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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Automation of Data Analysis Programs Used in the Cryogenic Characterization of Superconducting Microwave Resonators

Knowledge of the microwave properties at cryogenic temperatures of components fabricated using High-Temperature-Superconductors (HTS) is useful in the design of HTS-based microwave circuits. Therefore, fast and reliable characterization techniques have been developed to study the aforementioned properties. In this paper, we discuss computer analysis techniques employed in the cryogenic characterization of HTS-based resonators. The revised data analysis process requires minimal user input. and organizes the data in a form that is easily accessible by the user for further examination. These programs retrieve data generated during the cryogenic characterization at microwave frequencies of HTS based resonators and use it to calculate parameters such as the loaded and unloaded quality factors (Q and Q(sub o), respectively), the resonant frequency (f(sub o)), and the coupling coefficient (k), which are important quantities in the evaluation of HTS resonators. While the data are also stored for further use, the programs allow the user to obtain a graphical representation of any of the measured parameters as a function of temperature soon after the completion of the cryogenic measurement cycle. Although these programs were developed to study planar HTS-based resonators operating in the reflection mode, they could also be used in the cryogenic characterization of two ports (i.e., reflection/transmission) resonators.

Creason, A. S.↗
NASA NTRS1989

Growth and patterning of laser ablated superconducting YBa2Cu3O7 films on LaAlO3 substrates

A high quality superconducting film on a substrate with a low dielectric constant is desired for passive microwave circuit applications. In addition, it is essential that the patterning process does not effect the superconducting properties of the thin films to achieve the highest circuit operating temperatures. YBa2Cu3O7 superconducting films were grown on lanthanum aluminate substrates using laser ablation with resulting maximum transition temperature (T sub c) of 90 K. The films were grown on a LaAlO3 which was at 775 C and in 170 mtorr of oxygen and slowly cooled to room temperature in 1 atm of oxygen. These films were then processed using photolithography and a negative photoresist with an etch solution of bromine and ethanol. Results are presented on the effect of the processing on T(sub c) of the film and the microwave properties of the patterned films.

Warner, J. D.↗
NASA NTRS1986

Advances in gallium arsenide monolithic microwave integrated-circuit technology for space communications systems

Future communications satellites are likely to use gallium arsenide (GaAs) monolithic microwave integrated-circuit (MMIC) technology in most, if not all, communications payload subsystems. Multiple-scanning-beam antenna systems are expected to use GaAs MMIC's to increase functional capability, to reduce volume, weight, and cost, and to greatly improve system reliability. RF and IF matrix switch technology based on GaAs MMIC's is also being developed for these reasons. MMIC technology, including gigabit-rate GaAs digital integrated circuits, offers substantial advantages in power consumption and weight over silicon technologies for high-throughput, on-board baseband processor systems. In this paper, current developments in GaAs MMIC technology are described, and the status and prospects of the technology are assessed.

Bhasin, K. B.↗
NASA NTRS1978

The present situation and forecasts of semiconductor elements performance within the microwave range, 1970-1985

The present situation and possible developments over the period 1970-1985 for active semiconductor elements in the microwave range are outlined. After a short historical survey of FT techniques, the following are discussed: Generation, power amplification, amplification of small signals, frequency conversion, detection, electronic signal control and integrated microwave circuits.

Peterson, B.↗
NASA NTRS1983

Travelling wave effects in large space structures

Several aspects of travelling waves in Large Space Structures(LSS) are discussed. The dynamic similarity among LSS's, electric power systems, microwave circuits and communications network is noted. The existence of time lag between actuation and response is illuminated with the aid of simple examples, and their prediction is demonstrated. To prevent echoes, communications lines have matched terminations; this idea is applied to the design of dampers of one dimensional structures. Periodic structures act as mechanical band pass filters. Implications of this behavior are examined on a simple example. It is noted that the implication is twofold; continuum models of periodic lattice structures may err considerably; on the other hand, it is possible to design favorable transmission (and resonance) characteristics into the structure.

