A sensor apparatus includes a sensor head and a measurement unit. The sensor head includes a first probe and a second probe. The first probe includes a first tiny antenna section for transmission and a second tiny antenna section for transmission. The second probe is arranged at a predetermined distance from the first probe, and includes a first tiny antenna section for reception and a second tiny antenna section for reception. The measurement unit generates a measurement signal that includes information regarding characteristics of a propagation of an electromagnetic wave in a medium between the first tiny antenna section for transmission and the first tiny antenna section for reception, and information regarding characteristics of the propagation of the electromagnetic wave in the medium between the second tiny antenna section for transmission and the second tiny antenna section for reception. The first probe and the second probe have different probe lengths, or a distance between the first tiny antenna section for transmission and the first tiny antenna section for reception, and a distance between the second tiny antenna section for transmission and the second tiny antenna section for reception are different from each other.

An imaging device includes: an area light source including an emission surface from which a sub-terahertz wave is emitted to a measurement target; and a detector including an image sensor that receives a reflected wave generated by the measurement target reflecting the sub-terahertz wave emitted from the emission surface. The area light source includes: at least one point light source that emits a sub-terahertz wave; and a reflector that reflects the sub-terahertz wave emitted from the at least one point light source, to generate a sub-terahertz wave to be emitted from the emission surface. The reflector has a reflection surface that is a bumpy surface which includes two or more frequency components in a spatial frequency range and whose roughness curve element mean length RSm is at least 0.3 mm.

An apparatus and methods for measuring dielectric constant of prepared samples of construction materials or measuring dielectric constant of a surface of a structure fabricated from the construction materials is provided in the present invention. The present invention provides use of a dielectric waveguide to couple energy from an impulse radar to create the apparatus for testing building materials, where the dielectric waveguide is longer than one wavelength so that the Material Under Test (MUT) is in the far-field region of radar antennas.

An apparatus and methods for measuring dielectric constant of prepared samples of construction materials or measuring dielectric constant of a surface of a structure fabricated from the construction materials is provided in the present invention. The present invention provides use of a dielectric waveguide to couple energy from an impulse radar to create the apparatus for testing building materials, where the dielectric waveguide is longer than one wavelength so that the Material Under Test (MUT) is in the far-field region of radar antennas.

The present disclosure relates to a complex permittivity estimating apparatus and a method. More specifically, the complex permittivity estimating apparatus according to the present disclosure includes: a receiver that irradiates a transmission signal such that the transmission signal is reflected on a test dielectric or transmitted through the test dielectric and receives a reflected wave and a transmitted wave for the test dielectric; a determiner that determines simulation data from a simulation table set in advance based on information extracted from at least one of the reflected wave or the transmitted wave; and an estimator that estimates complex permittivity for the test dielectric based on the determined simulation data.

The present disclosure relates to a complex permittivity estimating apparatus and a method. More specifically, the complex permittivity estimating apparatus according to the present disclosure includes: a receiver that irradiates a transmission signal such that the transmission signal is reflected on a test dielectric or transmitted through the test dielectric and receives a reflected wave and a transmitted wave for the test dielectric; a determiner that determines simulation data from a simulation table set in advance based on information extracted from at least one of the reflected wave or the transmitted wave; and an estimator that estimates complex permittivity for the test dielectric based on the determined simulation data.

An apparatus for electromagnetic characterisation of internal features of an object, including a lens for placement between a source of electromagnetic energy and the object, the lens being composed of a first material having a first permittivity with openings therein containing or configured to receive one or more second materials having respective second permittivities different to the first permittivity, the openings being configured such that, when the openings contain the one or more second materials, the lens has a graded refractive index wherein an electromagnetic wave generated by the source and incident upon a first surface of the lens as a spherical wave exits a second surface of the lens in contact with a receiving surface of the object substantially as a plane wave, and a refractive index of the lens at the second surface of the lens substantially matches a refractive index of the object at the receiving surface to increase penetration of the plane wave into the object.

A composition ratio estimation device estimates a composition ratio of a content having mixed substances with different boiling points in a tank. The content is retained as a liquid in the tank lower part. The substances are partially floatable as a gas or liquid in a space in the tank upper part. The device includes a reference object disposed in the space, a transmitting-receiving unit that transmits radar waves toward the reference object and the surface of the liquid and receives reflected radar waves, a temperature measuring unit that acquires a level at which a boiling point of a floating substance is reached, a dielectric constant calculating unit that stores in advance a physical distance between the unit and the object and calculates a dielectric constant of a space between the unit and the object, and a composition ratio derivation unit that derives a composition ratio of the liquid.

The present disclosure relates to a steady-state microwave conductivity method that includes modulating a light beam to form an amplitude modulated light having a modulation frequency ω.sub.1, producing a microwave waveform, exposing a sample to the amplitude modulated light and a first portion of the microwave waveform to produce an amplitude modulation signal on the first portion of the microwave waveform, and mixing a second portion of the microwave waveform and the amplitude modulation signal to produce a first signal and a second signal.

This water vapor observation device comprises an antenna, an RF amplifier, and processing circuitry. The antenna receives radio waves radiated from an atmosphere including water vapor. The RF amplifier amplifies the received radio waves and generates an observation signal. The processing circuitry is programmed to at least: use the observation signal to select a plurality of observation frequencies excluding an accuracy degraded frequency; and calculate a water vapor index using the spectral intensities of the plurality of observation frequencies. This configuration makes it possible to accurately observe a water vapor amount.