The combined antenna for satellite and terrestrial radio communications includes: a support structure (1); a crossed dipole compact broadband satellite antenna (10), in turn including a pair of dipoles (11,12), which extend from the support structure (1), and which are substantially perpendicular to each other and connected so as to be electrically out of phase. A broadband monopole antenna (50) for terrestrial communications is included, having a plurality of linear electric mass elements (52) extending radially from the support structure (1) to provide an electric mass surface (53), and a radiating arm (55), is also included extending from the support structure (1) away from the electric mass surface (53). The radiating arm (55) is arranged around the central column (2) and includes thread-like radiating elements (56); and the dipoles (11,12) further include one or more thread-like dipole elements (111,112), arranged to define a flattened configuration of the respective dipole (11,12).

The combined antenna for satellite and terrestrial radio communications includes: a support structure (1); a crossed dipole compact broadband satellite antenna (10), in turn including a pair of dipoles (11,12), which extend from the support structure (1), and which are substantially perpendicular to each other and connected so as to be electrically out of phase. A broadband monopole antenna (50) for terrestrial communications is included, having a plurality of linear electric mass elements (52) extending radially from the support structure (1) to provide an electric mass surface (53), and a radiating arm (55), is also included extending from the support structure (1) away from the electric mass surface (53). The radiating arm (55) is arranged around the central column (2) and includes thread-like radiating elements (56); and the dipoles (11,12) further include one or more thread-like dipole elements (111,112), arranged to define a flattened configuration of the respective dipole (11,12).

A printed board including an external interface, a frame ground trace electrically connected to the external interface, a circuit member spaced from the frame ground trace, and a resonance trace disposed between the frame ground trace and the circuit member with a gap present between the resonance trace and the frame ground trace. The resonance trace is connected to the circuit member at at least two positions. The resonance trace and the circuit member together form a loop member configured in the form of a closed circuit of the resonance trace and the circuit member.

A cognitive HF radio is disclosed having a cognitive engine that optimizes HF transmission parameters on the basis of learned experience with previous transmission under varying transmission and environmental conditions. Additionally, electrically small HF antennas optionally using non-Foster matching elements are disclosed. Furthermore, another electrically small HF antenna and associated impedance matching networks are disclosed, including an impedance matching network using non-Foster matching elements.

A cognitive HF radio is disclosed having a cognitive engine that optimizes HF transmission parameters on the basis of learned experience with previous transmission under varying transmission and environmental conditions. Additionally, electrically small HF antennas optionally using non-Foster matching elements are disclosed. Furthermore, another electrically small HF antenna and associated impedance matching networks are disclosed, including an impedance matching network using non-Foster matching elements.

An antenna may include a tower extending vertically upward from a ground location, a first set of elongate antenna elements extending outwardly from the tower at a first height above the ground location, and a second set of elongate antenna elements extending outwardly from the tower at a second height above the ground location and below the first height. In some embodiments, at least one elongate antenna element of the first and second sets of elongate antenna elements may be electrically coupled to the ground location. A radio frequency (RF) feed may be electrically coupled to the first and second sets of elongate antenna elements.

A helicoidal, mixed polarization mono-conical antenna has: a supporting structure (2) with a longitudinal axis (2a); ground conductors (3) connected to an area around a first portion (4) of the supporting structure (2) defining a ground plane (21) of the antenna (1) orthogonal to the axis (2a); at least three signal conductors (7), which have respective first ends (8) that are connected to a second portion (5) of the supporting structure (2) and respective second ends (10) that are connected to a third portion (6) of the supporting structure (2) located between the first portion (4) and the second portion (5) along the axis (2a), the conductors wound in a helicoidal manner relative to the axis (2a) and shaped so as to define a substantially frusto-conical volume (12) which is coaxial to the axis (2a) and is oriented with a smaller base towards the first portion (4).

A helicoidal, mixed polarization mono-conical antenna has: a supporting structure (2) with a longitudinal axis (2a); ground conductors (3) connected to an area around a first portion (4) of the supporting structure (2) defining a ground plane (21) of the antenna (1) orthogonal to the axis (2a); at least three signal conductors (7), which have respective first ends (8) that are connected to a second portion (5) of the supporting structure (2) and respective second ends (10) that are connected to a third portion (6) of the supporting structure (2) located between the first portion (4) and the second portion (5) along the axis (2a), the conductors wound in a helicoidal manner relative to the axis (2a) and shaped so as to define a substantially frusto-conical volume (12) which is coaxial to the axis (2a) and is oriented with a smaller base towards the first portion (4).

An antenna may include a tower extending vertically upward from a ground location, a first set of elongate antenna elements extending outwardly from the tower at a first height above the ground location, and a second set of elongate antenna elements extending outwardly from the tower at a second height above the ground location and below the first height. In some embodiments, at least one elongate antenna element of the first and second sets of elongate antenna elements may be electrically coupled to the ground location. A radio frequency (RF) feed may be electrically coupled to the first and second sets of elongate antenna elements.

An antenna comprising: a radio frequency (RF) coupler; a transceiver communicatively coupled to the RF coupler; a laser configured to generate a plurality of femtosecond laser pulses so as to create, without the use of high voltage electrodes, a laser-induced plasma filament (LIPF) in atmospheric air, wherein the laser is operatively coupled to the RF coupler such that RF energy is transferred between the LIPF and the RF coupler; and wherein the laser is configured to modulate a characteristic of the laser pulses at a rate within the range of 1 Hz to 1 GHz so as to modulate a conduction efficiency of the LIPF thereby creating a variable impedance LIPF antenna.