Abstract: The antenna architectures disclosed herein may include a magnetic dipole antenna that includes a radiating element formed in an open loop that includes at least first and second portions that are positioned opposite each other. The magnetic dipole antenna may further include an electrically conductive via connecting the first and second opposing portions of the radiating element. The magnetic dipole antenna may further include an antenna feed disposed within the electrically conductive via. The first portion of the radiating element may be shorter in length than the second, opposite portion of the radiating element, and the difference in length between the first and second portions of the radiating element may form a capacitive gap across the radiating element. Various other systems, apparatuses, wearable electronic devices, and methods of manufacturing are also disclosed.

Abstract: The invention relates to a cable for electrically linking electronic assemblies, components or peripherals of a magnetic resonance apparatus by means of a symmetrical shielded cable which shields a plurality of conductors for a useful signal with respect to influences of an electromagnetic alternating field by means of at least one shielding device. In order to suppress sheath waves, a shielding device comprises at at least one point an interruption which is bridged by an active resistance or a reactance.

Abstract: Provided is a loop antenna array that can easily create a magnetic field distribution which enables the boundary of a communication area to be clearly set. 2n loop antennae are provided adjacently to one another, where n is a natural number. The directions of currents in adjacent ones of the loop antennae are opposite to each other. For example, in a loop antenna array, two loop antennae are disposed adjacently to each other on an insulator substrate. First feed points energize one loop antenna and second feed points energize the other loop antenna.

Abstract: Disclosed herein, among other things, are methods and apparatus for mitigating antenna interference for hearing assistance devices. One aspect of the present subject matter includes a hearing aid for a wearer including hearing aid electronics and an antenna including a loop segment. According to various embodiments, one or more conductors are connected in parallel with a portion of the loop segment. The conductors electrically short the loop segment to change current distribution in the antenna. The conductors reduce unwanted coupling between the hearing aid electronics and the antenna, according to various embodiments.

Abstract: An antenna includes a base, and first and second supports coupled to the base and extending perpendicular therefrom. The first and second supports oppose one another and are spaced apart from one another. The antenna also includes a plurality of plates spaced apart and parallel to one another. Each plate is T-shaped to have a trunk and a top wherein a width of the trunk is less than a width of the top. Each trunk is coupled to one of the first support and second support, and extends perpendicular thereto wherein a corresponding top of the plate is spaced from an opposing one of the first support and second support to thereby generate a gap region that serpentines between the first support and second support and around the top of each of the plates.

Abstract: The present disclosure is directed towards direction finding (DF) systems that can detect and locals a radio frequency (RF) signal (e.g. an emergency beacon) is two dimensions (i.e., azimuth and elevation). In one embodiment, a DF system comprises an array of multipolarized loop antennas coupled to a beamformer which provides monopole, dipole, and loop antenna element modal signals. The DF system may also comprise a multi-channel digital receiver system coupled to the beamformer. The multi-channel digital receiver system is configured to receive modal signals provided thereto from the beamformer which can be used for accurate two-dimensional geolocation of RF signals including, but not limited to, location of RF emergency beacon sources.

Abstract: The present application provides an antenna system for use in an electronic device. The antenna system includes a conductive substrate. The antenna system further includes a conductive element, which extends along a length between two ends a distance away from the conductive substrate. An area between the conductive substrate and the conductive element form at least part of a loop which is internal to the antenna system. The antenna system still further includes a differential signal source coupled between two points along the length of the conductive element. Each of the two points are proximate a respective one of the two ends of the conductive element. The differential signal source is coupled to each of the two points via a high frequency blocking circuit. Further yet, the antenna system includes an alternative signal source coupled to the conductive element between the two ends of the conductive element toward a center of the conductive element via a low frequency blocking circuit.

Abstract: An antenna device is provided. The antenna device includes contact terminals including a first contact terminal and a second contact terminal, sub-coil antennas each including at least one loop, and a switch configured to selectively connect sub-coil antennas to the first contact terminal and the second contact terminal according to a control signal input through the first contact terminal and the second contact terminal.

Abstract: A radiating system transmits and receives in first and second frequency regions and includes a radiating structure comprising first and second radiation boosters having maximum sizes smaller than 1/30 times the free-space wavelength of the lowest frequencies of the first and second frequency regions, respectively. The radiating system further includes a radiofrequency system having first and second ports respectively connected to first and second internal ports of the radiating structure, and a third port connected to an external port of the radiating system.

