| 1. |
- Fan, Jin, et al.
(författare)
-
Development of wideband orthomode transducers for FAST cryogenic receiver system
- 2020
-
Ingår i: Research in Astronomy and Astrophysics. - : IOP Publishing. - 1674-4527. ; 20:5
-
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
-
Ingår i: Proceedings of Science. - 1824-8039. ; 2012-October
-
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
-
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)
-
Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals.
- 2018
-
Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 50:8, s. 1112-1121
-
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
-
Ingår i: Nature (London). - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 533:7604, s. 539-542
-
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
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 10:5, s. 554-557
-
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
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:9, s. 8051-8058
-
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
-
Ingår i: Journal of Infrared, Millimeter, and Terahertz Waves. - : Springer Science and Business Media LLC. - 1866-6892 .- 1866-6906. ; 31:4, s. 469-480
-
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)
-
Printed monopole antenna with extremely wide bandwidth on liquid crystal polymer substrates
- 2011
-
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
-
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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| 11. |
- Abtahi, Shirin, 1982, et al.
(författare)
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A new compact multiband antenna for stroke diagnosis system over 0.5–3 GHz
- 2012
-
Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 54:10, s. 2342-2346
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new compact multiband antenna for stroke diagnosis systems over 0.5–3 GHz—the miniaturized self-grounded Bow-Tie antenna in a compact water-filled cylindrical bolus. A prototype of the antenna has been manufactured. Simulated and measured results have shown a low reflection coefficient, directional radiation characteristic, and a low radiation leakage-out ratio of the antenna.
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| 12. |
- Al-Rawi, Ali, 1985, et al.
(författare)
-
A new compact wideband MIMO antenna – the double-sided tapered self-grounded monopole array
- 2014
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 62:6, s. 3365 - 3369
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new compact wideband multiple input multiple output (MIMO) antenna—the double-sided 4-port arm-tapered self-grounded monopole array, briefly referred to as the butterfly antenna, in the communication. The antenna is very compact with low correlation between ports and high diversity gain. The genetic algorithm optimization scheme has been employed in the design. Simulation results have been verified against measurements. The measured reflection coefficients at all ports are below -7 dB over 0.5–9 GHz and below -4.5 dB over 0.4–0.5 GHz and 9–15 GHz. The measured correlation coefficients are below 0.4 over 0.4–15 GHz and lower than 0.1 in most of the frequency band. This new MIMO antenna is developed as a transmit antenna in reverberation chambers, and we believe that it will find more applications in other systems, such as micro base station antennas in wireless communication systems.
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| 13. |
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| 14. |
- Al-Rawi, Ali, 1985, et al.
(författare)
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The Double-sided 4-port Bow-tie Antenna: A New Compact Wideband MIMO Antenna
- 2013
-
Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013, Gothenburg, Sweden, 8-12 April 2013. - 2164-3342. - 9788890701832 ; , s. 3731-3735
-
Konferensbidrag (refereegranskat)abstract
- We present a new compact ultra-wideband 4-port antenna for use in MIMO systems, such as in reverberation chambers for OTA measurements. The new antenna is based on the self-grounded bow-tie antenna with a very compact size. The design was done through an optimization by employing the genetic algorithm in order to obtain low reflection coefficient and mutual coupling between ports. The designed antenna has an embedded radiation efficiency higher than -0.35 dB, reflection coefficient below -7 dB, mutual coupling between ports below - 12.5 dB (in most frequencies below -20 dB), over a frequency range of 0.4–15 GHz.
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| 15. |
- Albadalejo Lijarcio, Juan Luis, 1994, et al.
