Dr Shadi Danesh

This paper presents a dual-functional Simultaneous Transmission and Reflection Reconfigurable Intelligent Surface (STAR-RIS) that integrates communication via reflection and computation/sensing via transmission within a single aperture. When an incoming wave impinges on the STAR-RIS, part of it is reflected for communication, while the transmitted portion, shaped by a lens phase profile, performs Fourier transformations in the k−domain enabling computational tasks. A coding metasurface approach is used to create a linear phase gradient in the reflection space and a lens phase profile in the transmission space. This enables tailored beam patterns for reflection and computational tasks, such as Fourier transforms, for accurate angle-of-arrival estimation and sensing applications. To validate the concept, a STAR-RIS with side-by-side reflection and transmission arrays is designed, fabricated, and tested at 26 GHz.

A metasurface-based thin flat lens operating at millimeter wave frequencies is presented. The three-layered Huygen Metalens indicates collimating/focusing of broadband frequencies from 60 to 74 GHz, with a gain enhancement of 22.5 dBi at a central frequency of 69 GHz while fed by a dipole antenna. The metasurface transmission performance is designed and simulated by numerical and analytical approaches. By integrating multilayered 1-bit Huygens unit cells, the metasurface produced 180 0 phase coverage with constant high amplitude. The proposed design comprised of 50 × 50 unilcells, creating an area of 75 × 75mm 2. The dipole antenna is applied to illuminate the proposed metasurface where the distance between the feeder and metalens is 27 mm. The result shows that the proposed metalens antenna achieves a maximum gain of 25 dBi at 69GHz GHz. The unique features of the proposed lightweight metalens will be widely used in wireless communication system for mmW wave frequencies.

A polarisation insensitive transparent metasurface with two pass bands and two stop bands is proposed for 5G outdoor to indoor (O2I) coverage enhancement. Genetic Algorithm (GA) has been applied in order to provide the structural geometry of the unit cell for this metasurface. The proposed periodic structure consists of a unit cell design consisting of five stacked transparent patterned layers of Indium Tin Oxide (ITO) coated on Polyethylene Terephthalate (PET) substrates. The proposed transmission metasurface can be easily mounted on conventional glass windows to assist the O2I 4G/5G signals for the n7 and n78 of the 5G new radio (5G-NR), as well as shielding the 2.4/5 GHz WiFi signals from penetrating outside the building thereby enhancing the security.

A novel high-isolation, monostatic, circularly polarized (CP) simultaneous transmit and receive (STAR) array dielectric resonator antenna (DRA) is presented. The proposed in-band full-duplex (IBFD) CP DRA system consists of 32 identical elements for each transmit and receiver part. Each element includes two rectangular dielectric resonators with different permittivity of 5 and 10 excited by a vertical strip connected to the microstrip line at the backplane. A stub connected to the ground plane is added between Rx and Tx to improve the isolation. In addition, an inverted U-shaped parasitic strip is carefully placed between two feeding networks to further enhance the TX/RX isolation. The measured results exhibit high TX/RX isolation of more than 50 dB over the desired operating bandwidth from 4.8 GHz to 4.95 GHz with a high total efficiency greater than 85% and a peak gain of about 18.7 dBi for both Port 1 and Port 2.