A.W. Glisson

University of Mississippi, Oxford, MS, United States

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Publications (118)112.3 Total impact

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    ABSTRACT: An analytical model is presented for the analysis of multilayer wire media loaded with 2-D arrays of thin material terminations, characterized in general by a complex surface conductivity. This includes the cases of resistive, thin metal, or graphene patches and impedance ground planes. The model is based on the nonlocal homogenization of the wire media with additional boundary conditions (ABCs) at the connection of thin (resistive) material. Based on charge conservation, new ABCs are derived for the interface of two uniaxial wire mediums with thin imperfect conductors at the junction. To illustrate the application of the analytical model and to validate the new ABCs, we characterize the reflection properties of multilayer absorbing structures. It is shown that in such configurations the presence of vias results in the enhancement of the absorption bandwidth and an improvement in the absorptivity performance for increasing angles of an obliquely incident TM-polarized plane wave. The results obtained using the analytical model are validated against full-wave numerical simulations.
    IEEE Transactions on Antennas and Propagation 12/2012; 60(12):5727-5742. DOI:10.1109/TAP.2012.2209196 · 2.46 Impact Factor
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    ABSTRACT: We present an analytical model to study the reflection properties of a multilayered wire media loaded with 2-D arrays of thin imperfect conductors. Based on charge conservation, generalized additional boundary conditions (ABCs) for the interface of two uniaxial wire mediums loaded with thin arbitrary imperfect conductors at the junction are derived. It is observed that by proper selection of the structural parameters, the mushroom structure acts as a wideband absorber for an obliquely incident TM-polarized plane wave. The presented model along with the new ABCs are validated using the full-wave numerical simulations.
    2012 IEEE AP-S International Symposium on Antennas and Propagation and USNC/URSI Radio Science Meeting, Chicago, IL; 07/2012
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    ABSTRACT: Design of a linear array of rectangular dielectric resonator antennas (DRAs) fed by dielectric image guide (DIG) is presented. Coupling between the DIG and the DRAs is predicted using the effective dielectric constant method. In order to achieve a specific power distribution, the power coupled to each DRA is controlled by changing the spacing between the DRAs and the DIG. Cross polarization reduction is achieved by wrapping a conducting strip around the middle of the DRA without affecting the co-polarized radiation pattern. The antenna is fabricated and tested. Good agreement between the measured and computed results is obtained.
    IEEE Transactions on Antennas and Propagation 04/2010; 58(3-58):697 - 705. DOI:10.1109/TAP.2009.2039294 · 2.46 Impact Factor
  • X.H. Wu, A.A. Kishk, A.W. Glisson
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    ABSTRACT: Multiple-input-multiple-output (MIMO) radar makes use of orthogonal signals to obtain the phase delay for each transmitting/receiving antenna pair, and thus increasing the accuracy of direction estimation. The previously proposed MIMO radar assumes narrowband signals that guarantee the waveform orthogonality during the signals- transmission, propagation and reception. However, a narrowband system is unstable in target localisation because of the fluctuation of the target-s radar cross section. An MIMO-OFDM radar is proposed for target localisation. It adopts the OFDM technique to simultaneously transmit and receive a set of multiple narrowband orthogonal signals at orthogonal frequencies. A practical model accommodating a physical target is presented to simulate the MIMO-OFDM radar. As an example, a composite target composed of five infinite dielectric cylinders is localised by a four-element uniform linear array. The performance of the MIMO-OFDM radar is investigated by examining the estimation error for different numbers of sub-bands, different signal-to-noise ratios and different target directions. It is demonstrated by simulation that the MIMO-OFDM radar gives more statistically stable estimation by spreading the signal power over a wider spectrum.
    IET Radar Sonar ? Navigation 03/2010; DOI:10.1049/iet-rsn.2008.0152 · 1.03 Impact Factor
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    ABSTRACT: This paper presents the design of a rectangular dielectric resonator antenna array coupled to narrow slot apertures that are fed by dielectric image guide (DIG). The DIG is excited by an X-band rectangular waveguide through a waveguide transition, and DIG tapering is used to match between the waveguide and the DIG. Reflection cancelling slots are added near the original slots to improve impedance matching. Since the slots radiate in both directions, a reflecting conducting plate is inserted above the DIG to decrease the back radiation of the antenna. The antenna is fabricated and the measured results are compared to the simulated results.
    IEEE Transactions on Antennas and Propagation 09/2009; 57(8-57):2252 - 2259. DOI:10.1109/TAP.2009.2024487 · 2.46 Impact Factor
  • Theory and Phenomena of Metamaterials, Edited by F. Capolino, 01/2009: chapter Corrugated Rectangular Waveguides: Composite Right/Left-Handed Metaguides: pages 29-1 – 29-24; Taylor and Francis.
