A guided wave radar (GWR)-based method of measuring steam pressure includes transmitting at least a first microwave pulse signal from a GWR sensor system having a pulsed radar gauge (PRG) implementing a steam measurement algorithm coupled to a transceiver that is coupled to a GWR probe in a steam boiler tank having a reference reflector (RR) providing an impedance discontinuity. The transmitting the first microwave pulse signal is with water and steam in the steam boiler tank. An echo emanating from the RR is received responsive to the first microwave pulse signal generates that respective time of flight (TOF) measurement data. A refractive index value for the steam is determined from the TOF measurement data and a reference TOF value representing a TOF measurement without the steam in the steam boiler tank. A physical property of the steam is determined from the refractive index value, such as the pressure.

A detector of microwave radiation comprises a signal input and a detector output. An absorber element of ohmic conductivity is coupled to said signal input through a first length of superconductor. A variable impedance element, the impedance of which is configured to change as a function of temperature, is coupled to the detector output through a second length of superconductor. There is also a heating input and a heating element coupled to the heating input through a third length of superconductor. The absorber element, the variable impedance element, and the heating element are coupled to each other through superconductor sections of lengths shorter than any of said first, second, and third lengths of superconductor.

Epoxy-based inline infrared (IR) filter assembly, and manufacture and use of the same. Co-axial infrared filter assemblies comprise a substantially cylindrical filter body forming a central cavity characterized by opposing holes at each end. The filter body forms an outer conductor, and SMA connectors coupled to the opposing holes at each end of the body are electrically coupled to form an inner conductor positioned along a long axis of the filter body. An infrared absorbing material (such as castable epoxy resin) fills the central cavity of the filter body. Methods for producing the co-axial infrared filter include pressing SMA connectors into the respective ends of the filter body, electrically coupling the SMA connectors, and filling the filter body with epoxy. Electronic systems for operating a dark matter detector include a feedline comprising a coaxial filter configured to advantageously block infrared noise.

An apparatus for accurate measurement of surface and sub-surface temperatures of an object from a distance without contacting the object is provided. Illustrative embodiments provide for simultaneous measurement of thermal emission and emissivity in the mm-wave regime thereby enabling real-time non-contact measurement of emissivity. Corrected temperatures for the object which may be used for calibration of infrared thermographic cameras are determined from the measurement of emissivity.

Embodiments of a code modulated phased-array interferometer are described. In one embodiment, a code modulated phased-array interferometer includes a phased array having a plurality of receiver elements that receive a plurality of received signals. A code multiplexer multiplexes each of the plurality of received signals to generate a plurality of code multiplexed signals, and a combiner combines the plurality of code multiplexed signals into a combined signal. After other processing for signal reception, a code demultiplexer demultiplexes the combined baseband signal, and a complex correlator correlates unique pairs of baseband signals to generate a plurality of visibility products. Finally, the plurality of visibility products are transformed to generate an image. The concepts described herein may be relied upon to reconfigure or repurpose a phased-array receiver to achieve imaging.

An omnidirectional measurement system for a time-varying characteristic of atmospheric vapor radiation includes an antenna and calibrator assembly, a receiver assembly, a room temperature IF assembly, and a data acquisition and system control assembly. Atmospheric vapor features a wide profile and strong radiation in a frequency band of 183 GHz, and is often seen in the characteristic measurement of atmospheric vapor in high-altitude areas. The omnidirectional measurement system combines a superconductor-insulator-superconductor (SIS) mixer with high detection sensitivity in the frequency band of 183 GHz with a structure that integrates pitch scanning, omnidirectional scanning, and automatic calibration to achieve fast and high-precision omnidirectional scanning measurement of the time-varying characteristic of atmospheric vapor radiation. The omnidirectional measurement system has a pitch adjustment-based fast omnidirectional scanning function, and can measure the time-varying characteristic of atmospheric vapor radiation with higher precision and higher temporal resolution through the SIS mixer with higher sensitivity.

Systems and methods are described for microwave-frequency, passive sensing of internal body temperature. Some implementations include one or more wearable sensors that wirelessly transmit temperature data continuously to a remote receiver. The sensor can include a probe designed to be placed on a skin site of an individual to receive near-field radiation at the skin site, and a radiometer to detect a total power of the received near-field radiation. The remote receiver includes a signal processing system that can convert the detected total power to an internal tissue temperature measurement by applying the detected power to a tissue stack model. The tissue stack model can characterize the skin site according to a set of weighting functions, each weighting function corresponding at least to electromagnetic characteristics of an associated tissue layer of the tissue stack model.

An exemplary microwave ablation system is provided. The system may use a switching antenna for both microwave heating of target tissue and microwave radiometry to monitor the temperature of the heated tissue to ensure that the desired temperatures are delivered to adequately treat the target tissue and achieve therapeutic goals. The system may integrate switching components into the switching antenna, which eliminates error from heating of the reference termination and heating of the electrical cables.

A highly integrated miniature radiometer chip includes a base board with opposing top and bottom etched metal layers to form interconnect and ground pads, and a cavity to provide space for surface mounted parts that are attached to the bottom of a middle board which mounts directly over the top of the base board. The middle board has radio frequency circuits and semiconductor chips at a top metal layer, and surface mounted parts, and ground and signal pads at a bottom metal layer. Metalized vias extending through the dielectric material connect the top and bottom layers. A top cover includes a feedhorn, a waveguide section, and isolation compartments and channels that overlie the RF circuits on the middle board. A dielectric insert is located inside the feedhorn to enhance the feedhorn performance and seal the radiometer chip from external air, humidity and contaminants.

A system includes an antenna having a predetermined directivity and a measurement data processing device that modifies spatial resolution of measurement data received from the antenna. The device includes a plurality of multipliers that multiply together measurement values, which are the signal intensity of the microwave output by the microwave radiometer, and weighting coefficients to be an element of a weighted vector a and output multiplication results; and an integrator that integrates the multiplication results of the plurality of multipliers. The weighted vector a modifies the accuracy of the corrected sensitivity function ?(x,y) with performance of the arithmetic processing of the inverse problem in order to reduce integrated values of a positive value region and a negative value region present on an outer side of the sensitivity distribution of the target antenna sensitivity distribution function F(x,y) in the corrected sensitivity function ?(x,y).