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: 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 bracket (12) is fixed to the rear surface of a reflector (2). The bracket has a planar plate (14) which, when the bracket is fixed to the reflector, is perpendicular to a polarity axis (16). Plural, spaced-apart arcuate slots (20) arranged on an imaginary circle on the planar plate (14) about the polarity axis (16) are formed in the planar plate (14). An adapter plate (24) is disposed in contact with the surface of the planar plate (14) facing the reflector (2). The bracket (12) is rotatable about the polarity axis (16) relative to the adapter plate (24). The adapter plate (24) has screw holes (26) in alignment with the arcuate slots (20) in the planar plate (14). A bracket (28) is disposed on the side of the planar plate (14) opposite to the reflector (2). The bracket (28) has a pair of wings (30, 32). A connecting member (34) is formed integral with the wings (30, 32). The connecting member (34) is perpendicular to the wings (30, 32).

Abstract: An antenna system includes a VHF dipole antenna having a pair of rod elements disposed substantially in a line, and a UHF Yagi antenna having a radiator and a director disposed on the rod elements.

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: An antenna system includes a VHF dipole antenna having a pair of rod elements disposed substantially in a line, and a UHF Yagi antenna having a radiator and a direction disposed on the rod elements.