Advances in Analytical-Numerical Techniques for Planar Microwave Circuits and Microstrip Antennas

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Electrical, Electronics and Communications Engineering".

Deadline for manuscript submissions: closed (10 August 2022) | Viewed by 11410

Special Issue Editor

Department of Electrical and Information Engineering “Maurizio Scarano”, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, FR, Italy
Interests: analytical–numerical methods for electromagnetics; electromagnetic diffraction and scattering; waveguide and optical waveguide; microwave circuits and antennas
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Special Issue Information

Dear Colleagues,

Microwave technology is essential for the realization of a wide number of nowadays indispensable applications ranging from the commercial to the industrial sectors, devised for healthcare or for defense systems. Modern planar microwave circuits and microstrip antennas are particularly attractive to satisfy the increased demand for wireless communications due to their low manufacturing costs, light weight, low profile, and suitability to be used as elements in microwave and millimeter-wave integrated circuits. The modelling of such kind of structures is nontrivial because distributed elements are predominantly involved. Moreover, the dielectric and conductive losses, the dielectric substrates inhomogeneity and/or anisotropy, the metallization thickness and cross-sectional shape, etc. cannot, in general, be neglected when a highly accurate characterization is required. As a result, the ability to design and optimize more and more sophisticated planar microwave structures goes hand in hand with the development of increasingly efficient computer aided design tools.

This Special Issue is focused on the latest results in the development of highly efficient analytical-numerical techniques to face the challenge of the analysis, design, and optimization of modern planar microwave circuits and microstrip antennas.

The topics of interest include but are not limited to:

  • Advances in Electromagnetic modeling techniques for planar devices
  • Analysis of high-speed planar interconnects
  • Radiation characteristics of broadband microstrip antennas
  • Design and optimization of planar devices

Dr. Mario Lucido
Guest Editor

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Keywords

  • Methods of analytical regularization
  • Method of moments
  • Variational methods
  • Finite-element method
  • Finite-difference method
  • Mode matching technique
  • Transmission line matrix method
  • Finite integration technique
  • Fast multipole method
  • Eigenmode expansion

Published Papers (9 papers)

