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Novel bandpass filter with high selectivity and very wide stopband using open stub loaded and DGS
摘要： A novel bandpass ?lter (BPF) based on half-wave-length (λ/2) stepped-impedance resonators (SIRs) is proposed in this paper. By properly designing the impedance ratios of the SIRs, the spurious harmonics of the ?lter can be pushed to upper frequency. With several bandstop structures such as open stubs and defected ground structures (DGSs) applied to the BPF, a good stopband performance is obtained. Moreover, 0° feed structure is used to improve the selectivity of the BPF. Then a BPF which has high selectivity and wide stopband is implemented. Measured results show good agreement with the simulated results.
关键词： high selectivity,BPF,widestopband,DGS
更新于2025-09-04 15:30:14
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From the Bottom-Up: Toward Area-Selective Atomic Layer Deposition with High Selectivity
摘要： Bottom-up nanofabrication by area-selective atomic layer deposition (ALD) is currently gaining momentum in semiconductor processing, because of the increasing need for eliminating the edge placement errors of top-down processing. Moreover, area-selective ALD offers new opportunities in many other areas such as the synthesis of catalysts with atomic-level control. This Perspective provides an overview of the current developments in the field of area-selective ALD, discusses the challenge of achieving a high selectivity, and provides a vision for how area-selective ALD processes can be improved. A general cause for the loss of selectivity during deposition is that the character of surfaces on which no deposition should take place changes when it is exposed to the ALD chemistry. A solution is to implement correction steps during ALD involving for example surface functionalization or selective etching. This leads to the development of advanced ALD cycles by combining conventional two-step ALD cycles with correction steps in multistep cycle and/or supercycle recipes.
关键词： surface functionalization,semiconductor processing,area-selective atomic layer deposition,catalysts synthesis,selectivity,bottom-up nanofabrication,selective etching,ALD
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - 140 GHz Linear to Circular Polarization Convertor Based on Modified Cross Slot Frequency Selective Surface with High Selectivity
摘要： A 140 GHz linear to circular polarization converter based on a frequency selective surface (FSS) with high selectivity is proposed and designed in this paper. The periodic element of the converter includes a square substrate integrated waveguide (SIW) cavity and two cross slots with stubs etched on the top and bottom conductor claddings of the cavity. Based on the SIW cavity, a transmission pole is provided to improve passband characteristics and sideband selectivity. Besides, this THz converter can be easily fabricated using normal PCB process instead of compacted and high-cost technologies.
关键词： high selectivity,frequency selective surface (FSS),circular polarization (CP),Terahertz (THz) technology,substrate integrated waveguide (SIW) cavity
更新于2025-09-04 15:30:14
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Atomic layer etching of chrome using ion beams
摘要： In this study, two Cr atomic layer etching (ALE) methods have been applied for the precise control of Cr etching. The first one involves O radical adsorption followed by Cl+ ion desorption (ALE with chemical ion desorption; chemical anisotropic ALE), and the second one involves Cl/O radical adsorption followed by Ar+ ion desorption (ALE with physical ion desorption; physical anisotropic ALE). Their effects on Cr etch characteristics were also investigated. For both the ALE methods, saturated Cr etch depth/cycle of 1.1 and 1.5 ? /cycle were obtained for the chemical and physical anisotropic ALE, respectively, while maintaining near-infinite etch selectivities with various Si-based materials like silicon, silicon dioxide, and silicon nitride. The ALE technique can be used to precisely control the thickness of materials, including metals such as Cr, without any surface damage.
关键词： etch selectivity,adsorption,atomic layer etching,x-ray photoelectron spectroscopy,ion beam,chrome
更新于2025-09-04 15:30:14
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COMPACT HIGH-SELECTIVITY DUAL/TRI-BAND BANDPASS FILTERS FOR WLAN APPLICATIONS
摘要： This paper presents compact dual/tri-band bandpass ?lters (BPFs) with controllable frequency and high selectivity for WLAN applications. A stepped impedance resonator with a shorting stub and a uniform impedance resonator with an open stub are applied in the designs. Several techniques that can generate transmission zeros are combined to improve the frequency selectivity. The resonators and the proposed ?lters are characterized by full-wave simulations. To validate the design strategies, a dual-band BPF centered at 2.4 GHz and 5.2 GHz was ?rst designed. With a minor modi?cation, a tri-band BPF centered at 2.4 GHz, 5.2 GHz and 5.8 GHz was then developed. Both simulations and measurements were carried out to demonstrate the e?ectiveness of the designs. Good agreements are achieved.
关键词： Dual/Tri-Band,Bandpass Filters,WLAN Applications,Compact,High-Selectivity
更新于2025-09-04 15:30:14
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A NOVEL DUAL-BAND SIW FILTER WITH HIGH SELECTIVITY
摘要： A novel dual-band substrate integrated waveguide (SIW) ?lter with multiple transmission zeros and good out-of-band rejection performance is presented in this paper. For this purpose, an orthogonal input/output (I/O) feeding structure directly connected to the substrate integrated waveguide (SIW) cavity is designed to split the resonant frequencies of the degenerate pair of mode. The ?lter can be modeled with a multi-path circuit formed by three modes (TE101, TE201 and TE102 modes) and weak cross coupling between I/O ports, thereby producing three transmission zeros which make the dual-band high selectivity. The o?set of the input/output ports shifts the second transmission zero to a lower frequency from the upper passband. Several ?lter prototypes are designed and fabricated for demonstration, and the measured results validate the new structure for high selectivity applications.
