The Experts below are selected from a list of 3273 Experts worldwide ranked by ideXlab platform

Yahia M. M. Antar - One of the best experts on this subject based on the ideXlab platform.

  • Segmented Circular Strip planar leaky-wave antenna designs for broadside radiation and one-sided beam scanning
    2010 International Workshop on Antenna Technology (iWAT), 2010
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    Planar antenna designs that utilize surface waves (SWs) for leaky wave (LW) excitation are investigated for millimeter wave frequencies of operation. Surface-wave launchers (SWLs) are employed as the antenna source generating cylindrical SWs for bound propagation on a grounded dielectric slab (GDS). By the addition of a segmented Circular Strip grating configuration, a partially reflecting surface (PRS) can be realized, providing suitable conditions for 2-D leaky-wave radiation. Directive pencil beam patterns at broadside, with gain values greater than 12 dBi at 19.5 GHz, can be achieved.

  • Single frequency 2-D leaky-wave beam steering using an array of surface-wave launchers
    2009
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    A planar antenna that utilizes surface-waves (SWs) for leaky-wave (LW) excitation is presented for millimeter-wave applications. Specifically, a two element array of directive Yagi-Uda like surface-wave launchers (SWLs) is used as the antenna feed, exciting cylindrical SWs on a grounded dielectric slab. By varying the relative phase difference between elements, the excited SW field distribution can be controlled. With the addition of metallic Circular Strip gratings, suitable conditions for LW excitation can be achieved. Essentially cylindrical LWs can be steered to confined regions on the guiding surface. For instance, by changing the relative phase difference between SWL sources such aperture fields can produce pencil and conical-sector beam patterns that can be steered in the far field at a single frequency. To the authors knowledge this is the first time such a LWA has been designed, fabricated and measured.

  • planar leaky wave antenna designs offering conical sector beam scanning and broadside radiation using surface wave launchers
    IEEE Antennas and Wireless Propagation Letters, 2008
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    Two planar antenna designs that utilize surface-waves for leaky-wave excitation are investigated. Specifically, a surface-wave launcher is implemented to excite cylindrical surface-waves, which are bound to a grounded dielectric slab. By the addition of Circular metallic Strip gratings, a partially reflecting surface is realized, providing appropriate conditions for 2-D leaky-wave radiation. In particular, two designs are investigated: a continuous Circular Strip and a segmented Circular Strip grating. Results illustrate conical-sector beam scanning for the continuous Circular Strip grating between 2022 GHz, while broadside radiation is observed at 21.2 GHz by the segmented Circular Strip design.

  • Broadside Radiation From a Planar 2-D Leaky-Wave Antenna by Practical Surface-Wave Launching
    IEEE Antennas and Wireless Propagation Letters, 2008
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    A planar 2-D leaky-wave (LW) antenna, capable of broadside radiation, is presented for millimeter wave applications. A directive surface-wave launcher (SWL) is utilized as the antenna feed exciting cylindrical surface-waves (SWs) on a grounded dielectric slab (GDS). With the addition of a segmented Circular Strip grating, cylindrical LWs can be excited on the antenna aperture. Measurements illustrate maximum gain at broadside at 19.48 GHz in both the E and H planes with a 10deg half power beamwidth. Specifically, a directive pencil beam is observed just at the edge of the TE1 SW mode cuttoff frequency of the slab (19.47 GHz), suggesting maximum radiation at the edge of a TE stopband.

Symon K. Podilchak - One of the best experts on this subject based on the ideXlab platform.

  • Segmented Circular Strip planar leaky-wave antenna designs for broadside radiation and one-sided beam scanning
    2010 International Workshop on Antenna Technology (iWAT), 2010
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    Planar antenna designs that utilize surface waves (SWs) for leaky wave (LW) excitation are investigated for millimeter wave frequencies of operation. Surface-wave launchers (SWLs) are employed as the antenna source generating cylindrical SWs for bound propagation on a grounded dielectric slab (GDS). By the addition of a segmented Circular Strip grating configuration, a partially reflecting surface (PRS) can be realized, providing suitable conditions for 2-D leaky-wave radiation. Directive pencil beam patterns at broadside, with gain values greater than 12 dBi at 19.5 GHz, can be achieved.