Abstract: A detecting device which detects electromagnetic waves includes an antennal configured to receive electromagnetic waves, and a plurality of semiconductor rectifying devices serially connected to the antenna, and connected in parallel to each other such that the polarity is aligned, so as to receive electromagnetic waves propagated from the antenna, wherein the plurality of semiconductor rectifying devices are each disposed at positions where the phase of electromagnetic waves propagated from the antenna is substantially the same phase.

Abstract: An antenna device in a wireless communication includes antenna wires of four sides which include three feeding points and have a loop structure and four main switches which are located among the antenna wires of the four sides, wherein the antenna device operates as a loop antenna when the antenna wires of the four sides are connected according to operations of the main switches and wherein the antenna device operates as dipole antennas when the antenna wires of the four sides are disconnected according to operations of the main switches.

Abstract: An antenna for receiving circularly polarized satellite radio signals has a conductive base surface and at least one a conductor loop oriented horizontally above the base surface by a height h. The conductor loop is configured as a polygonal or circular closed ring line radiator. The ring line radiator forms a resonant structure that is electrically excited so that the current distribution of a running line wave in a single rotation direction occurs on the ring line, wherein the phase difference of which, over one revolution, amounts to essentially 2?. A vertical radiator extends between the conductive base surface and the circumference of the ring line radiator. The height h is smaller than ? of the free-space wavelength ?.

Abstract: An antenna for receiving circularly polarized satellite radio signals has a conductive base surface and at least one a conductor loop oriented horizontally above the base surface by a height h. The conductor loop is configured as a polygonal or circular closed ring line radiator. The ring line radiator forms a resonant structure that is electrically excited so that the current distribution of a running line wave in a single rotation direction occurs on the ring line, wherein the phase difference of which, over one revolution, amounts to essentially 2?. A vertical radiator extends between the conductive base surface and the circumference of the ring line radiator. The height h is smaller than ? of the free-space wavelength ?.

Abstract: A structure for wireless communication having a plurality of conductor layers, an insulator layer separating each of the conductor layers, and at least one connector connecting two of the conductor layers wherein an electrical resistance is reduced when an electrical signal is induced in the resonator at a predetermined frequency.

Abstract: A magnetic field focusing assembly includes a magnetic field generating device configured to generate a magnetic field, and a split ring resonator assembly configured to be magnetically coupled to the magnetic field generating device and configured to focus the magnetic field produced by the magnetic field generating device.

Abstract: Electronic devices may be provided with antenna structures such as distributed loop antenna resonating element structures. A distributed loop antenna may be formed on an elongated dielectric carrier and may have a longitudinal axis. The distributed loop antenna may include a loop antenna resonating element formed from a sheet of conductive material that extends around the longitudinal axis. A gap may be formed in the sheet of conductive material. The gap may be located under an opaque masking layer on the underside of a display cover glass associated with a display. The loop antenna resonating element may have a main body portion that includes the gap and may have an extended tail portion that extends between the display and conductive housing structures. The main body portion and extended tail portion may be configured to ensure that undesired waveguide modes are cut off during operation of the loop antenna.

Abstract: A low profile antenna using a cavity-backed central radiating surface surrounded by one or more ground plane surfaces. Passively reconfigurable structure provide frequency dependent coupling between the surfaces. The frequency dependent couplings may be implemented using meander line structures, Variable Impedance Transmission Lines (VITLs), or tunable VITLs that used interspersed electroactive sections.

Abstract: A near field communications (NFC) device is disclosed that interacts with other NFC devices to exchange information and/or the data. An operator may touch, or be sufficiently proximate to, an antenna module of the NFC device to operate and/or control the NFC device. The antenna module includes antenna components that are characterized by a corresponding characteristic impedance. The touch, or sufficient proximity, of the operator changes the corresponding characteristic impedance of antenna components. The NFC device may determine a location of the touch, or proximity, of the operator based upon this change. The NFC device may interpret the location of the touch, or proximity, of the operator as information from the operator to operate and/or control the NFC device.

Abstract: An antenna device that radiates or receives a radio wave includes: a first wire line; a second wire line that is parallel to the first wire line; a power feeding/receiving point that is provided at proximal portions of the first wire line and second wire line; and a terminal resistance that is provided at distal end portions of the first wire line and second wire line.

