A compact, low-power, high image rejection sideband separation receiver is provided. The receiver observes an input radio frequency (RF) signal of multiple spectral lines (spectral observation), then downconverts the signals to intermediate frequency (IF), and then separates the signals to be observed simultaneously in multiple channels. An embodiment is used to observe a signal (G-band) with two spectral lines and utilizes a two stage Weaver architecture to downconvert the signal's frequency, including a combination of mixers in the second stage that achieves the separation of two different channels.

Provided are a liquid crystal member and a millimeter-wave modulation element with the liquid crystal member including a liquid crystal layer having a non-flat surface. The liquid crystal member includes a liquid crystal layer in which a liquid crystal composition which contains a liquid crystal compound having a polymerizable group and a polymerization initiator is immobilized in an aligned state, with at least one main surface of two main surfaces of the liquid crystal layer at both ends in a thickness direction is a non-flat surface having various shapes in a region on the non-flat surface side of one of the two main surfaces, a slow axis of the liquid crystal compound has an equal angle with respect to an adjacent non-flat surface, and in a region on the other main surface side, slow axes of the liquid crystal compound are parallel to each other.

An electromagnetic wave transmission apparatus of the present invention includes a transmission unit whose voltage-current characteristics have a local maximum value and a local minimum value located on a higher voltage side than the local maximum value and which transmits an electromagnetic wave indicating a modulation signal, an acquisition unit which acquires a digital signal, and a modulation unit which modulates the digital signal into the modulation signal which is a signal using voltage values of three levels or more in an oscillation region which is a voltage region that is equal to or more than a voltage of the local maximum voltage and equal to or less than a voltage of the local minimum voltage. The transmission unit preferably transmits a synchronization signal as at least a part of the modulation signal. In this case, the synchronization signal preferably includes a maximum value and a minimum value among the voltage values of three levels or more, and includes a pattern in which the voltage value transitions from one of the maximum value and the minimum value to the other.

One aspect of the present disclosure provides a terahertz-wave detector including a semiconductor substrate, an active element formed on the semiconductor substrate and a first resistive portion electrically connected in parallel with the active element.

One aspect of the present disclosure provides a terahertz-wave detector including a semiconductor substrate, an active element formed on the semiconductor substrate and a first resistive portion electrically connected in parallel with the active element.

Systems and methods for terahertz modulation in a terahertz frequency band from about 0.1 terahertz to about 10 terahertz propagating in a wellbore intersecting a subterranean earth formation. A transmitter generates the EM radiation in the terahertz frequency band. A modulator located in the wellbore receives the EM radiation and generates an amplitude modulated signal with the EM radiation.

Systems and methods for terahertz modulation in a terahertz frequency band from about 0.1 terahertz to about 10 terahertz propagating in a wellbore intersecting a subterranean earth formation. A transmitter generates the EM radiation in the terahertz frequency band. A modulator located in the wellbore receives the EM radiation and generates an amplitude modulated signal with the EM radiation.

A method for minimizing harmonic distortion and/or intermodulation distortion of a radiofrequency signal propagating in a radiofrequency circuit formed on a semiconductor substrate coated with an electrically insulating layer, wherein a curve representing the distortion as a function of a power of the input or output signal exhibits a trough around a given power (P.sub.Dip), the method comprises applying, between the radiofrequency circuit and the semiconductor substrate, an electrical potential difference (V.sub.GB) chosen so as to move the trough toward a given operating power of the radiofrequency circuit.

A method for minimizing harmonic distortion and/or intermodulation distortion of a radiofrequency signal propagating in a radiofrequency circuit formed on a semiconductor substrate coated with an electrically insulating layer, wherein a curve representing the distortion as a function of a power of the input or output signal exhibits a trough around a given power (P.sub.Dip), the method comprises applying, between the radiofrequency circuit and the semiconductor substrate, an electrical potential difference (V.sub.GB) chosen so as to move the trough toward a given operating power of the radiofrequency circuit.

One aspect of the present disclosure provides a terahertz-wave detector including a semiconductor substrate, an active element formed on the semiconductor substrate and a first resistive portion electrically connected in parallel with the active element.