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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Antenna assemblies and antenna systems

Antenna assemblies and antenna systems are described. According to one aspect, a printed circuit board antenna system includes a dielectric substrate comprising first and second surfaces that are opposite to one another, first electrically conductive material of an antenna element adjacent to the first surface of the dielectric substrate, wherein the antenna element is configured to emit electromagnetic energy, and second electrically conductive material of a ground plane adjacent to the second surface of the dielectric substrate, wherein the ground plane is aligned with the antenna element and configured to reflect some of the electromagnetic energy in a direction towards the antenna element.

Grando, Maurio B.↗
DOE OSTI2023

Benchmark between antenna code TOPICA, RAPLICASOL and Petra-M for the ICRH ITER antenna

ITER will be equipped with three plasma heating systems: neutral beam (NB), electron cyclotron (EC), and ion cy-clotron resonance heating (ICRH). The latter consists of two identical ICRH antennas to deliver 20 MW to the plasma (baseline, upgradable to 40 MW). ICRH will play a crucial role in the ignition and sustainment of burning plasmas in ITER. A high fidelity and robust modeling effort to understand the interaction of the IC waves with the scrape-off-layer (SOL) plasma is a very important aspect. Among the main important research topics, we have the assessment of the antenna loading for different plasma scenarios, the role of the lower hybrid resonance in front of the antenna and how to include it in our models, and the RF sheath boundary conditions to evaluate the antenna impurity generation. In this work, we tackle the first of these by reporting on ICRF simulations employing the Petra-M code, which is an electromagnetic simulation tool for modeling RF wave propagation based on MFEM [http://mfem.org] for the ITER ICRH antenna. Moreover, a benchmark between the well tested antenna codes TOPICA, RAPLI-CASOL, which is based on COMSOL [www.comsol.com], and the Petra-M code is also presented. In conclusion, S- and Z-matrices and wave electric field are compared showing an excellent agreement among these codes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Quieting a noisy antenna reproduces photosynthetic light-harvesting spectra

Photosynthesis achieves near unity light-harvesting quantum efficiency yet it remains unknown whether there exists a fundamental organizing principle giving rise to robust light harvesting in the presence of dynamic light conditions and noisy physiological environments. Here, we present a noise-canceling network model that relates noisy physiological conditions, power conversion efficiency, and the resulting absorption spectra of photosynthetic organisms. Using light conditions in full solar exposure, light filtered by oxygenic phototrophs, and light filtered under seawater, we derived optimal absorption characteristics for efficient solar power conversion. We show how light-harvesting antennae can be tuned to maximize power conversion efficiency by minimizing excitation noise, thus providing a unified theoretical basis for the observed wavelength dependence of absorption in green plants, purple bacteria, and green sulfur bacteria.

Science & Technology - Other Topics↗
DOE OSTI2021

Ensuring reliable connectivity to cellular-connected UAVs with up-tilted antennas and interference coordination

To integrate unmanned aerial vehicles (UAVs) in future large-scale deployments, a new wireless communication paradigm, namely, the cellular-connected UAV has recently attracted interest. However, the line-of-sight dominant air-to-ground channels along with the antenna pattern of the cellular ground base stations (GBSs) introduce critical interference issues in cellular-connected UAV communications. In particular, the complex antenna pattern and the ground reflection (GR) from the down-tilted antennas create both coverage holes and patchy coverage for the UAVs in the sky, which leads to unreliable connectivity from the underlying cellular network. To overcome these challenges, in this paper, we propose a new cellular architecture that employs an extra set of co-channel antennas oriented towards the sky to support UAVs on top of the existing down-tilted antennas for ground user equipment (GUE). To model the GR stemming from the down-tilted antennas, we propose a path-loss model, which takes both antenna radiation pattern and configuration into account. Next, we formulate an optimization problem to maximize the minimum signal-to-interference ratio (SIR) of the UAVs by tuning the up-tilt (UT) angles of the up-tilted antennas. Since this is an NP-hard problem, we propose a genetic algorithm (GA) based heuristic method to optimize the UT angles of these antennas. After obtaining the optimal UT angles, we integrate the 3GPP Release-10 specified enhanced inter-cell interference coordination (eICIC) to reduce the interference stemming from the down-tilted antennas. Our simulation results based on the hexagonal cell layout show that the proposed interference mitigation method can ensure higher minimum SIRs for the UAVs over baseline methods while creating minimal impact on the SIR of GUEs.