Abstract: An antenna device includes: a plurality of loop metal wires that form loops out of metal wires and that are radially arranged around a center line; a power feeding portion that feeds power to the loop metal wires or a power receiving portion that receives power from the loop metal wires and that is provided on the center line; and a variable impedance element that is inserted in each of the loop metal wires.

Abstract: An antenna for receiving circularly polarized satellite radio signals has a conductive base surface and at least one a conductor loop oriented horizontally above the base surface by a height h. The conductor loop is configured as a polygonal or circular closed ring line radiator. The ring line radiator forms a resonant structure that is electrically excited so that the current distribution of a running line wave in a single rotation direction occurs on the ring line, wherein the phase difference of which, over one revolution, amounts to essentially 2?. A vertical radiator extends between the conductive base surface and the circumference of the ring line radiator. The height h is smaller than ? of the free-space wavelength ?.

Abstract: An antenna apparatus and a radio communication apparatus are capable of separately controlling a resonance frequency in a basic mode and a resonance frequency in a higher mode and have a wide bandwidth in which the resonance frequency in the basic mode is variable. The antenna apparatus includes a feeding electrode 2, a loop-shaped radiation electrode 3, a capacitance portion 4, and inductors 5 and 6. The capacitance portion 4 is formed by a gap between an open end 3a of the loop-shaped radiation electrode 3 and the feeding electrode 2. The inductor 5 is disposed at a position where a large current is obtained in the basic mode and a small current is obtained in the higher mode. The inductor 6 is disposed at a position where a large current is obtained in the higher mode and a small current is obtained in the basic mode.

Abstract: An antenna for receiving circularly polarized satellite radio signals has a conductive base surface and at least one a conductor loop oriented horizontally above the base surface by a height h. The conductor loop is configured as a polygonal or circular closed ring line radiator The ring line radiator forms a resonant structure that is electrically excited so that the current distribution of a running line wave in a single rotation direction occurs on the ring line, wherein the phase difference of which, over one revolution, amounts to essentially 2?. A vertical radiator extends between the conductive base surface and the circumference of the ring line radiator. The height h is smaller than ? of the free-space wavelength ?.

Abstract: First, second and third feed ports interface to an antenna that has an impedance disposed between its ends which are defined by the first and second feed ports. The third feed port interfaces to the antenna at an intermediate point between the ends. In a first mode (balanced mode) the impedance enables signals to/from the first and second feed ports to resonate along the whole of the antenna, and in a second mode the impedance enables signals to/from the third feed port to resonate along a portion of the antenna, the portion terminating at the impedance. In embodiments, the first mode is for RFID signals and the second mode is for any one or more of Bluetooth/WLAN/GPS/FM signals. The first and second mode may operate simultaneously. Also detailed is a method for making an electronic device having such an antenna.

Abstract: Apparatus including: an antenna configured for efficient far field communication at a first frequency; an inductive element including a plurality of series-connected coiled portions, including a first coiled portion and a second coiled portion, wherein the inductive element is configured to provide near field communication at a second frequency; and at least one reactive element parallel connected between the first coiled portion and the second coiled portion, wherein the at least one reactive element has a lower impedance at the first frequency than at the second frequency.

Abstract: The present receive antenna interface for an RF (radio frequency) transceiver includes a transmitting and receiving antenna. The receive antenna interface also includes a relay and an electrically-isolated transmit-ground connector that are configured such that the receiving antenna is not capable of being used by the transceiver unless the transmit-ground connector is connected to a ground-on-transmit connector provided by the transceiver. As a result, damage from the accidental transmission of RF signals into the receiving circuitry of the transceiver is prevented.

Abstract: A magnetic and/or magneto-electric antenna that has a plurality of conducting loops where each individual loop can be resonated at a frequency that is offset from the frequency of the other loops to provide a composite band-pass response that is broader than that of the individual loops. A receiving circuit acts to sum the signals from each of the antennas to provide a combined frequency response that is broader in bandwidth than any of the individual loops. Similarly a combination of multiple transmitter loops where a transmit circuit drives a common transmit waveform to each of the combined antennas to provide a combined transmitter frequency response that is broader in bandwidth than any of the individual loops.