(författare)
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Substrate-Less Vertical Chip-to-Waveguide Transition for W-Band Array Antenna Integration
- 2023
-
Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - 2164-3342. - 9788831299077
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a vertical transition from a high permittivity GaAs MMIC to rectangular waveguide using bondwires as a coupling structure. The transition is advantageous for the direct integration of any off-the-shelf chip into a waveguide antenna since no modification of the GSG-pad or additional substrate is needed. An EBG structure consisting of pins is used for the packaging of the chip in order to avoid field propagation in undesired directions. The simulations results show that the reflection coefficient is lower than -10 dB and the average insertion loss is better than 0.5 dB from around 87 to 101 GHz (14% relative bandwidth).
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| 16. |
- Algaba Brazalez, Astrid, 1983, et al.
(författare)
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Design of F-Band Transition From Microstrip to Ridge Gap Waveguide Including Monte Carlo Assembly Tolerance Analysis
- 2016
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 64:4, s. 1245-1254
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes the design and realization of a transition from a microstrip line to a ridge gap waveguide operating between 95 and 115 GHz. The study includes simulations, measurements, and a Monte Carlo analysis of the assembly tolerances. The purpose of this tolerance study is to identify the most critical misalignments that affect the circuit performance and to provide guidelines about the assembly tolerance requirements for the proposed transition design.
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| 17. |
- Alibakhshikenari, Mohammad, et al.
(författare)
-
Dual-Polarized Highly Folded Bowtie Antenna with Slotted Self-Grounded Structure for Sub-6 GHz 5G Applications
- 2022
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:4, s. 3028-3033
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a novel dual-polarized highly-folded self-grounded Bowtie antenna that is excited through I-shaped slots is proposed for applications in sub-6GHz 5G multiple-input-multiple-output (MIMO) antenna systems. The antenna consists of two pairs of folded radiation petals whose base is embedded in a double layer of FR-4 substrate with a common ground-plane which is sandwiched between the two substrate layers. The ground-plane is defected with two I-shaped slots located under the radiation elements. Each pair of radiation elements are excited through a microstrip line on the top layer with RF signal that is 180° out of phase with respect to each other. The RF signal is coupled to the pair of feedlines on the top layer through the I-shaped slots from the two microstrip feedlines on the underside of the second substrate. The proposed feed mechanism gets rid of the otherwise bulky balun. The Bowtie antenna is a compact solution with dimensions of 32 32 33.8 mm3. Measured results have verified that the antenna operates over a frequency range of 3.1–5 GHz and exhibits an average gain and antenna efficiency in the vertical and horizontal polarizations of 7.5 dBi and 82.6%, respectively.
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| 18. |
- Alibakhshikenari, Mohammad, et al.
(författare)
-
Wideband Sub-6 GHz Self-Grounded Bow-Tie Antenna with New Feeding Mechanism for 5G Communication Systems
- 2019
-
Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. ; March 2019
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a self-grounded directional Bow-Tie antenna with a novel feed structure for sub-6 GHz applications in 5G communication systems covering 3.35-4.4 GHz. The antenna consists of two petal shaped metal structures that are fed by a bend microstrip line with an out-of-phase excitation. The petals are anchored on a common ground-plane. The feed mechanism used to excite the petals is by EM coupling from a single open-circuited microstrip line implemented behind the ground-plane. The coupling of EM energy from the input microstrip line to the feed microstrip line is controlled via an I-shaped slot printed on the ground-plane. The proposed antenna offers good impedance matching across its operating frequency range with VSWR<2 and exhibits an average gain of 20 dBi for an 8×8 element antenna array.
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| 19. |
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| 20. |
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| 21. |
- Cao, Jianyin, et al.
