Behnam Zarghooni

Millimeter-Wave High-Gain SIW End-Fire Bow-tie Antenna

This communication presents a high-gain bow-tie antenna that operates across 57-64 GHz for application in high data rate point-to-point communication systems. The proposed antenna consists of a pair of bow-tie radiators, where each radiator is etched on the opposite side of the common dielectric substrate and fed through substrate integrated waveguide (SIW) feed-line. The bow-tie radiators are arranged to cross each other symmetrically by tilting the feed-lines by 30° to enhance the antenna gain and to obtain the required radiation pattern. The antenna is loaded with a pair of double G-shaped resonators (DGRs) that are located in a region between the radiators and SIW to suppress the back-lobe level in the H-plane. Embedded in the E-plane of the antenna is an array of zero-index metamaterial (ZIM) unit-cells whose purpose is to effectively confine the electromagnetic waves in the end-fire direction to enhance its gain performance. A prototype antenna was fabricated and its performance was measured to validate the simulation results. The proposed structure exhibits a gain of 11.8-12.5 dBi over the frequency range of 57-64 GHz with reflection coefficient less than

Beam Tilting Antenna Using Integrated Metamaterial Loading

- 11\;\hbox{dB}

One- and Two-Dimensional Beam-Switching Antenna for Millimeter-Wave MIMO Applications

. In addition, the proposed antenna exhibits good cross-polarization, which is less than

Beam-Deflection Using Gradient Refractive-Index Media for 60-GHz End-Fire Antenna

- 17\;\hbox{dB}

New Compact Metamaterial Unit-Cell Using SIR Technique

in both E- and H-planes at 60 GHz.

Greek-Key Pattern as a Miniaturized Multiband Metamaterial Unit-Cell

This communication presents a technique to re-direct the radiation beam from a planar antenna in a specific direction with the inclusion of metamaterial loading. The beam-tilting approach described here uses the phenomenon based on phase change resulting from an EM wave entering a medium of different refractive index. The metamaterial H-shaped unit-cell structure is configured to provide a high refractive index which was used to implement beam tilting in a bow-tie antenna. The fabricated unit-cell was first characterized by measuring its S-parameters. Hence, a two dimensional array was constructed using the proposed unit-cell to create a region of high refractive index which was implemented in the vicinity bow-tie structure to realize beam-tilting. The simulation and experimental results show that the main beam of the antenna in the E-plane is tilted by 17 degrees with respect to the end-fire direction at 7.3, 7.5, and 7.7 GHz. Results also show unlike conventional beam-tilting antennas, no gain drop is observed when the beam is tilted; in fact there is a gain enhancement of 2.73 dB compared to the original bow-tie antenna at 7.5 GHz. The reflection-coeflicient of the antenna remains <; - 10 dB in the frequency range of operation.

Improvement of Gain and Elevation Tilt Angle Using Metamaterial Loading for Millimeter-Wave Applications

One- (1-D) and two-dimensional (2-D) beamforming is presented for a planar dipole antenna operating at millimeterwave bands. 1-D beamforming was achieved by using mu (μ) -near-zero (MNZ) metamaterial slabs that were integrated in the dipole antenna, where each slab was loaded with an array of low refractive-index unit-cells. The resulting radiated beam can be scanned by 35° due to the phase shift in the beam introduced by its interaction with the metamaterial slabs. In addition, the proposed antenna configuration provides gain improvement of 8 dB as the slabs effectively increase the aperture size of the antenna. An array of MNZ inclusions in the E-plane of a double dipole antenna is shown to provide scanning from -35° to +35° with respect to the end-fire direction over 57-64 GHz. 2-D beam-scanning was realized by increasing the number of MNZ unit-cells in the elevation plane of double dipole antenna. Loading the slabs in front of the double dipole antenna with 10 × 7 array of MNZ unit-cells is shown to provide a beam deflection of 35° in both the azimuth and elevation planes.

Enhancement of Tilted Beam in Elevation Plane for Planar End-Fire Antennas Using Artificial Dielectric Medium

This communication describes a beam-tilting technique for planar dipole antennas utilizing gradient refractive-index metamaterial (GRIM) unit-cells. Beam-deflection mechanism is based on the phase shift phenomena resulting from the interaction of the EM waves with media of different refractive-indices implemented using GRIM unit-cells. The GRIM unit-cell comprises of a stub-loaded I-shaped resonant structure that is directly integrated onto the dipole antenna. The simulation and experimental results show that an antenna with a 5 × 4 array of GRIM unit-cells can steer the main beam in the E-plane by +26° with respect to the end-fire direction over 57-64 GHz. The antenna exhibits 4-dB gain enhancement and S11 better than -10 dB from 57-64 GHz. It is also shown that a quad-feed dipole antenna with GRIM arrays can deflect the beam by ±56°.

Mutual Coupling Reduction in Dielectric Resonator Antennas Using Metasurface Shield for 60 GHz MIMO Systems

In this letter, a new compact metamaterial unit-cell called SIR-DSR is presented. This unit-cell is designed by applying the stepped-impedance resonator (SIR) technique to a conventional double split-ring resonator (DSR) structure. The S parameters and the extracted effective relative permittivity and permeability for the presented unit-cell show a miniaturization factor of 0.75 compared to a conventional DSR. The results are validated through the fabrication and measurement of the unit-cell.

Millimeter-Wave Antenna Using Two-Sectioned Metamaterial Medium

In this letter, a new metamaterial unit-cell is designed, fabricated, and measured. The unit-cell is based on a Greek-key pattern and operates at the frequency range from 1 to 5 GHz. The proposed structure offers a multiband metamaterial behavior and at the same time provides a miniaturization factor compared to conventional multiband metamaterial unit-cells. The Greek-key unit-cell is first simulated and its S-parameters are calculated and then its effective constitutive parameters are extracted using a well-known algorithm. To validate the simulation results, a 10 ×10 array of the unit-cell is fabricated and measured using the free-space measurement method.