Abstract: A loop antenna may include first and second electrical conductors arranged to define a circular shape with first and second spaced apart gaps therein. Opposing portions of the first and second electrical conductors at the first gap may define a signal feedpoint, and opposing portions of the first and second electrical conductors at the second gap may define an impedance tuning feature. The second gap may be circumferentially spaced from the first gap less than ninety degrees, and the second gap may be greater than the first gap to provide a predetermined impedance. A coaxial transmission line may form a feed inset into the loop conductor. The loop antenna may be planar and have a reduced size for ease of manufacture and use, and it may provide an isotropic radiating pattern at a predetermined operating frequency, which may avoid the need for antenna aiming.

Abstract: The present invention relates to a self-contained counterpoise compound field antenna. Improvements relate particularly, but not exclusively, to compound loop antennas having coplanar electric field radiators and magnetic loops with electric fields orthogonal to magnetic fields that achieve performance benefits in higher bandwidth (lower Q), greater radiation intensity/power/gain, and greater efficiency. Embodiments of the self-contained antenna include a transition formed on the magnetic loop and having a transition width greater than the width of the magnetic loop. The transition substantially isolates a counterpoise formed on the magnetic loop opposite or adjacent the electric field radiator.

Abstract: An antenna apparatus is disclosed that includes a feeding portion; a looped antenna element connected to the feeding portion; and a resistor inserted into the looped antenna element.

Abstract: An RFID antenna comprising an elongated structure existing along an axis that is long compared to the signal wavelength and including twin ribbon-like feed lines of electrically conductive material, the feed lines being in a common plane and being uniformly laterally spaced from one another, and a plurality of radiating perturbations associated with the feed lines at a plurality of locations spaced along the feed lines, at each location each feed line has its own individual perturbation or portion of a perturbation.

Abstract: An electromagnetic reactive edge treatment including an array of capacitively-loaded loops is disposed at or near an edge of a conductive wedge. The axes of the loops are oriented parallel to the edge of the wedge. This edge treatment may enhance or suppress the hard diffraction coefficient, depending on the resonant frequency fo of the array of loaded loops. Diffraction of incident waves that are lower (higher) in frequency than fo may be enhanced (suppressed) due to the increase (decrease) in effective permeability of the volume occupied by the array of loops. Applications include controlling antenna patterns, side lobe levels, and backlobe levels for antennas mounted on conductive surfaces near edges or corners.

Abstract: An antenna receiving circularly polarized satellite radio signals has a conductive base surface and a conductor loop oriented horizontally above the base. The loop is configured as a ring line radiator, incorporating a polygonal or circular closed ring line, in a horizontal plane above the conductive base surface. The conductor loop is electromagnetically excited by a device including an antenna connector. The ring line radiator forms a resonance structure that is electromagnetically excited, whereby the current distribution of a running line wave in a single rotation direction occurs on the ring line. At least one vertical radiator extends toward the conductive base surface and is disposed on the ring line radiator, wherein the vertical radiator is electromagnetically coupled both with the ring line radiator and the electrically conductive base surface, to support the vertically oriented component of the electromagnetic field.

Abstract: A planar antenna device (AD) for a TV receiver (R) comprises i) a loop antenna (LA) comprising first (E1) and second (E2) ends spaced one from the other, ii) a tuning means (TM) connected to the first (E1) and second (E2) ends of the loop antenna (LA) and arranged to control the frequency of the VHF TV signals this loop antenna (LA) is able to receive from command signals, iii) a first ground plane (GP1) cooperating with the loop antenna (LA) in order to act as a UHF monopole in receiving TV signals with UHF frequencies, iv) a first coupling means (CM1) coupled to the loop antenna (LA) at a first chosen location and arranged to deliver the received VHF signals, v) a second coupling means (CM2) coupled to the loop antenna (LA) at a second chosen location and arranged to deliver the received UHF signals, vi) an amplification means (AM) coupled to the first ground plane (GP1) and arranged to amplify TV signals, and vii) a switching means (SM) arranged to couple the amplification means (AM) to the first coupling

Abstract: The present invention is concerned with a transmitting/receiving antenna, which includes a dielectric board, a driven loop antenna provided to the dielectric board, transmit processing portion connection terminals connected to the driven loop antenna, a transmitting/receiving loop antenna arranged in close vicinity to the driven loop antenna in a non-contact state, a resonance capacitor connected to both ends of the transmitting/receiving loop antenna, and receive processing portion connection terminals connected to the transmitting/receiving loop antenna. The driven loop antenna is constructed to have a loop wound in a single turn, and the transmitting/receiving loop antenna is constructed to have a loop wound in plural turns. According to this configuration, a wider frequency band of the frequency characteristic and a reduction of the power consumption can be achieved.

