Abstract: An antenna apparatus includes: an extension conductor connected to a first section of an outer perimeter of an antenna element and along an entire length of the first section; connecting conductors connecting the antenna element to a ground conductor between the extension conductor and feed points on the antenna element; and a slit extending from the extension conductor to the antenna element so as to intersect a portion between connecting points of the connecting conductors and to intersect a portion between the feed points on the antenna element. The slit has a short-circuited end on the extension conductor.

Abstract: A transmitting signal from a signal generator is divided in seven transmitting signals in a divider, and the phase and the amplitude of each of divided transmitting signals are changed in a phase shifter circuit and an attenuator circuit. The respective transmitting signals from the attenuator circuit are radiated from scatterer antennas. A receiver receives a multiple wave of radiated radio waves by using a receiving antenna. A computer substantially simultaneously starts operations of a D/A converter, the signal generator, and the receiver by using a trigger generator circuit.

Abstract: An antenna apparatus includes a slit provided on an antenna element between first and second feed ports; and a series resonant circuit provided at a location along the slit, with a distance from an opening of the slit. When the antenna apparatus operates at a first isolation frequency identical to a resonance frequency of the series resonant circuit, the series resonant circuit is short-circuited, and only a section of the slit from its opening to the series resonant circuit resonates, thus providing isolation between the feed ports at the first isolation frequency. When the antenna apparatus operates at a second isolation frequency lower than the first isolation frequency, the series resonant circuit is open, and the entire slit resonates, thus providing isolation between the feed ports at the second isolation frequency.

Abstract: An antenna apparatus includes a first feeding point and a second feeding point provided at respective positions on an antenna element. The antenna element is excited through the first and second feeding points simultaneously so as to operate as a first antenna portion and a second antenna portion simultaneously, the first antenna portion and the second antenna portion correspond to the first and second feeding points, respectively. The antenna element further includes, between the first and second feeding points, an electromagnetic coupling adjuster for making an amount of isolation between the first and second antenna portions.

Abstract: An antenna element has a slit including a first portion and a second portion, the first portion extending in a first direction so as to separate first and second feed points from each other, and the second portion extending in a second direction different from the first direction. The slit is configured to resonate at an isolation frequency to produce isolation between the first and second feed points, and configured to form a current path around the slit. A current distribution along the current path generated by exciting through the first feed point is different from a current distribution along the current path generated by exciting through the second feed point, thus providing different radiation characteristics by the different current distributions.

Abstract: An antenna evaluation apparatus includes receiving antennas to be evaluated, scatterer antennas provided around them, signal generators, delay circuits, dividers, phase-shift circuits, and attenuation circuits. A computer controls the delay circuits to add delay times to radio frequency signals, and controls the phase-shift circuits and attenuation circuits to change phases and amplitudes of the radio frequency signals to produce a first fading. The antenna evaluation apparatus radiates the radio frequency signals from the scatterer antennas, thus creating multipath waves including delay and fading around the receiving antenna.

Abstract: A computer measures amplitudes and phases respective received signals S60a relative to a transmitting signal when radio waves are radiated solely from each of the scatterer antennas and received by using a calibration receiving antenna, determines a target amplitude based on measured amplitudes, and determines a target phase based on measured phases. Reference attenuation amount control voltages for respective attenuators are set to attenuation amount control voltages for making the measured amplitudes coincidence with an identical target amplitude, and a reference phase shift amount control voltage for each phase shifter is set to phase shift amount control voltages for making the measured phases coincidence with an identical target phase.

Abstract: An antenna element has first and second feed ports, and is simultaneously excited through the feed ports so as to simultaneously operate as first and second antenna portions respectively, associated with the feed ports. The antenna element is excited at one of a first frequency and a second frequency higher than the first frequency. An antenna apparatus is provided with: a slit that provides isolation between the feed ports; a trap circuit that allows the slit to provide isolation at the first or second frequency when the antenna element is excited at the first or second frequency; and a reactance element that shifts a frequency at which the slit provides isolation between the feed ports, to the first frequency, when the antenna element is excited at the first frequency.

Abstract: An antenna evaluation apparatus includes receiving antennas to be evaluated, scatterer antennas surrounding the receiving antennas, a signal generator, a divider, a phase-shift circuit, and a computer. The computer generates first and second initial phase vectors each corresponding to a different set of multipath waves, determines a third initial phase vector including arbitrary initial phases each between a pair of corresponding initial phases in the first and second initial phase vectors, adjusts the phases of the radio frequency signals using the phase-shift circuit such that the phases of the radio frequency signals have corresponding initial phases in the third initial phase vector, and makes the adjusted radio frequency signals radiate.

Abstract: An array antenna apparatus includes a first antenna element resonating at a first frequency and a second antenna element resonating at the first frequency, and includes a first connecting line that connects the first connection point located in the first antenna element with a third connection point located in the second antenna element, and a second connecting line that connects the second connection point located in the first antenna element with a fourth connection point located in the second antenna element. Electrical lengths of the first and second antenna elements and those of the first and second connecting lines are set so that a phase difference, between first and second high-frequency signals respectively propagating through first and second signal paths, becomes substantially 180 degrees at the first feeding point, and then, the array antenna apparatus resonances at the first frequency and the second frequency.

