Accurate Wide-Range Design Equation for the Frequency Dependent Characteristics of Parallel Coupled Microstrip Lines

IEEE Transactions on Microwave Theory and Techniques (Impact Factor: 2.24). 04/1985; 32(3):288 - 288. DOI: 10.1109/TMTT.1985.1133005
Source: IEEE Xplore


In the above paper, the following misprints have to be corrected.

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    • "[10] [11] Designing equations for the coupled line parameters such as space gap between lines and line widths and lengths, can be found in classical microwave books.[12] [13] Closed-form expressions for modeling the frequency dependency of the even-and odd-mode characteristics of the parallel-coupled microstrip line were developed by Hammerstad, Kirschning, and Jansen [14] [15] [16]. Following this formulation, and considering L the resonator length, W the width, and S the coupling gap, the quasi static even-and odd-mode characteristic impedance of a coupled line, Z 0e and Z 0o , are, respectively, estimated as per (1) and (2): "
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    ABSTRACT: In this paper, we describe a method to implement compact multiband bandpass filters with suppression of second harmonic frequency. This filter design approach is based on decreasing the coupling gap between adjacent resonators of a parallel-coupled-line bandpass filter in order to achieve both the desired multiband frequency response and the spurious suppression. We present the theoretical analysis of the proposed structure that consists of modeling the frequency dependence of the even- and odd-mode characteristic impedances as well as due to the different phase velocities of the parallel-coupled microstrip lines. As an example, a compact tri-band parallel-coupled-line bandpass filter with suppression of second harmonic frequency was implemented operating at 1.9/3.2/4.6 GHz to cover PCS1900, WiMAX, and C-band applications. A three-pole Chebyshev parallel-coupled microstrip bandpass filter was designed at a center frequency of 3.2 GHz and used as the basis to validate the gapping effect on the filter response which also achieves a narrower bandwidth for the second harmonic. Finally, the filter performance with minimized coupling gap is compared to a filter enhanced by the insertion of apertures in the ground plane. Generally speaking, good agreement was accomplished between simulated, calculated, and measured results.
    Journal of Electromagnetic Waves and Applications 08/2015; 29(14):1813-1828. DOI:10.1080/09205071.2015.1043029 · 0.73 Impact Factor
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    • "The next step is to calculate the even-and odd-mode characteristic impedances of the coupled microstrip pair. Improved expressions have been derived [6], [7]. The accuracy of these static expressions is better than 0.6% for both modes in the range of validity 0.1 ≤u≤ 10, 0.1 ≤g≤ 10, 1 ≤ ε r ≤ 18 (where u = w h denotes normalized strip width and g = s h is the normalized line spacing). "
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    ABSTRACT: This paper presents a new efficient numerical formulations procedure to predict the responses of a N-poles Chebyshev parallel-coupled Microstrip bandpass filter for wireless communication technologies. Based on the transmission line theory approach, these numerical formulations have been developed using the mathematical analysis concept to predict the desired s-parameters of the desired filter. To validate the theoretical method developed in this work, a third and a second order parallel coupled microstrip band pass filters for WiMAX and ISM band respectively have been fabricated and measured. The measured scattering-parameters show a very good agreement with predictions by the theoretical responses, which validates the design procedure of the proposed filter.
    Mediterranean Microwave Symposium MMS’14, Marrakech, Morocco; 12/2014
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    • "Again the attempt was made to use static formulas [4], However, detailed test computations revealed that the error in these increases to about 1.5 percent for special parameter combinations near the limits of (0.1 ≤u≤ 10 and g ≥ 0.01). So, for the static values of the even-and odd-mode characteristic impedances of coupled microstrip lines further improved expressions have been derived by [5] (equation 3 and 4). The accuracy of these static expressions is better than 0.6 percent for both modes in the range of validity 0.1 ≤u≤ 10, 0.1 ≤g≤ 10, 1 ≤ ε r ≤ 18. "
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    ABSTRACT: On the one hand this paper presents a theoretical method to predict the responses for the parallel coupled microstrip bandpass filters, and on the other hand proposes a new MATLAB simulation interface including all parameters design procedure to predict the filter responses. The main advantage of this developed interface calculator is to enable researchers and engineers to design and determine easily all parameters of the PCMBPF responses with high accuracy and very small CPU time. To validate the numerical method and the corresponding new interface calculator, two PCMBP filters for wireless communications are designed and compared with the commercial electromagnetic CST simulator and the fabricated prototype respectively. Measured results show good agreement with those obtained by numerical method and simulations.
    Mediterranean Microwave Symposium MMS’14, Marrakech, Morocco; 12/2014
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