The Theory of Characteristic Modes Revisited: A Contribution to the Design of Antennas for Modern Applications

Univ. Politecnica de Valencia, Valencia
IEEE Antennas and Propagation Magazine (Impact Factor: 1.32). 11/2007; 49(5):52 - 68. DOI: 10.1109/MAP.2007.4395295
Source: IEEE Xplore


The objective of this paper is to summarize the work that has been developed by the authors for the last several years, in order to demonstrate that the Theory of Characteristic Modes can be used to perform a systematic design of different types of antennas. Characteristic modes are real current modes that can be computed numerically for conducting bodies of arbitrary shape. Since characteristic modes form a set of orthogonal functions, they can be used to expand the total current on the surface of the body. However, this paper shows that what makes characteristic modes really attractive for antenna design is the physical insight they bring into the radiating phenomena taking place in the antenna. The resonance frequency of modes, as well as their radiating behavior, can be determined from the information provided by the eigenvalues associated with the characteristic modes. Moreover, by studying the current distribution of modes, an optimum feeding arrangement can be found in order to obtain the desired radiating behavior.

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    • "T HE theory of characteristic modes (CMs), formally developed by Garbacz [1] and Harrington and Mautz [2], has become very popular in recent years as this theory constitutes a general approach to characterizing the modal resonant behavior of arbitrarily shaped antennas and scaterrers [3]. In its original form, which is considered here, the CM assumes perfectly conducting electric conductors (PEC) in a vacuum. "
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    ABSTRACT: Aspects of the theory of characteristic modes, based on its variational formulation, are presented and an explicit form of a related functional, involving only currents in a spatial domain, is derived. The new formulation leads to deeper insight into the modal behavior of radiating structures as demonstrated by a detailed analysis of three canonical structures: a dipole, an array of two dipoles and a loop. Important numerical aspects related to modal superposition and the residual ("evanescent") mode are also considered. It is shown that due to numerical issues, certain modes may actually exhibit incorrect (negative) radiated power, which, in turn, destabilize the solution of the generalized eigenvalue problem. A simple solution, based on splitting the superposition into two parts, is proposed.
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    • "Later, Harrington, Mautz and Chang reformulated this theory considering integro-differential formulations using the impedance matrix of the Method of Moments (MoM), [2], [3]. Recently, there have been many works on metal structures [4], and it is now being extended to applications including dielectric materials. For both metals and dielectrics it is important to find those electromagnetic modes that provides the desired radiation characteristics, and this is where the CMT plays an important role. "
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    ABSTRACT: In this paper Complex Natural Resonances of an infinite dielectric circular cylinder based on the PMCHWT formulation are presented. The relation between them and the Characteristic Mode resonances are explained. In addition, the reasons for different characteristic modes using different integral equations are explained. A connection between the resonances of series solution and integral formulations are carried out.
    IEEE International Symposium on Antennas and Propagation and USNC-URSI National Radio ScienceMeeting, Vancouver (Canada), July, 2015.; 07/2015
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    • "La naturaleza de bajas pérdidas en estos substratos a frecuencias de microondas y ondas milimétricas hace de LTCC una tecnología de fabricación muy interesante. Cabe destacar, que tras eí exito en losúltimos años por diseñar antenas metálicas con la Teoría de Modos Característicos (TMC) [4], la TMC está siendo extendida en la actualidad para el diseño de las DRA [5], [6]. Hasta ahora no hay muchas aplicaciones , pero crecen cada día por el papel tan importante que la TMC juega a la hora de buscar resonancias en las cavidades diléctricas, o para entender mejor su naturaleza radiante. "
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    DESCRIPTION: A novel method to design a Coplanar-Waveguide Fed Slot-Coupled Rectangular Dielectric Resonator Antenna is presented in this paper. A new concept of Characteristic Modes to design a slot-coupled rectangular Dielectric Resonator Antenna is applied here for the first time. This study permits to optimize the radiation bandwidth in the same analysis process for both, the dielectric and the slot. The complete antenna is designed for Low-Temperature Co-fired Ceramic fabrication. The goals are to fabricate all the antenna for low permittivity in the same process, to match the dielectric resonator to the CPW feed line for the frequency range of ISM at 60GHz. The obtained results show that the radiation bandwidth, determined by 10-dB return loss, of the proposed antenna can be as large as 14GHz, more than 23 %, centered at about 60GHz.
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