Vonflotow, A.↗
NASA NTRS1984

LEC GaAs for integrated circuit applications

Recent developments in liquid encapsulated Czochralski techniques for the growth of semiinsulating GaAs for integrated circuit applications have resulted in significant improvements in the quality and quantity of GaAs material suitable for device processing. The emergence of high performance GaAs integrated circuit technologies has accelerated the demand for high quality, large diameter semiinsulating GaAs substrates. The new device technologies, including digital integrated circuits, monolithic microwave integrated circuits and charge coupled devices have largely adopted direct ion implantation for the formation of doped layers. Ion implantation lends itself to good uniformity and reproducibility, high yield and low cost; however, this technique also places stringent demands on the quality of the semiinsulating GaAs substrates. Although significant progress was made in developing a viable planar ion implantation technology, the variability and poor quality of GaAs substrates have hindered progress in process development.

Kirkpatrick, C. G.↗
NASA NTRS1988

Development of 20 GHz monolithic transmit modules

The history of the development of a transmit module for the band 17.7 to 20.2 GHz is presented. The module was to monolithically combine, on one chip, five bits of phase shift, a buffer amplifier and a power amplifier to produce 200 mW to the antenna element. The approach taken was MESFET ion implanted device technology. A common pinch-off voltage was decided upon for each application. The beginning of the total integration phases revealed hitherto unencountered hazards of large microwave circuit integration which were successfully overcome. Yield and customer considerations finally led to two separate chips, one containing the power amplifiers and the other containing the complete five bit phase shifter.

Higgins, J. A.↗
NASA NTRS1989

Screen-Printed YBa2Cu3O7-x Films On Alumina

Superconducting films made in relatively simple process. Thick films of YBa2Cu3O7-x superconductor deposited on highly-polished alumina substrates by screen printing. In addition to simplicity, screen-printing technique offers advantage that patterns for electronic and microwave circuits and devices printed directly, without additional etching steps.

Bansal, Narottam P.↗
NASA NTRS1989

Measurements of complex permittivity of microwave substrates in the 20 to 300 K temperature range from 26.5 to 40.0 GHz

A knowledge of the dielectric properties of microwave substrates at low temperatures is useful in the design of superconducting microwave circuits. Results are reported for a study of the complex permittivity of sapphire (Al2O3), magnesium oxide (MgO), silicon oxide (SiO2), lanthanum aluminate (LaAlO3), and zirconium oxide (ZrO2), in the 20 to 300 Kelvin temperature range, at frequencies from 26.5 to 40.0 GHz. The values of the real and imaginary parts of the complex permittivity were obtained from the scattering parameters, which were measured using a HP-8510 automatic network analyzer. For these measurements, the samples were mounted on the cold head of a helium gas closed cycle refrigerator, in a specially designed vacuum chamber. An arrangement of wave guides, with mica windows, was used to connect the cooling system to the network analyzer. A decrease in the value of the real part of the complex permittivity of these substrates, with decreasing temperature, was observed. For MgO and Al2O3, the decrease from room temperature to 20 K was of 7 and 15 percent, respectively. For LaAlO3, it decreased by 14 percent, for ZrO2 by 15 percent, and for SiO2 by 2 percent, in the above mentioned temperature range.

Miranda, Felix A.↗
NASA NTRS1990

Analysis of radiometer calibration effects with TOUCHSTONE

The microwave circuit analysis program TOUCHSTONE is used to study two effects of importance in radiometer calibration. The two effects are impedance mismatches at the antenna-air and cold load-air interfaces and dissipatives losses, which radiate thermal noise into the system. The results predicted by TOUCHSTONE are shown to be in very close agreement with earlier results obtained by purely analytical methods. The techniques used in establishing the circuit models and in processing the resulting data are described in detail.