Abstract: An antenna apparatus is provided with two feed ports respectively provided at positions on an antenna element, and the antenna element is simultaneously excited through the two feed ports so as to simultaneously operate as two antenna portions respectively associated with the two feed ports. The antenna apparatus is further provided with a slit provided between the two feed ports, for changing a resonant frequency of the antenna element and producing isolation between the feed ports at a isolation frequency, and provided with matching means for shifting an operating frequency of the antenna element from the changed resonant frequency to the isolation frequency.

Abstract: An antenna apparatus includes: an extension conductor connected to a section of an outer perimeter of an antenna element and along an entire length of the section; and a slit extending from the antenna element to the extension conductor so as to intersect a portion between feed points on the antenna element. The slit has an open end on the extension conductor.

Abstract: An antenna apparatus includes: an extension conductor connected to a first section of an outer perimeter of an antenna element and along an entire length of the first section; connecting conductors connecting the antenna element to a ground conductor between the extension conductor and feed points on the antenna element; and a slit extending from the extension conductor to the antenna element so as to intersect a portion between connecting points of the connecting conductors and to intersect a portion between the feed points on the antenna element. The slit has a short-circuited end on the extension conductor.

Abstract: When first and second housings are in an open state, first and second switches are electrically opened, and thus, a first antenna element and a ground conductor operate as a first dipole antenna, and a second antenna element and the ground conductor operate as a second dipole antenna with isolation from the first dipole antenna by the slit. When the first and second housings are in the closed state, the first and second switches are electrically closed, and thus, the first antenna element operates as a first inverted F antenna on the ground conductor, and the second antenna element operates as a second inverted F antenna on the ground conductor with isolation from the first inverted F antenna by the slit.

Abstract: A MIMO antenna apparatus is provided with: an upper housing having slits; first feed points through which the upper housing itself is excited as first antennas; second feed points through which the slits are excited as second antennas; switch, each of which is connected to one of the first feed points and one of the second feed points, and connects one of the two feed points to an A/D converter circuit-; a signal level detector circuit detecting signal levels of received radio signals; and a controller that controls the switches to change a feed point connected to the A/D converter circuit, when the detected signal level is less than or equal to a predetermined threshold value. The slits are located between the first antennas.

Abstract: An antenna element has a slit including a first portion and a second portion, the first portion extending in a first direction so as to separate first and second feed points from each other, and the second portion extending in a second direction different from the first direction. The slit is configured to resonate at an isolation frequency to produce isolation between the first and second feed points, and configured to form a current path around the slit. A current distribution along the current path generated by exciting through the first feed point is different from a current distribution along the current path generated by exciting through the second feed point, thus providing different radiation characteristics by the different current distributions.

Abstract: An antenna element has first and second feed ports, and is simultaneously excited through the feed ports so as to simultaneously operate as first and second antenna portions respectively, associated with the feed ports. The antenna element is excited at one of a first frequency and a second frequency higher than the first frequency. An antenna apparatus is provided with: a slit that provides isolation between the feed ports; a trap circuit that allows the slit to provide isolation at the first or second frequency when the antenna element is excited at the first or second frequency; and a reactance element that shifts a frequency at which the slit provides isolation between the feed ports, to the first frequency, when the antenna element is excited at the first frequency.

Abstract: An antenna apparatus includes a slit provided on an antenna element between first and second feed ports; and a series resonant circuit provided at a location along the slit, with a distance from an opening of the slit. When the antenna apparatus operates at a first isolation frequency identical to a resonance frequency of the series resonant circuit, the series resonant circuit is short-circuited, and only a section of the slit from its opening to the series resonant circuit resonates, thus providing isolation between the feed ports at the first isolation frequency. When the antenna apparatus operates at a second isolation frequency lower than the first isolation frequency, the series resonant circuit is open, and the entire slit resonates, thus providing isolation between the feed ports at the second isolation frequency.

Abstract: A computer measures amplitudes and phases respective received signals S60a relative to a transmitting signal when radio waves are radiated solely from each of the scatterer antennas and received by using a calibration receiving antenna, determines a target amplitude based on measured amplitudes, and determines a target phase based on measured phases. Reference attenuation amount control voltages for respective attenuators are set to attenuation amount control voltages for making the measured amplitudes coincidence with an identical target amplitude, and a reference phase shift amount control voltage for each phase shifter is set to phase shift amount control voltages for making the measured phases coincidence with an identical target phase.

Abstract: A transmitting signal from a signal generator is divided in seven transmitting signals in a divider, and the phase and the amplitude of each of divided transmitting signals are changed in a phase shifter circuit and an attenuator circuit. The respective transmitting signals from the attenuator circuit are radiated from scatterer antennas. A receiver receives a multiple wave of radiated radio waves by using a receiving antenna. A computer substantially simultaneously starts operations of a D/A converter, the signal generator, and the receiver by using a trigger generator circuit.