Antenna system for radio signals in at least two spaced-apart frequency bands
First Claim
1. An antenna system for radio signals in at least two spaced-apart frequency bands comprising:
- an antenna having an elongate dielectric core with a relative dielectric constant greater than 5, at least one pair of elongate conductive elements located in a longitudinally coextensive and laterally opposed relationship on or adjacent an outer surface of a distal part of the core, a conductive sleeve surrounding a proximal part of the core, and a longitudinal feeder structure extending through the core, said elongate conductive elements extending between distal connections to the feeder structure and a distal rim of the sleeve, wherein the antenna is resonant in a first mode of resonance at an upper frequency lying in one of said two frequency bands and in a second mode of resonance at a lower frequency lying in the other of said two frequency bands; and
an impedance matching diplexer which has filters coupled between a common port connected to a proximal end of the feeder structure and respective further ports for connection to radio signal processing equipment operating in the two frequency bands, the filters comprising a first filter tuned to the upper frequency, and a second filter tuned to the lower frequency.
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Accused Products
Abstract
In an antenna system for radio signals in at least two spaced-apart frequency bands above 200 MHz, a quadrifilar helical antenna having an elongate dielectric core with a relative dielectric constant greater than 5 has a conductive sleeve surrounding a proximal part of the core and a longitudinal feeder structure extending through the core to a connection with the helical antenna elements at a distal end of the core. The antenna is operated in an upper frequency band in which it exhibits a first mode of resonance characterized by current maxima at the connections of the helical elements to the feeder structure and at their junctions with the rim of the sleeve, and in a lower frequency band in which the antenna exhibits a second mode of resonance characterized by current minima in the region of the junctions of the helical elements and the sleeve rim. To permit dual mode operation, the antenna system includes an impedance-matching diplexer having filters coupled between a common port for the antenna and further ports for connection to radio signal processing equipment such as a GPS receiver and a mobile telephone operating in the two frequency bands. In the preferred embodiment, the filters and impedance matching elements are formed as microstrip elements on a single substrate.
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Citations
39 Claims
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1. An antenna system for radio signals in at least two spaced-apart frequency bands comprising:
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an antenna having an elongate dielectric core with a relative dielectric constant greater than 5, at least one pair of elongate conductive elements located in a longitudinally coextensive and laterally opposed relationship on or adjacent an outer surface of a distal part of the core, a conductive sleeve surrounding a proximal part of the core, and a longitudinal feeder structure extending through the core, said elongate conductive elements extending between distal connections to the feeder structure and a distal rim of the sleeve, wherein the antenna is resonant in a first mode of resonance at an upper frequency lying in one of said two frequency bands and in a second mode of resonance at a lower frequency lying in the other of said two frequency bands; and an impedance matching diplexer which has filters coupled between a common port connected to a proximal end of the feeder structure and respective further ports for connection to radio signal processing equipment operating in the two frequency bands, the filters comprising a first filter tuned to the upper frequency, and a second filter tuned to the lower frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An antenna comprising:
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an elongate core with a relative dielectric constant greater than 5; at least one pair of elongate conductive elements located in a longitudinally coextensive and laterally opposed relationship on or adjacent an outer surface of a distal part of the core; a conductive sleeve surrounding a proximal part of the core; and a longitudinal feeder structure extending through the core, said elongate conductive elements extending between distal connections to the feeder structure and a distal rim of the sleeve, wherein the elongate conductive elements are adapted such that the antenna operates in at least two spaced apart frequency bands, one of the bands containing a first frequency at which the antenna exhibits a first mode of resonance and which corresponds substantially to the frequency of signals transmitted in a satellite positioning service, and another of the bands containing a second frequency at which the antenna exhibits a second mode of resonance which is different from the first mode, the frequency of the second resonance corresponding substantially to a frequency used for mobile telephone signals. - View Dependent Claims (13, 14, 15)
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16. An antenna system for radio signals in at least two spaced-apart frequency bands comprising:
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an antenna having a solid elongate dielectric core, at least one elongate conductive element on or adjacent an outer surface of a distal part of the core, a conductive sleeve surrounding a proximal part of the core, and a longitudinal feeder structure extending through the core, wherein the said elongate conductive element extends between a distal connection to the feeder structure and a distal rim of the sleeve, and the sleeve is proximally coupled to the feeder structure; and
wherein the antenna is resonant in a first mode of resonance at an upper frequency lying in one of said two frequency bands and in a second mode of resonance at a lower frequency lying in the other of said two frequency bands; anda coupling stage having a common signal line associated with the feeder structure, at least two further signal lines for connection to radio signal processing equipment operating in the said frequency bands and, connected between the feeder structure and the further signal lines, an impedance matching section and a signal directing section, wherein the signal directing section is arranged to couple together the common signal line and one of the two further signal lines for signals which lie in one of said frequency bands, and to couple together the common signal line and the other of the two further signal lines for signals which lie in the other of said frequency bands. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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- 34. A radio communication apparatus comprising an antenna and, connected to the antenna, radio communication circuit means operable in at least two radio frequency bands, wherein the antenna comprises an elongate dielectric core, a feeder structure which passes through the core substantially from one end to the other end of the core, and, located on or adjacent the outer surface of the core, the series combination of at least one elongate conductive antenna element and a conductive trap element which has a grounding connection to the feeder structure in the region of the said one end of the core, the or each antenna element being coupled to a feed connection of the feeder structure in the region of the said other end of the core, and wherein the radio communication circuit means have two parts operable respectively in a first and a second of the radio frequency bands and each associated with respective signal lines for conveying signals between the antenna feeder structure and the respective circuit means part, the antenna being resonant in a first resonance mode in the first frequency band and in a second resonance mode in the second frequency band.
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39. An antenna comprising:
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an elongate core with a relative dielectric constant greater than 5; at least one pair of elongate conductive elements located in a longitudinally coextensive and laterally opposed relationship on or adjacent an outer surface of a distal part of the core; a conductive sleeve surrounding a proximal part of the core;
a longitudinal feeder structure extending through the core, said elongate conductive elements extending between distal connections to the feeder structure and a distal rim of the sleeve;wherein the elongate conductive elements are adapted such that the antenna operates in at least two spaced apart frequency bands, one of the bands containing a first frequency at which the antenna exhibits a first mode of resonance, said first frequency being 1.575 GHz, and another of the bands containing a second frequency at which the antenna exhibits a second mode of resonance which is different from the first mode, said second frequency being in the band of from 800 to 900 MHz.
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Specification