(författare)
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W-band high-gain low profile circularly polarized magneto-electric dipole antenna array with gap waveguide feeding technology
- 2018
-
Ingår i: IET Conference Publications. ; 2018:CP741
-
Konferensbidrag (refereegranskat)abstract
- In this paper, a high gain circularly polarized (CP) aperture-coupled magneto-electric (ME) dipole antenna array excited by the air cavity in gap waveguide (GWG) feeding technology in W-band is proposed. This antenna array is composed of two layers, upper CP ME-dipole antenna subarrays and lower metallic GWG feeding networks. The planar antenna array structure is realized by the high mode air cavity feeding network, which is realized by extending the 1×2 cavity to 3×2 cavity using more shorted pins to split the electromagnetic field. The whole single-layer GWG feeding network is composed of a ridge gap waveguide (RGWG) transmission structure and short-ended vertical polarized groove gap waveguide (VP-GGWG) high mode air cavities. The transmission loss caused by the coupling and the fabrication tolerance can be reduced by combining the RGWG and GGWG in the same layer. In addition, the feeding network is fabricated all in metal with no substrate loss. Transverse slots are etched at the right position of the printed circuit board (PCB) backside to excite the CP ME-dipoles. The antenna element has stable radiation patterns and wide axial-ratio (AR) bandwidth. The proposed 3×8 planner antenna array has a maximum boresight gain of 22 dBi and an AR bandwidth of 10.8% for AR < 3 dB. In the frequency band from 87.7 to 97.7 GHz, a boresight gain above 20 dBi is achieved.
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| 22. |
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| 23. |
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| 24. |
- Chen, Lei, et al.
(författare)
-
A Method of Reducing Mutual Coupling for a Finite Array
- 2020
-
Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020. - 9788831299008
-
Konferensbidrag (refereegranskat)abstract
- A method of reducing mutual coupling for a finite array with the characteristics of wideband and beam steering is presented in this paper. By adding an extra decoupling network, the mutual coupling can be efficiently suppressed for the antenna array. To verify the validity of the proposed method, a 1 x 8 millimeter-wave array antenna based on the gap waveguide technology is used in this work. The simulation results show that the active reflection coefficients are improved from 6.98 dB to -8.29dB, and the mutual coupling between adjacent elements is reduced to below -16.73 dB covering 20-33 GHz with the beam steering angle range of +/- 70 degrees.
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| 25. |
- Chen, Lei, 1982, et al.
(författare)
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A Method of Reducing Mutual Coupling Using an Extra Coupling Path
- 2019
-
Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019.
-
Konferensbidrag (refereegranskat)abstract
- A method of reducing mutual coupling for a large-scale array with the wideband and beam steering characteristics is proposed in this work. An extra coupling path is intentionally introduced to reduce the mutual coupling among adjacent radiating elements. A millimeter wave array is used to verify the proposed method. The simulation results show that the mutual coupling between adjacent elements can be reduced to below -15 dB over the band of 19-39.5 GHz and this concept is viable even for the beam steering angle range of ±45°.
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| 26. |
- Chen, W., et al.
(författare)
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Directional dual-band slotted semi-circular inverted-F antenna for WLAN applications
- 2015
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 51:24, s. 1960-1961
-
Tidskriftsartikel (refereegranskat)abstract
- A simple and compact directional dual-band semi-circular inverted-F antenna for wireless local area network applications is reported. Two pairs of semi-circular slots as well as a pair of arms are employed to generate the dual resonances in the 2.4-2.48 and 5.2-5.8 GHz bands. The measured results show that the proposed antenna can provide two 10 dB impedance bandwidths of 160 MHz (2.40-2.56 GHz) and 900 MHz (4.95-5.85 GHz). Nearly constant directivities (about 4.7 dBi) are observed in the lower band, while directivities in the upper band vary between 6.3 and 8.6 dBi.
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| 27. |
- Chen, Zhixing, 1983, et al.
(författare)
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Design of Sector Antenna with Wideband 2D Hat-fed Reflector for Wireless Communications
- 2016
-
Ingår i: International Symposium on Antennas and Propagation (ISAP), Hobart, Australia, 9-12 November, 2015. ; , s. Art no 7447340-
-
Konferensbidrag (refereegranskat)abstract
- We present the design of a new sector reflector antenna with 2-dimensional hat feed in order to avoid the radio link disconnection in point-to-point link communication systems due to the swinging of link antennas when there is a strong wind or vibration. The antenna has a 32% bandwidth for both the reflection coefficient below -17.8dB and the sidelobes of the radiation pattern in vertical plane below ETSI Class 3 envelope, based on the simulated results.