3GPP↗
DOE OSTI2020

An Unbalanced Sinuous Antenna for Near-Surface Polarimetric Ground-Penetrating Radar

Sinuous antennas are capable of producing ultra-wideband radiation with polarization diversity. This capability makes the sinuous antenna an attractive candidate for UWB polarimetric radar applications. Additionally, the ability of the sinuous antenna to be implemented as a planar structure makes it a good fit for close-in sensing applications such as ground-penetrating radar (GPR). In this work, each arm of a four-port sinuous antenna is operated independently to achieve a quasi-monostatic antenna system capable of polarimetry while separating transmit and receive channels—which is often desirable in GPR systems. The quasi-monostatic configuration of the sinuous antenna reduces system size as well as prevents extreme bistatic angles, which may significantly reduce sensitivity when attempting to detect near-surface targets. A prototype four-port sinuous antenna is fabricated and integrated into a GPR testbed. The polarimetric data obtained with the antenna is then used to distinguish between buried target symmetries.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Ultra-light antennas via charge programmed deposition additive manufacturing

Abstract The demand for lightweight antennas in 5 G/6 G communication, wearables, and aerospace applications is rapidly growing. However, standard manufacturing techniques are limited in structural complexity and easy integration of multiple material classes. Here we introduce charge programmed multi-material additive manufacturing platform, offering unparalleled flexibility in antenna design and the capability for rapid printing of intricate antenna structures that are unprecedented or necessitate a series of fabrication routes. Demonstrating its potential, we present a transmitarray antenna composed of an interconnected, multi-layered array of dielectric/conductive S-ring unit cells, reducing 94% mass of conventional antenna configurations. A fully printed circular polarized transmitarray system fed by a source and a Risley prism antenna system operating at 19 GHz both show close alignment between testing results and numerical simulations. This printing method establishes a universal platform, propelling discovery of new antenna designs and enabling data-driven design and optimizations where rapid production of antenna designs is crucial.

Science & Technology - Other Topics↗
DOE OSTI2021

Shared aperture antenna array

A shared aperture antenna array including an array of antennas is disclosed. Elements of neighboring antennas are shared to create additional antennas. The shared elements include radiating patches and apertures. Each antenna shares an aperture with neighboring antennas. The array of antennas may be linear or two-dimensional. A phase shifting network with single-pole-single-throw reflective switches may be coupled to the antennas.

Tedeschi, Jeffrey R.↗
DOE OSTI2024

Shared aperture antenna array

A shared aperture antenna array including an array of antennas is disclosed. Elements of neighboring antennas are shared to create additional antennas. The shared elements include radiating patches and apertures. Each antenna shares an aperture with neighboring antennas. The array of antennas may be linear or two-dimensional. A phase shifting network with single-pole-single-throw reflective switches may be coupled to the antennas.

Tedeschi, Jonathan R.↗
DOE OSTI2025

Automated design of an additive manufactured compact broadband antenna for plasma reflectometry

Broadband antennas operating in the gigahertz frequency range are regularly used for plasma reflectometry diagnostics. Due to a lack of space and unique diagnostic constraints, these antennas are often custom in design and frequency range. Recent advances in additive manufacturing of high temperature copper alloys allow for expanded freedom in design of these diagnostic antennas. In this work, a heuristic simulated annealing algorithm is used alongside 3-D finite element simulation to automate the design of a double ridged rectangular horn antenna for a reflectometry diagnostic on the DIII-D tokamak. Optimization of antenna performance given the design constraints results in a compact broadband (6-20+ GHz) antenna design. Measured transmission from the additively manufactured antenna matches simulation within reasonable error, and experimental plasma electron density profiles from the DIII-D high-field side scrape-off layer are shown.