Stanley, William D.↗
NASA NTRS1990

Solid State Technology Branch of NASA Lewis Research Center Second Annual Digest, June 1989 - June 1990

A collection of papers and presentations authored by the branch between June 1989 and June 1990 is presented. The papers are organized into four sections. Section 1 deals with research in microwave circuits and includes full integrated circuits, the demonstration of optical/RF interfaces, and the evaluation of some hybrid circuitry. Section 2 indicates developments in coplanar waveguides and their use in breadboard circuits. Section 3 addresses high temperature superconductivity and includes: thin film deposition, transport measurement of film characteristics, RF surface resistant measurements, substrate permittivity measurements, measurements of microstrip line characteristics at cryogenic temperatures, patterning of superconducting films, and evaluation of simple passive microstrip circuitry based on YBaCuO films. Section 4 deals with carbon films, silicon carbide, GaAs/AlGaAs, HgCdTe, and other materials.

Source record↗
NASA NTRS1991

Superconducting Microwave Electronics at Lewis Research Center

Over the last three years, NASA Lewis Research Center has investigated the application of newly discovered high temperature superconductors to microwave electronics. Using thin films of YBa2Cu3O7-delta and Tl2Ca2Ba2Cu3Ox deposited on a variety of substrates, including strontium titanate, lanthanum gallate, lanthanum aluminate and magnesium oxide, a number of microwave circuits have been fabricated and evaluated. These include a cavity resonator at 60 GHz, microstrip resonators at 35 GHz, a superconducting antenna array at 35 GHz, a dielectric resonator at 9 GHz, and a microstrip filter at 5 GHz. Performance of some of these circuits as well as suggestions for other applications are reported.

Warner, Joseph D.↗
NASA NTRS1991

Design aspects and comparison between high T(sub c) superconducting coplanar waveguide and microstrip line

The high T sub c superconducting microstrip line and coplanar waveguide are compared in terms of the loss characteristics and the design aspects. The quality factor Q values for each structure are compared in respect to the same characteristic impedance with the comparable dimensions of the center conductor of the coplanar waveguide and the strip of the microstrip line. Also, the advantages and disadvantages for each structure are discussed in respect to passive microwave circuit applications.

Kong, K. S.↗
NASA NTRS1991

High temperature superconductor analog electronics for millimeter-wavelength communications

The performance of high temperature superconductor (HTS) passive microwave circuits up to X-band was encouraging when compared to their metallic counterparts. The extremely low surface resistance of HTS films up to about 10 GHz enables a reduction in loss by as much as 100 times compared to copper when both materials are kept at about 77 K. However, a superconductor's surface resistance varies in proportion to the frequency squared. Consequently, the potential benefit of HTS materials to millimeter-wave communications requires careful analysis. A simple ring resonator was used to evaluate microstrip losses at Ka-band. Additional promising components were investigated such as antennas and phase shifters. Prospects for HTS to favorable impact millimeter-wave communications systems are discussed.

Romanofsky, R. R.↗
NASA NTRS1991

High temperature superconductive microwave technology for space applications

Progress being made on space application technology research on film fabrication, passive microwave circuits, and semiconductor devices for cryogenic circuits is reviewed. Achievements in YBCO and TCBCO films are addressed along with circuit evaluations of microstrip resonators, phase shifters, microstrip filters, dielectric resonator filters, and superconducting antennas.

Leonard, R. F.↗
NASA NTRS1991

Resonant-tunnelling diode oscillator using a slot-coupled quasioptical open resonator

A resonant-tunneling diode has oscillated at X-band frequencies in a microwave circuit consisting of a slot antenna coupled to a semiconfocal open resonator. Coupling between the open resonator and the slot oscillator improves the noise-to-carrier ratio by about 36 dB relative to that of the slot oscillator alone in the 100-200 kHz range. A circuit operating near 10 GHz has been designed as a scale model for millimeter- and submillimeter-wave applications.

Stephan, K. D.↗