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| 28. |
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| 29. |
- Dobsicek Trefna, Hana, 1979, et al.
(författare)
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Numerical Evaluation of Clinical Applicator for Microwave Hyperthermia Treatment of Head & Neck Tumors
- 2013
-
Ingår i: 7th European Conference on Antennas and Propagation.
-
Konferensbidrag (refereegranskat)abstract
- Design, analysis and evaluation of a novel antenna applicator for microwave hyperthermia. The self-grounded Bow-Tie antenna immersed in cylindrical water bolus serves as an array element. The applicator consists of 12 to 18 elementsarranged in one to three ring set-ups and operates at frequency range between 400 and 1000 MHz.
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| 30. |
- Dong, Bin, 1984, et al.
(författare)
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Design of an Asymmetrical Quadruple-ridge Flared Horn Feed: a Solution to Eliminate Polarization Discrepancy in the Offset Reflecting Systems
- 2018
-
Ingår i: IET Conference Publications. ; 2018:CP741
-
Konferensbidrag (refereegranskat)abstract
- Quadruple-ridge Flared Horns (QRFHs) have been showing qualified performance as the feed antennas for the reflecting systems in the Square Kilometre Array (SKA). However, due to the offset optics of the SKA reflecting system, identical illuminations from dual polarizations of the feed would but result in different system performance. This difference would become more severe towards high frequencies and may cause the worse polarization unqualified for the desired specification. In this paper, an asymmetrical QRFH feed working over Band B (4.6–24 GHz) is proposed and optimized to tackle this problem.The asymmetrical Band-B feed is composed of two different and orthogonal pairs of both ridges and sidewall quad-pieces, so as to provide orthogonal polarizations but different illuminations. Simulated results show that, by this asymmetrical design different beamwidths and different combinations of sub-efficiencies can be provided for two polarizations, so as to eliminate the polarization discrepancy over most of the bandwidth. Benefitting from this elimination, both polarizations of the Band-B feed have now achieved the SKA specification in terms of aperture efficiency.
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| 31. |
- Dong, Bin, 1984, et al.
(författare)
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Optimization and Realization of Quadruple-ridge Flared Horn with New Spline-defined Profiles as a High-efficiency Feed over 4.6–24 GHz
- 2019
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:1, s. 585-590
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new optimization and realization of a quadruple-ridge flared horn (QRFH) as a feed for reflector antennas of the Square Kilometre Array (SKA) project. The QRFH has been numerically optimized by spline-defined profiles for both the ridges and the horn sidewall, with a conical cavity in the back-short for maximum aperture efficiency. The final aperture efficiency better than (for horizontal polarization) or around (for vertical polarization) 78% over 4.6–8 GHz, 70% over 8–15 GHz, 65% over 15–20 GHz and 60% over 20–24 GHz in the SKA offset-Gregorian dual-reflector antenna has been achieved. The realization of the horn has been carried out carefully by applying several new mechanical design solutions in order to guarantee the accurate positioning of the ridges, the feeding pins and a good electrical contact. The measured S11 is mostly better than -10 dB and the predicted aperture efficiency based on the measured far field patterns agrees well with the simulated result. System performance, such as the sensitivity and system noise temperature, are also estimated and presented.
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| 32. |
- Emrich, Anders, 1962, et al.
(författare)
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Wideband Receivers for VLBI2010 Applications
- 2013
-
Ingår i: Progress in Electromagnetics Research Symposium, PIERS 2013, Stockholm, Sweden, August 12-15, 2013.
-
Konferensbidrag (refereegranskat)
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| 33. |
- Fan, Chong, et al.
