Beam tilting antenna using integrated metamaterial loading

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-coefficient of the antenna remains < 10 dB in the frequency range of operation

Enhancement of tilted beam in elevation plane for planar end-fire antennas using artificial dielectric medium

This paper describes a simple and effective beam tilting technique for planar end-fire antennas using an artificial dielectric layer. The proposed approach is based on the phase differential resulting from a high refractive-index medium that is achieved by using double G-shaped resonators (DGR) in a 5×4 array. The array is oriented normal to the direction of the main beam emanating from the antenna. To demonstrate the principle, the technique is applied to a Bow-tie antenna, which is designed at the WiMAX frequency band (3.4–3.6 GHz). The antenna performance was verified practically, and the measured results confirm that the direction of the antenna’s maximum beam can be refracted by 35o in the H-plane, which is larger than conventional techniques. In addition, a maximum gain enhancement of 5 dB is achieved when the beam is tilted. Reflection-coefficient of the proposed structure is maintained better than -10 dB across its operational band

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 −11 dB. In addition, the proposed antenna exhibits good cross-polarization, which is less than −17 dB in both E- and H-planes at 60 GHz

Beam-deflection using gradient refractive-index media for 60-GHz end-fire antenna

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°

Single end-fire antenna for dual-beam and broad beamwidth operation at 60 GHz by artificially modifying the permittivity of the antenna substrate

Beamwidth radiation in the E-plane of a printed bow-tie antenna operating over 57–64 GHz. This is achieved by artificially modifying the dielectric constant of the antenna substrate using arrays of metamaterial inclusions realized using stub-loaded H-shaped unit cells to provide a high index of refraction. The H-shaped inclusions are tilted with respect to the axis of the antenna and embedded in the direction of the end-fire radiation. The resulting dual-beam radiation in the E-plane has maxima at +60° and 120° with respect to the end-fire direction (90°), with a maximum peak gain of 9 dBi at 60 GHz

Improvement of gain and elevation tilt angle using metamaterial loading for millimeter-wave applications

Elevation-plane beam tilting is demonstrated for a printed dipole antenna operating over 57–64 GHz. This is achieved using a 3x4 array of high refractive-index metamaterial (HRIM) unit cells. The unit cell comprises a modified H-shaped structure with stub loading to control the refractive index of the unit cell over a finite frequency range. Integration of the 3x4 array in the H-plane of a dipole antenna is shown to deflect the main beam by +30 degrees with respect to the endfire direction over 57–64 GHz. In addition, the proposed technique provides 5 dB gain enhancement

Mutual coupling reduction in dielectric resonator antennas using metasurface shield for 60 GHz MIMO systems

An effective technique for reducing the mutual coupling between two Dielectric Resonator Antennas (DRA) operating at 60 GHz bands is presented. This is achieved by incorporating a metasurface between the two DRAs, which are arranged in the H-plane. The metasurface comprises an array of unique split-ring resonator (SRR) cells that are integrated along the E-plane. The SRR configuration is designed to provide band-stop functionality within the antenna bandwidth. By loading the DRA with 1×7 array of SRR unit cells, a 28 dB reduction in the mutual coupling level is achieved without compromising the antenna performance. The measured isolation of the prototype antenna varies from -30 to -46.5 dB over 59.3–64.8 GHz. The corresponding reflection coefficient of the DRA is better than -10 dB over 56.6–64.8 GHz