Additive manufacturing↗
DOE OSTI2022

Design of a finline antenna for current drive in TST-2

A novel “finline” antenna was designed to excite lower-hybrid waves (LHWs) for plasma current drive at 2.45 GHz in the TST-2 spherical tokamak. A periodic fin array acts as a transmission line for electromagnetic surface waves. Cold tests confirmed propagation of the electromagnetic surface wave on the fin array which was dominantly Transverse Magnetic (TM). Unlike the conventional waveguide array “grill” antenna, the finline antenna requires only two ports to feed all the elements, and calculations show that there is little reflection regardless of the plasma conditions in front of the antenna. Characteristics of the microwave transmission on the fin array were investigated using a three-dimensional full-wave simulation and the fin geometry was tuned to achieve the desired refractive index. Coupling to LHWs under typical TST-2 scrape-off layer conditions was confirmed by the simulation. Finally, to demonstrate LHW excitation, the finline antenna was energized in the presence of a plasma generated by another 200 MHz LH antenna. The x-ray radiation showed strong enhancement during the finline antenna pulse which indicated successful generation of fast electrons by LHWs.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

ICRF antenna matching systems with ferrite tuners for the Alcator C-Mod tokamak

Real-time fast ferrite tuning (FFT) has been successfully implemented on the ICRF antennas on Alcator C-Mod. The former prototypical FFT system on the E-port 2-strap antenna has been upgraded using new ferrite tuners. A new FFT system with two ferrite tuners and one fixed-length stub has been installed on the transmission line of the D-port 2-strap antenna. These two systems are able to achieve and maintain the reflected power to the transmitters to less than 1% in real time under almost all plasma conditions and help ensure reliable high power operation of the antennas. The loading insensitivity feature vs. plasma conditions of the innovative field-aligned (FA) 4-strap antenna on the J-port allows us to significantly improve the matching by installing a carefully designed stub on each of the two transmission lines. The reduction of the RF voltages in the transmission lines has enabled the J-port FA antenna to deliver 3.7 MW RF power to plasmas out of 4 MW source power. The matching on the J-port antenna can be further improved by adding a single ferrite tuner under real-time control on each transmission line and this scheme will be implemented in the near future.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

De-tuning tolerant loop antenna

A loop antenna is described herein that is suitable for operation in free space or in proximity to a ground plane. The loop antenna comprises a looped conductive element with a gap formed therein and a tab extending toward the gap. A length of the tab of the loop antenna is selected such that a detuning loss of the loop antenna from operation in free space to operation in proximity to a ground plane is low. In an exemplary embodiment, the length of the tab is selected such that a reactance of the loop antenna in free space is within a threshold level of a reactance of the loop antenna when the antenna is in proximity to a ground plane.

42 ENGINEERING↗
DOE OSTI2023

High efficiency radio frequency antennas for amplifier free quantum sensing applications

Radio frequency (RF) signals are frequently used in emerging quantum applications due to their spin state manipulation capability. Efficient coupling of RF signals into a particular quantum system requires the utilization of carefully designed and fabricated antennas. Nitrogen vacancy (NV) defects in diamond are commonly utilized platforms in quantum sensing experiments with the optically detected magnetic resonance (ODMR) method, where an RF antenna is an essential element. We report on the design and fabrication of high efficiency coplanar RF antennas for quantum sensing applications. Single and double ring coplanar RF antennas were designed with -37 dB experimental return loss at 2.87 GHz, the zero-field splitting frequency of the negatively charged NV defect in diamond. The efficiency of both antennas was demonstrated in magnetic field sensing experiments with NV color centers in diamond. In conclusion, an RF amplifier was not needed, and the 0 dB output of a standard RF signal generator was adequate to run the ODMR experiments due to the high efficiency of the RF antennas.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Light regulation of light-harvesting antenna size substantially enhances photosynthetic efficiency and biomass yield in green algae

