Accurate Wide-Range Design Equations for the Frequency-Dependent Characteristic of Parallel Coupled Microstrip Lines
ABSTRACT In this paper, closed-form expressions are presented which model the frequency-dependent even- and odd-mode characteristics of parallel coupled microstrip lines with hitherto unattained accuracy and range of validity. They include the effective dielectric constants, the characteristic impedances using the power-current formulation, as well as the open-end equivalent lengths for the two fundamental modes on coupled microstrip. The formulas are accurate into the millimeter-wave region. They are based on an extensive set of accurate numerical data which were generated by a rigorous spectral-domain hybrid-mode approach and are believed to represent a substantial improvement compared to the state-of-the-art and with respect to the computer-aided design of coupled microstrip filters, directional couplers, and related components.
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ABSTRACT: We analyze the microstrip directional couplers with a special focus on the phase difference between the coupled and isolated ports. The analysis uses the even-odd mode decomposition technique and network theory. The results show that the phase difference between the signals at the coupled port and the isolated port is close to pi in a very wide band. This property can be used to achieve a broadband directivity by inducing a voltage cancellation at the isolated port of the couplers. Two different cancellation methods are investigated. Analytical formulas for the required component values of both methods are given. Higher directivity can be obtained at the expense of reduced bandwidth.IEEE Transactions on Microwave Theory and Techniques 12/2013; 61(12):4063. · 2.23 Impact Factor
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ABSTRACT: In this paper, a bandpass filter is proposed with dumbbell shaped defected ground structure in ground plane of a 50Ω Microstrip line and a closed loop resonator in the conducting strip. This arrangement provides better coupling in pass band. Using DGS structure, forward transmission loss (S21) is -1 dB and return loss (S11) is -20 dB at the centre frequency 3.2 GHz with bandwidth of 200 MHz. A conventional parallel coupled line bandpass filter has also been implemented with exactly same design goals for the sake of comparison. The proposed bandpass filter with DGS is quite promising with 28% size reduction.
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ABSTRACT: In this paper, a compact microstrip bandpass filter is designed using defected ground structure (DGS) with narrow bandwidth. Here a 50Ω quarter wave microstrip line is used for designing the bandpass filter. A circular head dumbbell shaped DGS in the ground plane of a microstrip line is used which provides the bandstop characteristics. Two series gap slot is introduced for achieving the bandpass characteristics in the conducting strip. These slots in conducting strip are also called defected microstrip structure (DMS). This arrangement provides better coupling in the pass band. In this paper no stubs and via are used. The bandwidth of the filter is 500 MHz and insertion loss less than 0.5 dB in passband at 5.4 GHz. The measured insertion loss (S21) is 0.6 dB at the center frequency 5.4 GHz with a bandwidth of 500 MHz which is good in agreement with measured results after the fabrications)Communications (NCC), 2013 National Conference on; 01/2013