An antenna device includes an antenna base having a longitudinal direction, a first antenna element on the antenna base, and a pair of second antenna elements on the antenna base, the pair of second antenna elements being capable of transmitting and receiving radio waves in a higher frequency band than the first antenna element. In a planar view, when the antenna base is divided into four regions by a first line segment along the longitudinal direction and a second line segment orthogonal to the first line segment intersecting each other at the center point of the first antenna element, a region where one of the pair of second antenna elements is located is not adjacent to a region where the other of the pair of second antenna elements is located.

A spiral antenna, comprising a first arm and a second arm. The first arm and second arm are interlaced with each other. Each arm has a plurality of turns comprising an inner subset of circular turns, and an outer subset of turns, electrically coupled to the inner subset, having a shape with only four lines of symmetry. An array of such spiral antennas disposed a substrate that extends in a direction of a longitudinal axis and having a round cross section in a plan transverse to the longitudinal axis.

A multi-resonant, electrically-small antenna having a first helical arm and a second helical arm. The first helical arm encircles a first central axis and includes a proximal end. A radius between the first helical arm and the first central axis decreases in a distal direction away from the proximal end of the first helical arm. The second helical arm is nested in the first helical arm and encircles a second central axis. The second helical arm also includes a proximal end. A radius between the second helical arm and the second central axis decreases in a distal direction away from the proximal end of the second helical arm.

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).

Aspects of the subject disclosure may include, for example, a launching device including a transmitter configured to generate a radio frequency signal in a microwave frequency band. A helical antenna is configured to launch the radio frequency signal as a guided electromagnetic wave that is bound to an outer surface of a transmission medium, wherein the guided electromagnetic wave propagates along the outer surface of the transmission medium without an electrical return path. Other embodiments are disclosed.

A quadrifilar helical antenna includes a conical supporting medium, a feed network, and four sets of antenna composite elements. Each set of antenna composite element includes at least one short-circuit helical arm and at least one open-circuit helical arm. The short-circuit helical arm and the open-circuit helical arm in each set of antenna composite element are sequentially wound on an outer wall of the conical supporting medium in one winding direction. In an axial direction of the conical supporting medium, a projection length of the short-circuit helical arm is greater than that of the open-circuit helical arm in each set of antenna composite element. The four sets of antenna composite elements are respectively coupled to a feeding point of the feed network for feeding, and the short-circuit helical arms in the four sets of antenna composite elements are in short-circuit connection. The antenna provided by embodiments of the present disclosure can efficiently improve the gain and gain bandwidth of the antenna under the condition that total occupation space is limited.

An antenna system comprises a transmission member and an antenna at a distal end of the transmission member. The antenna includes a first conductive arm, an insulator extending around the first conductive arm, and a second conductive arm wound around at least a first portion of the insulator to form a second conductive arm coil. A property of the insulator varies along an insulator longitudinal axis of the insulator.

A radio frequency (RF) communications system may include a local RF communications device and an RF antenna coupled to the local RF communications device. The RF antenna may include a cavity backing housing, a conical RF launch structure having an apex positioned within the cavity backing housing, and an elongate electrical conductor having a proximal end extending through the apex of the conical RF launch structure and a distal end spaced apart from the conical RF launch structure to define an elongate RF coverage pattern. The system may further include at least one remote RF communications device within the elongate RF coverage pattern to wirelessly communicate with the local RF communications device.

An antenna system comprises a substrate, an antenna positioned on the substrate, and a circuit component positioned on the substrate. The antenna is positioned on a first surface of the substrate and operable to emit a radiation pattern. The circuit component is positioned on the substrate in a null region of the radiation pattern. The thickness of portions of the substrate are modified to achieve a desired performance characteristic of the antenna.

A demultiplexer/multiplexer includes an input terminal, which receives input signals from respective phases of a quadrifilar helix antenna; phase shifter/separator/mixers, which alternately phase-shift right-handed and left-handed circularly polarized waves of the input signals, respectively, by 90/90 to produce phase-shifted waves to be combined in an inphase combination; phase shifter/mixers, which receive the left-handed or right-handed circularly polarized waves from the phase shifter/separator/mixers, and phase-shift one of the left-handed and right-handed circularly polarized waves by 180/180 to produce a phase-shifted wave to be combined with the other of the left-handed and right-handed circularly polarized waves in an antiphase combination; a variable phase shifter, which adjusts an output signal from the phase shifter/mixers by a phase-shift amount that is received in advance; and an output terminal, which outputs an output signal from the variable phase shifter and the other output signal that is not input to the variable phase shifter.