Tunable coupling for semiconfocal Fabry-Perot cavity in 150 to 500 Gc region.
Tunable coupling of open waveguide type for semiconfocal Fabry-Perot cavity gives high transmission and high Q
WAVEGUIDE TUNER↗
SEARCH · Engineering Papers
Results for “WAVEGUIDES”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Far-infrared laser power measurements.
Peak and average output power of cyanide laser in far IR measured, indicating usefulness of available oversize waveguide instrumentation at HF
FAR INFRARED↗
Mode matching method for anisotropic guides.
Mode-matching technique for bifurcated anisotropic waveguide, discussing Bresler biorthogonality relationships to derive anisotropic guide mode equations
MODE SHAPE↗
A wave-guide model for turbulent shear flow.
Waveguide model for turbulent shear flow, calculating streamwise dependence of cross-power spectral density using Orr-Sommerfeld equation
SURFACE PRESSURE↗
Response of a grounded dielectric slab to an impulse line source using leaky modes
This paper describes how expansions in leaky (or improper) modes may be used to represent the continuous spectrum in an open radiating waveguide. The technique requires a thorough knowledge of the life history of the improper modes as they migrate from improper to proper Riemann surfaces. The method is illustrated by finding the electric field resulting from an impulsively forced current located in the free space above a grounded dielectric slab.
DIELECTRIC SLABS↗
X/X/Ka-Band Horn Design
Tne NASA's Deep Space Network has a need for a multi frequency horn for simultaneous X/X/Ka-band operation in a beam waveguide antenna. The multi frequency horn will receive X-band downlink (8.4-8.5 GHz) and Ka-band downlink (3.18-32.3 GHz), and transmit X-band uplink (7.145-7.235 GHz) signals simultaneously. The horn is designed for circularlly polarized wave operation. Low loss (noise) and high power (up to 20 kilowatts) operation are considered in the horn design.
Deep Space Network beam waveguide antenna multi fr↗
A Planar Dielectric-Filled-Parabolic-Feed Frequency Multiplier
In this paper, we present a novel quasi-optical all-planar frequency doubler that could provide an alternative approach to conventional waveguide circuits for millimeter- and submillimeter-wave signal generation. By utilizing a quad-bridge-diode configuration, we are able to isolate the input and the output circuits without the use of complicated filter structures.
frequency doubler waveguide circuits signal genera↗
Thin Ribbon Tapered Coupler for Dielectric Waveguide/Optical Fiber
This paper presents a new way to design a low-loss couipler for high- or low-dielectric constant, dielectric waveguide for optical or millimeter/submillimeter waves.
coupler dielectric waveguide↗
On-wafer vector network analyzer measurements in the 220-325 Ghz frequency band
We report on a full two-port on-wafer vector network analyzer test set for the 220-325 GHz (WR3) frequency band. The test set utilizes Oleson Microwave Labs frequency extenders with the Agilent 8510C network analyzer. Two port on-wafer measurements are made with GGB Industries coplanar waveguide (CPW) probes. With this test set we have measured the WR3 band S-parameters of amplifiers on-wafer, and the characteristics of the CPW wafer probes. Results for a three stage InP HEMT amplifier show 10 dB gain at 235 GHz [1], and that of a single stage amplifier, 2.9 dB gain at 231 GHz. The approximate upper limit of loss per CPW probe range from 3.0 to 4.8 dB across the WR3 frequency band.
coplanar waveguides↗
Synthesis of Novel All-Dielectric Grating Filters using Genetic Algorithms
The feasibility of novel all-dielectric waveguide grating filters is demonstrated, using a genetic algorithm to solve for material dielectric constants and geometric boundaries separating homogeneous regions of the periodic cell.
all-dielectric↗
Implementation of a Gravity Compensating Mirror on a Large Aperture Antenna
A proposed technique for compensating gravity-induced structural deformations on the main reflector of a large aperture antenna is to utilize a deformable flat plate (DFP) installed at one of the mirror locations in the beam waveguide optics.
deformable↗
Speed Up of Near-Field Physical Optics Scattering Calculations by Use of the Sampling Theorem
Physical optics scattering calculations performed on the NASA Deep Space Network (DSN) 34-meter beam-waveguide antennas at Ka-band requires approximately 12 hours CPU time on a Cray Y-MP2 computer - exessive in terms of resource utilization. The calculations are done two mirrors at a time.