  • Single frequency 2-D leaky-wave beam steering using an array of surface-wave launchers
    2009
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    A planar antenna that utilizes surface-waves (SWs) for leaky-wave (LW) excitation is presented for millimeter-wave applications. Specifically, a two element array of directive Yagi-Uda like surface-wave launchers (SWLs) is used as the antenna feed, exciting cylindrical SWs on a grounded dielectric slab. By varying the relative phase difference between elements, the excited SW field distribution can be controlled. With the addition of metallic Circular Strip gratings, suitable conditions for LW excitation can be achieved. Essentially cylindrical LWs can be steered to confined regions on the guiding surface. For instance, by changing the relative phase difference between SWL sources such aperture fields can produce pencil and conical-sector beam patterns that can be steered in the far field at a single frequency. To the authors knowledge this is the first time such a LWA has been designed, fabricated and measured.

  • planar leaky wave antenna designs offering conical sector beam scanning and broadside radiation using surface wave launchers
    IEEE Antennas and Wireless Propagation Letters, 2008
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    Two planar antenna designs that utilize surface-waves for leaky-wave excitation are investigated. Specifically, a surface-wave launcher is implemented to excite cylindrical surface-waves, which are bound to a grounded dielectric slab. By the addition of Circular metallic Strip gratings, a partially reflecting surface is realized, providing appropriate conditions for 2-D leaky-wave radiation. In particular, two designs are investigated: a continuous Circular Strip and a segmented Circular Strip grating. Results illustrate conical-sector beam scanning for the continuous Circular Strip grating between 2022 GHz, while broadside radiation is observed at 21.2 GHz by the segmented Circular Strip design.

  • Broadside Radiation From a Planar 2-D Leaky-Wave Antenna by Practical Surface-Wave Launching
    IEEE Antennas and Wireless Propagation Letters, 2008
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    A planar 2-D leaky-wave (LW) antenna, capable of broadside radiation, is presented for millimeter wave applications. A directive surface-wave launcher (SWL) is utilized as the antenna feed exciting cylindrical surface-waves (SWs) on a grounded dielectric slab (GDS). With the addition of a segmented Circular Strip grating, cylindrical LWs can be excited on the antenna aperture. Measurements illustrate maximum gain at broadside at 19.48 GHz in both the E and H planes with a 10deg half power beamwidth. Specifically, a directive pencil beam is observed just at the edge of the TE1 SW mode cuttoff frequency of the slab (19.47 GHz), suggesting maximum radiation at the edge of a TE stopband.

Al P. Freundorfer - One of the best experts on this subject based on the ideXlab platform.

  • Segmented Circular Strip planar leaky-wave antenna designs for broadside radiation and one-sided beam scanning
    2010 International Workshop on Antenna Technology (iWAT), 2010
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    Planar antenna designs that utilize surface waves (SWs) for leaky wave (LW) excitation are investigated for millimeter wave frequencies of operation. Surface-wave launchers (SWLs) are employed as the antenna source generating cylindrical SWs for bound propagation on a grounded dielectric slab (GDS). By the addition of a segmented Circular Strip grating configuration, a partially reflecting surface (PRS) can be realized, providing suitable conditions for 2-D leaky-wave radiation. Directive pencil beam patterns at broadside, with gain values greater than 12 dBi at 19.5 GHz, can be achieved.

  • Single frequency 2-D leaky-wave beam steering using an array of surface-wave launchers
    2009
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    A planar antenna that utilizes surface-waves (SWs) for leaky-wave (LW) excitation is presented for millimeter-wave applications. Specifically, a two element array of directive Yagi-Uda like surface-wave launchers (SWLs) is used as the antenna feed, exciting cylindrical SWs on a grounded dielectric slab. By varying the relative phase difference between elements, the excited SW field distribution can be controlled. With the addition of metallic Circular Strip gratings, suitable conditions for LW excitation can be achieved. Essentially cylindrical LWs can be steered to confined regions on the guiding surface. For instance, by changing the relative phase difference between SWL sources such aperture fields can produce pencil and conical-sector beam patterns that can be steered in the far field at a single frequency. To the authors knowledge this is the first time such a LWA has been designed, fabricated and measured.

