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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

UAVSAR Phased Array Aperture

This paper describes the development of a patch antenna array for an L-band repeat-pass interferometric synthetic aperture radar (InSAR) instrument that is to be flown on an unmanned aerial vehicle (UAV). The antenna operates at a center frequency of 1.2575 GHz and with a bandwidth of 80 MHz, consistent with a number of radar instruments that JPL has previously flown. The antenna is designed to radiate orthogonal linear polarizations in order to facilitate fully-polarimetric measurements. Beam-pointing requirements for repeat-pass SAR interferometry necessitate electronic scanning in azimuth over a range of -20degrees in order to compensate for aircraft yaw. Beam-steering is accomplished by transmit/receive (T/R) modules and a beamforming network implemented in a stripline circuit board. This paper, while providing an overview of phased array architecture, focuses on the electromagnetic design of the antenna tiles and associated interconnects. An important aspect of the design of this antenna is that it has an amplitude taper of 10dB in the elevation direction. This is to reduce multipath reflections from the wing that would otherwise be detrimental to interferometric radar measurements. This taper is provided by coupling networks in the interconnect circuits as opposed to attenuating the output of the T/R modules. Details are given of material choices and fabrication techniques that meet the demanding environmental conditions that the antenna must operate in. Predicted array performance is reported in terms of co-polarized and crosspolarized far-field antenna patterns, and also in terms of active reflection coefficient.

Unmanned Aerial Vehicle (UAV)↗
NASA NTRS1975

Electro-optical processing of phased-array antenna data

An on-line two-dimensional optical processor has been used to process simulated linear and planar phased-array radar data off-line but at real-time data rates. The input transducer is an electron-beam-addressed KD2PO4 light valve.

Casasent, D.↗
NASA NTRS1978

Control of small phased-array antennas

Series of reports, patent descriptions, calculator programs, and other literature describes antenna control and steering apparatus for seven-element phased array. Though series contains information specific to particular system, it illustrates methods that can be applied to antennas with greater or fewer numbers of elements. Included are programs for calculating beam parameters and design functions and information to interfacing digital controller to beam-steering apparatus.

Doland, G. D.↗
NASA NTRS1997

A Simplified Theory of Coupled Oscillator Array Phase Control

Linear and planar arrays of coupled oscillators have been proposed as means of achieving high power rf sources through coherent spatial power combining. In such - applications, a uniform phase distribution over the aperture is desired. However, it has been shown that by detuning some of the oscillators away from the oscillation frequency of the ensemble of oscillators, one may achieve other useful aperture phase distributions. Notable among these are linear phase distributions resulting in steering of the output rf beam away from the broadside direction. The theory describing the operation of such arrays of coupled oscillators is quite complicated since the phenomena involved are inherently nonlinear. This has made it difficult to develop an intuitive understanding of the impact of oscillator tuning on phase control and has thus impeded practical application. In this work a simpl!fied theory is developed which facilitates intuitive understanding by establishing an analog of the phase control problem in terms of electrostatics.

Pogorzelski, R. J.↗
NASA NTRS1972

Coherent Optical Processing of Phased Array Radar Data

Interfacing a coherent optical processor, which utilizes an electron-beam addressed, potassium dideuterium phosphate (KDP) crystal modulator, with a linear phased array is studied. An abbreviated development of typical radar signals from a linear array is included. A plan for formating the spatial modulator with linear array signals is presented. The theoretical expectations which include target angle and Doppler are derived. A simulated set of M signals which are typical of a linear array of M elements was devised. This set of signals was used to modulate the wave front of collimated laser light via the KDP crystal according to the format presented.

Rogers, J. W.↗
NASA NTRS2012

Assessment of Microphone Phased Array for Measuring Launch Vehicle Lift-off Acoustics

The specific purpose of the present work was to demonstrate the suitability of a microphone phased array for launch acoustics applications via participation in selected firings of the Ares I Scale Model Acoustics Test. The Ares I Scale Model Acoustics Test is a part of the discontinued Constellation Program Ares I Project, but the basic understanding gained from this test is expected to help development of the Space Launch System vehicles. Correct identification of sources not only improves the predictive ability, but provides guidance for a quieter design of the launch pad and optimization of the water suppression system. This document contains the results of the NASA Engineering and Safety Center assessment.

Garcia, Roberto↗
NASA NTRS2005

RF MEMS Phase Shifters and their Application in Phase Array Antennas

Electronically scanned arrays are required for space based radars that are capable of tracking multiple robots, rovers, or other assets simultaneously and for beam-hopping communication systems between the various assets. ^Traditionally, these phased array antennas used GaAs Monolithic Microwave Integrated Circuit (MMIC) phase shifters, power amplifiers, and low noise amplifiers to amplify and steer the beam, but the development of RF MEMS switches over the past ten years has enabled system designers to consider replacing the GaAs MMIC phase shifters with RF Micro-Electro Mechanical System (MEMS) phase shifters. In this paper, the implication of replacing the relatively high loss GaAs MMICs with low loss MEMS phase shifters is investigated.

