The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Mohamed Himdi - One of the best experts on this subject based on the ideXlab platform.
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Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: M. Kamran Saleem, Hamsakutty Vettikaladi, Majeed A. S. Alkanhal, Mohamed HimdiAbstract:This communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 ( $\varepsilon _{r} = 1.12$ ), which is drilled and pressed to achieve the different dielectric constant needed to follow the Index Law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz.
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Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: M. Kamran Saleem, Majeed A. S. Alkanhal, Hamsakutty Vettikaladi, Mohamed HimdiAbstract:This communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 (r = 1.12), which is drilled and pressed to achieve the different dielectric constant needed to follow the Index Law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz. © 1963-2012 IEEE.
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Smooth plate Luneburg lens with superstrate
2015Co-Authors: J. Bór, O. Lafond, Mohamed Himdi, H. Merlet, P. LebarsAbstract:This paper deals with a new technological process allowing to manufacture a Luneburg lens antenna with a smooth gradient Index Law following the theoretical one. The technological process is validated through the design of a 60GHz plate Luneburg lens. Moreover, a dielectric superstrate is added front of the lens to narrow the beam in the E plane and so increase the antenna gain. Measurement results are compared to simulated ones and a good accuracy is demonstrated.
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Foam Based Luneburg Lens Antenna at 60 GHz
Progress In Electromagnetics Research Letters, 2014Co-Authors: Jonathan Bor, Olivier Lafond, Herve Merlet, Philippe Le Bars, Mohamed HimdiAbstract:An innovative technological process is investigated to easily manufacture inhomogeneous Luneburg lenses. A unique foam material is drilled and pressed to achieve the difierent dielectric constant needed to follow the Index Law inside the lens. The performance of such 60GHz antenna is described and the antenna prototype is measured in terms of gain and radiation patterns. The results show a good e-ciency (60% with a directivity of 18{19dBi) and demonstrate the feasibility of this kind of Luneburg lens, through the use of a simple technological process. The lens with a diameter of 56mm and a thickness of 3mm operates in the 57{66GHz bandwidth. The magnitude of S11 parameter is under i10dB in the whole bandwidth and an half-power beamwidth of 5 - and 50 - in H-plane and E-plane respectively is reached.
J.n. Ness - One of the best experts on this subject based on the ideXlab platform.
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Relationship between melt shear viscosity and molecular parameters based on high impact polystyrenes in capillary extrusion
Polymer Testing, 1999Co-Authors: Ji-zhao Liang, J.n. NessAbstract:The flow behaviour of three high impact polystyrene (HIPS) melts in extrusion has been investigated by using a capillary rheometry in a wide range of shear rates. It was found that the relationship between end pressure drop and apparent shear rate approximately obeyed the Index Law; the shear flow behaviour of the sample melts was more in keeping with the Index Law at higher shear rates than at lower shear rates; and the dependence of the apparent shear viscosity on temperature could be described by the Arrhenius equation under the experimental conditions. On the basis of comparison of the shear-sensitivity and the temperature-sensitivity for the melts, the relationship between steady-shear melt viscosity and molecular parameters was discussed.
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Effect of die angle on flow behaviour for high impact polystyrene melt
Polymer Testing, 1997Co-Authors: Ji-zhao Liang, J.n. NessAbstract:Abstract The influence of die angle on the flow behaviour for high impact polystyrene (HIPS) melt is investigated by using a set of capillaries with a series of entry angles (2α) in this work. It appears that the melt flow basically obeys the Index Law; the dependence of apparent shear viscosity (η a ) on temperature roughly accords with the Arrhenius equation and the values of η a changes with 2α to some extent. The end effect of the melt is significant under experimental conditions, and the end pressure losses (ΔP ends ) decrease with increasing 2α; there is a local minimal value of ΔP ends at 2α around 75 °.
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Influence of the extrusion conditions on the flow behaviour of polystyrene melts
Journal of Materials Processing Technology, 1997Co-Authors: Ji-zhao Liang, J.n. NessAbstract:Abstract The influence of the extrusion conditions on the flow behaviour of a general polystyrene and a high impact polystyrene melt was investigated with a capillary rheometer. It was found that the end effect and the non-Newtonian property of the latter were more evident than those of the former, and that the shear-sensitivity of viscosity of the latter was greater than that of the former; but the temperature-sensitivity of viscosity for the former melt was relatively pronounced. The shear flow of the two sample melts basically obeyed the Index Law. In addition, the effect of the die angle on the flow behaviour of the melts was significant.
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Studies on melt flow properties of low density and linear low density polyethylene blends in capillary extrusion
Polymer Testing, 1997Co-Authors: Ji-zhao Liang, J.n. NessAbstract:Abstract Two linear low density polyethylenes (LLDPE) with a different melt flow Index (MI) are selected to blend with a low density polyethylene (LDPE) in molten state by means of a screw extruder. The flow behaviour of the blend melts is studied by using capillary rheometry under rear practical processing conditions. The results indicate that with addition of the weight percentage content ( φ LD ) of LDPE the end pressure losses decrease for the blends with low MI LLDPE and increase for the blends with high MI LLDPE. These are similar to the case of apparent shear viscosity ( η a ) of the blend melts. The dependence of η a on temperature can be described by the Arrhenius equation. The relationship between η a and component viscosity accords with the logarithmic mixing rule, and the shear flow of the blend melts basically obeys the Index Law.