(författare)
-
Online Diagnostic High Voltage Polymeric Outdoor Insulation Using Patch Antenna System
- 2019
-
Ingår i: 2019 International Symposium on Antennas and Propagation, ISAP 2019 - Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- To realize an online diagnosis system for accurate detection of internal defects in high voltage polymeric outdoor insulations, a novel patch antennas system which would detect the transmission signal level difference caused by internal defects of insulations is proposed. In this work, investigation by simulation is performed with regard to the conventional interfacial mm-ordered cracks in both transverse and longitudinal orientations in one kind of insulation, namely insulator. Receiving signal differences of 30-50 dB and 30-60 dB between insulators with and without defects have been observed over 1-10 GHz, respectively to transverse and longitudinal defects. The proposed method by patch antennas system is promising to realize online diagnostic high voltage polymeric outdoor insulations with defects.
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| 34. |
- Fan, Fangfang, 1981, et al.
(författare)
-
Bandwidth Investigation on Half-Height Pin in Ridge Gap Waveguide
- 2018
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:1, s. 100-108
-
Tidskriftsartikel (refereegranskat)abstract
- Gap waveguide is a promising transmission structure, especially for millimeter-wave (mmW) and terahertz applications. It does not require conductive connection between the upper and the lower plates, which makes this technology gain advantages over conventional rectangular waveguides and substrate integrated waveguides in an mmW and terahertz regime. Different fabrication methods for gap waveguides should be employed for different frequency bands applied, such as molding, milling, die forming, electrical discharge machining, microelectromechanical systems, and 3-D printing. Therefore, different pin forms used in gap waveguides are required to match the applied fabrication methods. In this paper, a new pin form, the half-height-pin form, in gap waveguides is proposed for reducing the fabrication cost, and its stopband characteristics are investigated and compared with the previous full-height pins in gap waveguides at the V -band. A device of a double-ridged gap waveguide with two 90° bends for verifying the stopband characteristic analysis of the new pin form has been designed and manufactured. The measured data confirm our analysis and simulations.
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| 35. |
- Fan, Fangfang, 1981, et al.
(författare)
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Half-height Pins – a New Pin Form in Gap Waveguide for Easy Manufacturing
- 2016
-
Ingår i: 2016 10th European Conference on Antennas and Propagation, EuCAP 2016. - 9788890701863 ; , s. Art. no. 7481931-
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Konferensbidrag (refereegranskat)abstract
- Gap waveguide is a promising transmission structure, especially for millimeter wave and THz applications. It does not require conductive connection between the top and bottom plates, and therefore this technology gain advantages over conventional rectangular waveguides and SIWs (Substrate Integrated Waveguides) above 100 GHz. In this paper, a new pin form, the half-height pin, is proposed for the gap waveguide. This new half-height pin form has similar stop-band performance as the previous quarter-wavelength long pin form. However, there must be such half-height pins on both the upper and lower plates, in contrast to one of the two having pins in the original gap waveguide. The shorter length of the pins makes the fabrication of the pin surface much easier, such as by e.g. die-forming, molding or MEMS technology. The current work paves the way for mass production of gap waveguide devices and systems at millimeter wave and THz.
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| 36. |
- Fan, F., et al.
(författare)
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Q factor and insertion loss analysis of half-height pin ridge gap waveguide
- 2016
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Ingår i: Proceedings of the 2016 18th International Conference on Electromagnetics in Advanced Applications, ICEAA 2016. Cairns; Australia; 19-23 September 2016. ; 2 November, s. Art no 7731472, Pages 622-624
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Konferensbidrag (refereegranskat)abstract
- The promising millimeter wave transmission structure, gap waveguide, has advantageous characteristic compared to conventional ones. As for the ridge gap waveguide (RGW) and groove gap waveguide (GGW), they usually can be fabricated by milling technology, the height and the gap between the pins always are the main factors for the cost. Recently, half-height pin, a new pin form, is proposed for the gap waveguide technology to effectively reduce the manufacture cost and difficulty. In this paper, the Q values and insertion loss of the RGW using half-height pins will be investigated carefully in terms of the structure of the ridge and pins.
