The impedance of a loopstick antenna is directly modulated utilizing a mechanically actuated magnetoelastic material preferably placed in the core (or center) of looped wires forming the loopstick antenna. Using one or more mechanical actuators the permeability in the center of the loopstick antenna can be modulated at a rapid rate (such as with data or audio information), allowing the magnetic field outside of the antenna to be modulated at large bandwidths without requiring switches or modulators capable of high voltage thus reducing the overall complexity and cost of the transmitter. The external magnetic field is created by an AC source which is preferably impedance matched to the loopstick antenna by means of a matching network and is FM modulated according to a modulating signal applied to the one or more mechanical actuators.

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.

A wireless communication system including an electrically conductive passive medium capable of simultaneously propagating therealong electromagnetic first and second currents at different respective frequencies F1 and F2, the electrically conductive passive medium including an electrically conductive first passive linear medium portion adjacent an electrically conductive first passive nonlinear medium portion, the first passive nonlinear medium portion capable of generating an intermodulation current based on a nonlinear interaction between the first and second currents, the intermodulation current having a frequency Fi equal to nF1+mF2 and propagating along the first passive nonlinear medium portion, m and n being positive or negative integers; and a first magnetic film disposed proximate an electrically conductive external surface of the first linear medium portion, such that when the first and second currents propagate along the first passive linear medium portion toward the first passive nonlinear medium portion, the magnetic film reduces or prevents the generation of the intermodulation current in the first passive nonlinear medium portion by attenuating at least portions of the first and second currents.

A wireless communication system includes a transmitter configured to transmit at least first and second radio waves having respective different frequencies F1 and F2, an electrically conductive first passive substantially linear medium, an electrically conductive first passive substantially nonlinear medium disposed proximate the first passive substantially linear medium, and a first magnetic film covering at least a portion of the first passive substantially linear medium. When the transmitter transmits the first and second radio waves, the first passive substantially linear and nonlinear media receive the first and second radio waves and generate first and second signals propagating therein at the respective frequencies F1 and F2. At least one intermodulation signal having a frequency F3 equal to nF1+mF2, where m and n positive or negative integers, is generated in the first passive substantially nonlinear medium. The first magnetic film reduces the at least one intermodulation signal by at least 2 dB.

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 microwave amplitude-phase controller and a method of controlling amplitude and/or phase of a microwave are provided. The microwave amplitude-phase controller includes: a first substrate and a second substrate opposite to each other; a liquid crystal layer between the first substrate and the second substrate; a conductive layer on a side of the first substrate facing the liquid crystal layer, the conductive layer being configured to receive a first voltage signal; and a resonant structure on a side of the second substrate facing the liquid crystal layer, the resonant structure being configured to receive a second voltage signal and to transmit a microwave signal.

A radiation device includes: a first substrate; a second substrate; a dielectric layer disposed between the first substrate and the second substrate; and a film layer structure disposed on the first substrate. The resistivity of the film layer structure is between 10.sup.8 and 510.sup.14 -cm. Therefore, frequency modulation range of radiation signals of the radiation device can be increased.

A radiation device includes: a first substrate; a second substrate; a dielectric layer disposed between the first substrate and the second substrate; and a film layer structure disposed on the first substrate. The resistivity of the film layer structure is between 10.sup.8 and 510.sup.14 -cm. Therefore, frequency modulation range of radiation signals of the radiation device can be increased.

A microwave amplitude-phase controller and a method of controlling amplitude and/or phase of a microwave are provided. The microwave amplitude-phase controller includes: a first substrate and a second substrate opposite to each other; a liquid crystal layer between the first substrate and the second substrate; a conductive layer on a side of the first substrate facing the liquid crystal layer, the conductive layer being configured to receive a first voltage signal; and a resonant structure on a side of the second substrate facing the liquid crystal layer, the resonant structure being configured to receive a second voltage signal and to transmit a microwave signal.