Abstract: A tag device that performs high-quality radio communication without radio wave radiation or receiving characteristics being deteriorated near a person's body and without hindering communication by another IC tag. A main loop section sends and receives radio waves. The main loop section is a metal foil and has the shape of a long thin loop. The area of the main loop section is smaller than the area of a dielectric substrate. The main loop section covers part of surfaces of the dielectric substrate and part of sides of the dielectric substrate so as to put the dielectric substrate inside the loop. The main loop section is mounted in a horizontal direction of the dielectric substrate. Each of capacitive load sections is a metal foil and has a load corresponding to a capacitance component.

Abstract: An easy-to-fabricate and relatively strong circularly polarized loop antenna of a simple construction is built. A circularly polarized loop antenna 1 has a loop section 11, which is made up of a loop-shaped conductor whose length is equal to 1 wavelength (?) of the transmitted and received signals, and a coupling section 12, made up of a conductor, is connected thereto at a prescribed point. The coupling section 12 is shaped such that it is connected to the loop section 11 at a connection point 201 at one end and extends along the loop section 11 throughout a length equal to ?/4. A reflective plate 2 is placed in a predetermined position in the vertical direction from the circumferential plane of the loop section 11, in parallel to the circumferential plane. In addition, the other end of the loop section 11 is connected to external circuitry carrying out the processing of signals transmitted and received via a first feed conductor 13 and a second feed conductor 14 and operates as a feed point, 200.

Abstract: A broadband antenna is capable of generating an upper resonant mode (at about 700 MHz) from a first radiating arm and a lower resonant mode (at about 500 MHz) from a second radiating arm. The first and second radiating arms are bent at least one time. An open end of the second radiating arm is extended toward an open end of the first radiating arm with a predefined distance there between. The predefined distance can be adjusted to improve the impedance matching of lower resonant mode, which can be further combined with the upper resonant mode to achieve a broad bandwidth covering the complete spectrum of digital TV channels (470-862 MHz).

Abstract: A planar antenna device (AD) for a TV receiver (R) comprises i) a loop antenna (LA) comprising first (E1) and second (E2) ends spaced one from the other, ii) a tuning means (TM) connected to the first (E1) and second (E2) ends of the loop antenna (LA) and arranged to control the frequency of the VHF TV signals this loop antenna (LA) is able to receive from command signals, iii) a first ground plane (GP1) cooperating with the loop antenna (LA) in order to act as a UHF monopole in receiving TV signals with UHF frequencies, iv) a first coupling means (CM1) coupled to the loop antenna (LA) at a first chosen location and arranged to deliver the received VHF signals, v) a second coupling means (CM2) coupled to the loop antenna (LA) at a second chosen location and arranged to deliver the received UHF signals, vi) an amplification means (AM) coupled to the first ground plane (GP1) and arranged to amplify TV signals, and vii) a switching means (SM) arranged to couple the amplification means (AM) to the first coupling

Abstract: An antenna coil formed on a substrate surface of an insulating substrate has conductor lines forming four sides of a basic loop shape. Furthermore, the antenna coil has corner lines at a corner portion of the loop. For example, by forming trimming lines on the inner side of one of the corner lines, it becomes possible to adjust the resonant frequency in various ways without considerably disturbing the shape of distribution of magnetic flux density generated by the antenna coil as a whole.

Abstract: A headset has a first and an optional second earpiece 12, 16 respectively coupled to a plug 30 via first and an optional second conductors 14, 20, 18, 22. An antenna loop section 36 has a first loop section 31 at least partially bound to a portion of the first conductor 20, and a second loop section 33 bound to at least a portion of the second conductor 22. Where bound, the first conductor and first loop section may be coaxial or side-by-side. The loop sections include inductors 42,44, and the conductors include ferrite rings 38,40 near the earpieces. A connector 24 mechanically holds the first and second conductors in proximity to one another, and also includes a conductive bridge 34 to electrically couple the first and second loop segments, which may be via a contact connection or a capacitive connection. Audio and RF signals are separated by frequency in a device 50 to which the headset is coupled.

Abstract: Described is the transformation of a mono-band antenna into a or multi-band antenna by adding matching circuits, in either serial or parallel fashion, to a mono-band antenna. The matching circuits contain reactive elements such as inductors and capacitors which create impedance matching for two or more frequency bands. These multi-band loop antennas can be used for frequencies extending from a few megahertz to several hundred megahertz. The method of tuning such multi-band antennas is also described.

