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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

An Internal ALD-Based High Voltage Divider and Signal Circuit for MCP-based Photodetectors

We describe a pin-less design for the high voltage (HV) resistive divider of the all-glass LAPPD (TM) 8 in,square thin photodetector module. The divider, which distributes high voltage applied to the photocathode to the two micro-channel plates (MCPs) that constitute the amplification stage, is comprised of the two MCPs and three glass mechanical spacers, each of which is coated with a resistive layer using atomic layer deposition (ALD). The three glass grid spacers and the two MCPs form a continuous resistive path between cathode and anode, with the voltages across the MCPs and the spacers determined by the resistance of each. High voltage is applied on an external tab on the top glass window that connects to the photocathode through the metal seal. The DC ground is supplied by microstrips on the bottom glass plate that form the high-bandwidth anode. The microstrips exit the package through the glass-frit seal of the anode base-plate and the package sidewall. The divider is thus completely internal, with no HV pins penetrating the low-profile flat glass package. Measurements of the performance of the divider are presented for the 8 in.-square MCP and spacer package in a custom test fixture and for an assembled externally pumped LAPPD (TM) prototype with an aluminum photocathode. (C) 2015 Elsevier B.V. All rights reserved.

Adams, Bernhard W.↗
DOE OSTI2013

Design methodology and performance analysis of a wideband 90° phase switch for radiometer applications

This paper presents the analysis, design, and characterization of a wideband 90° phase switch in Ka-band. The phase switch is based on two microstrip bandpass filters in which the commutation is performed by a novel single-pole double-throw (SPDT) switch. The analysis of π-network bandpass filters is provided, obtaining the phase difference and amplitude imbalance between filters and their scattering parameters; tested results show an average phase difference of 88.9° ± 5° and an amplitude imbalance of 0.15 dB from 24 to 37 GHz. The new broadband SPDT switch is based on a coplanar waveguide-to-slotline-to-microstrip structure, which enables a full planar integration with shifting branches. PIN diodes are used to perform the switching between outputs. The SPDT shows isolation better than 19 dB, insertion loss of around 1.8 dB, and return loss better than 15 dB. The full integration of the phase switch achieves a return loss better than 11 dB and insertion loss of around 4 dB over the band 26–36 GHz, with an average phase difference of 87.1° ± 4° and an average amplitude imbalance of 0.3 dB. It provides an excellent performance for this frequency range, suitable for radio-astronomy receivers.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Microwave magnetic dynamics in highly conducting magnetic nanostructures

We performed low-noise broadband microstrip ferromagnetic resonance (FMR) measurements of the resonant modes of an array of metallic ferromagnetic nanostripes. In addition to a strong signal of the fundamental mode, we observed up to five weak-amplitude peaks in the field-resolved FMR traces, depending on the frequency. These higher-order absorption peaks have been theoretically identified as due to resonant excitation of odd and even standing spin waves across the direction of confinement in array plane (i.e., across the stripe width). The theory we developed suggests that the odd modes become excited in the spatially uniform microwave field of the FMR setup due to the large conductivity of metals. This promotes excitation of large-amplitude eddy currents in the sample by the incident microwave magnetic field and ultimately results in excitation of these modes. Following this theory, we found that the eddy current contribution is present only for patterned materials and when the microwave magnetic field is incident on one surface of sample surface, as it is in the case of a microstrip FMR.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Circularly polarized microwaves for magnetic resonance study in the GHz range: Application to nitrogen-vacancy in diamonds

The ability to create time-dependent magnetic fields of controlled polarization is essential for many experiments with magnetic resonance. We describe a microstrip circuit that allows us to generate strong magnetic field at microwave frequencies with arbitrary adjusted polarization. The circuit performance is demonstrated by applying it to an optically detected magnetic resonance and Rabi nutation experiments in nitrogen-vacancy color centers in diamond. Thanks to high efficiency of the proposed microstrip circuit and degree of circular polarization of 85%; it is possible to address the specific spin states of a diamond sample using a low power microwave generator. The circuit may be applied to a wide range of magnetic resonance experiments with a well-controlled polarization of microwaves.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Multiplexed infrared photodetection using resonant radio-frequency circuits

We demonstrate a room-temperature semiconductor-based photodetector where readout is achieved using a resonant radio-frequency (RF) circuit consisting of a microstrip split-ring resonator coupled to a microstrip busline, fabricated on a semiconductor substrate. The RF resonant circuits are characterized at RF frequencies as function of resonator geometry, as well as for their response to incident IR radiation. The detectors are modeled analytically and using commercial simulation software, with good agreement to our experimental results. Though the detector sensitivity is weak, the detector architecture offers the potential for multiplexing arrays of detectors on a single read-out line, in addition to high speed response for either direct coupling of optical signals to RF circuitry, or alternatively, carrier dynamics characterization of semiconductor, or other, material systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Higher order mode of a microstripline fed cylindrical dielectric resonator antenna

