Journal Articles

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Browsing Journal Articles by Author "Cheng, Qingsha S."

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    Compactwideband Siw Based Bandpass Filter For X, Ku And K Band Applications
    (Czech Technical University, 2021-03-23) Duraisamy, Tharani; Kamakshy, Selvajyothi; Karthikeyan, Sholampettai Subramanian; Barik, Rusan Kumar; Cheng, Qingsha S.
    This paper presents a miniaturized bandpass filter (BPF) with characteristics of wider passband and stopband rejection using substrate integrated waveguide (SIW) technology. Slot loading mechanisms deployed on the upper layer of SIW and defective ground structure (DGS) on the ground plane are utilized to achieve wider passband and stopband respectively. The slots on the top layer along with DGS significantly enhances the selectivity of the filter by generating three transmission zeros (TZs) on the upper side of the passband. The proposed filter is simulated using fullwave simulators and the performance is validated through fabrication and testing of the prototype. The proposed SIW filter exhibits a low insertion loss of 1.52 dB over a wider passband from 9.17 GHz to 20.31 GHz with a 3 dB fractional bandwidth (FBW) of 76%. Further, a wider upper stopband is achieved with the rejection of more than 16 dB in the frequency range of 23 GHz to 40 GHz. The filter provides a flat group delay response of approximately 0.19 ns over the wider passband. The electrical size of the fabricated prototype is 1.05λg* 0.67λg, where λgdenotes the guided wavelength in the dielectric substrate for the designed center frequency of 16 GHz.
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    Design of Miniaturized SIW Filter Loaded with Open-Loop Resonators and its Application to Diplexer
    (Czech Technical University, 2020-09-01) Barik, Rusan Kumar; Cheng, Qingsha S.; Pradhan, Nrusingha Charan; Karthikeyan, Sholampettai Submaranian
    This paper presents a novel design of miniaturized substrate-integrated waveguide (SIW) filter loaded with a pair of unit-cell resonators. Two identical open-loop resonators are connected face-to-face to form a unit-cell. A pair of unit-cells is engraved on the surface of the SIW to develop an evanescent-mode bandpass filter. The proposed unit-cells behave as an electric-dipole and produce a passband smaller than the waveguide frequency. This reduction in resonant frequency allows us to achieve size miniaturization. An equivalent electrical-circuit model is developed and investigate for characterization of passband and transmission-zero. This filter structure is then employed to develop a SIW planar diplexer. Two SIW filter structures loaded with unit-cells are excited with a T-shaped feed line to achieve lower and upper channels of the diplexer. To demonstrate the analysis, both SIW filter and diplexer loaded with open-loop resonators are implemented and fabricated. The proposed SIW filter and diplexer prototypes exhibit size miniaturization, low insertion-loss and high-selectivity due to evanescent-mode transmission and sub-wavelength resonators. The measurement responses are very similar to the simulation responses.