Flanched-Cross: An Efficient Cell Geometry for Beam Steering Metasurfaces with Orthogonal Polarisation Handling Capability

Geometry plays an important part in the characteristics of meta-cells used to design beam steering metasurfaces. One of the most desirable aspects of these cells is a large phase shift range that can be achieved with good transmission amplitude. However, the existing and most commonly used geometries for these cells are not able to produce a complete 360° phase range with an acceptable level of transmission amplitude. In this article, we present a new cell geometry, Flanched-Cross, that has superior transmission properties due to its unique shape and parametric variability than the commonly used geometries. The results are verified in simulation and further confirmed through prototyping and measurement. One- and two-dimensional steering are also performed for a dual-polarised base array to confirm the applicability of Flanched-Cross cell for beam steering purposes.

Flanched-Cross: An Efficient Cell Geometry for Beam Steering Metasurfaces with Orthogonal Polarisation Handling Capability

Geometry plays an important part in the characteristics of meta-cells used to design beam steering metasurfaces. One of the most desirable aspects of these cells is a large phase shift range that can be achieved with good transmission amplitude. However, the existing and most commonly used geometries for these cells are not able to produce a complete 360° phase range with an acceptable level of transmission amplitude. In this article, we present a new cell geometry, Flanched-Cross, that has superior transmission properties due to its unique shape and parametric variability than the commonly used geometries. The results are verified in simulation and further confirmed through prototyping and measurement. One- and two-dimensional steering are also performed for a dual-polarised base array to confirm the applicability of Flanched-Cross cell for beam steering purposes.

Novel Beam Scan Method of Fabry–Perot Cavity (FPC) Antennas

A new beam scanning method of a Fabry–Perot cavity (FPC) antenna is proposed. To obtain high gain in a target direction with a reduced sidelobe level (SLL), we devised a tapered partially reflective surface (PRS) as a superstrate. Moreover, to attain various beam scanning directions, a phase-controllable artificial magnetic conductor (AMC) ground plane with a broad reflection phase range and high reflection magnitudes was introduced. In the proposed method, a new formula to satisfy an FP resonance condition in a cavity for a scanned beam is also suggested. According to the formula, the FPC antenna can precisely scan the main beam in designed target directions with well-maintained high gain, which has been hardly achievable. In addition, our method demonstrates the potential of electrical beam-scanning antennas by employing active RF chips on the AMC cells. To validate the method, we fabricated a prototype FPC antenna for a scanned beam at θ = 30°. Furthermore, we conducted an additional simulation for a different beam scanning angle as well. Good agreement between the expected and experimental results verifies our design approach.

Reconfigurable Reflectarray Antenna: A Comparison between Design Using PIN Diodes and Liquid Crystals

This work presents the design and analysis of active reflectarray antennas with slot embedded patch element configurations within an X -band frequency range. Two active reflectarray design technologies have been proposed by digital frequency switching using PIN diodes and analogue frequency tuning using liquid crystal-based substrates. A waveguide simulator has been used to perform scattering parameter measurements in order to practically compare the performance of reflectarray designed based on the two active design technologies. PIN diode-based active reflectarray unit cell design is shown to offer a frequency tunability of 0.36 GHz with a dynamic phase range of 226°. On the other hand, liquid crystal-based design provided slightly lower frequency tunability of 0.20 GHz with a dynamic phase range of 124°. Moreover, the higher reflection loss and slow frequency tuning are demonstrated to be the disadvantages of liquid crystal-based designs as compared to PIN diode-based active reflectarray designs.

Reflectarray Resonant Element based on a Dielectric Resonator Antenna for 5G Applications

The performance of a proposed cross hybrid dielectric resonator antenna (DRA) element for dual polarization configuration operating at 26 GHz for 5G applications is presented in this paper. The new cross hybrid DRA unit cell is introduced which combines a cross shape DRA with a bottom loading cross microstrip patch. This technique of a bottom loading cross microstrip patch is chosen as the tuning mechanism (varying the length of the microstrip to tune the phase) instead of changing the DRA dimensions because of their ease of implementation and fabrication. By doing so, high reflection phase range with low reflection loss performance can be obtained, which is essential for a high bandwidth and high gain reflectarray for 5G applications. The design and simulation have been done using commercial software of CST MWS. The reflection loss, reflection phase and slope variation were analyzed and compared. A metallic cross microstrip patch of varying length placed beneath the DRA to act as the phase shifter to tune the phase and give smooth variation in slope with a large phase range. The proposed cross hybrid DRA unit cell provides a high reflection phase range of 342º and 1.8 dB reflection loss. The computed results are compared with experimental results revealing reasonable agreement, thereby confirming the viability of the design.

Novel silicon bipodal cylinders with controlled resonances and their use as beam steering metasurfaces

Metasurfaces have paved the way for high performance wavefront shaping and beam steering applications. Phase-gradient metasurfaces (PGM) are of high importance owing to the powerful and relatively systematic tool they offer for manipulating electromagnetic wave fronts and achieving various functionalities. Herein, we numerically present a novel unit cell known as bipodal cylinders (BPC), made of Silicon (Si) and placed on a Silicon dioxide (SiO2) substrate to be compatible with CMOS fabrication techniques and to avoid field leakage into a high index substrate. Owing to its geometrical structure, the BPC structure provides a promising unit cell for electromagnetic wave manipulation. We show that BPC offers a way to shift the electric dipole mode to a frequency higher than that of the magnetic dipole mode. We investigate the effect of varying different geometrical parameters on the performance of such unit cell. Building on that, a metasurface is then presented that can achieve efficient electromagnetic beam steering with high transmission of 0.84 and steering angle of 15.2°; with very good agreement with the theoretically predicted angle covering the whole phase range from 0 to 2$$\pi$$ π .