A two-way microwave power divider using microstrip transmission lines

The broadband metamaterial termination for use in planar superconducting transmission lines has been successfully demonstrated in CLASS circuit structures as an effective termination. This metamaterial implementation is fully compatible with microfabrication techniques commonly used for microwave circuitry, and its response is insensitive to geometric tolerances, material properties, and interface details of conductive elements in device fabrication. In the context of far-infrared imaging, polarimetric, and superconducting integral field unit (IFU) spectrometer arrays for astrophysics, this strategy leads to higher performance, increased device yield, and greater overall circuit density. The metamaterial termination achieves a broadband absorption response with lower reflectance in a smaller physical footprint compared to existing adiabatic structures. This absorption response demonstrates significantly lower sensitivity to fabrication tolerances, material properties, and modeling assumptions than previous designs. These characteristics are critical for cryogenic applications, but the termination can also enhance the performance of room-temperature planar transmission line structures used in microwave engineering. The termination is realized as a lossy stepped impedance transition between Nb and PdAu, which reduces the total meander length, device footprint, and sensitivity to detailed implementation. This broadband metamaterial termination is applicable in superconducting technologies, including quantum communications, computing, and sensors. It has reached Technology Readiness Level (TRL) 7 (technology demonstrated in an operational environment) and is now available for patent licensing.

Glenn's researchers originally created the MDC to improve the beacon sources for atmospheric propagation studies. These studies are typically conducted to test atmospheric conditions to determine the signal strength needed for satellite communications. A low-power transmitter (e.g., a beacon source) is attached to the satellite, and transmits a continuous waveform (CW) signal to a receiving station on Earth. However, when a separate frequency is desired, building a new beacon source for the transmitter on the satellite - especially one that will operate at higher frequencies - presents numerous challenges. For one, a single-frequency beacon source requires a temperature-stabilized oscillator for frequency generation separate from that provided by the spacecraft receiver. To solve such problems, Glenn's innovators fabricated the MDC from two sections of waveguide: a primary waveguide for the fundamental frequency (Ku-band), and a secondary waveguide for the harmonics (Ka-band). These sections are joined together so that precision-machined slots in the second waveguide selectively couple the harmonics, for amplification and transmission. The harmonics can then be used as an additional beacon source with very small power losses to the fundamental signal. Once the separation takes place, the second or higher harmonic can be amplified and transmitted to a station on Earth. The efficiency and performance of the MDC can be optimized through appropriate computer modeling software and currently available high-precision fabrication techniques. Without the complexity and expense involved in building separate traveling wave tube amplifiers to generate additional frequencies, Glenn's MDC enables satellites to produce multiple signals that can be received by multiple stations - a significant leap forward in satellite productivity.

This technology is a flexible, lighter weight radiation shield made from hybrid carbon/metal fabric and based on the Z-grading method of layering metal materials of differing atomic numbers to provide radiation protection for protons, electrons, and x-rays. To create this material, a high density metal is plasma spray-coated to carbon fiber. Another metal with less density is then plasma spray-coated, followed by another, and so on, until the material with the appropriate shielding properties is formed. Resins can be added to the material to provide structural adhesion, reducing the need for mechanical bonding. This material is amenable to molding and could be used to build custom radiation shielding to protect cabling and electronics in situations where traditional metal shielding is difficult to place.

Modern production of e-textiles utilizes an embroidery technique called “e-broidery” that directly stitches circuit patterns with conductive thread onto textiles. This automated manufacturing process combines steps of e-broidery and milling to expand the application of e-textiles to high-current and high-speed uses. Manufacturing begins with two layouts of the desired conductive pattern. After assembling the layers of conductive and nonconductive materials, e-broidery is performed with the second layout and nonconductive thread to secure the layers together and designate the pattern for the conductive material. The secured assembly is transferred to an automated milling or laser cutting machine, which cuts the desired conductive pattern and releases the unneeded portions of the conductive material. The resulting e-textiles are tightly woven together, providing higher surface conductivity and impedance control. Initial comparison tests assessing the performance of fabric-based spiral antennas developed with this method, compared to conventional antennas, indicated no loss in performance across multiple metrics, including voltage standing wave ratio (VSWR), radiation pattern, and axial ratio performance. The Method and Apparatus for Fabric Circuits and Antennas is a technology readiness level (TRL) 6 (system/subsystem prototype demonstration in a relevant environment). The innovation is now available for your company to license. Please note that NASA does not manufacture products itself for commercial sale.

Through low-loss signal combination, Glenn is leading the way to optimize radio transmission remotely during self-checking routines. Glenn's signal combiner offers a simple method to minimize signal loss significantly when combining two signals. Using conventional combiners in bit-error-rate testing results in a loss of 3 to 4 dB per band, and with a directional coupler the secondary signal experiences losses of 10 dB or more. Moreover, during signal measurements, the additional components must be placed and later removed to prevent any impact to the measurement, making for a cumbersome process. Glenn's solution is to combine the primary and secondary signals in the frequency domain through the use of a frequency division diplexer/multiplexer in combination with a wideband ADC. The multiplexer selects one or more bands in the frequency domain, and the ADC performs a non-linear conversion to digital domain by folding out-of-band signals in with the primary signal. NASA makes use of subsampling a given band within the ADC bandwidth to fold it into another band of interest, effectively frequency-shifting them to a common frequency bandwidth. Glenn's breakthrough method has two significant advantages over the conventional use of a power combiner or directional coupler in bit-error-rate testing: 1) it combines signal and noise (secondary signal) with very low loss, and 2) it enables the selection of the desired signal-to-noise ratio with no need for the later cumbersome removal of components. This streamlined process allows for invaluable in-situ or installed measurement. Glenn's novel technology has great potential for satellite, telecommunications, and wireless industries, especially with respect to equipment testing, measurement, calibration, and check-out.