| 1. |
- Fan, Jin, et al.
(författare)
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Development of wideband orthomode transducers for FAST cryogenic receiver system
- 2020
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Ingår i: Research in Astronomy and Astrophysics. - : IOP Publishing. - 1674-4527. ; 20:5
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the design, construction, and performance of the wideband orthomode transducers (OMTs) for the L- (1.2-1.8 GHz), the S- (2-3 GHz) and the P- (0.56-1.12 GHz) band receiver systems of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These OMTs operate at the cryogenic temperature of 70K to reduce their thermal noise contribution to the receiver chains. The development on the FAST L- and S-band quad-ridged waveguide (QRWG) OMTs is carried out based on the theoretical mode analysis. In view of the miniaturization of FAST cryogenic receiver system at P-band, a novel wideband compact bowtie dipole OMT is designed with an octave bandwidth as well as a length of only quarter wavelength. The proposed L-, S- and P-band OMTs are designed and optimized by using Ansys High Frequency Structure Simulator (HFSS), and then manufactured, tested at room temperature. Measurement of FAST cryogenic receiver system noise is also performed with the L-, S- and P-band OMTs installed. The measured results fully comply with the design specifications.
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| 2. |
- Geralt bij de Vaate, J., et al.
(författare)
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Wide bandwidth integrated 1-4 GHz feed development for VLBI and SKA
- 2012
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Ingår i: Proceedings of Science. - 1824-8039. ; 2012-October
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Konferensbidrag (refereegranskat)abstract
- Wide-band single pixel feeds such as the wide-band Eleven feed developed in Europe through Onsala Space Observatory/Chalmers are rapidly increasing in maturity. Compared to the traditional octave bandwidth feeds, wide bandwidth feeds, such as the Eleven feed, will create the possibility of significantly larger instantaneous frequency coverage observations with existing radio telescopes, such as those used in the VLBI networks, and for future radio telescopes, such as the Square Kilometre Array. This Project is supported by RadioNet3, Developments In VLBI Astronomy (DIVA).
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| 3. |
- Jian, Qiuchi, 1984, et al.
(författare)
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Detection of breathing and heartbeat by using a simple UWB radar system
- 2014
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Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - 2164-3342. - 9788890701849 ; , s. 3078-3081
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Konferensbidrag (refereegranskat)abstract
- We present the development on an ultra-wideband (UWB) radar system and its signal processing algorithms for detecting human breathing and heartbeat in the paper. The UWB radar system consists of two (Tx and Rx) antennas and one compact CMOS UWB transceiver. Several signal processing techniques are developed for the application. The system has been tested by real measurements. .
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| 4. |
- Lee, James J, et al.
(författare)
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Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals.
- 2018
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Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 50:8, s. 1112-1121
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Tidskriftsartikel (refereegranskat)abstract
- Here we conducted a large-scale genetic association analysis of educational attainment in a sample of approximately 1.1million individuals and identify 1,271independent genome-wide-significant SNPs. For the SNPs taken together, we found evidence of heterogeneous effects across environments. The SNPs implicate genes involved in brain-development processes and neuron-to-neuron communication. In a separate analysis of the X chromosome, we identify 10independent genome-wide-significant SNPs and estimate a SNP heritability of around 0.3% in both men and women, consistent with partial dosage compensation. A joint (multi-phenotype) analysis of educational attainment and three related cognitive phenotypes generates polygenic scores that explain 11-13% of the variance in educational attainment and 7-10% of the variance in cognitive performance. This prediction accuracy substantially increases the utility of polygenic scores as tools in research.
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| 5. |
- Smith, Jennifer A, et al.
(författare)
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Genome-wide association study identifies 74 loci associated with educational attainment
- 2016
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Ingår i: Nature (London). - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 533:7604, s. 539-542
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Tidskriftsartikel (refereegranskat)abstract
- Educational attainment is strongly influenced by social and other environmental factors, but genetic factors are estimated to account for at least 20% of the variation across individuals. Here we report the results of a genome-wide association study (GWAS) for educational attainment that extends our earlier discovery sample of 101,069 individuals to 293,723 individuals, and a replication study in an independent sample of 111,349 individuals from the UK Biobank. We identify 74 genome-wide significant loci associated with the number of years of schooling completed. Single-nucleotide polymorphisms associated with educational attainment are disproportionately found in genomic regions regulating gene expression in the fetal brain. Candidate genes are preferentially expressed in neural tissue, especially during the prenatal period, and enriched for biological pathways involved in neural development. Our findings demonstrate that, even for a behavioural phenotype that is mostly environmentally determined, a well-powered GWAS identifies replicable associated genetic variants that suggest biologically relevant pathways. Because educational attainment is measured in large numbers of individuals, it will continue to be useful as a proxy phenotype in efforts to characterize the genetic influences of related phenotypes, including cognition and neuropsychiatric diseases.
