Hussam Ayad

Performances of low profile dipole antenna AMC-based surface using metamaterials structures

Artificial Magnetic Conductors (AMCs), a real version of Perfect Magnetic Conductors (PMCs), are widely used to replace surfaces of high impedance. Based on unit cells of Multiple Split-Ring Resonators (MSRRs) that are printed on low-cost dielectric grounded substrate, AMCs are employed as a ground plane for antennas. In this paper, the performance of a low profile dipole antenna positioned above a planar AMC surface is examined. The characteristics of the AMC return loss are initially investigated at the resonant frequency of 2.4 GHz. Two arrays having 49 and 81 MSRR unit cells are then simulated and modeled with the dipole antenna placed above. The results are of great importance as the directivity reaches 6 dB for the configuration of 9 × 9 unit cells. This confirms that the MSRR can perfectly replace the conventional ground plane antenna in order to improve the gain and the directivity of their radiations.

Compact wide-band and low loss substrate integrated waveguide

Here in this article we propose a new design of Slow-Wave Substrate Integrated Waveguide (SW-SIW). The proposed design besides the miniaturization have the advantages of being low loss and Wide-Band. The reflection coefficient is decreased between 5dB and 10dB, the Band Width of the new transmission is almost 16.6GHz, the miniaturization is of 38% very slightly reduced from previous published works. The same transmission line is simulated with different type of substrates, Fr4-epoxy, RO4003, RO5880, results are compared and analyzed, in order show the effectiveness of the new SW-SIW transmission line.

Compact SIW leaky wave antenna

A compact Substrate Integrated Waveguide (SIW) Leaky-Wave Antenna (LWA) is proposed. Internal vias are inserted in the SIW in order to have narrow walls, and so reducing the size of the SIW-LWA, the new structure is called Slow Wave - Substrate Integrated Waveguide - Leaky Wave Antenna (SW-SIW-LWA), since inserting the vias induce the SW effect. After designing the antenna and simulating with HFSS a reduction of 30% of the transverse side of the antenna is attained while maintaining an acceptable gain. Other parameters like the radiation efficiency, Gain, directivity, and radiation pattern are analyzed. Finally a Comparison of our miniaturization technique with Half-Mode Substrate Integrated Waveguide (HMSIW) technique realized in recent articles is done, shows that SW-SIW-LWA technique could be a good candidate for SIW miniaturization.

Near-field measurement system with 3D magnetic-field probe design for dosimetric applications

In this paper the design of a new 3D magnetic field (H-field) probe with a near-field scanning system is presented. The proposed system was developed in order to determine the magnetic near-field emitted by electronic devices. The designed isotropic H-field probe consists of three orthogonal and identical loops each of diameter of 6 mm having 3 turns. The antenna factor of the designed probe is presented for a frequency range from 1 MHz to 1 GHz. In order to verify the performance of the designed probe, magnetic near-field measurements were done for a standard circuit. The comparison between the measured results and the theoretical calculations was performed for validation.

HALF-MODE SLOW-WAVE SUBSTRATE INTEGRATED WAVEGUIDE ANALYSIS

Design of a compact Substrate Integrated Waveguide (SIW) transmission line is presented in this paper. The main parameters of SIW were parametrically studied, and final designed component was fabricated and measured, which showed very good matching (near 90%) with simulations, demonstrating significant miniaturization factor. The miniaturization was done using Half-Mode (HM) and Slow-Wave (SW) principles together. It was found that the HM-SW method for SIW miniaturization reduced the SIW surface area with a remarkable factor value (70%) while maintaining acceptable characteristics compared to the original SIW. In fact, HM technique reduced 40% the lateral dimension of the SIW, and using the SW technique allowed 30% of size reduction added to the HM principle. Furthermore, a proper microstrip to HM-SW-SIW tapered transition was designed, which showed a return loss decrease between 3 dB and 7.5 dB, as well as facilitating measurement. On the other hand, the proposed transmission line could lead to a size reduction of 30% compared to the HM-SIW miniaturization technique. The HM-SW-SIW transmission line concept presented in this paper can be used to design other compact SIW components such as bandpass filters, couplers, and power divider.

Effective permittivity of snow for radar detection: Numerical validation by the fem method

This paper presents a step-by-step procedure to extract the effective permittivity of dry and wet snow in an electromagnetic simulator. The S-parameters are extracted using HFSS (High Frequency Structure Simulator), which is a Finite Element Method (FEM) full wave simulator. The permittivity curve is calculated using the S21 retrieval method. The calculated permittivity is compared with theoretical mixture models (Maxwell Garnett and Bruggeman Symmetric) with a verification that it lies between the effective permittivity theoretical bounds.

Compact multi-layer Band-Pass filter in Substrate Integrated Waveguide (SIW) technology

In this paper, a new miniaturized wide Band-Pass Substrate Integrated Waveguide (SIW) filter is proposed. The miniaturized design is based on two techniques, combining the Slow-Wave and Half-Mode SIW principles. Also different substrates for each layer with high contrast in the effective permittivity are used. This technique shows that the SIW filter is 90% miniaturized with a bandwidth covering the X-band, insertion loss are less than 2dB and return loss under -12.5dB. Results are compared with previous published papers and show a good efficiency when miniaturizing.

Development of a 3D scanning system for magnetic near-field characterization

This paper presents a near-field scanning system with the design and calibration of two three dimensional (3D) magnetic field probes. They consist of three orthogonal loops, combined together, the first probe (P1) contains three conventional loops joined in a plastic cube, and the second one (P2) is a PCB probe printed on an FR4 substrate of 3.2 mm thickness. Probe P1 has a total dimension of 10x12x13 mm3 whereas in probe P2 the dimensions are reduced to 9x9x3.2 mm3. The antenna factor of the designed probes was calculated using TEM cell for a frequency range from 10 MHz to 1 GHz. The probes were validated using a standard circuit. Then they are used to characterize the radiated magnetic field from an RFID reader antenna.

Multi-Frequency Approach for Oil Spill Remote Sensing Detection

Lebanon witnessed one of its biggest dangerous environmental crisis due to the oil spill caused by Israel bombard of fuel storage tanks in war 2006. Official reports stated that around 15000 tons of heavy fuel oil spilled in sea water. The spill threatened the maritime and human life and caused severe environmental disasters. On an international scale, the European Space Agency (ESA) stated that more than 4.5 million tons of oil is the estimate of the annual spill worldwide. Therefore, it is really crucial to have an oil spill detection system that is able to specify the spill area and to provide statistical information about the situation. One of the main techniques used nowadays is airborne and satellite remote sensing systems. The European Maritime Safety Agency (EMSA) lunched in 2016 the need to use a complementary system to the present satellite maritime surveillance system. In our work, we propose the use of drones for oil spill detection. In this paper, we present a multi-frequency technique in order to detect thick oil spill in ocean. This technique is also capable of providing an estimation of the oil thickness from reflectivity measurements affected by ocean roughness and noise in electronic devices. Numerical simulations are calculated using High Frequency Electromagnetic Field Simulation (HFSS) validating the theoretical calculations.

Sampled Antenna Array Digital Beamforming for LTE-Advanced

In this paper, a beamforming system for LTE- Advanced based on Array sampling technology is proposed. Antenna Array that has been designed covers LTE mid and high bands. RF multiplexer 8x1 switch has been designed and simulated. The system is composed of agile RF frontend and FPGA digital signal processing unit.