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Research

12 pages, 779 KiB  
Article
Analytically Regularized Evaluation of the Coupling of Planar Concentric Conducting Rings
by Fulvio Schettino
Appl. Sci. 2023, 13(1), 218; https://0-doi-org.brum.beds.ac.uk/10.3390/app13010218 - 24 Dec 2022
Viewed by 766
Abstract
In this paper, an accurate and efficient method for the analysis of coupled perfectly conducting annular rings is presented. The problem is first formulated as a couple of Integral Equation (IEs) in the Vector Hankel Transform (VHT) domain, considered as unknowns in the [...] Read more.
In this paper, an accurate and efficient method for the analysis of coupled perfectly conducting annular rings is presented. The problem is first formulated as a couple of Integral Equation (IEs) in the Vector Hankel Transform (VHT) domain, considered as unknowns in the cylindrical harmonics of the unknown surface current density. As a second step, Galerkin’s method is applied with suitable expansion functions. The selected functions have two main properties: they reconstruct the expected physical behavior of the nth cylindrical harmonic at the edges of the annular rings, and their VHT transform is analytical and can be expressed in closed-form. Consequently, the method is effective and the problem is regularized, as testified by the truncation error. Comparisons with the commercial software CST Microwave Studio have been carried out and are presented to validate the method. Full article
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9 pages, 1678 KiB  
Article
Fractance with Tunable Fractor’s Order for Microwave Circuit Applications
by Dario Assante
Appl. Sci. 2022, 12(19), 10108; https://0-doi-org.brum.beds.ac.uk/10.3390/app121910108 - 08 Oct 2022
Cited by 1 | Viewed by 864
Abstract
There is an increasing number of studies in the literature to implement fractional order components by means of equivalent circuits based on integer order components. Such implementations aim to realize laboratory equipment that can exhibit a fractional behavior in a certain range of [...] Read more.
There is an increasing number of studies in the literature to implement fractional order components by means of equivalent circuits based on integer order components. Such implementations aim to realize laboratory equipment that can exhibit a fractional behavior in a certain range of frequencies. One of the main limitations of the existing implementation is the fixed fractor’s order. In practice, every time the experimenter wants to change fractor’s order, it is necessary to calculate again the equivalent circuit and implement it again. In order to overcome this limitation, in this paper we propose a new implementation of a fractional order component that enables to tune the fractor’s order. This is achieved by means of variable resistors and a proper control methodology. The methodology can be applied in microwave circuits, for instance for the implementation of filters: a low-pass one is discussed in this paper. Full article
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9 pages, 11675 KiB  
Article
A Subwavelength Transmit-Array Lens Element Combining Functions of Phase Modulation and Polarization Conversion
by T. Xu, Y. Lu, G. He and X. Yang
Appl. Sci. 2022, 12(9), 4745; https://0-doi-org.brum.beds.ac.uk/10.3390/app12094745 - 09 May 2022
Cited by 1 | Viewed by 1188
Abstract
Advanced applications require transmit-array lenses featuring low profiles, covering 360° phase modulation, and, potentially, polarization conversion. Subwavelength metamaterial elements with multilayers manipulate electromagnetic waves with predesigned phase shifts, resulting in the transmit-array lens’s low profile and light weight. Conventional designs separate the transmit-array [...] Read more.
Advanced applications require transmit-array lenses featuring low profiles, covering 360° phase modulation, and, potentially, polarization conversion. Subwavelength metamaterial elements with multilayers manipulate electromagnetic waves with predesigned phase shifts, resulting in the transmit-array lens’s low profile and light weight. Conventional designs separate the transmit-array lens and polarization converter with two functional devices and suffer from high profiles and complicated mechanical assembly. In order to resolve these issues, a subwavelength lens element combining the functions of phase modulation and polarization conversion is proposed. The metamaterial lens element consists of phase modulation, linear-circular polarization conversion modules, and a metallic via structure electrically connecting these two modules. The multifunctional lens element modulates the transmitted phase with a three-bit phase shift and operates in the frequency range from 24.5 to 27 GHz, with less than −10 dB reflection coefficient, 1 dB transmission loss, and a 2.5 dB axial ratio. A transmit-array lens antenna with the proposed element is implemented to validate the abilities of beam focus and polarization conversion. The gain of the lens antenna reaches 26.3 dBi, with a 3 dB beamwidth of 6.7° and −18 dB sidelobe level, and the axial ratio of the converted circular polarization is below 1 dB. The aperture efficiency of the antenna is 45.2%. Full article
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10 pages, 3884 KiB  
