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NASA NTRS2014

A Novel Multimode Waveguide Coupler for Accurate Power Measurement of Traveling Wave Tube Harmonic Frequencies

This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from two dissimilar waveguides is capable of isolating the power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT). In addition to accurate power measurements at harmonic frequencies, a potential application of the MDC is in the design of a beacon source for atmospheric propagation studies at millimeter-wave frequencies.

harmonic frequencies↗

NASA NTRS2017

Waveguide Multimode Directional Coupler for Harvesting Harmonic Power from the Output of Traveling-Wave Tube Amplifiers

This paper presents the design, fabrication, and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from dissimilar frequency band waveguides, is capable of isolating power at the 2nd harmonic frequency from the fundamental power at the output port of traveling-wave tube amplifiers. Test results from proof-of-concept demonstrations are presented for Ku/Ka-band and Ka/E-band MDCs, which demonstrate sufficient power in the 2nd harmonic for a space borne beacon source for mm-wave atmospheric propagation studies.

Directional Coupler↗

NASA NTRS2017

Waveguide Multimode Directional Coupler for Harvesting Harmonic Power from the Output of Traveling-Wave Tube Amplifiers

The paper presents the design, fabrication, and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from dissimilar frequency band waveguides, is capable of isolating power at the 2nd harmonic frequency from the fundamental power at the output port of a high power traveling-wave tube amplifier. The major advantage of the MDC is significantly lower insertion loss compared to a diplexer. The presentation slides for the paper that was approved is attached. The tracking number for the paper that was approved is TN 37015.

Directional Coupler↗

NASA NTRS1979

Coupler for moving vehicles

Coupler for two moving vehicles gradually orients and retains target vehicle, avoiding any abrupt contact with parent vehicle. Mechanism gently releases captured vehicle with approximate speed and direction of parent vehicle. Coupler may be applicable to deployment and retrieval of oceanographic research equipment and vessels or coupling of aircraft in flight.

Rudmann, A. A.↗

NASA NTRS1977

A high-power dual-directional coupler

A dual-directional loop coupler in WR 430 waveguide was installed at DSS 14 as part of the system to measure station range delay. This installation was necessary to provide special test translator signal injection ports for the Voyager near-earth calibration sequence, which required that the SPD maser be bypassed to prevent saturation of the receivers. The design of the dual coupler and testing of this device at high power is discussed.

Wallace, K. B.↗

NASA NTRS1981

High-power dual-directional coupler

Water-cooled coupler installed in S-band polarization diversity (SPD) cone is used to calibrate receiving-station relay. Coupler operates without arcing at 400 kw and permits accurate calibration of entire system below antenna feed horn. Device has good directivity, contributes less than 0.01 K to system noise temperature, and eliminates saturation of ground station and spacecraft receivers during high-power operation.

Otoshi, T. Y.↗

NASA NTRS1986

Acoustic Coupler for Monitoring Bearing Wear

Concept for acoustic coupler allows sound efficiently conveyed from bearings to external sensor. Noise from bearings in bearing test machine monitored for signs of incipient failure. Straight through acoustic-coupler assembly inserted through existing ports in housing of bearing-testing machine. Threaded electrical connector at top rotated to adjust force applied to sensing element and contact bearing.

Jolly, W.↗

NASA NTRS1988

Study of optical output couplers for submillimeter wavelength backward-wave oscillators (BWO's)

The machining of slow wave structures for high frequency backward-wave oscillators (BWO) is extremely difficult beyond 1 THz. Recently a microfabrication technique using photolithography and ion-beam assisted etching has been used to construct a prototype BWO operating at 200 to 265 GHz. The output coupler for such tubes remains a problem. Waveguides do not exist or are very lossy at the frequencies of interest (300 to 2000 GHz). This paper discusses several scaled experiments of optical output couplers for submillimeter BWOs. Various designs of planar antennas (Vivaldi horns) and lens-feed systems (Hyperhemispherical lens) were constructed and tested between 20 and 100 GHz using a spectrum analyzer. The lens system was also tested at 337 GHz using a CO2 pumped FIR laser.

Cook, Jerry D.↗

NASA NTRS1990

Directional Couplers For Detecting Circular Waveguide Modes

Samples of TE11 and TE12 modes coupled selectively out of circular waveguide. Report presents additional details of theory, construction, and measured operating characteristics of directional couplers described in "Microwave Transmitter With Multimode Output Section" (NPO-16826). Couplers consist of tapered rectangular-cross-section waveguides fastened lengthwise to outside of circular waveguide, with uniformly-lengthwise-spaced round coupling holes between each rectangular waveguide and circular waveguide.

