A frequency converter (1) for generating an output signal (5a) from an input signal (5), the output signal (5a) having different frequency than the input signal (5), the frequency converter (1) including: an input (7) for receiving an input signal (5); a transmission line (3) formed of a non-linear medium (3a), the medium (3a) arranged such that when the input signal (5) propagates along the line (3), one or more harmonics (5a,5b) of the input signal (5) are generated; a plurality of dispersion control elements (13), the dispersion control elements (13) arranged to control the dispersion relationship of the medium (3a), to phase match the input signal (5) and the one or more harmonics (5a,5b), such that energy is transferred from the input signal (5) to the one or more harmonics (5a,5b); and an output (9) for providing the one or more harmonics (5a, 5b) as an output signal.

An unbalanced terahertz frequency doubler circuit with power handling capacity is provided, and the circuit includes a RF input waveguide, a quartz substrate and a RF output waveguide, where one end of the quartz substrate is disposed in a waveguide groove of the RF input waveguide and the other end of the quartz substrate is disposed in a waveguide groove of the RF output waveguide, where an input transition microstrip is disposed on the quartz substrate, and one end of the transition microstrip is connected to an output transition microstrip sequentially through a first transmission microstrip, a low pass filter, a RF matching microstrip and a second transmission microstrip, where anodes of four GaAs-based terahertz frequency multiplier diode groups are connected to the RF matching microstrip, and a cathode at the outermost position of each of the GaAs-based terahertz frequency multiplier diode groups is connected to a grounding quartz strip.

A frequency converter (1) for generating an output signal (5a) from an input signal (5), the output signal (5a) having different frequency than the input signal (5), the frequency converter (1) including: an input (7) for receiving an input signal (5); a transmission line (3) formed of a non-linear medium (3a), the medium (3a) arranged such that when the input signal (5) propagates along the line (3), one or more harmonics (5a,5b) of the input signal (5) are generated; a plurality of dispersion control elements (13), the dispersion control elements (13) arranged to control the dispersion relationship of the medium (3a), to phase match the input signal (5) and the one or more harmonics (5a,5b), such that energy is transferred from the input signal (5) to the one or more harmonics (5a,5b); and an output (9) for providing the one or more harmonics (5a, 5b) as an output signal.

The present application discloses an unbalanced terahertz frequency doubler circuit with power handling capacity including a RF input waveguide, a quartz substrate and a RF output waveguide, where one end of the quartz substrate is disposed in a waveguide groove of the RF input waveguide and the other end of the quartz substrate is disposed in a waveguide groove of the RF output waveguide, where an input transition microstrip is disposed on the quartz substrate, and one end of the transition microstrip is connected to an output transition microstrip sequentially through a first transmission microstrip, a low pass filter, a RF matching microstrip and a second transmission microstrip, where anodes of four GaAs-based terahertz frequency multiplier diode groups are connected to the RF matching microstrip, and a cathode at the outermost position of each of the GaAs-based terahertz frequency multiplier diode groups is connected to a grounding quartz strip.

Various NLTL frequency comb generator embodiments are disclosed for compressing rise time, fall time, or both rise time and fall time of an input signal to generate an output signal comprising multiple harmonics of the input signal. The NLTL frequency comb generator may comprise a plurality of segments cascaded in series with each segment comprising a series inductor, a shunt capacitor, and a reverse shunt capacitor for balanced signal compression. The shunt capacitor and the reverse shunt capacitor may be varactors or Schottky diodes that have voltage-dependent capacitance. As a result, both rise time and fall time of the input signal are compressed along the NLTL frequency comb generator. With a sinusoidal signal input, the output signal may be close to a square wave. Such a square wave output naturally suppresses all even harmonics, which can be valuable for odd harmonics signal extraction or filtration.

Various NLTL frequency comb generator embodiments are disclosed for compressing rise time, fall time, or both rise time and fall time of an input signal to generate an output signal comprising multiple harmonics of the input signal. The NLTL frequency comb generator may comprise a plurality of segments cascaded in series with each segment comprising a series inductor, a shunt capacitor, and a reverse shunt capacitor for balanced signal compression. The shunt capacitor and the reverse shunt capacitor may be varactors or Schottky diodes that have voltage-dependent capacitance. As a result, both rise time and fall time of the input signal are compressed along the NLTL frequency comb generator. With a sinusoidal signal input, the output signal may be close to a square wave. Such a square wave output naturally suppresses all even harmonics, which can be valuable for odd harmonics signal extraction or filtration.

An imaging device includes an antenna configured to transmit millimeter waves, a connector adapted to connect a radio frequency (RF) signal source with the imaging device and a signal path connected between the connector and the antenna. A nonlinear transmission line (NLTL)-based frequency multiplier is arranged along the signal path to receive an RF signal from the RF signal source and increase a frequency of the RF signal to millimeter frequency to produce a millimeter wave. A NLTL-based variable delay line is arranged along the signal path between the NLTL-based frequency multiplier and the antenna. A time delay of an NLTL of the NLTL-base variable delay line is variable to steer a beam of the millimeter wave in at least one dimension as the millimeter wave is transmitted by the antenna. A receiver processes a return signal received in response to the millimeter wave.

An imaging device includes an antenna configured to transmit millimeter waves, a connector adapted to connect a radio frequency (RF) signal source with the imaging device and a signal path connected between the connector and the antenna. A nonlinear transmission line (NLTL)-based frequency multiplier is arranged along the signal path to receive an RF signal from the RF signal source and increase a frequency of the RF signal to millimeter frequency to produce a millimeter wave. A NLTL-based variable delay line is arranged along the signal path between the NLTL-based frequency multiplier and the antenna. A time delay of an NLTL of the NLTL-base variable delay line is variable to steer a beam of the millimeter wave in at least one dimension as the millimeter wave is transmitted by the antenna. A receiver processes a return signal received in response to the millimeter wave.

An imaging device includes an antenna configured to transmit millimeter waves, a connector adapted to connect a radio frequency (RF) signal source with the imaging device and a signal path connected between the connector and the antenna. A nonlinear transmission line (NLTL)-based frequency multiplier is arranged along the signal path to receive an RF signal from the RF signal source and increase a frequency of the RF signal to millimeter frequency to produce a millimeter wave. A NLTL-based variable delay line is arranged along the signal path between the NLTL-based frequency multiplier and the antenna. A time delay of an NLTL of the NLTL-base variable delay line is variable to steer a beam of the millimeter wave in at least one dimension as the millimeter wave is transmitted by the antenna. A receiver processes a return signal received in response to the millimeter wave.

An imaging device includes an antenna configured to transmit millimeter waves, a connector adapted to connect a radio frequency (RF) signal source with the imaging device and a signal path connected between the connector and the antenna. A nonlinear transmission line (NLTL)-based frequency multiplier is arranged along the signal path to receive an RF signal from the RF signal source and increase a frequency of the RF signal to millimeter frequency to produce a millimeter wave. A NLTL-based variable delay line is arranged along the signal path between the NLTL-based frequency multiplier and the antenna. A time delay of an NLTL of the NLTL-base variable delay line is variable to steer a beam of the millimeter wave in at least one dimension as the millimeter wave is transmitted by the antenna. A receiver processes a return signal received in response to the millimeter wave.