H.B. El-Shaarawy

French National Centre for Scientific Research, Lutetia Parisorum, Île-de-France, France

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Publications (10)9.27 Total impact

  • Ahmed A. M. Ali, Heba B. El-Shaarawy, Hervé Aubert
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    ABSTRACT: A millimeter-wave passive Van Atta retrodirective antenna (RDA) array is presented in substrate integrated waveguide technology. The proposed RDA design is based on alternating SIW slot antenna arrays whose longitudinal slots are etched in a continuous ground plane covering the entire circuit thus minimizing the diffraction at the edges of the feeding network. Owing to its closed guiding medium and high Q factor, the SIW feed topology provides an optimum coupling to the radiating elements with minimum losses and spurious feed radiation allowing a simple passive design with enhanced radar cross section (RCS). Two SIW-based prototypes are presented in both single- and double-layer configurations at 30 GHz. While the single layer design can be extended to larger RDAs with minimum losses, the double-layer configuration is exploited to provide a more compact design that reduces the scattering of the structure while providing the same re-radiated pattern of the corresponding single layer configuration. Simulated and measured results are in good agreement showing more than 10 dB enhancement in the monostatic RCS of the passive RDA over an angle of from boresight, compared to the equal-size reference rectangular metallic sheet.
    IEEE Transactions on Antennas and Propagation 03/2013; 61(3):1465-1470. · 2.33 Impact Factor
  • A.A.M. Ali, H.B. El-Shaarawy, H. Aubert
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    ABSTRACT: A novel compact Ridge Substrate Integrated Waveguide (RSIW)-based hybrid ring coupler is hereby presented. The size miniaturization is accomplished through a twofold approach. First, the RSIW is used to reduce the coupler waveguide transverse dimension. The RSIW of the hybrid ring is then loaded by Electromagnetic Bandgap (EBG) structures, etched in its non-ridged broadwall, exploiting their slow wave effect to reduce the longitudinal dimension. It is demonstrated that the use of EBG-loaded RSIW can lead to a size reduction of more than 48% and 91% with respect to the unloaded RSIW and conventional SIW hybrid ring couplers, respectively.
    IEEE Microwave and Wireless Components Letters 10/2011; · 1.78 Impact Factor
  • A.A.M. Ali, H.B. El-Shaarawy, H. Aubert
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    ABSTRACT: Presented are two novel double layer substrate integrated waveguide (SIW)-based couplers, the longitudinal-slots-based broadwall SIW coupler and its corresponding half-mode SIW coupler. Coupling takes place through a set of narrow, offset slots, which feature a flexible design providing a wide coupling dynamic range with wideband characteristics. This technique provides a compact design through both the double layer scheme and the half-mode structure. Isolation and input reflection characteristics better than 15 dB and 13 dB, respectively, are experimentally validated over 24% fractional bandwidth at 12.5 GHz. Measured coupling magnitudes and phases exhibit dispersive characteristics lower than 1 dB, and 8 with respect to the adopted design values, respectively, over the entire frequency band.
    Electronics Letters 06/2011; · 1.04 Impact Factor
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    ABSTRACT: A novel reconfigurable defected ground structure (DGS) resonator fabricated on coplanar waveguide (CPW) technology is presented. The resonator is endowed with an original design which enables the generation of multiple transmission zeros at arbitrary frequencies. The chosen design is indeed based on a slot defect created on the lateral ground planes of the CPW with the double advantage to allow a simple reconfiguration, by means of surface mounted (or fabricated) components, and a very compact solution, by exploiting the transversal dimension of the coplanar wave transmission line (CPW-TL). Four different states of the diodes configuration are investigated, where in each state multiple transmission zeros are produced in the frequency range from 1 GHz to 11 GHz. The equivalent circuit of each state is obtained using a conventional circuit parameter extraction method. Moreover, the slotline design equations are used to identify the transmission zeros and validated using the magnetic field distribution inside the slot. In this work, the reconfigurability is first proven by means of short bridges mounted in specific locations. These bridges are then replaced by PIN diodes. Simulated and measured results are in good agreement.
    IEEE Transactions on Antennas and Propagation 12/2010; · 2.33 Impact Factor