Hoppe, Daniel J.↗

NASA NTRS1990

Self-Aligning Coupler

Joint reduces assembly time and eliminates fumbling. Self-aligning coupler easy to use for people wearing heavy gloves or other restrictive clothing. Consists of two threaded sections, one with blade, other with slot - joined by threaded collar. Blade fits precisely in slot. Notch in blade engages pin in slot to form temporary attachment. Collar turned on continuous thread of joined sections to form tight, rigid joint. Designed for assembly of structures by astronauts in space suits, coupler used on Earth by firefighters wearing protective garments, technicians handling hazardous materials, and others working underwater or in other difficult environments.

Cooney, Earl T.↗

NASA NTRS1990

Coplanar-waveguide/microstrip probe coupler and applications to antennas

A method to couple microwave power from a coplanar waveguide to a microstrip line on opposite sides of a ground plane is demonstrated. The coupler uses a metallic post which passes through an aperture on the ground plane connecting the strip conductor of the coplanar waveguide to the microstrip line. The measured insertion loss and return loss are about 1 dB and 10 dB, respectively, across the frequency range of 0.045-6.5 GHz. To demonstrate potential applications of the coupler as a feeding network for a microstrip patch array, measured radiation patterns of two rectangular patch antennas with a direct coplanar-waveguide/microstrip feed and with a proximity coupled coplanar-waveguide/microstrip feed are presented.

Simons, R. N.↗

NASA NTRS1992

Obtaining Patterns Of Holes In Directional Couplers

Technique enables reproduction of pattern of holes in hidden common wall of microwave directional coupler. Talcum-dusting procedure yields pattern of powder on adhesive tape showing sizes of distances between holes. Later, coupler cleaned with water or compressed air. Applicable to other equipment containing inaccessible holes in common wall between adjacent tubes.

Perez, Raul M.↗

NASA NTRS1991

Effects of beam focusing on the efficiency of planar waveguide grating couplers

Results of a theoretical and experimental study into the variation of coupling efficiency with a grating angle are presented for various beam focusing conditions for an integrated optical grating coupler. The study shows that the acceptance angle of the grating coupler can be broadened within a relatively large range and with a relatively small loss of coupling efficiency, by focusing the incident laser beam.

Li, Lifeng↗

NASA NTRS1991

Length minimization design considerations in photonic integrated circuits incorporating directional couplers

Because directional couplers involve channel waveguides which are very close to one another, transition regions to regions where channel waveguides are widely separated are utilized. The total length of a directional coupler and transition regions can be minimized for a particular degree of field confinement. Calculations presented for LiNbO3-, GaAlAs-, and SiO2/Si-based optical channel waveguides demonstrate the presence of a minimum total length corresponding to a particular degree of field confinement. The overall length at the minimum is shown to be significantly lower than for other values of field confinement allowing single-mode operation. This implies that either more devices can be integrated on a substrate or that less material is needed for an integrated optical circuit.

Boyd, Joseph T.↗

NASA NTRS1992

The design and fabrication of a single leakage-channel grating coupler

The modeling and fabrication is described of waveguide grating couplers with out-coupling efficiencies into a single diffracted order nearing 100 pct. Termed Single Leakage Channel Grating Couplers (SLCGCs), these devices use a high reflectivity dielectric stack to reflect the out-coupled beam diffracted toward the substrate, back up into the air region where it constructively adds with the beam diffracted into the air region. Computer modeling shows that the branching ratio and the leakage rate can be independently controlled, and that the branching ratio is independent of grating depth and grating period. A SLCGC with a branching ratio of 97.1 pct. was fabricated using a combination of vacuum evaporation and wet chemical techniques.

Roncone, Ronald L.↗

NASA NTRS1996

Thin-Ribbon Tapered Couplers For Dielectric Waveguides

Thin-ribbon tapered couplers proposed for launching electro-magnetic waves into dielectric waveguides, which include optical fibers. Intended for use with ribbon dielectric waveguides designed for operation at millimeter or submillimeter wavelengths, made of high-relative-permittivity, low-loss materials and thicknesses comparable to or less than free-space design wavelengths. Coupling efficiencies exceeds those of older tapered couplers.

Otoshi, Tom Y.↗

NASA NTRS2003

Calibration of Passive Microwave Hybrid Coupler-based Polarimeters

Passive microwave polarimeters, or polarimetric radiometers, are important tools for Earth remote sensing. They have found utility in ocean surface wind-vector remote sensing and polarization basis rotation systems for compensating instrument or ionospheric induced rotation. The hybrid coupler-based polarimeter is a specific class of polarimeter that utilizes a 180-degree hybrid coupler to affect a correlation between the received vertical and horizontal polarization signals. This type of polarimeter requires at least four calibration states for complete calibration. One state must be a polarized signal, such as the application of a correlated noise source. The phase balance of the noise source directly determines the quality of the calibration.

Piepmeier, J. R.↗

NASA NTRS2015

A Novel Ku-Band/Ka-Band and Ka-Band/E-Band Multimode Waveguide Couplers for Power Measurement of Traveling-Wave Tube Amplifier Harmonic Frequencies

This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).

Wintucky, Edwin G.↗