Demonstrate Beam Steering Research Articles

Toward High-Power Beam-Steerable Reflectarrays Using Tunable-Height Dielectric

A novel method for a high-power reconfigurable reflectarray (RRA) with a moderate 30° beam scanning is demonstrated. The proposed technique eliminates the need for mechanical steering of reflectors for satellite communication. A small mechanical movement of a patterned dielectric structure under multislot elements achieves beam steering by changing the coupling. Due to the unique shape of the multislot element, the unit cell is capable of tuning the phase for both linear polarization and circular polarization (CP) within a single design operating at 20 GHz. The maximum phase range obtained in this design is a continuous 280° for RHCP, LHCP, and two linear polarizations at 20 GHz. The phase of the reconfigurable unit cell is verified and measured using a waveguide simulator attached to a micromotor. Maximum element loss is simulated to be 0.5 dB. To demonstrate beam steering, three reflectarrays with frozen dielectrics and square array lattices composed of 400 elements ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\lambda _{0}\,\,\times 10\lambda _{0}$ </tex-math></inline-formula> ) are fabricated. The frozen reflectarrays demonstrate beams at 0°, 15°, and 30°. The measured gain is found to be 23.2 dB at broadside with 21.8 and 23.3 dB, respectively, when scanned to 15° and 30°. The 1 dB gain bandwidth is measured to be 7.45% with a 3 dB axial ratio bandwidth of 12.1%. Unlike other architectures that use nonlinear semiconductor devices, the proposed reflectarray uses a dielectric insert with a height that can be controlled by a micromotor suitable for high-power applications supporting up to 80 MW/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}^{2}$ </tex-math></inline-formula> .

Demonstration of beam steering using a passive silica optical phased array with wavelength tuning.

We demonstrate beam steering using a passive silica optical phased array (OPA) with wavelength tuning. In this OPA, a constant path difference is built up to assign sequential phase delays with a wavelength variation in arrayed waveguide channels for the beam steering. From as-fabricated 1 × 101 passive silica OPA chips, we successfully achieved beam forming with a transversal divergence angle of 0.57° at a 1548.3-nm wavelength and also beam steering of 15.4° by wavelength tuning of 30.7 nm. Combining a cylindrical lens in front of the end-fire radiators, the longitudinal divergence angle could be reduced from 13.0° to 0.42°. The side-mode suppression ratio of the beam was 10.3 dB at the center position. Through simulation, we analyzed the effects of the phase errors on the beam quality, due to the effective index fluctuation of the waveguide channels, and provided an allowable error range to attain beam forming from the passive OPA.

Integrated Optical Phased Array Based on a Binary Splitter Tree With Reduced Number of Control Voltages

We experimentally demonstrate beam steering in an optical phased array (OPA) featuring a mixture of individual and cascaded phase modulator architecture embedded in the binary splitter tree. We show equivalent beam forming in a 16 channel OPA with 16 separate applied voltages and a cascaded 16ch OPA with 6 control voltages. A 32ch OPA with 10 control voltages is also demonstrated. These results illustrate a flexible means of designing an OPA with significantly fewer electrical connections than the optical channel count, while minimizing the impact of waveguide phase errors on the output beam quality.

Multi-Layer and Conformally Integrated Structurally Embedded Vascular Antenna (SEVA) Arrays.

This work presents the design and fabrication of two multi-element structurally embedded vascular antennas (SEVAs). These are achieved through advances in additively manufactured sacrificial materials and demonstrate the ability to embed vascular microchannels in both planar and complex-curved epoxy-filled quartz fiber structural composite panels. Frequency-reconfigurable antennas are formed by these structures through the pressure-driven transport of liquid metal through the embedded microchannels. The planar multi-layer topology examines the ability to fabricate two co-located radiating structures separated by a single ply of quartz fabric within the composite layup. The multi-element linear array topology composed of microchannels embedded on to a single-layer are used to demonstrate the ability to conformally-integrate these channels into a complex curved surface that mimics an array of antennas on the leading edge of an Unmanned Aerial Vehicle (UAV). A parallel-strip antipodal dipole feed structure provides excitation and serves as the interface for fluid displacement within the microchannels to facilitate reconfiguration. The nominal design of the SEVAs achieve over a decade of frequency reconfiguration with respect to the fundamental dipole mode of the antenna. Experimental and predicted results demonstrate the operation for canonical states of the antennas. Additional results for the array topology demonstrate beam steering and contiguous operation of interconnected elements in the multi-element structure.

Wavefront shaping in underwater with soft gradient-index metasurfaces at ultrasonic frequencies

Metasurfaces are planar metamaterials with a subwavelength thickness that allows wavefront shaping by introducing in-plane variations, namely, gradients, in the spatial wave response of these flat structures. Most of the recently reported acoustic metasurfaces were designed to control air-borne waves. Here, we report a new class of acoustic gradient-index (GRIN) metasurfaces engineered from soft graded-porous silicone rubber with a high and tunable acoustic index for broadband ultrasonic 3-D wavefront shaping in aqueous media. The functionalities of these soft flat lenses are illustrated through various experiments, which demonstrate beam steering and beam focusing, as well as vortex beam generation in free water. These new GRIN metasurfaces may have important applications in various domains using designed ultrasonic fields (biomedical imaging, industrial non-destructive testing, contactless particle manipulation), since their fabrication is very straightforward with common polymer science engineering. Y. Jin, R. Kumar, O. Poncelet, O. Mondain-Monval, and T. Brunet, Nat. Commun. 10, 143 (2019).