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| 37. |
- Fan, Jin, et al.
(författare)
-
Compact wideband bowtie dipole orthomode transducer
- 2019
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Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 61:4, s. 883-885
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Tidskriftsartikel (refereegranskat)abstract
- A compact wideband orthomode transducer (OMT) with an octave bandwidth is proposed for a 0.56-1.12 GHz receiver system in the five hundred meter aperture spherical radio telescope. The OMT operates in a cryostat at a temperature of 70 K and therefore it is critical to minimize its dimension while insuring good electrical properties. The complete OMT comprises 2 bowtie dipoles orthogonally arranged in a circular waveguide. Because of the innovative structure, competing modes, TM01 TE21, and TE01, have been effectively suppressed, and the bandwidth of the dominate mode TE11 has achieved to 2.08:1. The final optimized OMT has a length of 300 mm, shorter than a half of the popular quardruple-ridged waveguide OMT. Measurements at room temperature agree well with simulation results, with a reflection coefficient below -10 dB for both polarizations and cross-coupling levels of -30.5 dB over the whole required frequency range.
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| 38. |
- Fan, Jin, et al.
(författare)
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Design of Novel Flat Bend Crossed Dipole for Wideband Phased Array Feed Applications
- 2019
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Ingår i: 2019 International Symposium on Antennas and Propagation, ISAP 2019 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- This paper presents a novel Phased Array Feed (PAF) element based on flat bend crossed dipole fed by 50-Ohm coaxial line. The PAF element is dual-polarized and made from all-metal to minimize Ohmic losses and simplify cryogenic integration. It is optimized for 4- 8 GHz band aiming to possible later integration in the SKA pathfinder PHAROS2. The proposed design can also be a good element candidate of PAF for the Five hundred meter Aperture Spherical Telescope (FAST) and Qi Tai Telescope (QTT) as well as other large radio telescopes.
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| 39. |
- Fan, Jin, et al.
(författare)
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Design of Octave-bandwidth Phased Array Feed for Large Radio Telescope
- 2019
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Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019.
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Konferensbidrag (refereegranskat)abstract
- This paper presents design scenarios of Octave-bandwidth Phase Array Feed (PAF) based on a novel wideband dual polarized tightly-fed Bowtie antenna element. The PAF is optimized for the 4 - 8GHz band aiming to possible later integration in the SKA pathfinder PHAROS2. The proposed design can be a good candidate of PAF for the Five hundred meter Aperture Spherical Telescope (FAST) and Qi Tai Telescope (QTT) as well as other large radio telescopes.
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| 40. |
- Fan, Jin, et al.
(författare)
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Design of Ultra-Wideband Phased Array Feed for Radio Telescope
- 2020
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Ingår i: 2020 33rd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2020.
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Konferensbidrag (refereegranskat)abstract
- This paper presents an ultra-wideband Phased Array Feed (PAF) based on novel flat bend crossed dipole fed by 50Ohm coaxial line. The PAF is dual-polarized and made from all-metal to minimize Ohmic losses and simplify cryogenic integration. It is optimized for 1-2 GHz band and can be good PAF candidate for the Five hundred meter Aperture Spherical Telescope (FAST) and Qi Tai Telescope (QTT) as well as other radio telescopes.
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| 41. |
- Fan, Jin, et al.
(författare)
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Investigation of ultra-wideband Bowtie antennas for phased array feed application
- 2020
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Ingår i: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 30:11
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Tidskriftsartikel (refereegranskat)abstract
- In this article, two new ultra-wideband (UWB) dual-polarized Bowtie antennas are investigated as the elements for a phased array feed for reflectors. In addition to its UWB impedance matching characteristic, the Bowtie antennas have stable large beam-width and a low cross-polar level over a wide frequency band with a compact size, which is an essence for phased array applications. The simulated and measured results state a low ohmic loss, good impedance matching (S11 below −15 dB) and good radiation performance, with a simple structure for easy manufacturing. The proposed antennas can be good candidates for phased array feed (PAF) in FAST and the SKA (square kilometer array) pathfinder PHAROS2 projects, and massive MIMO antennas in wireless communication systems.