Scardelletti, Maximilian↗
NASA NTRS1991

Millimeter-wave pseudomorphic HEMT MMIC phased array components for space communications

Recent advances in pseudomorphic HEMT MMIC (PMHEMT/MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. This paper describes the development of PMHEMT/MMIC components at Ka-band and V-band. Specifically, the following PMHEMT/MMIC components will be described: power amplifiers at Ka-band; power amplifiers at V-band; and four-bit phase shifters at V-band. For the Ka-band amplifier, 125 mW output power with 5.5 dB gain and 21 percent power added efficiency at 2 dB compression point has been achieved. For the V-band amplifier, 112 mW output power with 6 dB gain and 26 percent power added efficiency has been achieved. And, for the V-band phase shifter, four-bit (45 deg steps) phase shifters with less than 8 dB insertion loss from 61 GHz to 63 GHz will be described.

Lan, G. L.↗
NASA NTRS1992

V-band pseudomorphic HEMT MMIC phased array components for space communications

Recent advances in pseudomorphic high-electron-mobility transistor (PMHEMT) monolithic microwave integrated circuit (MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. The development of V-band PMHEMT/MMIC components including power amplifiers and phase shifters is described. For the single-stage MMIC power amplifier employing a 200 micron PMHEMT, we achieved 151.4 mW output power (757.0 mW/mm) with 1.8 dB associated gain and 26.4 percent power-added efficiency at 60 GHz. A two-stage MMIC amplifier utilizing the same devices demonstrated small-signal gain as high as 15 dB at 58 GHz. And, for the phase shifter, a four-bit phase shifter with less than 8 dB insertion loss from 61 to 63 GHz was measured.

Lan, G. L.↗
NASA NTRSDate not supplied

A Dual Linear/Circular Polarized Wideband Flat Panel Phased Array Antenna for K/Ka-band 6U CubeSat Communications Applications

Circular polarized (CP) electromagnetic waves are preferred for space-to-space and space-to-ground satellite communications (SATCOM). CubeSats with 6U sizes (1U represents a 10 cm x 10 cm x 10 cm), that will rotate together with the Moon as it orbits Earth require high gain CP antenna systems to maintain reliable communication links. Here, we have designed an 8x8 dual linear and dual circularly polarized phased array antenna (PAA) aperture that offers 22-28 GHz bandwidth, with maximum gain of 23 dBic, and beam scanning capability of ±50o with acceptable axial ratio over all scan angles. A stacked patch topology is selected to achieve wide impedance bandwidth. Each driven patch has two via feed point locations that are connected to grounded coplanar waveguide (CPW) feed structures. By utilizing phase shifters from the Anokiwave RFICs (AWMF-0165) employed for the beamforming network (BFN), we have generated both dual linear polarization and dual circular polarization in each patch. Each driven and parasitic patch is innovatively shaped to achieve excellent isolation between two feed points which, in turn, leads to low cross polarization, high efficiency and good axial ratio over the entire bandwidth. Each chip has eight outputs which feed one 2x2 sub-array consisting of four dual linear or dual circularly polarized driven patches, simultaneously. Each 2x2 sub-array of the 8x8 array are sequentially rotated which improves axial ratio performance when the antenna operates in the dual circularly polarized mode. By utilizing a mirror effect, cross-polarized fields are also improved when operated in a dual linear polarized mode. The 8x8 array aperture is simulated taking into account the effect of the multilayer printed circuit board (PCB) stack-up of the BFN and co-simulated with the power splitter outputs and chip outputs and results are compared with only passive array performance. The performance of the antenna is still excellent when non-ideal chip performances are included in the simulation analysis. The fabricated array will be tested for radiation patterns in the Antenna and Microwave Laboratory (AML) of the San Diego State University and the NASA Glenn Research Center (GRC) spherical near field chambers. The design of the 8x8 antenna array with BFN layout is shown in Fig. 1.

5G↗
NASA NTRS2002

Multi-beam Phased Array Antennas

Many of NASA's future missions require multiple accesses to work together as a single system. To accomplish these missions, multi-beam phased array antennas are required to communicate between satellites flying in fixed formation. In this paper, a comparison of different multi-beam systems will be given followed by detailed discussions of the lens array architecture and test results.