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    ABSTRACT: This paper addresses the characterization of Ba<sub>0.6</sub>Sr<sub>0.4</sub>TiO<sub>3</sub> dielectric properties on different dielectric substrates using three different components. First, for low frequencies, metal-insulator-metal (MIM) capacitors are used to determine the BST dielectric constant, loss tangent and tunability for different biasing voltages from 0-30 V showing a tunability range of 66%. For microwave frequency ranges, coplanar waveguides (CPW), and interdigital capacitors (IDCs) are investigated on silicon, R-plane sapphire (Al<sub>2</sub>O<sub>3</sub>) and magnesium oxide (MgO) substrates. CPW is used to determine the complex propagation constant, while IDCs are used to determine the BST voltage tunability from 0-55 V over 1-20 GHz. Sapphire and MgO introduce low loss tangent values of 0.03, while sapphire gives better tunability (20% at 18 GHz) than MgO (8.3% at 18 GHz).
    Microwave Conference (EuMC), 2010 European; 10/2010
  • H.B. El-Shaarawy, F. Coccetti, R. Plana
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    ABSTRACT: This paper presents a novel reconfigurable DGS cell on CPW. The structure consists of two independent ring resonators. A diode is used to connect and/or disconnect the second resonator, switching the structure from single band to multi-band resonance circuit. An equivalent circuit has been extracted from the simulated results representing the DGS in both states of the diode. EM simulation, equivalent circuit model and measured results show good agreement. Finally, design rules and considerations have been illustrated.
    Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE; 08/2010
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    ABSTRACT: This paper reports the DC and Radio Frequency (RF) characterization of Ba0.6S0.4TiO3 thin films using three different components. For DC characterization, two single circle patch MIM capacitors of different radii are fabricated over Pt/Ti/SiO2/Si substrate covered with a 350 nm BST film. The measurement results show a tunability range of 61% for 0V to 20V biasing voltage. For higher frequency characterization, another MIM structures consisting of two imbricate circle patches are fabricated on the same substrate, where BST intrinsic parameters are extracted using a differential method. Results show that BST dielectric constant is nearly frequency independent; giving a tunability of 53% up to 20 GHz. On the other hand, a reflection IDC fabricated on BST/Al2O3 substrate is investigated. The IDC exhibits a capacitance tunability of 20% at 18 GHz.
    01/2010;
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    ABSTRACT: In this paper, a novel reconfigurable bandpass filter based on defected ground structures has been presented. The filter consists of two basic elements. The first is the inductively coupled resonator giving the bandpass filter response, and the second is the novel DGS cell allowing reconfigurability and miniaturization. Simulated and measured results are in good agreement. The flexibility of the design in the different cases has also been demonstrated.
    Antennas and Propagation Society International Symposium, 2009. APSURSI '09. IEEE; 07/2009
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    ABSTRACT: A novel defected ground structure cell was presented. The cell was built on coplanar waveguide technology. Two diodes in each side of the ground planes allow us to switch the filter between different passbands. Simulated and measured responses were presented showing very good agreement. An electromagnetic explanation of the structure based on slot transmission line was also presented. The cell shows very promising features for the implementation of small and efficiently reconfigurable building block for filters. The very narrow stopbands in the responses may be enhanced by putting more cells in cascade. This work is a first step toward implementation of a silicon integrated reconfigurable filter using MEMS switches in place of diodes.
    Microwave Conference, 2008. APMC 2008. Asia-Pacific; 01/2009
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    ABSTRACT: This letter addresses a modified bandpass ring resonator filter providing compact size, low insertion-loss, wide bandwidth, sharp rejection, and suppressed higher order modes. It is demonstrated that the use of internal folded stubs translates into an overall size reduction of more than 70% through the exploitation of the internal ring area. The introduction of defected ground structures enhances the rejection of higher order modes beside offering a further advantage in terms of size reduction. It is furthermore shown that electromagnetic simulations, transmission line model, as well as measurement results are in very good agreement.
    IEEE Microwave and Wireless Components Letters 09/2008; · 1.78 Impact Factor

Publication Stats

28 Citations
9.27 Total Impact Points

Institutions

  • 2010
    • French National Centre for Scientific Research
      • Laboratoire d'analyse et d'architecture des systèmes (LAAS)
      Lutetia Parisorum, Île-de-France, France
  • 2009
    • University of Toulouse
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 2008
    • Laboratoire d’Analyse et d’Architecture des Systèmes (LAAS)
      Tolosa de Llenguadoc, Midi-Pyrénées, France