Abstract: A variable directivity antenna apparatus (1) includes an output terminal (40) at which reception signals transmitted through a coaxial cable (42) are outputted. The directivity pattern of the antenna apparatus (1) is varied in response to a directivity control signal supplied to the output terminal (40) through the coaxial cable (42). The variable directivity antenna apparatus (1) further includes changeover switches (8, 12, 14, 22, 32, 34, 38) operated to fix the orientation of directivity in a predetermined direction in response to the coupling of a power supply adapter (64).

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 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: First, second, third and fourth dipole antennas (14, 16, 18, 20) are disposed in a casing (1). The first through fourth dipole antennas are arranged in the same plane, and are disposed in line symmetry with respect to first through fourth imaginary lines (A, B, C, D) passing through the center of the casing (1) at an angle of 45 degrees between adjacent imaginary lines.

Abstract: First, second, third and fourth dipole antennas (14, 16, 18, 20) are disposed in a casing (1). The first through fourth dipole antennas are arranged in the same plane, and are disposed in line symmetry with respect to first through fourth imaginary lines (A, B, C, D) passing through the center of the casing (1) at an angle of 45 degrees between adjacent imaginary lines.

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: An antenna device (2a) includes first and second dipole antennas (4a, 6a) spaced from each other by a distance smaller than a quarter of a received wavelength. An antenna device (2b) includes third and fourth dipole antennas (4a, 6a) spaced from each other by the distance and is disposed orthogonal to the antenna device (2a). A first phase adjusting circuit (104a) combines signals from the first and second antennas (4a, 6a) after adjusting their phases, in such a manner that the resultant combined signal selectively assumes a forward directivity state exhibiting a forward directivity and a backward directivity state exhibiting a backward directivity. Similarly, a second phase adjusting circuit (104b) combines signals from the third and fourth antennas (4b, 6b) after adjusting their phases, in such a manner that the resultant combined signal selectively assumes a rightward directivity state exhibiting a rightward directivity and a leftward directivity state exhibiting a leftward directivity.

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: 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).