenna contains the same modes, their weighting coefficients are calculated by comparing the far field of the actual antenna to the modal far field of the simplified structure. It can be shown that the weighting coefficients of all significant modes can be reconstructed with good accuracy even for complex real structures such as mobile phones.

68 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new expression for the total $Q$ factor, which is independent of the excitation and based on the eigenvalues of the structure.
Abstract: Evaluating the $Q$ factor of antennas using metamaterial substrates is a challenge and requires new analysis techniques. This challenge is even more important for arbitrary-shaped antennas. In this paper, we address the problem of analysis and evaluation of metamaterial-based antennas through the use of characteristic modes. We propose a new expression for the total $Q$ factor, which is independent of the excitation and based on the eigenvalues of the structure. The proposed expression is used to compute the $Q$ factor of an arbitrary-shaped resonant antenna and shows excellent agreement with other expressions in the literature such as the ones proposed by Yaghjian, Best, and Gustafsson. The approach is then used to analyze small patch antennas over metamaterial and magnetodielectric substrates. It is shown using the defined $Q$ factor expression that a magnetic substrate offers a significant bandwidth enlargement for the first active modes, and a dielectric substrate presents the opposite effect. This agrees with other works based on analytical approaches. Furthermore, we demonstrate that a reactive impedance metamaterial substrate presents identical modal significances that are identical to a conventional magnetodielectric substrate when associated with a patch antenna. This analysis is suitable for structures presenting noncanonical geometries and arbitrary shapes such as metamaterial inclusions.

21 citations

Proceedings ArticleDOI
29 Dec 2014
Abstract: A modal comparative study of patch antennas over a normal, high permittivity, high permeability and artificial substrates, respectively, is presented. It is based on the theory of characteristic modes. It is shown using some defined metrics that a magnetic substrate offers a significant bandwidth enlargement for the first active modes, and a dielectric substrate presents the opposite effect. This agrees with previously published works based on analytical approaches. An expression for the modal quality factor without defining particular excitation is presented and computed for the studied cases in order to approve these conclusions. Furthermore, numerical results demonstrate that a reactive impedance substrate presents a similar response to a conventional magnetic substrate when associated to a patch antenna near to the resonance. The modal currents are computed using a numerical method. Therefore, this analysis is suitable for electrically small antennas or structures presenting non canonical geometries and arbitrary shapes such as metamaterial inclusions.

1 citations

##### References
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Book
01 Jan 1968
TL;DR: This first book to explore the computation of electromagnetic fields by the most popular method for the numerical solution to electromagnetic field problems presents a unified approach to moment methods by employing the concepts of linear spaces and functional analysis.
Abstract: From the Publisher: "An IEEE reprinting of this classic 1968 edition, FIELD COMPUTATION BY MOMENT METHODS is the first book to explore the computation of electromagnetic fields by the most popular method for the numerical solution to electromagnetic field problems. It presents a unified approach to moment methods by employing the concepts of linear spaces and functional analysis. Written especially for those who have a minimal amount of experience in electromagnetic theory, this book illustrates theoretical and mathematical concepts to prepare all readers with the skills they need to apply the method of moments to new, engineering-related problems.Written especially for those who have a minimal amount of experience in electromagnetic theory, theoretical and mathematical concepts are illustrated by examples that prepare all readers with the skills they need to apply the method of moments to new, engineering-related problems."

6,593 citations

Journal ArticleDOI
TL;DR: In this paper, the electric field integral equation (EFIE) is used with the moment method to develop a simple and efficient numerical procedure for treating problems of scattering by arbitrarily shaped objects.
Abstract: The electric field integral equation (EFIE) is used with the moment method to develop a simple and efficient numerical procedure for treating problems of scattering by arbitrarily shaped objects. For numerical purposes, the objects are modeled using planar triangular surfaces patches. Because the EFIE formulation is used, the procedure is applicable to both open and closed surfaces. Crucial to the numerical formulation is the development of a set of special subdomain-type basis functions which are defined on pairs of adjacent triangular patches and yield a current representation free of line or point charges at subdomain boundaries. The method is applied to the scattering problems of a plane wave illuminated flat square plate, bent square plate, circular disk, and sphere. Excellent correspondence between the surface current computed via the present method and that obtained via earlier approaches or exact formulations is demonstrated in each case.

4,835 citations

Proceedings ArticleDOI
28 May 1980
TL;DR: Very accurate and simple equations are presented for both single and coupled microstrip lines' electrical parameters, i.e. impedances, effective dielectric constants, and attenuation including the effect of anisotropy in the substrate as mentioned in this paper.
Abstract: Very accurate and simple equations are presented for both single and coupled microstrip lines' electrical parameters, i.e. impedances, effective dielectric constants, and attenuation including the effect of anisotropy in the substrate. For the single microstrip the effects of dispersion and non-zero strip thickness are also included.

754 citations

Journal ArticleDOI
TL;DR: In this article, a method is described for determining characteristic mode currents on thin wires of general shape and is applied to several shapes to generate certain backscattering and input admittance data.
Abstract: At a given frequency every perfectly conducting obstacle has associated with it a particular set of surface currents and corresponding radiated fields which are characteristic of the obstacle shape and independent of any specific excitation. These characteristic modes form a useful basis set in which to expand fields radiated or scattered at a great distance from the obstacle. Once these modes are known for a given obstacle, the scattering of plane waves incident from arbitrary source directions into arbitrary receiver directions may be evaluated concisely. To support the theory, a method is described for determining characteristic mode currents on thin wires of general shape and is applied to several shapes to generate certain backscattering and input admittance data. Wherever possible comparison is made with existing data.

625 citations

Journal ArticleDOI
TL;DR: In this paper, the L-shaped probe is shown to be an attractive feed for the thick microstrip antenna (thickness around 10% of the operating wavelength), and a parametric study on the rectangular patch antenna is presented.
Abstract: The L-shaped probe is shown to be an attractive feed for the thick microstrip antenna (thickness around 10% of the operating wavelength). A parametric study on the rectangular patch antenna is presented. It is found that the antenna attains 36% impedance bandwidth (SWR/spl les/2) as well as gain bandwidth and about 7-dBi average gain. A two-element array fed by L-probes is also proposed. Experiments show that the array design can substantially suppress the cross polarization of the proposed antenna. Both the antennas have stable radiation patterns across the passband. Moreover, the measured resonant frequencies of the proposed antenna agree well with an existing formula and the L-probe does not have much effect on the resonant frequency.

382 citations