Article

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

ABSTRACT

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    • "Detailed analysis and corresponding graphs of the evenand odd-mode impedances are depicted in [12]. Using the closed formulas developed by Hammerstad, Kirschning and Jansen for modelling the frequencydependency of the even-and odd-mode characteristics of a parallel coupled microstrip line [10,11]. The variation of the static characteristic impedances for even-and oddmodes is calculated easily, as well as the fractional bandwidth (FBW) variation of the PCLM filter type. "
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    ABSTRACT: This paper presents the design of UWB three-pole modified parallel coupled line bandpass filter with improved rejection in the out-of-band frequencies. To achieve the desired UWB requirements using the conventional bandpass filter design, a physical dimension optimization of space-gap between lines, line widths and lengths was applied. An equivalent circuit model is also presented and demonstrates reasonable agreement with simulation results. The optimized filter demonstrates an excellent UWB performance, covering the Federal Communication Commission spectrum bandwidth with low insertion loss and acceptable selectivity. However, this resulting filter structure presents very small gapping between adjacent resonators; that means the filter is unmanufactured. Then an example of an alternative filter structure is finally proposed with null gaping and short circuited stubs that yields to a fabricated prototype with selectivity improvement. Generally speaking, reasonable agreement is achieved between measurement and simulation results.
    No preview · Article · Jan 2016 · Applied Computational Electromagnetics Society Journal
    • "[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.
    No preview · Article · Aug 2015 · Journal of Electromagnetic Waves and Applications
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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.
    Full-text · Conference Paper · Dec 2014
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