  • planar leaky wave antenna designs offering conical sector beam scanning and broadside radiation using surface wave launchers
    IEEE Antennas and Wireless Propagation Letters, 2008
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    Two planar antenna designs that utilize surface-waves for leaky-wave excitation are investigated. Specifically, a surface-wave launcher is implemented to excite cylindrical surface-waves, which are bound to a grounded dielectric slab. By the addition of Circular metallic Strip gratings, a partially reflecting surface is realized, providing appropriate conditions for 2-D leaky-wave radiation. In particular, two designs are investigated: a continuous Circular Strip and a segmented Circular Strip grating. Results illustrate conical-sector beam scanning for the continuous Circular Strip grating between 2022 GHz, while broadside radiation is observed at 21.2 GHz by the segmented Circular Strip design.

  • Broadside Radiation From a Planar 2-D Leaky-Wave Antenna by Practical Surface-Wave Launching
    IEEE Antennas and Wireless Propagation Letters, 2008
    Co-Authors: Symon K. Podilchak, Al P. Freundorfer, Yahia M. M. Antar
    Abstract:

    A planar 2-D leaky-wave (LW) antenna, capable of broadside radiation, is presented for millimeter wave applications. A directive surface-wave launcher (SWL) is utilized as the antenna feed exciting cylindrical surface-waves (SWs) on a grounded dielectric slab (GDS). With the addition of a segmented Circular Strip grating, cylindrical LWs can be excited on the antenna aperture. Measurements illustrate maximum gain at broadside at 19.48 GHz in both the E and H planes with a 10deg half power beamwidth. Specifically, a directive pencil beam is observed just at the edge of the TE1 SW mode cuttoff frequency of the slab (19.47 GHz), suggesting maximum radiation at the edge of a TE stopband.

Sallam, Mai Osama Mohamed Ibrahim - One of the best experts on this subject based on the ideXlab platform.

  • Plasmonische golfgeleiders en nano-antennes voor optische communicaties
    2017
    Co-Authors: Sallam, Mai Osama Mohamed Ibrahim
    Abstract:

    The field of plasmonics has received great attention during the past years. Plasmonic devices are characterized by their small electrical size which enabled researchers to overcome the challenge of the size mismatch between the bulky photonic devices and the small electronic circuits. Plasmonic metals are characterized by their lossy dielectric nature which is different from the highly conductive classical metals. Consequently, the design of plasmonic devices necessitates upgrading the existing solvers to incorporate their material properties at the optical frequency range. In this thesis, a plasmonic transmission line mode solver is developed in which the propagation characteristics of plasmonic waveguides are calculated. Specifically, the solver calculates the propagation constant, losses, and mode profile(s) of the propagating mode(s). The transmission lines can have any topology and are assumed to be placed within a stack of flat layers. The solver is developed using the Method of Moments technique which is characterized by its tremendously decreased number of unknowns compared to the finite element/difference methods leading to much faster calculation time. The solver is tested on several plasmonic transmission lines of various topologies, number of metallic Strips and/or surrounding media. These transmission lines include rectangular Strip, Circular Strip, triangular Strip, U-shaped Strip, horizontally coupled Strips, and vertically coupled Strips. The obtained results are compared with those calculated by the commercial tool “CST”. Very good agreement between both solvers is achieved. The solver is also used to study the effect of varying the geometrical parameters of various plasmonic transmission lines on their propagation characteristics. The second line presented within this thesis is concerned with the design of plasmonic wire-grid nano-antenna arrays. The basic element of this array is a nano-rod, whose propagation characteristics are first obtained using the developed solver. The arrays are then optimized using “CST”. Within this thesis, three nano-antenna arrays are proposed: a five-element wire-grid array, an eleven-element wire-grid array, and a Circularly polarized wire-grid array. The first and second arrays provide linearly polarized radiation. The third design presents a novel Circularly polarized wire-grid array. All the presented antennas are characterized by their high directivity which increases by increasing the number of radiators. The proposed arrays are designed to operate at 193.55 THz making them suitable for inter-/intra-chip optical communication in which they replace the lossy transmission lines. The thesis also presents two prototypes of fabricated wire-grid arrays designed for operation at 400 THz. The transmission from the periodic arrays are measured and compared with simulations. In general a good agreement between simulations and measurements is obtained with some differences for the resonance locations and amplitudes which can be due to the dimensions of the fabricated antenna which is different from the designed ones.status: publishe

