A device, comprising: an antenna array provided with a plurality of antennas each having a semiconductor layer having terahertz-wave gain; and a coupling line for mutual frequency-locking of at least two of the antennas at a frequency of the terahertz-wave, wherein the coupling line is connected to a shunt device, and the shunt device is connected in parallel to the semiconductor layer of each of the two antennas.

A device, comprising: an antenna array provided with a plurality of antennas each having a semiconductor layer having terahertz-wave gain; and a coupling line for mutual frequency-locking of at least two of the antennas at a frequency of the terahertz-wave, wherein the coupling line is connected to a shunt device, and the shunt device is connected in parallel to the semiconductor layer of each of the two antennas.

An eLORAN receiver may include an antenna and eLORAN receiver circuitry coupled to the antenna. The antenna may include a ferromagnetic core and an H-field signal winding coupled to the ferromagnetic core. The eLORAN receiver may have an antenna tuning device including a tuning winding surrounding the ferromagnetic core, and a tuning circuit coupled to the tuning winding.

An eLORAN receiver may include an antenna and eLORAN receiver circuitry coupled to the antenna. The antenna may include a ferromagnetic core and an H-field signal winding coupled to the ferromagnetic core. The eLORAN receiver may have an antenna tuning device including a tuning winding surrounding the ferromagnetic core, and a tuning circuit coupled to the tuning winding.

A communications device may include an RF device having an operating frequency range, and an antenna coupled to the RF device and being electrically small with respect to the operating frequency range of the RF device. The communications device may include an active capacitor coupled between the RF device and the antenna. The active capacitor may include a settable operating curve with a decreasing capacitance versus increasing frequency over a portion of the operating frequency range of the RF device. The communications device may further include a control circuit coupled to the active capacitor to set the settable operating curve.

It is disclosed an antenna array comprising a number of radiating elements and a supporting elongated flat printed circuit board (PCB) having a substrate and two opposite faces. Each radiating element is attached to the PCB; each radiating element is dipole-like and has a respective axis of symmetry; the axes of symmetry are aligned along a direction parallel to a longitudinal axis of the PCB and lie on a longitudinal plane parallel to a longitudinal center plane of the PCB and located between the opposite faces; the PCB comprises at least one conductive trace on one of the faces, the conductive trace acting as a ground plane; and for each radiating element, the PCB carries a respective feeding line to provide a feeding signal to the radiating element at a feed point located on the PCB and substantially belonging to the axis of symmetry.

It is disclosed an antenna array comprising a number of radiating elements and a supporting elongated flat printed circuit board (PCB) having a substrate and two opposite faces. Each radiating element is attached to the PCB; each radiating element is dipole-like and has a respective axis of symmetry; the axes of symmetry are aligned along a direction parallel to a longitudinal axis of the PCB and lie on a longitudinal plane parallel to a longitudinal center plane of the PCB and located between the opposite faces; the PCB comprises at least one conductive trace on one of the faces, the conductive trace acting as a ground plane; and for each radiating element, the PCB carries a respective feeding line to provide a feeding signal to the radiating element at a feed point located on the PCB and substantially belonging to the axis of symmetry.

An active biconical antenna and a receive array comprising a combination of active biconical and Vivaldi antennas. In one configuration, the active biconical antenna includes upper and lower cones. Each cone has a respective truncated apex. First and second feed points are respectively connected to the truncated apexes of the upper and lower cones and to first and second conductors. The active biconical antenna further includes a buffer amplifier having respective input terminals connected to the first and second conductors. The buffer amplifier has an input impedance that is impedance matched to an antenna impedance at and above but not below a frequency f.sub.c and is higher than the antenna impedance at frequencies substantially less than f.sub.c. The buffer amplifier also has an output impedance that is impedance matched to a system impedance at frequencies both above and below f.sub.c. A length of the first and second conductors is less than a wavelength at the frequency f.sub.c.

A semiconductor element comprising: an antenna array that is provided with a plurality of antennas each including a semiconductor layer having an electromagnetic wave gain or carrier nonlinearity with respect to a terahertz wave; and a coupling line that synchronizes adjacent antennas in the antenna array with each other at a frequency of the terahertz wave, wherein the coupling line includes a plurality of first regions connected to the adjacent antennas respectively and a second region provided between the plurality of first regions, wherein the second region has impedance different from impedance of each of the first regions, and wherein the second region has a loss larger than a loss of the individual first region at a frequency other than a resonance frequency of the antenna array.

A semiconductor element comprising: an antenna array that is provided with a plurality of antennas each including a semiconductor layer having an electromagnetic wave gain or carrier nonlinearity with respect to a terahertz wave; and a coupling line that synchronizes adjacent antennas in the antenna array with each other at a frequency of the terahertz wave, wherein the coupling line includes a plurality of first regions connected to the adjacent antennas respectively and a second region provided between the plurality of first regions, wherein the second region has impedance different from impedance of each of the first regions, and wherein the second region has a loss larger than a loss of the individual first region at a frequency other than a resonance frequency of the antenna array.