Mohamad Mantash

In this paper, a novel methodology using electrotextile fabrics is employed for designing a highly transparent, wideband frequency selective surface (FSS) in the millimeter-wave (MM-wave) band. The standard metallization is replaced by a low cost, extremely fine conductive mesh (RadioScreen or VeilShield) that gives to the periodic structure high see-trough properties in the 27-35 GHz frequency band. An acrylic dielectric material that is easily available and very low cost has been used as a substrate. Simulation and measurement results alike are presented to validate the principle. By assessing the high transparency properties of the FSS and its high performance in terms of stop-band, this FSS could be seen as a potential candidate for multiple 5G applications like for on-chip shielding, autonomous vehicles, antenna and on-chip antenna devices, radar cross section (RCS) augmentation, robotic guided paths and electromagnetic interference (EMI) protection.

This letter describes a reconfigurable frequency‐selective surfaces (FSSs) unit cell using cantilever switches resonating at X‐band frequency. The shape of the FSS is inspired by supershaped structures and the arms of the top layer are used as cantilever switches. It allows a transparent band around 10 GHz in one state and a reflective band with high isolation about 40 dB in the other state. A prototype of the proposed FSS was fabricated and measured in a waveguide transmission line.

The resonant characteristics of a printed ridge gap waveguide cavity are analyzed using the eigenmode method. The field distributions of typical modes and the relevant eigen frequencies are presented. One cavity-backed slot antenna based on the eigenmode results is proposed with the desirable input matching and radiation performance. That could demonstrate the feasibility of antenna design using printed ridge gap waveguide as a resonant cavity.

In this article, a novel wideband polarizer is presented, to convert the linear polarization of a directive antenna into circular polarization. This innovative polarizer is based on a 3D frequency selective surface (FSS) and consists of an array of 4×4 metal axial‐mode helices. The proposed broadband polarizer operates in the 28 to 31 GHz frequency band. To demonstrate the principle, the 3D FSS is applied to a linearly polarized Yagi‐Uda antenna operating in the same millimeter‐wave frequency band. The measured and simulated results, by integrating the proposed 3D polarizer in front of the antenna, show that an axial ratio smaller than 3 dB is obtained over a wide bandwidth with gain enhancement.

This paper proposes a novel circularly-polarized electromagnetic band-gap (EBG) antenna array backed by an artificial magnetic conductor (AMC) that operates in the 26 – 32GHz band. The designed antenna is a 2 x 2 Yagi-Uda antenna array that uses as directors semicircles to direct the radiation in the horizontal end-fire direction. The feeding of the array is designed with two parallel T-junction portions forming a parallel feeding network that converts the polarization from linear to circular. An AMC is placed underneath the antenna to suppress the backward radiation and obtain the propagation only in the +z plane. The novel approach is based on the fact that EBGs are placed around the array to give to the antenna, beam switching capability. This simple technique provides a high beam tilting angle of +90o from the end-fire to the full broadside plane. The final EBG-AMC-antenna array is circularly polarized and presents, at 29GHz, a gain of 11.9dBi, and an AR bandwidth of 10% from 28 to 31GHz. By assessing the high antenna performances presented in this paper, and the high angle beam switching capability by adding the EBG, the novel array could be seen as a potential candidate for implementation in future 5G applications.

A novel flexible and reconfigurable pattern antenna, integrated with an artificial magnetic conductor (AMC) surface, operating in the 29–31 GHz millimetre‐wave frequency band, is proposed. The designed antenna is a modified Yagi‐Uda antenna that uses as directors loop diamond shapes, allowing the bending of the structure in an easy way at high frequencies. The AMC structure is also composed of an array of diamond loops, printed on a grounded dielectric substrate without vias. Furthermore, an equivalent circuit model that allows the estimation of the resonant frequency and reflection coefficient phase of the AMC is presented. Using a flexible substrate in designing the proposed AMC antenna, different beam‐tilting angles can be obtained. Moreover, multiple pattern configurations are studied. The performance of the proposed AMC antenna is measured for flat and curved configurations. The maximum beam‐tilting angle is obtained for the curved AMC antenna configuration and is equal to +32° towards the + z direction with a realised gain of 12.1 dBi. Additionally, a beam‐tilting in the ± z elevation plane is achieved by integrating a single pole, double throw switching system. This method eliminates the complex steering system that uses phase shifters, which is traditional for the targeted applications.

This letter presents a new design of tilted-beam antenna with gain enhancement based on the multilayer frequency selective surfaces (FSSs) for fifth-generation applications. A dual-sided printed FSS element with two C-shaped resonators at the top layer and a slotted circular patch at the bottom side, is proposed. The FSS element holds a size of 0.46λ × 0.46λ (at 28 GHz). A wideband Vivaldi antenna with an end-fire radiation is used to excite the elements of the FSS layers. The effects of different sizes, number, and the angular rotation of the FSS layers are employed to achieve the best antenna performance in terms of beam-tilting, realized gain, and reducing the sidelobe level (SLL). The best antenna performance is achieved when two unequal-sized FSS layers rotated to 45° and fixed under the Vivaldi. The proposed antenna is fabricated and measured. The obtained measured results show a maximum beam tilt angle of 38°, realized gain of 9 dBi, and SLL at –8 dB. The beam tilt angles are validated with the results obtained using the Snell's law in a multilayer environment and found a good agreement.

In this paper, a novel wideband polarizer based on a 2D Frequency Selective Surface (FSS), operating in the frequency range of 28 to 32 GHz, is designed and characterized. This polarizer consists of an array of 9 x 9 “T” shaped unit-cells that converts a linearly polarized wave to a circular polarized wave. To demonstrate the principle, the proposed single layer FSS is applied to a linearly polarized Vivaldi antenna operating in the same millimeter-wave frequency band. The simulation results, by placing the proposed polarizer in front of the antenna, show that an axial ratio (AR) smaller than 3 dB is obtained over a wide bandwidth with a gain enhancement, confirming the polarization conversion.

A beam‐switching antenna for millimetre‐wave applications at 30 GHz is presented in this study. The radiation reconfigurability for a cylindrical dielectric resonator antenna (DRA) is obtained by using a cantilever‐enabled frequency selective surface (FSS). The proposed cantilever‐enabled FSS provides reconfigurable bandpass and band‐stop performance with good isolation between them. The investigation of designed FSS is performed using electromagnetic simulation and an array of the proposed FSS unit cell is fabricated and measured using the free‐space measurement method, which shows a good agreement with the simulation results. Finally, six panels of the 1 × 5 array of the proposed reconfigurable FSS are arranged in a hexagonal configuration around a cylindrical DRA to obtain a reconfigurable radiation pattern in the azimuth plane. A prototype of the proposed radiation reconfigurable DRA is fabricated and the switching radiation patterns are measured at 30 GHz.

This letter describes a simple beam-tilting technique for an end-fire antenna using only a single-layer Frequency Selective Surface (FSS). The proposed approach is based on placing a parasitic FSS element under the antenna to tilt the beam in the desired direction. This is achieved by using a modified uniplanar compact FSS (MUC-FSS). To demonstrate the principle, the periodic structure is applied to a Yagi-Uda antenna operating in the millimeter-wave frequency band from 28 to 31 GHz. The measured results, by integrating the proposed FSS (1 layer of 3x5 unit cells) under the directors of the antenna, show that at 30 GHz, the main beam radiation tilts the end-fire direction (YZ plane) by +23° and -29° when the FSS structure is rotated by 90°, respectively. The simplicity of this method makes it suitable for 5G communication networks.