Broadband Metamaterial Termination for Planar Superconducting Transmission Line Circuits

The patch antenna consists of two radiating metal patch elements, a metal feed circuit, choke rings, several alignment spacers, a SMA connector, and a mounting lid giving the antenna a total diameter of 54 mm; small enough to fit in a coffee cup. The signal is carried between the lower patch and the circuit via a coaxial transmission structure, in which the probes are the inner conductor and the antenna structure is the outer conductor. The patch antenna is constructed entirely of metal, offering rugged physical durability while delivering superior performance. This advanced material not only enables the antenna to handle higher power loads (exceeding 10 watts) but also ensures exceptional stability under demanding conditions—outperforming standard patch antennas made with traditional dielectric materials. It is also not susceptible to the manufacturing variability incurred from using dielectrics. Ideally, this metallic design also allows for reentry and reuse across missions. The patch antenna is designed with integrated choke rings to effectively mitigate multipath signal interference, delivering an impressive front-to-back ratio of over 35 dB. Its integrated polarizer circuit enhances signal clarity and boosts overall efficiency, ensuring reliable communication in challenging environments. With support for both right- and left-handed circular polarization, the antenna achieves a co-polarization peak gain of 9 dBi and an axial ratio of less than 3 dB within a wide 50-degree orientation range. These advanced features provide superior signal performance and consistent clarity across diverse applications. Although designed for space and planetary exploration applications, the antenna may also be valuable for terrestrial use cases with rugged conditions. The X-band patch antenna is at technology readiness level (TRL) 5 (component and/or breadboard validation in relevant environment) and is available for patent licensing.

The electromagnetic properties of the material are engineered by optimizing its complex dielectric function through the volume filling fraction of its components. A low-index polymeric binder, such as thermal polymers and epoxies, serves as the host medium to minimize reflectance in the conductively loaded dielectric media. To ensure thermal compatibility with metal substrates in cryogenic environments, dielectric powders are incorporated to match thermal expansion. Additionally, alumina frit compensates for thermal contraction at cryogenic temperatures, while non-magnetic conductive particles such as bronze, carbon allotropes, and degenerately doped silicon help tailor the material’s dielectric response. To enhance performance, small-particle scatterers reduce heat capacity and limit resonant dispersion, while dirty alloys stabilize resistance under conductive loading. The formulation incorporates reststrahlen materials and supports applications across the microwave to terahertz range, making it suitable for baffles, Lyot stops, and optical terminations, or as a primer for enhancing near-infrared and visible black paints. This high-emissivity, non-magnetic coating is designed for microwave to far-infrared instrumentation in space and cryogenic systems. It also benefits industries producing absorptive epoxies, EMI/EMC shielding, and quantum sensing components. It has reached Technology Readiness Level (TRL) 5 (component validation in relevant environment) and is now available for patent licensing.

The prior art offers a variety of thermal blocking filter construction techniques and designs. In the devices most basic form, a large shunt capacitor forms a single-pole low-pass-filter. More generally, multiple low-pass lumped element stages can be combined in series to produce compact and broadband non-dissipative filter structures. The challenges presented by these implementations include controlling inter-stage isolation and spurious transmission resonances, limiting the filters total shunt capacitance, and achieving adequate control over circuit parameters as a function of temperature. In this work, simple matched filter designs based on easily realized absorptive dielectric transmission lines are improved upon. Innovators at NASA Goddard Space Flight Center have designed, fabricated, and characterized absorptive thermal blocking filters for cryogenic microwave applications. The device allows direct integration of the high frequency signal and microwave readout and mitigates spurious resonances in the circuit response. This leads to improved electrical performance and a reduction in the required circuit area. The transmission line filters input characteristic impedance is designed to match 50 ohms and its response has been validated from 0 to 50 GHz. The observed return loss in the 0 to 20 GHz design band is greater than 20 dB and shows graceful degradation with frequency. The filters response is calculable, repeatable under cryogenic cycling, and is capable of providing an intrinsically broadband matched impedance termination. This technology is generally applicable in the realm of high frequency circuits, is scalable and can be modified for use in other applications.

Initially developed for missions to Mars, Teletenna integrates RF and optical communication technologies to transmit data from deep space to Earth at extremely high speeds. The system combines a co-boresighted telescope and a Ka-band RF antenna to minimize system mass and enhance performance. Designed with an optimal focal length-to-diameter ratio, the apparatus features a classical Cassegrain geometry, including a sub-reflector in front of the RF feed which acts as a mirror for the optical signal while being transparent to the RF signal. The apparatus also mechanically and thermally isolates the RF reflector system from the optics to offer maximum stability. Teletenna was created to overcome two significant challenges to DSOC: 1) laser inefficiency due to poor alignment during spacecraft disturbances and 2) performance degradation due to lack of rigidity in vibrational environments (such as space). The first challenge is addressed by the telescope portion of this technology, which facilitates the acquisition and maintenance of the link with ease - even in less than ideal conditions. The second challenge is addressed by rigidly fixing the RF reflector to the spacecraft body and attaching the optical section to a vibration isolation platform. The result is a device that can point to within 0.5 degrees of the sun (traditional optical systems are limited to 3 degrees), allowing for approximately 20 extra days of contact time between Earth and Mars. By combining RF and optical communications, this breakthrough innovation has the power to transform communications as we know it. Glenn welcomes co-development opportunities.

The HDRSC hardware implementation employs the latest cutting edge silicon technologies to calculate the time delay between signals of spatially disparate antennas. After first converting the incoming signals to the digital domain, the unit determines the time difference between the antenna arrivals. Knowing the time delay to within utmost accuracy, the unit while still in the digital domain adds the signals. The resulting coherently combined signal is then converted back to the analog domain. Updates to the time difference estimates are accomplished on the order of milliseconds so the whole process can be completed in real time during a spacecraft pass.