关键词： high selectivity,substrate integrated waveguide (SIW),dual-band,orthogonal input/output feeding structure,transmission zeros
更新于2025-09-04 15:30:14
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A wideband omnidirectional filtering patch antenna with high selectivity
摘要： A wideband omnidirectional filtering patch antenna with high selectivity is proposed in this article. The annular ring is surrounded by the hexagonal patch with inner circle, whereas a series of shorting vias are regularly distributed among them and a copper top hat is suspended right on the top of the radiator, respectively. And, omnidirectional pattern is mainly performed on account of the symmetry and center-fed structure. In addition, broadband performance is achieved by merging three resonant modes, which include the TM01 and TM02 modes of the annular ring and the TM02 mode of the hexagonal patch with inner circle. Taking advantages of the hexagonal patch and six shorting vias in it, two radiation nulls are provided in the upper band. Besides, another radiation null is generated in the lower band by reason of the top hat and other shorting vias. As a result, an ideal quasi-elliptic bandpass response, high selectivity, and good out-of-band rejection are obtained simultaneously. The proposed filtering patch antenna, with a profile of 0.056 λ0, shows a wide impedance bandwidth of 30.2% from 2.05 to 2.78 GHz. The average gain in the passband is about 6.5 dBi, and the out-of-band suppression level is greater than 15 dB in the wide stopband.
关键词： filtering antenna,wideband,high selectivity,omnidirectional antenna
更新于2025-09-04 15:30:14
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Metal-organic frameworks as SERS substrates with high tailorability
摘要： Surface enhanced Raman scattering (SERS) is a widely used analytical technique for detecting trace-level molecules based on an indispensable SERS substrate. SERS substrates with high tailorability are assumed to be attractive and desirable for SERS detection, because the substrates match the need for the selective detection of different species. Nevertheless, the rational design of such SERS substrates is rather challenging for both noble-metal and semiconductor substrates. Herein, expanding beyond conventional SERS substrates, we demonstrate that metal-organic framework (MOF) materials can serve as a type of SERS substrate with molecular selectivity, which are rarely realized for SERS detection without any special pretreatment. A salient structural characteristic of MOF-based SERS substrates benefiting the SERS selectivity is their high tailorability. By controlling the metal centers, organic ligands, and framework topologies of our MOF-based SERS substrates, we show that the electronic band structures of MOF-based SERS substrate can be purposively manipulated to match those of the target analytes, thus resulting in different detectable species. Going further, the SERS enhancement factors (EFs) of the MOF-based SERS substrates can be greatly enhanced to as high as 106 with a low detection limit of 10-8 M by pore-structure optimization and surface modification, which is comparable to the EFs of noble metals without “hot spots” and recently-reported semiconductors. This selective enhancement is interpreted as being due to the controllable combination of several resonances, such as the charge-transfer, interband and molecule resonances, together with the ground-state charge-transfer interactions. Our study opens a new venue for the development of SERS substrates with high-design flexibility, which is especially important for selective SERS detection towards specific analytes.
关键词： Surface enhanced Raman scattering (SERS),tailorability,charge-transfer,molecular selectivity,interband and molecule resonances,enhancement factors (EFs),metal-organic framework (MOF),ground-state charge-transfer interactions,SERS substrates
更新于2025-09-04 15:30:14
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DESIGN OF NOVEL COMPACT TRI-BAND BANDPASS FILTER WITH CONTROLLABLE FREQUENCIES AND HIGH SELECTIVITY
摘要： This paper presents a compact tri-band bandpass ?lter (BPF) with high selectivity. The proposed ?lter utilizes novel stub-loaded quarter-wavelength resonators and conventional uniform quarter-wavelength resonators. The latter is embedded in the former, and they are separated by a feed line. Due to these quarter-wavelength resonators, the total size is greatly reduced. Moreover, the passband frequencies can be controlled individually. To enhance its selectivity, source-load coupling is employed. For demonstration, an experimental ?lter is implemented. High skirt selectivity and suppression levels are observed in the measured results. The circuit area of the ?lter is 0.17λg × 0.19λg, featuring compact size.
关键词： high selectivity,compact size,stub-loaded quarter-wavelength resonators,tri-band bandpass filter,source-load coupling
更新于2025-09-04 15:30:14
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A high‐selectivity dual‐polarization filtering antenna with metamaterial for 5G application
摘要： A high-selectivity dual-polarization filtering antenna with metamaterial is presented in this letter. The multilayer coupled radiation structure of the antenna determines a filtering function. With the metamaterial layer designed above the antenna, a sharp roll-off rate at high pass band edge and a better out-of-band rejection occurs, thus a better high selective filtering characteristic can be achieved. Simulating the impedance bandwidth and measuring the antenna, (VSWR <2) of the antenna is from 3.25 GHz to 3.85 GHz; meanwhile, the maximum gain can reach 9dBi. The gain of antenna can quickly decrease 43dBi at the high pass band edge from 3.85 GHz to 4.05 GHz and the antenna has an out-of-band rejection level of 27dBi from 4.05 GHz to 5 GHz. The tested results verify our designs and the antenna could be a good candidate for the 5G anti-interference wireless terminal communication system.
关键词： high selectivity,metamaterial,filtering antenna,out-of-band rejection,dual polarization
更新于2025-09-04 15:30:14