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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 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Multi-Step Ka/Ka Dichroic Plate with Rounded Corners for NASA's 34m Beam Waveguide Antenna

A multi-step Ka/Ka dichroic plate Frequency Selective Surface (FSS structure) is designed, manufactured and tested for use in NASA's Deep Space Network (DSN) 34m Beam Waveguide (BWG) antennas. The proposed design allows ease of manufacturing and ability to handle the increased transmit power (reflected off the FSS) of the DSN BWG antennas from 20kW to 100 kW. The dichroic is designed using HFSS and results agree well with measured data considering the manufacturing tolerances that could be achieved on the dichroic.

antenna↗
NASA NTRS2010

Accurate Insertion Loss Measurements of the Juno Patch Array Antennas

This paper describes two independent methods for estimating the insertion loss of patch array antennas that were developed for the Juno Microwave Radiometer instrument. One method is based principally on pattern measurements while the other method is based solely on network analyzer measurements. The methods are accurate to within 0.1 dB for the measured antennas and show good agreement (to within 0.1dB) of separate radiometric measurements.

insertion loss↗
NASA NTRS2015

Integrated Solar Array and Reflectarray Antenna for High Bandwidth Cubesats

The Integrated Solar Array and Reflectarray Antenna (ISARA) mission will demonstrate a reflectarray antenna that increases downlink data rates for Cube- Sats from the existing baseline rate of 9.6 kilobits per second (kbps) to more than 100 megabits per second (Mbps). The ISARA spacecraft is slated for launch no earlier than Dec. 1, 2015.

Downlink data rates for CubeSats↗
NASA NTRS2017

Reconfigurable Wideband Circularly Polarized Stacked Square Patch Antenna for Cognitive Radios

An almost square patch, a square patch and a stacked square patch with corner truncation for circular polarization (CP) are researched and developed at X-band for cognitive radios. Experimental results indicate, first, that the impedance bandwidth of a CP almost square patch fed from the edge by a 50 ohm line is 1.70% and second, that of a CP square patch fed from the ground plane side by a surface launch connector is 1.87%. Third, the impedance bandwidth of a CP stacked square patch fed by a surface launch connector is 2.22%. The measured center frequency for the CP square patch fed by a surface launch connector without and with an identical stacked patch is 8.45 and 8.1017 GHz, respectively. By stacking a patch, separated by a fixed air gap of 0.254 mm, the center frequency is observed to shift by as much as 348.3 MHz. The shift in center frequency, brought about by the reconfiguring of the physical layer antenna, can be exploited in a cognitive system since it expands the usable frequency spectrum for software reconfiguration in the presence of interference. In addition, varying the fixed air gap in the stacked antenna geometry by increments of 0.254 mm further expands the usable frequency spectrum.

Cognitive↗
NASA NTRS2018

Artificial Intelligence Integration for the ISS Antenna Management (IAM) Software

On the integration of artificial intelligence into the ISS (International Space Station) Antenna Manager software. Overview: Background/Description of the problem we are solving; Overview of ISS Antenna Manager capabilities; Overview of the US Air Force Academy's Neural Network development; Proposed integration approach; Future developments.

Artificial Intelligence↗
NASA NTRS1997

Resource Scheduling for a Network of Communications Antennas

This paper describes tha Demand Access Network Scheduler (DANS) system for automatically scheduling and rescheduling resources for a network of communication antennas. DANS accepts a baseline schedule and supports rescheduling of antenna and subsystem resources to satisfy tracking goals in the event of changing track requests, equipment outages, and inclement weather.

Deep↗
NASA NTRS1996

The S/X-Band Microwave Feed System for NASA's First Beamwaveguide Antenna

The configuration, detail design, and performance of a dual S/X- band microwave feed system for the first Deep Space Network beamwaveguide antenna is reported. This antenna, which is primarily used for research and development tasks, is an elevation-over-azimuth type using wheel and track azimuth bearings. The S/X-band microwave feed system is super low noise for support of deep space missions.

microwave↗
NASA NTRS1994

An Initial Study of Using the 34-m Antenna for Lunar Missions Support

As a part of the long-range planning of future Mars and lunar missions, a rudimentary study has been made of a 34-m antenna system with differentially pointed multiple beams. The performance loss mechanisms of the differentially pointed multiple-beam systems were identified and quantified. The goal is to determine the feasibility of using the 34-m antenna to support widely separated elements associated with lunar missions.