A microstrip transmission line can be used to excite the broadside radiating mode of a cylindrical dielectric resonator antenna (CDRA). The same is found to excite considerably well a higher order mode (HOM) as well. However unlike the broadside mode, the higher order mode gives distorted radiation pattern which makes this mode less useful for practical applications. The cause of distortion in the HOM radiation and the dependence of HOM coupling on the microstrip feed line are explored using HFSS simulations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

A fast chopper for medium energy beams

The key elements have been constructed for a fast chopper system capable of removing single 2.5 MeV proton bunches spaced at 325 MHz. The average chopping rate is ~ 1 MHz. The components include a pulse delaying microstrip structure for deflecting the beam, high voltage (1.2 kV) fast (ns rise time) pulsers, and an associated wideband combiner. Various designs for the deflecting structures have been studied. Measurements of the microstrip structures' coverage factors and pulse shapes are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Multimaterial Aerosol Jet Printed Magnetic Nanocomposites for Microwave Circuits

Here this article demonstrates the process and characterization of additively manufactured polymer-matrix magnetic nanocomposites. These nanocomposites are composed of nickel-zinc ferrite (Ni 0.5 Zn 0.5 Fe 2 O 4 ) nanoparticles in a polyimide matrix. These materials are printed using multimaterial aerosol jet printing where aerosols of nickel-zinc ferrite and polyimide inks are mixed in place to fabricate structures with nonunity relative permeability. To characterize these materials, we use energy-dispersive X-ray spectroscopy to estimate the content of ferrite in the composite, fitted simulation models, and ring resonator measurements to estimate the permeability. In fully aerosol jet printed 1-mm 2 inductors, we demonstrate an increase in inductance density of 40% in a 4.5-turn microstrip spiral inductor using this printed composite. These fully printed inductors demonstrate an inductance density of 4.2-nH/mm 2 . EDS analysis shows films with 18 wt.% Ni 0.5 Zn 0.5 Fe 2 O 4 . Finally, we show microstrip transmission lines on printed composite compared to the same on polyimide subjected to a dc magnetic bias, displaying a magnetic resonance behavior.

42 ENGINEERING↗
DOE OSTI2018

Characterization and performance of the second-year SPT-3G focal plane

The third-generation instrument for the 10-meter South Pole Telescope, SPT-3G, was first installed in January 2017. In addition to completely new cryostats, secondary telescope optics, and readout electronics, the number of detectors in the focal plane has increased by an order of magnitude from previous instruments to ~16,000. The SPT-3G focal plane consists of ten detector modules, each with an array of 269 trichroic, polarization-sensitive pixels on a six-inch silicon wafer. Within each pixel is a broadband, dual-polarization sinuous antenna; the signal from each orthogonal linear polarization is divided into three frequency bands centered at 95, 150, and 220 GHz by in-line lumped element filters and transmitted via superconducting microstrip to Ti/Au transition-edge sensor (TES) bolometers. Properties of the TES film, microstrip filters, and bolometer island must be tightly controlled to achieve optimal performance. For the second year of SPT-3G operation, we have replaced all ten wafers in the focal plane with new detector arrays tuned to increase mapping speed and improve overall performance. Here we discuss the TES superconducting transition temperature and normal resistance, detector saturation power, bandpasses, optical efficiency, and full array yield for the 2018 focal plane.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1977

Solid state Ku-band spacecraft transmitters

A transmitter is considered that consists of GaAs IMPATT and Read diodes operating in a microstrip circuit environment to provide amplification with a minimum of 63 db small signal gain and a minimum compressed gain at 5 W output of 57 db. Reported are Schottky-Read diode design and fabrication, microstrip and circulator optimization, preamplifier development, power amplifier development, dc-to-dc converter design, and integration of the breadboard transmitter modules. A four-stage power amplifier in cascade with a three-stage preamplifier had an overall gain of 56.5 db at 13.5 GHz with a power output of 4.5 W. A single-stage Read amplifier delivered 5.9 W with 4 db gain at 22% efficiency.

Wisseman, W. R.↗
NASA NTRS1979

The 2.2 GHz Surface Acoustic Wave (SAW) oscillator development Ku-band frequency source development

Two 2.2 GHz SAW oscillators using aluminum nitride on sapphire (AlN/Al2O3) delay lines were fabricated. The oscillators were electronically temperature compensated and characterized. One of the oscillators was used as the frequency reference for the Ku band source; the second oscillator is available for continued evaluation. A 15 GHz frequency source was designed and fabricated. The 15 GHz source consists of a Ku band FET oscillator which is phase locked to the frequency multiplied (X7) output of the 2.2 GHz SAW reference source. The Ku band source was built using microstrip circuit designs, which are hybrid compatible. Two wafer runs of 2.2 GHz TED devices were fabricated and evaluated. The devices were mounted on microstrip test substrates and evaluated as 15 GHz divide by 7 circuits. The device evaluation indicated that in their present form the TED is not a practical circuit element.