  • Plasmonic Waveguides and Nano-Antennas for Optical Communications
    2017
    Co-Authors: Sallam, Mai Osama Mohamed Ibrahim
    Abstract:

    The field of plasmonics has received great attention during the past years. Plasmonic devices are characterized by their small electrical size which enabled researchers to overcome the challenge of the size mismatch between the bulky photonic devices and the small electronic circuits. Plasmonic metals are characterized by their lossy dielectric nature which is different from the highly conductive classical metals. Consequently, the design of plasmonic devices necessitates upgrading the existing solvers to incorporate their material properties at the optical frequency range. In this thesis, a plasmonic transmission line mode solver is developed in which the propagation characteristics of plasmonic waveguides are calculated. Specifically, the solver calculates the propagation constant, losses, and mode profile(s) of the propagating mode(s). The transmission lines can have any topology and are assumed to be placed within a stack of flat layers. The solver is developed using the Method of Moments technique which is characterized by its tremendously decreased number of unknowns compared to the finite element/difference methods leading to much faster calculation time. The solver is tested on several plasmonic transmission lines of various topologies, number of metallic Strips and/or surrounding media. These transmission lines include rectangular Strip, Circular Strip, triangular Strip, U-shaped Strip, horizontally coupled Strips, and vertically coupled Strips. The obtained results are compared with those calculated by the commercial tool “CST”. Very good agreement between both solvers is achieved. The solver is also used to study the effect of varying the geometrical parameters of various plasmonic transmission lines on their propagation characteristics. The second line presented within this thesis is concerned with the design of plasmonic wire-grid nano-antenna arrays. The basic element of this array is a nano-rod, whose propagation characteristics are first obtained using the developed solver. The arrays are then optimized using “CST”. Within this thesis, three nano-antenna arrays are proposed: a five-element wire-grid array, an eleven-element wire-grid array, and a Circularly polarized wire-grid array. The first and second arrays provide linearly polarized radiation. The third design presents a novel Circularly polarized wire-grid array. All the presented antennas are characterized by their high directivity which increases by increasing the number of radiators. The proposed arrays are designed to operate at 193.55 THz making them suitable for inter-/intra-chip optical communication in which they replace the lossy transmission lines. The thesis also presents two prototypes of fabricated wire-grid arrays designed for operation at 400 THz. The transmission from the periodic arrays are measured and compared with simulations. In general a good agreement between simulations and measurements is obtained with some differences for the resonance locations and amplitudes which can be due to the dimensions of the fabricated antenna which is different from the designed ones.status: publishe

Rossen Dandoloff - One of the best experts on this subject based on the ideXlab platform.

  • Curvature induced quantum potential on deformed surfaces
    Physics Letters A, 2007
    Co-Authors: Victor Atanasov, Rossen Dandoloff
    Abstract:

    We investigate the effect of curvature on the behaviour of a quantum particle bound to move on a surface. For the Gaussian bump we derive and discuss the quantum potential which results in the appearance of a bound state for particles with vanishing angular momentum. The Gaussian bump provides a characteristic length for the problem. For completeness we solve the inverse problem and show the way to derive a surface with prescribed quantum properties. We also show that there exist surfaces in the form of a Circular Strip around the axis of symmetry which allow particles with generic angular momentum to bind.

  • Curvature induced quantum potential on deformed surfaces
    Physics Letters A, 2007
    Co-Authors: Victor Atanasov, Rossen Dandoloff
    Abstract:

    We investigate the effect of curvature on the behaviour of a quantum particle bound to move on a surface. For the Gaussian bump we derive and discuss the quantum potential which results in the appearance of a bound state for particles with vanishing angular momentum. The Gaussian bump provides a characteristic length for the problem. For completeness we propose an inverse problem in differential geometry, i.e. what deformed surfaces produce prescribed curvature induced quantum potentials. We solve this inverse problem in the case of rotational surfaces. We also show that there exist rotational surfaces in the form of a Circular Strip around the axis of symmetry which allow particles with generic angular momentum to bind