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| 42. |
- Fang, Mu, 1992, et al.
(författare)
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1-Dimensional Wide Scanning Gap Waveguide Based Slot Array Antenna using Decoupling Technique for 100 GHz Applications
- 2024
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 72:4, s. 3438-3450
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a 1-dimenional wide scanning slot array antenna based on ridge gap waveguide (RGW), operating at a 100 GHz band. A novel half wall decoupling structure is proposed to reduce the mutual coupling and the reflection coefficient simultaneously, thus achieving a more stable active reflection coefficient (ARC) within the ±60° scanning range. At the same time, special attention has been given in retaining the embedded pattern suitable for wide scanning performance. An 8-element slot array antenna (8×8 slots) with two different feeding networks is fabricated and measured to verify the scanning performance. The prototype achieves 91% total efficiency while scanned up to 60° with 3 dB scanning loss. The measured results show good agreement with the simulations both for the reflection coefficient and radiation performance.
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| 43. |
- Fang, Mu, 1992, et al.
(författare)
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A Comparative Study of Decoupling Techniques for Waveguide Slot Array Antennas
- 2024
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Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024.
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a comparative study of three decoupling techniques for waveguide slot array antennas, including half wall, corrugation and metal fence. Their decoupling efficacy and impact on element patterns are investigated under two typical element spacings: 0.5λ0 and 1λ0. A summary highlighting the differences among these three decoupling techniques is provided to gain insight into which specific application scenarios are best suited for each technique.
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| 44. |
- Fang, Mu, 1992, et al.
(författare)
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Design of a Gap Waveguide Based Unit Cell for 1-D Beam Scanning Application at W-band
- 2023
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Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023.
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a 1-D scanning slot array unit cell column based on ridge gap waveguide technology which can be a good candidate for wide scanning antenna applications at 100GHz. A parametric analysis of the proposed model is organized to demonstrate the merits and potential performance. Simulated data in terms of H-plane pattern and impedance bandwidth as well as the scanning characteristics has been investigated for the unit cell column of slot array. Also, design concerns regarding manufacturing issues and corresponding mechanical challenges have been taken into account while doing the electromagnetic design. The chosen unit cell which consists of a column of slot array works with 6-16% impedance bandwidth and achieves a scanning up to ± 60° in one dimension.
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| 45. |
- Fayazi, Seyedeh Shaghayegh, et al.
(författare)
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Microwave imaging of near-field object using ultra-wideband synthetic aperture radar algorithm
- 2012
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Ingår i: 2012 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM (APSURSI). - 1522-3965. - 9781467304627
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Konferensbidrag (refereegranskat)abstract
- A simple procedure that suppresses artefact from ultra-wideband (UWB) synthetic aperture radar (SAR) images is proposed and verified using experimental data. The proposed imaging solution is useful for imaging small objects located in the near-field region with less ambiguity.
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| 46. |
- Fayazi, Seyedeh Shaghayegh, et al.
(författare)
-
UWB SAR Imaging of Near-Field Object for Industrial Process Applications
- 2013
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Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013, Gothenburg, Sweden, 8-12 April 2013. - 2164-3342. - 9781467321877 ; , s. 2245-2248
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Konferensbidrag (refereegranskat)abstract
- Ultra wideband technology becomes more widely used for near-field object detection. We present an aperture synthetic radar (SAR) system using ultra-wideband (UWB) signals for such applications. One of the problems with UWB time-domain SAR imaging algorithm is the artefact originated from scattered field of adjacent objects. In this paper an algorithm based on the Range Point Migration (RPM) method is used to alleviate this problem. This method estimates a possibility distribution of the optimal Direction of Arrival (DOA) of the scattered field from objects. A weighting factor based on this possibility is used to suppress the effect of artifact scattered fields. The results in the paper show that the UWB SAR accompanied with RPM can produce an image of an object with a significant suppression of undesired artifact from scattered field of adjacent objects.