Dynamic beam steering with all-dielectric electro-optic III\u2013V multiple-quantum-well metasurfaces

Tunable metasurfaces enable dynamical control of the key constitutive properties of light at a subwavelength scale. To date, electrically tunable metasurfaces at near-infrared wavelengths have been realized using free carrier modulation, and switching of thermo-optical, liquid crystal and phase change media. However, the highest performance and lowest loss discrete optoelectronic modulators exploit the electro-optic effect in multiple-quantum-well heterostructures. Here, we report an all-dielectric active metasurface based on electro-optically tunable III–V multiple-quantum-wells patterned into subwavelength elements that each supports a hybrid Mie-guided mode resonance. The quantum-confined Stark effect actively modulates this volumetric hybrid resonance, and we observe a relative reflectance modulation of 270% and a phase shift from 0° to ~70°. Additionally, we demonstrate beam steering by applying an electrical bias to each element to actively change the metasurface period, an approach that can also realize tunable metalenses, active polarizers, and flat spatial light modulators.

Flat acoustics with soft gradient-index metasurfaces

Recently, metasurfaces have been proven to be effective and compact devices for the design of arbitrary wavefronts. Metasurfaces are planar metamaterials with a subwavelength thickness that allows wavefront shaping by introducing in-plane variations, namely, gradients, in the spatial wave response of these flat structures. Here we report a new class of acoustic gradient-index (GRIN) metasurfaces engineered from soft graded-porous silicone rubber with a high acoustic index for broadband ultrasonic three-dimensional wavefront shaping in water. The functionalities of these soft flat lenses are illustrated through various experiments, which demonstrate beam steering and beam focusing, as well as vortex beam generation in free space. These new GRIN metasurfaces may have important applications in various domains using designed ultrasonic fields (biomedical imaging, industrial non-destructive testing, contactless particle manipulation), since their fabrication is very straightforward with common polymer science engineering.

Inkjet printed array antennas with frequency controlled beamsteering and multi-angle receiving

This paper presents the first frequency scanning array on a flexible substrate constructed using printed electronics methods and systems. Devices were designed using a printed wide band stacked ellipsoid antenna and phase shifter network with 50 ohm matching power splitters which was developed using Ansys Electromagnetics. These devices were produced in both 1 × 4 and 1 × 8 antenna patch configurations. The resulting devices were then tested to demonstrate beam steering as a function of frequency at 4.35 GHz, 5.32 GHz, 6.27 GHz, and 7.2 GHz and compared. Additionally, bending tests were performed to demonstrate the usability of the devices in a flexible, internet of things oriented application. The demonstrated devices have a multibeam receiving and transmitting capability while being inexpensive and easy to produce in a flexible package.

Beam steering and impedance matching of plasmonic horn nanoantennas.

In this paper, we study a plasmonic horn nanoantenna on a metal-backed substrate. The horn nanoantenna structure consists of a two-wire transmission line (TWTL) flared at the end. We analyze the effect of the substrate thickness on the nanoantenna's radiation pattern, and demonstrate beam steering in a broad range of elevation angles. Furthermore, we analyze the effect of the ground plane on the impedance matching between the antenna and the TWTL, and observe that the ground plane increases the back reflection into the waveguide. To reduce the reflection, we develop a transmission line model to design an impedance matching section which leads to 99.75% power transmission to the nanoantenna.

Terahertz beam steering and variable focusing using programmable diffraction gratings

We propose a freely programmable THz diffraction grating based on an electrostatically actuated, computer controlled array of metallic cantilevers. Switching between different grating patterns enables tailoring spatio-temporal profiles of the THz waves. By characterizing the device with spatially resolved THz time domain spectroscopy, we demonstrate beam steering for a wide frequency band extending from 0.15 THz to 0.9 THz. The steerable range at 0.3 THz exceeds 40°. Focusing is also demonstrated by programming a chirped grating. The proposed approach could be employed to mimic arbitrary diffraction optics, enabling highly integrated and extremely flexible systems indispensable for THz stand-off imaging and communications.

A 60-GHz Active Receiving Switched-Beam Antenna Array With Integrated Butler Matrix and GaAs Amplifiers

This paper presents for the first time a 60-GHz receiving switched-beam antenna on organic liquid crystal polymer (LCP) platform. A 4 × 1 quasi-Yagi array is incorporated with a 4 × 4 Butler matrix beamforming network and GaAs low-noise amplifiers on an LCP substrate. The active beam is controlled by GaAs single-pole-double-throw switches to access the four output states of the Butler matrix. The entire 4 × 1 active array is 1.4 cm × 1.75 cm and consumes 1.1 W of dc power. Successful comparisons of the measured and simulated results verify a working phased array with a return loss better than 10 dB across the frequency band of 56.7-63.7 GHz. A comparison of radiation patterns demonstrate beam steering of ±40° with a peak active gain of 27.5 dB. The combined antenna and receiver noise performance at 60 GHz exhibits an estimated merit G/T of -18.6 dB/K and noise figure of 5.4 dB.

Fiber-optic prism true time-delay antenna feed

Experimental results for an optical-control technique for implementing a true time-delay function for array antennas are reported. A microwave signal is transmitted on a wavelength-tunable optical carrier through a fiber-optic prism-a set of nominally equal-delay fibers with differing net dispersion-to photodetectors that feed each antenna element. The relative interelement time-delay (beam angle) adjustment is accomplished by tuning the optical carrier wavelength. Measured antenna patterns of a two-element array clearly demonstrate beam steering and true time-delay operation over a two-octave bandwidth of 2-8 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>