One of the major factors limiting biomass productivity in algae is the low thermodynamic efficiency of photosynthesis. The greatest thermodynamic inefficiencies in photosynthesis occur during the conversion of light into chemical energy. At full sunlight the light-harvesting antenna captures photons at a rate nearly 10 times faster than the rate-limiting step in photosynthetic electron transport. Excess captured energy is dissipated by non-productive pathways including the production of reactive oxygen species. Substantial improvements in photosynthetic efficiency have been achieved by reducing the optical cross-section of the light-harvesting antenna by selectively reducing chlorophyll b levels and peripheral light-harvesting complex subunits. Smaller light-harvesting antenna, however, may not exhibit optimal photosynthetic performance in low or fluctuating light environments. Additionally, we describe a translational control system to dynamically adjust light-harvesting antenna sizes for enhanced photosynthetic performance. Furthermore, by expressing a chlorophyllide a oxygenase (CAO) gene having a 5' mRNA extension encoding a Nab1 translational repressor binding site in a CAO knockout line it was possible to continuously alter chlorophyll b levels and correspondingly light-harvesting antenna sizes by light-activated Nab1 repression of CAO expression as a function of growth light intensity. Significantly, algae having light-regulated antenna sizes had substantially higher photosynthetic rates and two-fold greater biomass productivity than the parental wild-type strains as well as near wild-type ability to carry out state transitions and non-photochemical quenching. These results have broad implications for enhanced algae and plant biomass productivity.

09 BIOMASS FUELS↗
DOE OSTI2020

Flexible Magnetic Polymer Composite Substrate with Ba 1.5 Sr 1.5 Z Hexaferrite Particles of VHF/Low UHF Patch Antennas for UAVs and Medical Implant Devices

Our goal is to fabricate flexible magnetic polymer composites as antenna substrates for very high frequency (VHF)/low ultra high frequency (UHF) antennas for unmanned aerial vehicles (UAVs) and medical devices. Magnetodielectric materials, which have permeability (μ) similar to permittivity (ε), have attracted great attention, because they facilitate miniaturization of microwave devices while keeping or enhancing electromagnetic characteristics. Mechanically millled Ba 1.5 Sr 1.5 Co 2 Fe 24 O 41 (Ba 1.5 Sr 1.5 Z) hexaferrite particles were used to increase permeability in the interesting frequency band. The microwave properties of Ba 1.5 Sr 1.5 Z composites were predicted and measured. Hansen’s zero-order analysis of antenna bandwidth and electromagnetic field simulation showed that the hexaferrite-based flexible composite could enhance a bandwidth and achieve the miniaturization of antennas as well. The magnetic antenna substrates can be a good solution to integrate antennas into the UAVs whose dimensions are comparable to or larger than communication wavelength.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A High Gain Lens-Coupled On-Chip Antenna Module for Miniature-Sized Millimeter-Wave Wireless Transceivers

This paper presents high gain and compact Transmit/Receive (TX/RX) integrated antennas in a standard BiCMOS 130nm technology for millimeter-scale millimeter-wave (mm-wave) applications, including high data rate radios and high resolution radars. The proposed TX/RX antenna module utilizes an integrated dipole antenna for the receiver and a slot antenna for the transmitter, placed orthogonally. The achieved gain and radiation efficiency are 5.7dBi and 41.3% for the slot antenna, respectively, and 6dBi and 39% for the dipole antenna. The link budget is improved by 16dB by optimization on the geometry aswell as application of a high resistivity hemispheric silicon dielectric lens.

Engineering↗