Quasi-TEM approach of coupled-microstrip lines and its application to the analysis of microstrip filters

Xiao, Fei; Norgren, Martin; He, Sailing

doi:10.1002/mmce.20592

Cited by 5 publications

(5 citation statements)

References 40 publications

(27 reference statements)

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“…A second case was considered in which the dielectric layers were replaced by free space; therefore, the capacitances C (o,e) a can be calculated using Eqs. ( 17) and (18).…”

Section: Electromagnetic Simulation and Modelingmentioning

confidence: 99%

Quasi-Tem Analysis of Symmetrical Shielded Broadside-Coupled Microstrip Lines

Bououden¹,

Riabi²,

Saadi³

et al. 2021

PIER M

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In this work, a numerical quasi-static approach is proposed to efficiently analyze symmetrical shielded broadside-coupled microstrip line (SBCML) structures. Based on the modified least squares boundary residual method combined with a variational technique, this approach allows accurate computation of the electrical/geometrical parameters of different SBCML configurations. The errors for the quasi-TEM electrical parameters range are less than 4%. The proposed technique was demonstrated through successful comparison with data from published works and results obtained from commercial EM simulators like CST-EMS and COMSOL. INTRODUCTIONBroadside-coupled microstrip line (BCML) structures are frequently used in microwave and millimeterwave (mm-wave) passive/active circuits such as couplers [1, 2], baluns [3,4], antennas [5], filters [6], phase shifters [7], and impedance transformers [8]. In fact, compared to conventional edge-coupled microstrip lines, such circuits present some enhanced design parameters like tight coupling (3 dB), low VSWR, and low insertion loss. They can also produce equal even-and odd-mode phase velocities. Accurate computation of their quasi-TEM static parameters is essential for successful design of microwave systems, optical integrated circuits, and sensors. During the last years, various works have been devoted to the analysis of shielded/partial shielded and open planar transmission line configurations and to the computation of their quasi-static parameters. Existing quasi-TEM approaches include conformal mapping [9, 10], point matching method [11], neuro-fuzzy [12], method of lines [13], variational method [14,15], finite element method [16,17], orthogonal expansion method [18], quasi-static spectral domain method [19], Fourier series expansion [20], and closed-form expression [21]. From that list, the conformal mapping method is one of the most widely used. However, it is valid only over a limited range of physical dimensions and restricted configurations. On the other hand, discretization methods, like the finite element and finite difference time-domain methods, suffer from discretization errors and long CPU time, especially for very thin material layers.Recently, the quasi-TEM approach has shown several advantages like good convergence rate and accuracy, minimum memory storage and CPU time, while avoiding the need for an expansion function to solve the unknown charge density. Furthermore, it reduces the Gibbs phenomenon effect. Based on the Least Squares Boundary Residual method (LSBR), which has already been successfully and accurately applied to the characterization of multilayer isotropic and anisotropic planar transmission lines with arbitrary geometry for both the quasi-TEM and full-wave modes, the proposed method, called Modified Least Squares Boundary Residual (MLSBR), uses weighting functions (rectangular

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“…A second case was considered in which the dielectric layers were replaced by free space; therefore, the capacitances C (o,e) a can be calculated using Eqs. ( 17) and (18).…”

Section: Electromagnetic Simulation and Modelingmentioning

confidence: 99%

Quasi-Tem Analysis of Symmetrical Shielded Broadside-Coupled Microstrip Lines

Bououden¹,

Riabi²,

Saadi³

et al. 2021

PIER M

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“…After some conditions at the ends of the coupled three lines section in Figure 2 are applied, for example, the opencircuited condition or the load condition, the Eq. (3) will be finally degraded to the one about a two-port network [12].…”

Section: Uwb Bandpass Response P Of the Proposed Structurementioning

confidence: 99%

“…A tight coupling can be achieved for given coupled-line via tapped-line structure or dual-line coupling structure [10]. Coupled-line with stepped-impedance resonators and "wiggly-line" sections were proposed for the multispurious suppression [11,12]. Moreover, a tight coupling factor with wide spurious-free stopband can be achieved by using three sections that have different lengths and coupling factors [13].…”

Section: Received 6 May 2015mentioning

confidence: 99%

“…After some conditions at the ends of the coupled three lines section in Figure are applied, for example, the open‐circuited condition or the load condition, the Eq. will be finally degraded to the one about a two‐port network .

true[\begin{matrix} U_{1} \\ U_{3} \end{matrix} true] = true[\begin{matrix} Z_{11} - \frac{Z_{15} \cdot Z_{51}}{Z_{u} + Z_{55}} & Z_{13} - \frac{Z_{15} \cdot Z_{53}}{Z_{u} + Z_{55}} \\ Z_{31} - \frac{Z_{35} \cdot Z_{51}}{Z_{u} + Z_{55}} & Z_{33} - \frac{Z_{35} \cdot Z_{51}}{Z_{u} + Z_{55}} \end{matrix} true] true[\begin{matrix} I_{1} \\ I_{3} \end{matrix} true]

where Z u is the impedance of the load at the center line.…”

Section: Uwb Bandpass Response P Of the Proposed Structurementioning

confidence: 99%

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Compact UWB bandpass filters with two superposable notched bands

Xiao

Tang

et al. 2015

Micro & Optical Tech Letters

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In this article, compact microstrip ultrawideband (UWB) bandpass filters with two superposable notched bands are discussed. By cascading n + 1 T‐shaped structures where n = 1 or 2 to a three coupled‐line section, UWB bandpass frequency response with one or two notched bands can be obtained. The analysis shows that these notched bands are superposable and can be relatively independently adjusted in wide frequency range. The simulated and measured results are presented for verification. The filters are characterized by easy tuning and compact size. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2819–2824, 2015

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“…The parallel coupled microstrip lines (PCML) have been widely used in microwave circuits [1] such as directional couplers [2,3], phase shifters [4], and filters [5,6]. For the traditional PCML, the coupling factor is mainly dependent on the spacing between the two coupled microstrip lines and the dielectric constant of the used substrate.…”

Section: Introductionmentioning

confidence: 99%

An ANN-Based Synthesis Model for Parallel Coupled Microstrip Lines with Floating Ground-Plane Conductor and Its Applications

Cao

Wang

Fang

2016

International Journal of Antennas and Propagation

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To directly obtain physical dimensions of parallel coupled microstrip lines with a floating ground-plane conductor (PCMLFGPC), an accurate synthesis model based on an artificial neural network (ANN) is proposed. The synthesis model is validated by using the conformal mapping technique (CMT) analysis contours. Using the synthesis model and the CMT analysis, the PCMLFGPC having equal even- and odd-mode phase velocities can be obtained by adjusting the width of the floating ground-plane conductor. Applying the method, a 7 dB coupler with the measured isolation better than 27 dB across a wide bandwidth (more than 120%), a 90° Schiffman phase shifter with phase deviation ±2.5° and return loss more than 17.5 dB covering 63.4% bandwidth, and a bandpass filter with completely eliminated second-order spurious band are implemented. The performances of the current designs are superior to those of the previous components configured with the PCMLFGPC.

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Quasi-TEM approach of coupled-microstrip lines and its application to the analysis of microstrip filters

Cited by 5 publications

References 40 publications

Quasi-Tem Analysis of Symmetrical Shielded Broadside-Coupled Microstrip Lines

Quasi-Tem Analysis of Symmetrical Shielded Broadside-Coupled Microstrip Lines

Compact UWB bandpass filters with two superposable notched bands

An ANN-Based Synthesis Model for Parallel Coupled Microstrip Lines with Floating Ground-Plane Conductor and Its Applications

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