Abstract: An antenna device includes a rectangular parallelepiped base member made of a dielectric or magnetic material, a band-shaped first radiation conductor, including a plurality of divided first radiation conductor portions, spirally wound around the base member, a plurality of variable capacitance elements connected between pairs of adjacent portions and disposed on a upper surface of the base member, and a feeding conductor for supplying a tuning voltage to the variable capacitance elements. The first radiation conductor has first radiation conductor parts respectively formed on upper, lower, and rear side surfaces of the base member and first connecting through-holes passing through the upper and lower surfaces are provided in the base member, and the first radiation conductor part on the upper surface and the first radiation conductor part on the lower surface are connected to each another by the first through-holes, and the feeding conductor is disposed on the front surface of the base member.

Abstract: An antenna device includes a prism-shaped or plate-shaped base member made of a dielectric or magnetic material, band-shaped first and second radiation conductors wound around the base member and connected to each other, and a third radiation conductor wound around the base member and connected to the second radiation conductor. The first and second radiation conductors include a plurality of divided portions, and the divided first radiation conductor portions are connected in series by first variable capacitance elements, the divided second radiation conductor portions are connected in series by second variable capacitance elements, and a node between the first and second radiation conductors is used as a feeding end.

Abstract: An energy density diversity antenna (EDA) has a least a pair of antenna elements, whose feeding points are connected to outputs of a hybrid coupler configured such that a sum and a difference signal may exist at the feed points of the antenna elements. First reactive elements are respectively inserted in the antenna elements proximal the respective feed points. The antenna elements are joined at a point distal from the feed points by a second reactive element, and a third reactive element is coupled between feed lines coupled to the feed points at a location between the feed points and the outputs of the hybrid coupler.

Abstract: There are disposed first coupling conductors, which comprise a pair of coupling branch lines 1 and 2 connected to the first antenna conductor 3 and extend inward from the first antenna conductor. The coupling branch lines 1 and 2 have open ends 1a and 2a disposed so as to be adjacent to each other and be capacitively coupled to each other. The open ends 1a and 2a of the coupling branch lines 1 and 2 are located at closest or substantially closest portions to each other. The second antenna conductor 13 includes second coupling conductors, which comprise a pair of coupling branch lines 11 and 12 connected the second antenna conductor 13 and extending inward from the second antenna conductor. The coupling branch lines 11 and 12 have open ends disposed so as to be adjacent to each other and be capacitively coupled to each other. The open ends of the coupling branch lines 11 and 12 are located at closest or substantially closest portions to each other.

Abstract: An antenna system comprising a plurality of antennas designed and oriented to provide one or more of radiation pattern, signal polarization and spatial diversity. The various diversity operational characteristics are achieved by using similar antennas physically oriented to provide the diversity attributes or by using dissimilar antennas, that is, antennas having different radiation pattern and/or signal polarization characteristics.

Abstract: The present invention provides an antenna device capable of automatically obtaining excellent receiving sensitivity over a wide band. The antenna device comprises a rod-shaped base made of a dielectric material or a magnetic material; a stripe-shape radiating conductor divided into a plurality of radiating conductors wound around the base; and variable capacitive elements provided to correnspond to the same number of the radiating conductors. The radiating conductors and the variable capacitive elements are alternatively arranged on the base and are connected in series to each other, the radiating conductor having its one end connected to the variable capacitive element serves as an opening side and the variable capacitive element having its one end connected to the radiating conductor serves as a signal feeding side, and capacitance values of the variable capacitive elements increase or decrease in the same direction to be tuned to a predetermined frequency.

Abstract: An antenna includes a radiating ring element formed as a spherical sector or about a one-half wavelength circumference in natural resonance for obtaining uniform current distribution and enhancing the gain relative to the size of the antenna. A capacitive element, such as a gap, can be formed therein for forcing the radiating ring element to resonance. A variometer feeds the radiating ring element and is operative for varying feed impedance.

Abstract: An antenna device of transmission line type having two antenna elements opposed to each other, and a signal is fed between the two antenna elements. A variable-capacitance unit capable of changing the electrostatic capacity is provided at one or both of connection points at which opposite ends of the two antenna elements are connected to each other. Each variable-capacitance unit has a variable-capacitance diode, the electrostatic capacity of which changes according to a direct-current voltage applied between the anode and the cathode.