Source record↗
NASA NTRS1984

Monolithic microwave integrated circuit devices for active array antennas

Two different aspects of active antenna array design were investigated. The transition between monolithic microwave integrated circuits and rectangular waveguides was studied along with crosstalk in multiconductor transmission lines. The boundary value problem associated with a discontinuity in a microstrip line is formulated. This entailed, as a first step, the derivation of the propagating as well as evanescent modes of a microstrip line. The solution is derived to a simple discontinuity problem: change in width of the center strip. As for the multiconductor transmission line problem. A computer algorithm was developed for computing the crosstalk noise from the signal to the sense lines. The computation is based on the assumption that these lines are terminated in passive loads.

Mittra, R.↗
NASA NTRS1982

Low gain and steerable vehicle antennas for communications with land mobile satellite

Current development activities at JPL for ground mobile vehicle antennas to be used with the Land Mobile Satellite Service (LMSS) system are described. Both low gain and electronically steerable high gain type antennas are discussed in terms of their design concept and RF performance. For the low gain type, three classes of antennas are under various stages of development. These are the crossed-drooping dipole, quadrifilar helix, and microstrip patch designs. The antennas are intended to provide circularly-polarized radiation with a minimum of 3-dB gain in the angular region from 19 degrees to 60 deg from the horizon in elevation plane and with an omnidirectional pattern in azimuthal plane. For the electronically steerable high gain type, circularly-polarized microstrip patch phased arrays formed on a planar surface and on the surface of a truncated cone are under study. The arrays are intended to provide a minimum of 12 dB gain in the same angular region in elevation plane at all azimuthal angles. This coverage is accomplished by scanning the high gain pencil beam in both elevation and azimuthal directions. Both types of antennas are to transmit at 821-831 MHz band and to receive at 866-876 MHz band. They must be of low cost design and reasonably conformal to the vehicle.

Woo, K.↗
NASA NTRS1985

Land vehicle antennas for satellite mobile communications

Antenna designs applicable to future satellite mobile vehicle communications are examined. Microstrip disk, quadrifilar helix, cylindrical microstrip, and inverted V and U crossed-dipole low gain antennas (3-5 dBic) that provide omnidirectional coverage are described. Diagrams of medium gain antenna (9-12 dBic) concepts are presented; the antennas are classified into three types: (1) electronically steered with digital phase shifters; (2) electronically switched with switchable power divider/combiner; and (3) mechanically steered with motor. The operating characteristics of a conformal antenna with electronic beam steering and a nonconformal design with mechanical steering are evaluated with respect to isolation levels in a multiple satellite system. Vehicle antenna pointing systems and antenna system costs are investigated.

Haddad, H. A.↗
NASA NTRS1987

Exact image theory for the problem of dielectric/magnetic slab

Exact image method, recently introduced for the exact solution of electromagnetic field problems involving homogeneous half spaces and microstrip-like geometries, is developed for the problem of homogeneous slab of dielectric and/or magnetic material in free space. Expressions for image sources, creating the exact reflected and transmitted fields, are given and their numerical evaluation is demonstrated. Nonradiating modes, guided by the slab and responsible for the loss of convergence of the image functions, are considered and extracted. The theory allows, for example, an analysis of finite ground planes in microstrip antenna structures.

Lindell, I. V.↗
NASA NTRS1988

Array trade-off study using multilayer parasitic subarrays

The use of multilayer parasitic patch arrays in a microstrip phased array offers many potential advantages. An analytical study of microstrip arrays with high gain multilayer parasitic patch subarrays and conventional patch antennas is presented. It is indicated that a thinned array of half as many multilayer parasitic patch subarrays (per row and column) at twice the spacing will perform as well as the full array of ordinary patch antennas. The criterion for comparison was array gain, 3 dB beamwidth and sidelobe level. The attendant reduction in the required number of patch antennas and consequently, MMIC phase shifters is very significant in terms of array complexity, cost and power loss.

Zaman, A.↗
NASA NTRS1988

Exact image theory for the slab problem

Exact image theory, recently introduced for the exact solution of problems involving homogeneous half spaces and microstrip-like geometries, is developed here for the problem of homogeneous slab of isotropic dielectric and/or magnetic material in free space. Expressions for image sources, creating the exact reflected and transmitted fields, are given and their numerical evaluation is demonstrated. Nonradiating modes, guided by the slab and responsible for the loss of convergence of the image functions, are considered and extracted. The theory can be applied, for example, in an analysis of finite ground planes in microstrip antenna structures.

Lindell, I. V.↗
NASA NTRS1989

Testing Fixture For Microwave Integrated Circuits

Testing fixture facilitates radio-frequency characterization of microwave and millimeter-wave integrated circuits. Includes base onto which two cosine-tapered ridge waveguide-to-microstrip transitions fastened. Length and profile of taper determined analytically to provide maximum bandwidth and minimum insertion loss. Each cosine taper provides transformation from high impedance of waveguide to characteristic impedance of microstrip. Used in conjunction with automatic network analyzer to provide user with deembedded scattering parameters of device under test. Operates from 26.5 to 40.0 GHz, but operation extends to much higher frequencies.

Romanofsky, Robert↗