Characterizing microstrip superconducting film at millimeter-wave frequencies is difficult without undergoing a complex thin film fabrication process. This characterization includes measuring the ohmic loss at a resolution of 10100 parts per million (ppm).

Typically, characterizing microstrip superconducting film utilizes antenna-coupled bolometers as part of the superconducting film structure. Bolometers are components that measure incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance; however, this process is disadvantageous as embedded detectors, such as bolometers, make the superconducting film fabrication process more difficult. This process also requires various millimeter-wave components, further complicating film fabrication. Additionally, characterizing superconducting film requires custom equipment and can vary among various fabrication processes.

The Microstrip Circuit and Material Characterization System can measure superconducting film ohmic loss at millimeter-wave frequencies using a vector network analyzer (VNA) that measures amplitude and phase properties of the network parameters of the film.

The system consists of a two-port waveguide structure. The ports are used to transmit and receive millimeter-wave power into and out of the superconducting film. The waveguide structure is used to transform waveguide characteristic impedance to microstrip line impedance over broad ranges of frequencies to make contact with the superconducting film. The superconducting film contains microstrip line resonators that can be used to measure ohmic loss and the effective dielectric constant at various frequencies.

The system functions by connecting to a millimeter-wave transmitter and receiver. The system is used to measure transmission loss of a microstrip line sample. For superconducting microstrip film measurement, the device needs to be cooled below the superconductor’s critical temperature in order to measure the film ohmic loss and the transmission line’s propagation constant. The system can be used to measure loss in the microstrip line as low as 10 ppm and is operable within a temperature range from 0 K to 320 K.

NASA is actively seeking licensees to commercialize this technology. Please contact NASA’s Licensing Concierge at This email address is being protected from spambots. You need JavaScript enabled to view it. or call us at 202-358-7432 to initiate licensing discussions. Follow this link here  for more information.


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This article first appeared in the January, 2021 issue of Tech Briefs Magazine.

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