Lee, R. Q.↗
NASA NTRS1999

Microphone Array Phased Processing System (MAPPS): Version 4.0 Manual

A processing system has been developed to meet increasing demands for detailed noise measurement of individual model components. The Microphone Array Phased Processing System (MAPPS) uses graphical user interfaces to control all aspects of data processing and visualization. The system uses networked parallel computers to provide noise maps at selected frequencies in a near real-time testing environment. The system has been successfully used in the NASA Ames 7- by 10-Foot Wind Tunnel.

Watts, Michael E.↗
NASA NTRS1985

Coupled-mode analysis of gain and wavelength oscillation characteristics of diode laser phased arrays

The lasing wavelengths and gain characteristics of the modes of phase-locked arrays of channel-substrate-planar (CSP) lasers are presented. The gain values for the array modes are determined from complex coupling coefficients calculated using the fields of neighboring elements of the array. The computations show that, for index guided lasers which have nearly planar phase fronts, the highest order array mode will be preferred. The 'in-phase' or fundamental mode, which produces only one major lobe in the far-field radiation pattern, has the lowest modal gain of all array modes. The modal gain differential between the highest order and fundamental modes is less than 10/cm for weak coupling between the elements.

Butler, J. K.↗
NASA NTRS1988

GaAs MMIC elements in phased-array antennas

Over the last six years NASA Lewis Research Center has carried out a program aimed at the development of advanced monolithic microwave integrated circuit technology, principally for use in phased-array antenna applications. Arising out of the Advanced Communications Technology Satellite (ACTS) program, the initial targets of the program were chips which operated at 30 and 20 GHz. Included in this group of activities were monolithic power modules with an output of 2 watts at GHz, variable phase shifters at both 20 and 30 GHz, low noise technology at 30 GHz, and a fully integrated (phase shifter, variable gain amplifier, power amplifier) transmit module at 20 GHz. Subsequent developments are centered on NASA mission requirements, particularly Space Station communications systems and deep space data communications.

Leonard, Regis F.↗
NASA NTRS1977

The optimization of self-phased arrays for diurnal motion tracking of synchronous satellites

The diurnal motion of a synchronous satellite necessitates mechanical tracking when a large aperture, high gain antenna is employed at the earth terminal. An alternative solution to this tracking problem is to use a self phased array consisting of a number of fixed pointed elements, each with moderate directivity. Non-mechanical tracking and adequate directive gain are achieved electronically by phase coherent summing of the element outputs. The element beamwidths provide overlapping area coverage of the satellite motion but introduce a diurnal variation into the array gain. The optimum element beamwidth and pointing direction of these elements can be obtained under the condition that the array gain is maximized simultaneously with the minimization of the diurnal variation.

Theobold, D. M.↗
NASA NTRS1991

Effects of space environment on space-based radar phased-array antenna: Status and preliminary observations

The overall objective is to evaluate the effect of the space environment on Kapton films considered for the Grumman space based radar (SBR) phased-array antenna. The most striking result is the overall good condition of the Kapton antenna planes and Kapton tensile specimens. This is largely attributable to the orientation of the Kapton (parallel and flush on the space end) and the stability of the LDEF in orbit. Results on elongation and mechanical properties of the plain and fiberglass reinforced Kapton will be described. Stress-dependent permanent deformation and some reductions in strain to failure were observed. Physical property testing of the materials is in progress. Electronic data acquisition and memory systems appeared to operate correctly, but functional tests were not yet performed. An evaluation of the high voltage-plasma interaction data is underway. Some minor systems anomalies (e.g., fastener sheared during removal, strong odor inside electronics container) were noted. Other observations such as radiation, contamination, impacts, and orientation features of atomic oxygen erosion are reported.

Whiteside, J. B.↗
NASA NTRS2003

Measurement of the Earth-Observer-1 Satellite X-Band Phased Array

The recent launch and successful orbiting of the EO-1 Satellite has provided an opportunity to validate the performance of a newly developed X-Band transmit-only phased array aboard the satellite. This paper will compare results of planar near-field testing before and after spacecraft installation as well as on-orbit pattern characterization. The transmit-only array is used as a high data rate antenna for relaying scientific data from the satellite to earth stations. The antenna contains distributed solid-state amplifiers behind each antenna element that cannot be monitored except for radiation pattern measurements. A unique portable planar near-field scanner allows both radiation pattern measurements and also diagnostics of array aperture distribution before and after environmental testing over the ground-integration and prelaunch testing of the satellite. The antenna beam scanning software was confirmed from actual pattern measurements of the scanned beam positions during the spacecraft assembly testing. The scanned radiation patterns on-orbit were compared to the near-field patterns made before launch to confirm the antenna performance. The near-field measurement scanner has provided a versatile testing method for satellite high gain data-link antennas.

Perko, Kenneth↗