Abstract: A radiator includes two dipole elements as plate-shaped conductors. The radiator further includes two conductive line portions provided on opposite sides of a prescribed axis, sandwiching both of the two dipole elements, each having one end connected to one dipole element and the other end connected to the other dipole element. The two conductive line portions are formed to conform to the shapes of the dipole elements. As the conductive line portions having such shapes are connected to the dipole elements, better characteristics can be attained over wide frequency range and the size can be made smaller than the conventional radiator. Thus, an antenna having smaller size and improved characteristics can be provided.

Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a half of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).

Abstract: A transmission line includes transmission lines parallel and perpendicular, respectively, to a flat portion of a reflector, and the parallel transmission line and the flat portion form a first strip line and the perpendicular transmission line and a conductive plate similarly form a second strip line. Radiators and the transmission line have a radiation impedance and a characteristic impedance, respectively, both set at 150? when the antenna's output terminal has a reference impedance of 75?. If the parallel transmission line has a midpoint serving as the output terminal of the antenna this portion's receiving current is divided in two so that an impedance of half that of the strip line can be provided and a coaxial cable can directly be connected to the transmission line. A matcher or a mixer is not included in the antenna, and matching and mixing losses can be prevented.

Abstract: A radiator includes two dipole elements as plate-shaped conductors. The radiator further includes two conductive line portions provided on opposite sides of a prescribed axis, sandwiching both of the two dipole elements, each having one end connected to one dipole element and the other end connected to the other dipole element. The two conductive line portions are formed to conform to the shapes of the dipole elements. As the conductive line portions having such shapes are connected to the dipole elements, better characteristics can be attained over wide frequency range and the size can be made smaller than the conventional radiator. Thus, an antenna having smaller size and improved characteristics can be provided.

Abstract: A signal receiving system includes a variable directivity antenna having its directivity varied in accordance with a control signal applied thereto. A control signal generator generating the control signal is provided in a receiving apparatus. The receiving apparatus includes also a modulator operating to ASK (amplitude-shift-keying) modulate a carrier with the control signal from the control signal generator into an ASK modulated signal. The ASK modulated signal is applied through a transmission line to the variable directivity antenna, and a controller associated with the variable directivity antenna demodulates the ASK modulated signal to recover the control signal for use in varying the directivity of the variable directivity antenna.

Abstract: A transmission line includes transmission lines parallel and perpendicular, respectively, to a flat portion of a reflector, and the parallel transmission line and the flat portion form a first strip line and the perpendicular transmission line and a conductive plate similarly form a second strip line. Radiators and the transmission line have a radiation impedance and a characteristic impedance, respectively, both set at 150 ? when the antenna's output terminal has a reference impedance of 75 ?. If the parallel transmission line has a midpoint serving as the output terminal of the antenna this portion's receiving current is divided in two so that an impedance of half that of the strip line can be provided and a coaxial cable can directly be connected to the transmission line. A matcher or a mixer is not included in the antenna, and matching and mixing losses can be prevented.

Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a half of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).

Abstract: A multiple frequency band antenna includes a dipole antenna (4a), which is formed of two dipole antenna elements (8a, 10a). Two extension elements (24a, 26a) extend outward from respective ones of opposed outer ends of the dipole antenna (4a). The length of the dipole antenna (4a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the UHF band, and the sum of the lengths of the dipole antenna (4a) and the extension elements (24a, 26a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the VHF band. PIN diodes (28a, 34a) are connected between the respective extension elements (24a, 26a) and the respective outer ends of the dipole antenna (4a).

Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a quarter of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).

Abstract: A multiple frequency band antenna includes a dipole antenna (4a), which is formed of two dipole antenna elements (8a, 10a). Two extension elements (24a, 26a) extend outward from respective ones of opposed outer ends of the dipole antenna (4a). The length of the dipole antenna (4a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the UHF band, and the sum of the lengths of the dipole antenna (4a) and the extension elements (24a, 26a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the VHF band. PIN diodes (28a, 34a) are connected between the respective extension elements (24a, 26a) and the respective outer ends of the dipole antenna (4a).

Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a quarter of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).

Abstract: A signal receiving system includes a variable directivity antenna having its directivity varied in accordance with a control signal applied thereto. A control signal generator generating the control signal is provided in a receiving apparatus. The receiving apparatus includes also a modulator operating to ASK (amplitude-shift-keying) modulate a carrier with the control signal from the control signal generator into an ASK modulated signal. The ASK modulated signal is applied through a transmission line to the variable directivity antenna, and a controller associated with the variable directivity antenna demodulates the ASK modulated signal to recover the control signal for use in varying the directivity of the variable directivity antenna.

Abstract: Antennas (8a-8d) are disposed within an antenna body (2) of an antenna system in such a manner as to receive UHF band radio waves coming to the main body (2) from a plurality of first, different directions around the main body (2). Combinations of the antennas (8a-8d) makes the antenna system possible to receive UHF band radio waves coming to the main body (2) from a plurality of second, different directions between adjacent ones of the first directions. Switches (26a-26d) disposed within the main body (2) select one of outputs provided by the individual antennas (8a-8d) and their combinations. An antenna controller (64a), a unit separate from the main body (2), supplies a selection control signal to the switches (26a-26d).

Abstract: Antennas (8a-8d) are disposed within an antenna body (2) of an antenna system in such a manner as to receive UHF band radio waves coming to the main body (2) from a plurality of first, different directions around the main body (2). Combinations of the antennas (8a-8d) makes the antenna system possible to receive UHF band radio waves coming to the main body (2) from a plurality of second, different directions between adjacent ones of the first directions. Switches (26a-26d) disposed within the main body (2) select one of outputs provided by the individual antennas (8a-8d) and their combinations. An antenna controller (64a), a unit separate from the main body (2), supplies a selection control signal to the switches (26a-26d).