lunar↗
NASA NTRS1996

On the Accurate Calibration of the SeaWinds Radar Antenna: A Cylindrical Near-Field Measurement Approach

This paper demonstrates the utility of a cylindrical near-field measurement approach for the SeaWinds radar antenna calibration. Both generalized measurement error models and measured tests on a standard gain horn and NASA Scatterometer instrument antenna have been performed to achieve and verify the desired calibration accuracy. A comparison between far-field measured data and those obtained from cylindrical near-field measurements was found in excellent agreement.

spaceborne↗
NASA NTRS1997

Air Mass Effects on the Cassini High Gain Antenna

The high gain antenna for the Cassini spacecraft is a lightweight, large surface area structural element, and therefore its dynamic characteristics are noticeably altered by air mass effects...This paper describes the method ultimately used to quantify these effects on the Cassini HGA (High Gain Antenna).

Cassini↗
NASA NTRS1998

The "Myth" of the Minimum SAR Antenna Area Constraint

A design constraint traceable to the early days of spaceborne Synthetic Aperture Radar (SAR) is known as the minimum antenna area constraint for SAR. It specifies, as the name suggests, a minimum area for SAR antennas, to optimize performance.

design↗
NASA NTRS2022

Simulated 8x8 Ku-Band Array Antenna Performance on Airplane Door

An 8x8, Ku-band antenna array composed of circular patches was simulated both on an infinite ground plane and mounted on an airplane door. The radiated far field was calculated for both cases to determine the effect of mounting the antenna on the side of the airplane. It was found that the main beam was relatively unaffected, while the sidelobes were increased by 15 to 20 dB at angles more than 30° off boresight..

array antenna↗
DOE OSTI2024

Polycaprolactone‐Based Zinc Ink for High Conductivity Transient Printed Electronics and Antennas

Abstract Distributed sensors and electronics can be used in agriculture to optimize crop management and improve environmental outcomes. Electronic devices in these outdoor spaces require medium to long range (>1m) wireless communication of data over several weeks or months, which in turn requires high conductivity (1 × 10 5 Sm −1 ) antennas. Printed bioinert or ecoresorbable conductors, comprising carbon, magnesium, or zinc fillers, typically exhibit conductivity on the order of 10–1000 Sm −1 and lifetimes from a few hours to a few days. A print‐based fabrication process for chemically treated zinc traces, which achieves conductivity of up to 6 × 10 5 Sm −1 is reported here. The ink formulation uses a non‐water‐soluble soil biodegradable polycaprolactone binder. The ink and printing processes reported here led to stable conductive traces that are used in ultra high frequency radio frequency identification (UHF‐RFID) folded dipole antennas operating at 915 MHz. The conductivity of the printed traces is maintained for over 70 days in ambient environments when traces are protected by a biodegradable beeswax encapsulation layer.

Baumbauer, Carol L.↗
DOE OSTI2023

Holographic Nano‐Imaging of Terahertz Dirac Plasmon Polaritons in Topological Insulator Antenna Resonators

Abstract Excitation of Dirac plasmon polaritons (DPPs) in bi‐dimensional materials have attracted considerable interest in recent years, both from perspectives of understanding their physics and exploring their transformative potential for nanophotonic devices, including ultra‐sensitive plasmonic sensors, ultrafast saturable absorbers, modulators, and switches. Topological insulators (TIs) represent an ideal technological platform in this respect because they can support plasmon polaritons formed by Dirac carriers in the topological surface states. Tracing propagation of DPPs is a very challenging task, particularly at terahertz (THz) frequencies, where the DPP wavelength becomes over one order of magnitude shorter than the free space photon wavelength. Furthermore, severe attenuation hinders the comprehensive analysis of their characteristics. Here, the properties of DPPs in real TI‐based devices are revealed. Bi 2 Se 3 rectangular antennas can efficiently confine the propagation of DPPs to a single dimension and, as a result, enhance the DPPs visibility despite the strong intrinsic attenuation. The plasmon dispersion and loss properties from plasmon profiles are experimentally determined, along the antennas, obtained using holographic near‐field nano‐imaging in a wide range of THz frequencies, from 2.05 to 4.3 THz. The detailed investigation of the unveiled DPP properties can guide the design of novel topological quantum devices exploiting their directional propagation.

Chemistry↗