Article
A New Observation in Spiral and Curl Antenna Configurations above the Ground Plane
by Kazuhide Hirose, Masayuki Hirukawa and Hisamatsu Nakano
Appl. Sci. 2022, 12(9), 4272; https://0-doi-org.brum.beds.ac.uk/10.3390/app12094272 - 23 Apr 2022
Cited by 1 | Viewed by 1480
Abstract
We report here that spiral and curl antennas are essentially the same when using the moment method. This aids in the understanding and design of the two antennas, and serves as the groundwork for new ideas regarding antennas. First, the spiral antenna height [...] Read more.
We report here that spiral and curl antennas are essentially the same when using the moment method. This aids in the understanding and design of the two antennas, and serves as the groundwork for new ideas regarding antennas. First, the spiral antenna height above the ground plane was gradually reduced, and at each height, the spiral configuration parameters were optimized for an axial ratio of less than 0.1 dB. It was found that the spiral antenna had configuration parameters almost the same as those for a curl antenna at a height of 0.15 wavelengths. Next, the curl antenna was analyzed with a reduced height. The antenna, at a height of 0.10 wavelengths, showed a 3 dB axial ratio bandwidth of 3%, with a VSWR of less than two. The analysis results are verified with experimental results. Full article
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13 pages, 647 KiB  
Article
Multilayer Dielectric Periodic Antenna Structure in a Cascade View
by Marian Wnuk
Appl. Sci. 2022, 12(9), 4185; https://0-doi-org.brum.beds.ac.uk/10.3390/app12094185 - 21 Apr 2022
Cited by 2 | Viewed by 994
Abstract
The spectral response of the periodic antenna structure placed in a dielectric homogeneous medium depends on the antenna geometry, the parameters of the medium, the angle of incidence, polarization, and the geometry of the excitation field. Increasing the number of antenna structure parameters [...] Read more.
The spectral response of the periodic antenna structure placed in a dielectric homogeneous medium depends on the antenna geometry, the parameters of the medium, the angle of incidence, polarization, and the geometry of the excitation field. Increasing the number of antenna structure parameters can be achieved by introducing a multilayer dielectric medium with a certain number of metallized periodic surfaces located on flat boundaries between the dielectric layers. There are two complementary approaches to the analysis of such structures. In the first, the composite antenna system is analysed by constructing supermodes of the entire structure. In the second, the system is considered as a cascade assembly of flat discrete elements, i.e., the boundaries between two dielectrics, periodic metallized planes, and dielectric layers. The latter approach leads to the definition of the scattering, transmission, or impedance matrix of the entire structure by cascading the corresponding matrices associated with the individual discrete elements of the antenna structure. It is particularly useful in modelling dielectric multilayer antenna walls, where the stored data on one planar antenna element can be used many times in the analysis of various antenna systems with modified parameters of other discrete structure elements. Microstrip antennas combine field and peripheral problems and require the use of analytical methods of a high degree of complexity. Therefore, at present, there are no standard methods that can be used in engineering practice. This work is a step towards filling these gaps. Full article
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9 pages, 3644 KiB  
Article
Bent and Branched Microstrip-Line Antennas for Circular Polarization
by Kazuhide Hirose, Kohei Nakamura and Hisamatsu Nakano
Appl. Sci. 2022, 12(3), 1711; https://0-doi-org.brum.beds.ac.uk/10.3390/app12031711 - 07 Feb 2022
Cited by 2 | Viewed by 1363
Abstract
We analyze three transmission-line antennas using the moment method. Each line antenna comprises a coplanar feed line, loops, and straight segments connecting the loops and feedline. First, we investigate bent and branched line antennas with loops on one side of the feedline. It [...] Read more.
We analyze three transmission-line antennas using the moment method. Each line antenna comprises a coplanar feed line, loops, and straight segments connecting the loops and feedline. First, we investigate bent and branched line antennas with loops on one side of the feedline. It is found that the segment length affects both the beam direction and axial ratio for the bent line antenna; in contrast, it only affects the branched line antenna’s axial ratio, resulting in a more straightforward design. Subsequently, the branched line antenna is modified with loops on both sides of the feedline to enhance the gain. It is observed that the antenna shows a gain enhancement of 2.0 dB, maintaining the same axial-ratio bandwidth as that of the original branched line antenna. The simulated results are validated by experimental work. Full article
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16 pages, 4150 KiB  
Article
Analysis of the Scattering from a Two Stacked Thin Resistive Disks Resonator by Means of the Helmholtz–Galerkin Regularizing Technique
by Mario Lucido