  • Xuan Hui Wu, Ahmed A. Kishk, A.W. Glisson
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    ABSTRACT: It has been found that a set of Hertzian dipoles can be optimized to model the radiation characteristics of an antenna. However, the existing models are normally for narrowband antennas and invalid for a wideband antenna. In addition, it is difficult to combine several such models at different frequencies into a wideband model because the interpolation of dipole parameters is not applicable. This paper presents a procedure to optimize a Hertzian dipole model for a wideband antenna, where each dipole parameter is a polynomial in the phase constant. The tangential electric field on a surface enclosing the antenna is first obtained by full wave analysis at multiple frequencies. An optimization method is then applied to determine the polynomial coefficients for each dipole parameter, by minimizing the error between the exact field and the field due to the dipoles. As an example, a wideband stacked dielectric resonator antenna (DRA) is modeled by four electric and three magnetic Hertzian dipoles. The dipole model is used to efficiently study the radiation characteristics of the DRA mounted on a circular ground plane. Moreover, it is pointed out that the dipole model is resistant to Gaussian noise added to the near-field data, and is frequency scalable.
    IEEE Transactions on Antennas and Propagation 09/2008; DOI:10.1109/TAP.2008.927546 · 2.46 Impact Factor
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    A. Al-Zoubi, A. Kishk, A.W. Glisson
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    ABSTRACT: The aperture coupled dielectric resonator antenna array fed by dielectric image line backed with a reflector was simulated using HFSS. A good return loss was obtained for an array of 7 DRA elements by adding cancelling slots with the radiating slots. Adding a reflector in the DIL side decreases the back radiation and increases the gain for the array.
    Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE; 08/2008
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    A. Al-Zoubi, A. Kishk, A.W. Glisson
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    ABSTRACT: A linear dielectric resonator antenna array fed by dielectric image line is presented. The effective dielectric constant method is used to approximate the coupling between the DIL and the DRAs. A Dolph-Chebyshev amplitude distribution was used to control the sidelobe level of the array radiation pattern. The cross polarization is suppressed by inserting a metal sheet at the center of the DRA or by inserting a microstrip line around the DRA at the center.
    Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE; 08/2008
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    ABSTRACT: A linear array of longitudinal shunt slots etched on top of a substrate integrated waveguide was presented. This array was fed using the grounded co-planar waveguide mechanism to take advantage of the planar structure. A linear slot-array antenna was designed, fabricated and tested. We showed the concept of extending the linear array to a planar array using the appropriate microstrip feeding network.
    Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE; 08/2008
  • X H Wu, AA Kishk, AW Glisson
    Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE; 01/2008
  • Xuan Hui Wu, Ahmed A. Kishk, A.W. Glisson
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    ABSTRACT: A transmission line (TL) method was proposed to compute the far-field radiation of Hertzian dipoles in a multilayer dielectric structure previously. This method is generalized here to deal with a structure embedded with perfectly electric conducting (PEC) strip interfaces. The problem is solved by analyzing an equivalent network, where each PEC strip interface is mapped into a four-port network, and each dielectric layer is mapped into two two-port networks for transverse electric (TE) and transverse magnetic (TM) modes. The S matrix of a four-port network is obtained analytically by applying the asymptotic boundary conditions. As an application, the PEC strip interfaces are used to reduce the cross polarization or rotate the polarization of a dielectric resonator antenna (DRA). In addition, the TL method is valid for a structure with any type of homogeneous and reciprocal layers whose S matrices are known. It is also able to solve two kinds of problems which cannot be done by a full-wave analysis equipped with a periodic boundary condition. Furthermore, the investigation of the system matrix singularity helps us to avoid the cavity mode in designing a radiating structure.
    IEEE Transactions on Antennas and Propagation 12/2007; 55(11-55):3191 - 3198. DOI:10.1109/TAP.2007.908836 · 2.46 Impact Factor
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    ABSTRACT: Analysis of dielectric resonator probe (DRP) arrays operating in an oversized hard waveguide with sectoral hard horn excitation is presented. A single DRP excited by a coaxial probe is first investigated inside a hollow rectangular waveguide and a waveguide loaded with hard walls, respectively. Simulation results are compared with measurement results and show a good agreement. Then, a one-dimensional DRP array is analysed inside a dielectric-loaded, oversized waveguide with sectoral hard horn excitation. A full-wave analysis based on the region-by-region finite-difference time-domain technique is applied for the optimisation of array parameters such as inter-element coupling, active reflection coefficients and uniform excitation. Numerical results are compared with those generated by using commercial software and exhibit a very good agreement.