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| 6. |
- Yang, Xinxin, 1988, et al.
(författare)
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A linear-array of 300-GHz antenna integrated GFET detectors on a flexible substrate
- 2020
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 10:5, s. 554-557
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Tidskriftsartikel (refereegranskat)abstract
- Terahertz imaging has potential in a variety of applications, such as non-invasive inspection, medical examination, and security. Many of these applications call for flexible focalplane arrays with large fields of view. Here, we demonstrate the implementation of a flexible, 300 GHz, 1 6 linear detector array based on graphene field-effect transistors and integrated bowtie antennas. Conservative estimates based on room temperature measurements at 300 GHz show element voltage responsivities in he range from 20 V/W to 70 V/W, and noise equivalent powers in the range from 0.06 nW/Hz0.5 to 0.2 nW/Hz0.5. Measured radiation patterns, showing good agreement with simulations, reveal half-power beamwidths of 45 and 60 for H- and E-planes, respectively. Characterization of the antenna array in a curved configuration shows that the voltage response is reduced up to 3 dB compared to the flat configuration due to a decrease of the antenna directivity. We believe that our preliminary results could serve as an enabling platform for the future development of flexible antenna arrays based on GFETs for curved focal plane imaging, important for wearable sensors and many other applications.
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| 7. |
- Zhang, Tianling, 1981, et al.
(författare)
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Ultra-wideband Full-metal Planar Array Antenna with a Combination of Ridge Gap Waveguide and E-plane Groove Gap Waveguide
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:9, s. 8051-8058
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Tidskriftsartikel (refereegranskat)abstract
- An ultra-wideband (UWB) full-metal planar array antenna based on a combination of ridge gap waveguide (RGW) and E-plane groove gap waveguide (E-GGW) is presented for millimeter-wave (mmWave) applications. First, the radiation element of a double-step double-ridged slot structure is proposed and designed. With removing the vertical walls of the cavity in the H-plane, the impedance matching characteristics presents a UWB bandwidth of 53%. Second, a UWB double-layer feeding network is achieved by combining RGWs and double-side-pin E-GGWs for the radiation elements. Finally, an 8 × 8 full-metal planar array antenna with the presented elements and network is designed, prototyped and measured. The measured results agree well with the simulated results. The proposed antenna provides an impedance matching bandwidth (|S11| < -10 dB) of 46.8% from 18.8 to 30.3 GHz. The maximum gain is 27.7 dBi at 27 GHz and a stable gain of 26 ± 1.7 dBi is obtained over the operation band.
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| 8. |
- Zhang, Xia, 1980, et al.
(författare)
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Design of Printed Monopole Antennas on Liquid Crystal Polymer Substrates
- 2010
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Ingår i: Journal of Infrared, Millimeter, and Terahertz Waves. - : Springer Science and Business Media LLC. - 1866-6892 .- 1866-6906. ; 31:4, s. 469-480
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a compact printed monopole antenna with an extremely wide bandwidth has been realized on Liquid Crystal Polymer (LCP) substrates by using standard processing technology. Both laminated and directed metalized LCP substrates were used in this experiment. The antenna made on the direct metalized LCP substrate performed well compared to on the laminated LCP substrate. To improve the adhesion, the surface of the LCP was further roughened and a certain adhesion layer was used prior to the deposition of Cu. The measured antenna on a metalized LCP substrate could cover this frequency band with an impedance bandwidth from 0.51 GHz to 14.4 GHz (28.2:1) for VSWRa parts per thousand currency sign2. Moreover, the antenna exhibits a nearly omni-directional radiation pattern. The size of this antenna is only about 0.18 lambda(1) x 0.13 lambda(1), where lambda(1) is the wavelength of the lowest operating frequency. The results show that LCP is a promising candidate for high frequency applications.
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| 9. |
- Zhang, X., et al.
(författare)
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Printed monopole antenna with extremely wide bandwidth on liquid crystal polymer substrates
- 2011
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Ingår i: Proceedings - 12th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2011, Shanghai, 8-11 August 2011. - 9781457717680 ; , s. 1157-1159
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Konferensbidrag (refereegranskat)abstract
- This letter presents a printed monopole antenna with extremely wide bandwidth on a liquid crystal polymer (LCP) substrate. It consists of a hollowed elliptical monopole, two trapeziform ground planes and a tapered co-planar waveguide (CPW) feeder. By using standard processing technology, this monopole antenna is fabricated on the direct metalized LCP film substrate. The fabricated antenna can achieve an extremely wide impedance bandwidth, a nearly omnidirectional radiation pattern and a compact size, which verifies that LCP materials are very suitable as substrates for commercial wireless applications.
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| 10. |
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