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| 47. |
- Ferrando-Rocher, Miguel, et al.
(författare)
-
8 x 8 Ka-Band Dual-Polarized Array Antenna Based on Gap Waveguide Technology
- 2019
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:7, s. 4579-4588
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes an 8 x 8 fully metallic high-efficiency dual-polarized array antenna working at the Ka-band, based on the gap waveguide (GW) concept. The radiating element is a circular aperture backed by two stacked cylindrical cavities, which are orthogonally fed to achieve a dual-polarized performance. Both feeding layers consist of a GW corporate network to reach all the cavities backing each radiating element. Cavities are naturally integrated within the bed of nails hosting grooves and ridges for the guiding electromagnetic (EM) field, leading to a low-profile dual-polarized array in the Ka-band. The experimental results present good agreement with simulations. The measured radiation patterns agree well with the simulation and the antenna provides an average gain over 27 dBi within its operating bandwidth (29.5-31 GHz).
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| 48. |
- Ferrando-Rocher, M., et al.
(författare)
-
A dual-polarized slotted-waveguide antenna based on gap waveguide technology
- 2017
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Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017. ; , s. 3726-3727
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Konferensbidrag (refereegranskat)abstract
- Euraap.This paper describes a wide-band dual-polarized slotted-waveguide antenna working at V-band (57-66 GHz) based on Gap Waveguide concept. The antenna has three layers. The first one (feeding-layer 1) is practically identical to the second one (feeding-layer 2). This optimizes the design and facilitates manufacturing. The corporate-feeding networks on the two layers are rotated 90 degrees to each other to get the two orthogonal polarizations. Radiating elements are square apertures located on the top of the antenna. Simulated results show both impedance bandwidth and radiation pattern bandwidth greater than 15% for both polarizations.
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| 49. |
- Flygare, Jonas, 1988, et al.
(författare)
-
Beyond-Decade Ultrawideband Quad-Ridge Flared Horn With Dielectric Load From 1 to 20 GHz
- 2023
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 71:3, s. 2110-2125
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we present a novel dielectrically loaded quad-ridge flared horn (QRFH) as a reflector feed with beyond-decade ultrawideband performance. The dielectric is machined in a low-loss, space-grade polyimide specified with low outgassing for a vacuum environment. The feed covers 1–20 GHz bandwidth with a measured band-average input reflection of −13.6 and 41.5 dB isolation between two orthogonal polarized ports. Predicted performance in a paraboloidal reflector with a 60° half-subtended angle is 62% aperture efficiency average over the band. The ridges of the horn are designed with analytic-spline-hybrid 3-D profiles with thickness flaring outwards toward the feed aperture, improving low-frequency polarization properties. The QRFH was manufactured in four quarters for accurate ridge-to-ridge alignment and a reduced number of interfaces for good thermal properties in cryogenic applications. A prototype feed has been installed and tested with promising results in one of the 6 m offset Gregorian reflectors of the Allen Telescope Array (ATA) located at the Hat Creek Observatory, Hat Creek, CA, USA.
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| 50. |
- Flygare, Jonas, 1988, et al.
(författare)
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Strategy and Overview for Development of Beyond-Decade-Bandwidth Quad-ridge Flared Horns for Radio Astronomy
- 2021
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Ingår i: 15th European Conference on Antennas and Propagation, EuCAP 2021.
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Konferensbidrag (refereegranskat)abstract
- This paper considers the potential of the dielectrically loaded Quad-ridge Flared Horn (QRFH) feed to provide continuous beyond-decade bandwidth in reflector telescopes for radio astronomy. An overview of the beam pattern evolution over frequency in a recent ultra-wideband feed designed for 1.5–15.5 GHz is presented.
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