Ji-zhao Liang - One of the best experts on this subject based on the ideXlab platform.
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Relationship between melt shear viscosity and molecular parameters based on high impact polystyrenes in capillary extrusion
Polymer Testing, 1999Co-Authors: Ji-zhao Liang, J.n. NessAbstract:The flow behaviour of three high impact polystyrene (HIPS) melts in extrusion has been investigated by using a capillary rheometry in a wide range of shear rates. It was found that the relationship between end pressure drop and apparent shear rate approximately obeyed the Index Law; the shear flow behaviour of the sample melts was more in keeping with the Index Law at higher shear rates than at lower shear rates; and the dependence of the apparent shear viscosity on temperature could be described by the Arrhenius equation under the experimental conditions. On the basis of comparison of the shear-sensitivity and the temperature-sensitivity for the melts, the relationship between steady-shear melt viscosity and molecular parameters was discussed.
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Effect of die angle on flow behaviour for high impact polystyrene melt
Polymer Testing, 1997Co-Authors: Ji-zhao Liang, J.n. NessAbstract:Abstract The influence of die angle on the flow behaviour for high impact polystyrene (HIPS) melt is investigated by using a set of capillaries with a series of entry angles (2α) in this work. It appears that the melt flow basically obeys the Index Law; the dependence of apparent shear viscosity (η a ) on temperature roughly accords with the Arrhenius equation and the values of η a changes with 2α to some extent. The end effect of the melt is significant under experimental conditions, and the end pressure losses (ΔP ends ) decrease with increasing 2α; there is a local minimal value of ΔP ends at 2α around 75 °.
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Influence of the extrusion conditions on the flow behaviour of polystyrene melts
Journal of Materials Processing Technology, 1997Co-Authors: Ji-zhao Liang, J.n. NessAbstract:Abstract The influence of the extrusion conditions on the flow behaviour of a general polystyrene and a high impact polystyrene melt was investigated with a capillary rheometer. It was found that the end effect and the non-Newtonian property of the latter were more evident than those of the former, and that the shear-sensitivity of viscosity of the latter was greater than that of the former; but the temperature-sensitivity of viscosity for the former melt was relatively pronounced. The shear flow of the two sample melts basically obeyed the Index Law. In addition, the effect of the die angle on the flow behaviour of the melts was significant.
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Studies on melt flow properties of low density and linear low density polyethylene blends in capillary extrusion
Polymer Testing, 1997Co-Authors: Ji-zhao Liang, J.n. NessAbstract:Abstract Two linear low density polyethylenes (LLDPE) with a different melt flow Index (MI) are selected to blend with a low density polyethylene (LDPE) in molten state by means of a screw extruder. The flow behaviour of the blend melts is studied by using capillary rheometry under rear practical processing conditions. The results indicate that with addition of the weight percentage content ( φ LD ) of LDPE the end pressure losses decrease for the blends with low MI LLDPE and increase for the blends with high MI LLDPE. These are similar to the case of apparent shear viscosity ( η a ) of the blend melts. The dependence of η a on temperature can be described by the Arrhenius equation. The relationship between η a and component viscosity accords with the logarithmic mixing rule, and the shear flow of the blend melts basically obeys the Index Law.
Majeed A. S. Alkanhal - One of the best experts on this subject based on the ideXlab platform.
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Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: M. Kamran Saleem, Hamsakutty Vettikaladi, Majeed A. S. Alkanhal, Mohamed HimdiAbstract:This communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 ( $\varepsilon _{r} = 1.12$ ), which is drilled and pressed to achieve the different dielectric constant needed to follow the Index Law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz.
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Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: M. Kamran Saleem, Majeed A. S. Alkanhal, Hamsakutty Vettikaladi, Mohamed HimdiAbstract:This communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 (r = 1.12), which is drilled and pressed to achieve the different dielectric constant needed to follow the Index Law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz. © 1963-2012 IEEE.
Hamsakutty Vettikaladi - One of the best experts on this subject based on the ideXlab platform.
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Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: M. Kamran Saleem, Hamsakutty Vettikaladi, Majeed A. S. Alkanhal, Mohamed HimdiAbstract:This communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 ( $\varepsilon _{r} = 1.12$ ), which is drilled and pressed to achieve the different dielectric constant needed to follow the Index Law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz.
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Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: M. Kamran Saleem, Majeed A. S. Alkanhal, Hamsakutty Vettikaladi, Mohamed HimdiAbstract:This communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 (r = 1.12), which is drilled and pressed to achieve the different dielectric constant needed to follow the Index Law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz. © 1963-2012 IEEE.