Appl. Sci. 2021, 11(17), 8173; https://0-doi-org.brum.beds.ac.uk/10.3390/app11178173 - 03 Sep 2021
Cited by 5 | Viewed by 1015
Abstract
In this paper, the scattering of a plane wave from a lossy Fabry–Perót resonator, realized with two equiaxial thin resistive disks with the same radius, is analyzed by means of the generalization of the Helmholtz–Galerkin regularizing technique recently developed by the author. The [...] Read more.
In this paper, the scattering of a plane wave from a lossy Fabry–Perót resonator, realized with two equiaxial thin resistive disks with the same radius, is analyzed by means of the generalization of the Helmholtz–Galerkin regularizing technique recently developed by the author. The disks are modelled as 2-D planar surfaces described in terms of generalized boundary conditions. Taking advantage of the revolution symmetry, the problem is equivalently formulated as a set of independent systems of 1-D equations in the vector Hankel transform domain for the cylindrical harmonics of the effective surface current densities. The Helmholtz decomposition of the unknowns, combined with a suitable choice of the expansion functions in a Galerkin scheme, lead to a fast-converging Fredholm second-kind matrix operator equation. Moreover, an analytical technique specifically devised to efficiently evaluate the integrals of the coefficient matrix is adopted. As shown in the numerical results section, near-field and far-field parameters are accurately and efficiently reconstructed even at the resonance frequencies of the natural modes, which are searched for the peaks of the total scattering cross-section and the absorption cross-section. Moreover, the proposed method drastically outperforms the general-purpose commercial software CST Microwave Studio in terms of both CPU time and memory occupation. Full article
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9 pages, 2962 KiB  
Article
A Compact Rectifier Design Method Utilizing Harmonics
by Xuelong Qin, Guoqiang He, Xuexia Yang and Steven Gao
Appl. Sci. 2021, 11(5), 2295; https://0-doi-org.brum.beds.ac.uk/10.3390/app11052295 - 05 Mar 2021
Cited by 2 | Viewed by 1374
Abstract
This paper proposes a compact rectifier design method for utilizing harmonics. Based on total reflection generated by pure reactance loads at the second harmonic (2nd) and open circuit at the third harmonic (3rd), a compact DC-pass filter is designed to effectively utilize the [...] Read more.
This paper proposes a compact rectifier design method for utilizing harmonics. Based on total reflection generated by pure reactance loads at the second harmonic (2nd) and open circuit at the third harmonic (3rd), a compact DC-pass filter is designed to effectively utilize the 2nd and 3rd harmonics excited by the rectifying diode. The amplitudes of the harmonics can be controlled by adjusting the input impedances of the DC-pass filter at harmonics. A prototype operating at 5.8 GHz fundamental frequency is implemented and measured to validate the scenario. When the input power is 18.3 dBm, the measured rectifying efficiency is 71.3%, while the 2nd and the 3rd harmonic amplitudes are −2.4 dBm and 0.1 dBm respectively. This method could also be extended to design a rectifier only utilizing the 2nd or the 3rd harmonic. Full article
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12 pages, 1034 KiB  
Article
Analysis of the Propagation in High-Speed Interconnects for MIMICs by Means of the Method of Analytical Preconditioning: A New Highly Efficient Evaluation of the Coefficient Matrix
by Mario Lucido
Appl. Sci. 2021, 11(3), 933; https://0-doi-org.brum.beds.ac.uk/10.3390/app11030933 - 20 Jan 2021
Cited by 2 | Viewed by 911
Abstract
The method of analytical preconditioning combines the discretization and the analytical regularization of a singular integral equation in a single step. In a recent paper by the author, such a method has been applied to a spectral domain integral equation formulation devised to [...] Read more.
The method of analytical preconditioning combines the discretization and the analytical regularization of a singular integral equation in a single step. In a recent paper by the author, such a method has been applied to a spectral domain integral equation formulation devised to analyze the propagation in polygonal cross-section microstrip lines, which are widely used as high-speed interconnects in monolithic microwave and millimeter waves integrated circuits. By choosing analytically Fourier transformable expansion functions reconstructing the behavior of the fields on the wedges, fast convergence is achieved, and the convolution integrals are expressed in closed form. However, the coefficient matrix elements are one-dimensional improper integrals of oscillating and, in the worst cases, slowly decaying functions. In this paper, a novel technique for the efficient evaluation of such kind of integrals is proposed. By means of a procedure based on Cauchy integral theorem, the general coefficient matrix element is written as a linear combination of fast converging integrals. As shown in the numerical results section, the proposed technique always outperforms the analytical asymptotic acceleration technique, especially when highly accurate solutions are required. Full article
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