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[IEEE 2019 IEEE Conference on Antenna Measurements & Applications (CAMA) - Kuta, Bali, Indonesia (2019.10.23-2019.10.25)] 2019 IEEE Conference on Antenna Measurements & Applications (CAMA) - Development of a Wideband Substrate Integrated Waveguide Bandpass Filter Using H-Slotted DGS
摘要： In the current work, a new Wideband Substrate Integrated Waveguide Bandpass Filter (SIW-BPF) is presented. The target is to allow vertical roaming between the X and Ku band applications. As a first step, we performed a parametric study of different etched slot geometries namely, H-Slotted, T-Slotted, and U-Slotted DGS in order to examine the effects of altering different geometrical parameters of the unit on its response. H-Slotted DGS shows the highest FBW with 82.89% on the average compared to other geometries. As a second step, the cell size and the numbers of the H-Slotted DGS were optimized with the use of finite element method with the following constraints taken into consideration: low cost fabrication, high Q-Factor, compact size and easy integration. One of the designs was chosen for fabrication to validate the designed circuit. The measured results show that our optimized filter achieves an insertion loss of 2.01 dB at 8.5 GHz, a return loss higher than 11 dB and fractional bandwidth of 90.87% for a single cell and a fractional bandwidth of 80.05% for multiple cells. The measured results are in good agreement with the simulated results.
关键词： Substrate Integrated Waveguide (SIW),Finite Element Method,Ku-Band,Bandpass filter (BPF),Electromagnetic Band Gap structure (EBG),Wideband,X-Band
更新于2025-09-23 15:21:01
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Optical band gap and dielectric abnormality in (Sr, Ce, Zr)TiO3 composite ceramics sintered in nitrogen
摘要： The crystal-chemical structure, band gap-grain structure and dielectric properties of (1?x)SrTiO3-xCe0.95Zr0.05O2 [(Sr,Ce,Zr) TiO3, for x = 0.0, 0.3 and 0.4] ceramics were investigated. Samples with 0.3 ≤ x ≤ 0.4 appeared cubic by X-ray diffraction (XRD), however, splitting of the peaks along with Rietveld refinement indicated tetragonal structure. The change in the band gap energy with Ce(x) have been investigated and are related to variation in the grain size, activation energy and octahedral tilting. The reduction in band gap energy with Ce0.95Zr0.05O2 ions (x = 0.4) is attributed to the widening of conduction band with octahedral tilting. The absence of TO2 (175 cm?1) mode while the existence of TO4 (521.72 cm?1) mode has been considered as sign of relaxor-like-dielectric behavior. The ε′?T curve and the P–E loop analysis confirms that there is no signature of the ferroelectric phase in all samples. Base on the X-ray photoelectrons spectroscopy (XPS) and high temperature ac conductivity analysis, the dielectric anomalies were due to the formation of lattice defects and defect dipoles ( Ti4+ ? e? ? V ?? o ) generated by the Ti3+ ions and ionized oxygen vacancies.
关键词： Crystal-band gap structure,Dielectric properties,Oxygen vacancies
更新于2025-09-19 17:15:36
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Efficient Photocatalytic Hydrogen Production Achieved by WO3 Coupled with NiP2 Over ZIF-8
摘要： The photo-catalyst WO3/NiP2@ZIF-8 was synthesized by modifying the WO3 with NiP2@MOFs structure. High H2 production was achieved (341.2 μmol and 11.3 times than pure WO3 after 5 h) and the catalytic property of WO3 was improved. The XRD, FESEM and TEM were used to characterize and analyze the crystalline phase structure, namely, WO3 has nanowire structure and good crystalline phase, meanwhlie, ZIF-8 exhibits regular dodecahedron morphology. The catalysts were characterized and analyzed by electrochemical, steady-state and transient state, those results show that the composite has more efficient charge separation effect and better electrical performance than single catalyst, which provides a reliable basis for relative higher H2 production activity. The band gap structure and elemental valence of the composite catalysts were calculated and analyzed by UV–Vis DR and XPS, respectively. The possible reaction equation and H2 production mechanism of WO3/NiP2@ZIF-8 in HER were proposed.
关键词： NiP2@ZIF-8,Photocatalytic H2 production,WO3,Band gap structure
更新于2025-09-11 14:15:04