antennas↗
(abstract) Vibration Method for Tracking the Resonant Mode and Impedance of a Microwave Cavity
We have developed a vibration technique to continuously maintain mode resonance and impedance match between a constant frequency magnetron source and resonant cavity. This method uses a vibrating metal rod to modulate the volume of the cavity that is equivalent to modulating an adjustable plunger. A similar vibrating metal rod attached to a stub tuner modulates the waveguide volume between the source and cavity. A phase sensitive detection scheme determines the optimum position of the adjustable plunger and stub tuner. The improved power transfer during the heating of a 99.8% pure alumina rod was demonstrated using this new technique. Temperature-time and reflected power-time plotswill be presented for the cases of no tracking, impedance tracker only, mode tracker only, and simultaneous impedance and mode tracking. Internal melting of the alumina rod near 2000°C with both trackers on will also be discussed.
microwave↗
Nanopore-Templated Silver Nanoparticle Arrays Photopolymerized in Zero-Mode Wavelengths
In situ fabrication of nanostructures within a solid-polymer electrolyte confined to subwavelength-diameter nanoapertures is a promising approach for producing nanomaterials for nanophotonic and chemical sensing applications. The solid-polymerelectrolyte can be patterned by lithographic photopolymerization of poly(ethyleneglycol) diacrylate (PEGDA)-based silver cation (Ag+)-containing polyelectrolyte. Here, we present a new method for fabricating nanopore-templated Ag nanoparticle (AgNP)arrays by in situ photopolymerization using a zero-mode waveguide (ZMW) array to simultaneously template embedded AgNPs and control the spatial distribution of the optical field used for photopolymerization. The approach starts with an array of nanopores fabricated by sequential layer-by-layer deposition and focused ion beam milling. These structures have an optically transparent bottom, allowing access of the optical radiation to the attoliter-volume ZMW region to photopolymerize a PEGDA monomer solution containing AgNPs and Ag+. The electric field intensity distribution is calculated for various ZMW optical cladding layer thicknesses using finite-element simulations, closely following the light-blocking efficiency of the optical cladding layer. The fidelity of the polyelectrolyte nanopillar pattern was optimized with respect to experimental conditions, including the presence or absence of Ag+ and AgNPs and the concentrations of PEGDA and Ag+. The self-templated approach for photo patterning high-resolution photolabile polyelectrolyte nanostructures directly within a ZMW array could lead to a new class of metamaterials formed by embedding metal nanoparticles within a dielectric in a well-defined spatial array.
Zero-mode waveguide↗
Suppressing Polarization Mode Dispersion with the Quantum Zeno Effect
Polarization mode dispersion can introduce quantum decoherence in polarization encoded information, limiting the range of quantum communications protocols. Therefore, strategies to completely nullify the affect would reduce quantum decoherence and potentially increase the operational range of such technology. We construct a quantum model of polarization mode dispersion alongside a two-level absorbing material. The two-level material serves to destructively measure one of two orthogonal polarization modes, thus projecting the polarization onto the other state. The theoretical results are supported by a numerical simulation in Mathematica Documentation where we and compare the evolution of the polarization state with and without the absorbing material. We find that this strategy is effective in suppressing the effects of polarization mode dispersion, and that this method produces a global phase shift related the waveguide’s birefringent properties.
waveguides↗
The spacecraft communications repeater
This paper describes the electrical characteristics of the waveguide components, the solid-state circuits and the traveling-wave tube used in the microwave communications repeater. The reflex-circuit method of obtaining local oscillator signals for the modulators and certain circuit stability problems are discussed.
MICROWAVE APPARATUS↗
Masers for the telstar satellite communications experiment
This paper discusses the design and characteristics of ruby traveling-wave masers operating at 4 gc. These masers, characterized by an average gain of ≈35 db over a bandwidth of 25 mc, are equipped with waveguide input transmission lines, rather than the previously employed coaxial cables. This change results in an over-all noise temperature of 3.5°K for these devices, rather than the 10°K exhibited by earlier masers. The maser noise temperature now closely approximates sky temperatures, which set the ultimate limit on earthbound receiver sensitivity. The improvements to be had by further reduction in amplifier noise are therefore almost negligible. A less well known maser property, i.e., its freedom from distortion, even when driven well into gain saturation, is discussed.
TELSTAR SATELLITE↗
A wave-guide model for turbulent shear flow
Mathematical waveguide model for turbulent shear flow
MATHEMATICAL MODEL↗