    IET Microwaves Antennas & Propagation 09/2007; 1(4-1):874 - 880. DOI:10.1049/iet-map:20060048 · 0.97 Impact Factor
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    ABSTRACT: Wideband probe-fed dielectric resonator antenna (DRA) arrays in an oversized dielectric loaded waveguide with hard horn excitation and radiating in free space are investigated for their use in waveguide-based spatial power-combining systems. A single embedded DRA element excited by a coaxial probe is analyzed first inside a hollow rectangular waveguide and a TEM waveguide. 1-D embedded DRA arrays are then studied inside the H- and E-plane sectoral hard horns. Finally, an entire spatial power-combining system with a 2-D embedded DRA array radiating in free space is analyzed. The analysis of the entire system is based on the finite-difference time-domain method with region-by-region discretization and subgridding schemes. The system's prototype of 2-D 3 times 3 embedded DRA array inside a pyramidal hard horn was fabricated and simulation results were compared with measurement results, showing a good agreement. Numerical results for radiation patterns are demonstrated for the examples of 2-D embedded dielectric resonator arrays excited by a pyramidal hard horn and radiating in free space.
    IEEE Transactions on Microwave Theory and Techniques 07/2007; DOI:10.1109/TMTT.2007.896777 · 2.94 Impact Factor
  • S M Mikki, A A Kishk, A W Glisson
    Antennas and Propagation Society International Symposium, 2007 IEEE; 01/2007
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    ABSTRACT: A generalized equivalent circuit model for waveguide transverse slots is proposed for the efficient analysis of waveguide transitions and waveguide slot antennas and slot-excited antennas. The transverse slots on the broad and end waveguide walls analyzed in this paper are decomposed into three structures: two apertures and an auxiliary waveguide section. The slot aperture in the host waveguide is modeled as an inductance-capacitance-transformer (LCT) combination, for which the equivalent inductance and capacitance are determined by first considering the case of zero-thickness slot, then the transformer turns ratio is calculated for the slot on a finite thickness wall. The effect of the wall thickness is accounted for by a waveguide section having cross-sectional dimensions equal to those of the slot, and length equal to the wall thickness. The loaded slot aperture is modeled along with the external load as a lumped load impedance. Expressions for the inductance, capacitance and transformer turns ratio are obtained in terms of the slot length and width. The obtained expressions facilitate the design of a variety of structures, including waveguide couplers, feeding networks and radiators. The equivalent circuit model proved to be accurate compared to the method of moments solution over a wide frequency band. Comparison of the scattering parameters obtained from the circuit analysis, the method of moments, and the finite-difference time-domain solutions exhibit very good agreement.
    Progress In Electromagnetics Research 01/2007; PIER 69:1-20. · 5.30 Impact Factor
  • Y Zhang, A A Kishk, A B Yakovlev, A W Glisson
    Microwave Symposium, 2007. IEEE/MTT-S International; 01/2007
  • Xuan Hui Wu, A.A. Kishk, A.W. Glisson
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    ABSTRACT: A transmission line method is proposed to compute the far-field radiation patterns of arbitrarily directed Hertzian dipoles that are embedded in a multilayer dielectric structure. The evaluation of the field in the far-zone region is transformed into the evaluation of the field inside the multilayer structure by applying the reciprocity theorem. The horizontal field component inside the structure is derived by analyzing a transmission line circuit, and the vertical component is obtained from the horizontal component by separating the forward and backward waves. This method is implemented and verified by IE3D for the case of a three-layer structure excited by either electric Hertzian dipoles, magnetic Hertzian dipoles, or their combination. The radiation patterns of any antenna embedded in a multilayer dielectric structure can be computed with this method after replacing the physical antenna with a set of Hertzian dipoles. As examples, a quarter wavelength thin wire monopole antenna and a dielectric resonator antenna, both embedded in a multilayer structure, are investigated. Furthermore, the arrangement of the structure is optimized to maximize the antenna directivity. The results are also verified by the simulation of the entire structure with IE3D
    IEEE Transactions on Antennas and Propagation 11/2006; DOI:10.1109/TAP.2006.882164 · 2.46 Impact Factor
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    ABSTRACT: Analysis and design of a probe-fed embedded dielectric resonator antenna (DRA) array in an oversized dielectric loaded waveguide with hard horn excitation are presented for its use in a waveguide-based spatial power combining system. Matching bandwidth as much as 15% (based on -10dB return loss level) is achieved in the proposed design. The finite-difference time-domain (FDTD) approach with region-by-region discretization and subgridding schemes is applied for the analysis of the entire spatial power combining system. Numerical results of the scattering parameters for the example of a 3 times 3 embedded DRA array excited by a hard horn are compared with those obtained using the commercial software HFSS and exhibit very good agreement. A parametric analysis is performed in order to optimize the system for scattering and coupling characteristics
    Microwave Conference, 2006. 36th European; 10/2006