Multiple frequency band antenna and signal receiving system using such antenna
First Claim
1. A multiple frequency band antenna comprising:
- a dipole antenna arranged on a straight line; and
at least two extension elements extending outward of respective ones of opposing outer ends of said dipole antenna along said straight line;
wherein;
the length of said dipole antenna is determined to enable the multiple frequency band antenna to receive radio waves in a first frequency band, and the sum of the lengths of said dipole antenna and said two extension elements is determined to enable the multiple frequency band antenna to receive radio waves in a second frequency band lower than said first frequency band;
said multiple frequency band antenna further comprises;
first and second switch devices connected between respective ones of said two extension elements and associated ones of said outer ends of said dipole antennas; and
control means operating, when a radio wave in said first frequency band is to be received, to selectively place said first and second switch devices in a first state in which said first and second switch devices are opened, a second state in which said first switch device is closed and said second switch device is opened, and a third state in which said first switch is opened and said second switch device is closed.
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Accused Products
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). When a radio wave in the UHF band is to be received, a control unit (180) places the diodes (28a, 34a) selectively in a state in which both are opened, a state in which one of the diodes (28a) is closed while the other (34a) is opened, and a state in which the one diode (28a) is opened while the other (34a) is closed.
79 Citations
12 Claims
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1. A multiple frequency band antenna comprising:
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a dipole antenna arranged on a straight line; and at least two extension elements extending outward of respective ones of opposing outer ends of said dipole antenna along said straight line;
wherein;the length of said dipole antenna is determined to enable the multiple frequency band antenna to receive radio waves in a first frequency band, and the sum of the lengths of said dipole antenna and said two extension elements is determined to enable the multiple frequency band antenna to receive radio waves in a second frequency band lower than said first frequency band; said multiple frequency band antenna further comprises; first and second switch devices connected between respective ones of said two extension elements and associated ones of said outer ends of said dipole antennas; and control means operating, when a radio wave in said first frequency band is to be received, to selectively place said first and second switch devices in a first state in which said first and second switch devices are opened, a second state in which said first switch device is closed and said second switch device is opened, and a third state in which said first switch is opened and said second switch device is closed. - View Dependent Claims (2, 3)
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4. A multiple frequency band antenna comprising:
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first and second dipole antennas disposed in parallel with each other, being spaced from each other by a distance equal to or smaller than a quarter of a wavelength in a first frequency band; a group of extension elements including at least two first extension elements extending outward of respective ones of opposed outer ends of said first dipole antenna element along a first straight line, and at least two second extension elements extending outward of respective ones of opposed outer ends of said second dipole antenna element along a second straight line, the sum of the lengths of said first dipole antenna and said first extension elements and the sum of the lengths of said second dipole antenna and said second extension elements being so determined as to enable said multiple frequency band antenna to receive radio waves in a second frequency band lower than said first frequency band; a group of switch devices including first and second switch devices connected between the respective ones of said first extension elements and the respective ones of said outer ends of said first dipole antenna, and third and fourth switch devices connected between the respective ones of said second extension elements and the respective ones of said outer ends of said second dipole antenna, said third and fourth switch devices being disposed at locations corresponding to the respective locations where said first and second switch devices are disposed; control means operating, when said multiple frequency band antenna is to receive a radio wave in said first frequency band, to place said first, second, third and fourth switch devices selectively in a first state in which said first, second, third and fourth switch devices are opened, a second state in which said first and third switch devices are closed and said second and fourth switch devices are opened, and a third state in which said first and third switch devices are opened and said second and fourth switch devices are closed; combining means connected to said first and second dipole antennas; and phase shift means connected between said first and second dipole antennas and said combining means, said phase shift means being switchable between; a first signal coupling state in which signals resulting from a radio wave coming to said multiple frequency band antenna from a first direction substantially perpendicular to said first and second dipole antennas, as received by said first and second dipole antenna elements, are coupled to said combining means substantially in phase with each other, and signals resulting from a radio wave coming to said multiple frequency band antenna from a second direction opposite to said first direction, as received by said first and second dipole antenna elements, are coupled to said combining means substantially in 180°
out of phase with each other, anda second signal coupling state in which signals resulting from a radio wave coming from said first direction as received by said first and second dipole antennas are coupled to said combining means substantially in 180°
out of phase with each other, and signals resulting from a radio wave coming from said second direction as received by said first and second dipole antennas are coupled to said combining means substantially in phase with each other. - View Dependent Claims (5)
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6. A multiple frequency band antenna including an antenna group including orthogonally disposed first and second antennas, each of said first and second antennas comprising:
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first and second dipole antennas disposed in parallel with each other, being spaced from each other by a distance equal to or smaller than a quarter of a wavelength in a first frequency band; a group of extension elements including at least two first extension elements extending outward of respective ones of opposed outer ends of said first dipole antenna element along a straight line, and at least two second extension elements extending outward of respective ones of opposed outer ends of said second dipole antenna element along a straight line, the sum of the lengths of said first dipole antenna and said first extension elements and the sum of the lengths of said second dipole antenna and said second extension elements being so determined as to enable said multiple frequency band antenna to receive radio waves in a second frequency band lower than said first frequency band; a group of switch devices including first and second switch devices connected between the respective ones of said first extension elements and the respective ones of said outer ends of said first dipole antenna, and third and fourth switch devices connected between the respective ones of said second extension elements and the respective ones of said outer ends of said second dipole antenna, said third and fourth switch devices being disposed at locations corresponding to the respective locations where said first and second switch devices are disposed; first combining means connected to said first and second dipole antennas; phase shift means connected between said first and second dipole antennas and said first combining means, said phase shift means being switchable between; and a first signal coupling state in which signals resulting from a radio wave coming to said multiple frequency band antenna from a first direction perpendicular to said first and second dipole antennas, as received by said first and second dipole antenna elements, are coupled to said first combining means substantially in phase with each other, and signals resulting from a radio wave coming to said multiple frequency band antenna from a second direction opposite to said first direction, as received by said first and second dipole antenna elements, are coupled to said first combining means substantially in 180°
out of phase with each other, anda second signal coupling state in which signals resulting from a radio wave coming from said first direction as received by said first and second dipole antennas are coupled to said first combining means substantially in 180°
out of phase with each other, and signals resulting from a radio wave coming from said second direction as received by said first and second dipole antennas are coupled to said first combining means substantially in phase with each other;said multiple frequency band antenna further comprising; first and second level adjusting means for adjusting the levels of the signals from said first and second antennas, respectively; second combining means for combining output signals of said first and second level adjusting means; and control means for controlling said first, second, third and fourth switch devices of each of said first and second antennas, said phase shift means of each of said first and second antennas, and said first and second level adjusting means in such a manner that said multiple frequency band antenna can receive a radio wave in said first or second frequency band from a desired direction. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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Specification