Santiago Capdevila

Tri-Band, Polarization-Independent Reflectarray at Terahertz Frequencies: Design, Fabrication, and Measurement

In this paper, two THz reflectarray surfaces have been designed and fabricated in order to deflect a plane wave with any polarization and with a specific incident angle to three different specific directions each at distinct three frequencies of 0.7, 1.0 and 1.5 THz. The surface is composed of an array of 100 ×100 cells, each comprised of gold crosses and parasitic dipoles printed on thin grounded high resistivity silicon. Finite-element method (FEM) simulations are in line with the measurement results obtained using THz time-domain spectroscopy (THz TDS) showing the intended deflections for the two fabricated samples each with an arbitrary frequency-vs-deflection angle relationship. In addition, the use of silicon as the substrate paves the way for the integration of reconfigurable technologies which enhances the reflectarray versatility.

Modulated scattering technique in the terahertz domain enabled by current actuated vanadium dioxide switches

The modulated scattering technique is based on the use of reconfigurable electromagnetic scatterers, structures able to scatter and modulate an impinging electromagnetic field in function of a control signal. The modulated scattering technique is used in a wide range of frequencies up to millimeter waves for various applications, such as field mapping of circuits or antennas, radio-frequency identification devices and imaging applications. However, its implementation in the terahertz domain remains challenging. Here, we describe the design and experimental demonstration of the modulated scattering technique at terahertz frequencies. We characterize a modulated scatterer consisting in a bowtie antenna loaded with a vanadium dioxide switch, actuated using a continuous current. The modulated scatterer behavior is demonstrated using a time domain terahertz spectroscopy setup and shows significant signal strength well above 0.5 THz, which makes this device a promising candidate for the development of fast and energy-efficient THz communication devices and imaging systems. Moreover, our experiments allowed us to verify the operation of a single micro-meter sized VO2 switch at terahertz frequencies, thanks to the coupling provided by the antenna.

Graphene Reflectarray Metasurface for Terahertz Beam Steering and Phase Modulation

We report a THz reflectarray metasurface which uses graphene as active element to achieve beam steering, shaping and broadband phase modulation. This is based on the creation of a voltage controlled reconfigurable phase hologram, which can impart different reflection angles and phases to an incident beam, replacing bulky and fragile rotating mirrors used for terahertz imaging. This can also find applications in other regions of the electromagnetic spectrum, paving the way to versatile optical devices including light radars, adaptive optics, electro-optical modulators and screens.

3D printed feed-chain and antenna components

This paper presents a set of additive manufactured (AM) monolithic waveguide-based feed-chain and antenna components, namely a Ku-band diplexer, a Ka-band dual-polarized directional antenna and W-band straight waveguides. These components provide representative examples of the current capabilities of AM technologies. Examples are provided over a large frequency spectrum and for diverse applications. Good performance and agreement between simulation and measurement results validate the presented designs and showcase the achievable performance of this new manufacturing technology.

Mm-wave antennas and components: Profiting from 3D-printing

The goal of this manuscript is to show the potential of additive manufacturing (AM) to produce cost-effective high-performance passive mm-wave components and antennas. We focus on the particular AM technique developed by SWISSto12 based on the so called Stereolithography (SLA), which consists on the 3D-printing of a skeleton of the component using a non-conductive polymer. Chemical copper plating is then applied in order to make all component surfaces RF-conductive. One of the most relevant advantages associated to this approach stems from its ability to produce low-weight monolithic devices. Two 3D-printed RF-devices operating at mm-waves are here presented: a Ka-band radiating element and a V-band orthomode-transducer. Both devices have been firstly designed using full-wave solvers, then manufactured and finally validated through measurements.