EP0522806A2
Expired / Lapsed
EP
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Retractable antenna system
Assignee: NTT Docomo Inc
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Filing: 1992-07-03
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Granted: —
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Expires: 2012-07-03
Abstract
Abstract An antenna element (1) has a linear antenna rod (1b) of predetermined length and a top load (1a) at the end of the rod (1b). The antenna element (1) takes a first position in which the rod is extracted out of a housing (8), and a second position in which the rod is retracted within the housing. There are provided two feed terminals (5, 6) along the rod (1b). The first feed terminal (5) is essentially matching the impedance of a node point in current distribution in the resonant antenna element, and feeds the antenna element at the end of the rod in the first position. The second feed terminal (5) is matching the impedance of an anti-node point in current distribution in the resonant antenna element, and feeds the antenna element at approximate center of the rod in the second position. A first feed terminal (5) might contact the rod in a second position, but it does not feed the same because of mismatching. Thus, the antenna system is always fed with matched condition whether it is extracted or retracted, through the automatic switching of feed terminals.
Inventors
- 👤 Koichi Tsunekawa
- 👤 Atsuya Ando
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 21:49
CPC Classifications
H; H01; H01Q; H01Q1/00; H01Q1/12; H01Q1/22; H01Q1/24; H01Q1/241; H01Q1/242; H01Q1/243; H01Q1/244
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
82 words
A retractable antenna system for a portable transceiver, the system comprising a housing (8) for holding an inner circuit (7); impedance matching means connected, in use, to the inner circuit; a retractable antenna (1), movable between extended and retracted positions; and connection means to enable the antenna to be connected to the impedance matching means in each of its extended and retracted positions such that in both positions the impedance of the antenna is matched with the impedance of the inner circuit.
Claim 2
Dependent Claim
37 words
A system according to claim 1, wherein the antenna comprises a substantially linear antenna element (1,13) having an electrical length substantially equal to an integer multiple of a half wavelength of an operating frequency of the transceiver.
Claim 3
Dependent Claim
69 words
A system according to claim 1 or claim 2, the system further comprising a feed line (4) connected with an output of the inner circuit (7) and the connection means comprising first and second connectors (5,6) positioned in the housing (8) along the path of movement of the antenna element so that the first connector is located closer to an outlet (8a) of the housing than a second connector.
Claim 4
Dependent Claim
37 words
A system according to claim 3, wherein the impedance matching means comprises first and second matching circuits (2,3) mounted in the housing (8) connected between the feed line (4) and the first and second connectors (5,6) respectively.
Claim 5
Dependent Claim
72 words
A system according to claim 4, wherein the first connector (5) is connected with the first matching circuit (3), the impedance of which is substantially equal to the impedance of a current node point on the resonant antenna element; and the second connector (6) is connected with the second matching circuit (2), the impedance of which is substantially equal to the impedance of a current anti-node point on the resonant antenna element.
Claim 6
Dependent Claim
58 words
A system according to claim 4 or claim 5, wherein the first connector (5) and matching circuit (3) are connected to the inner circuit (7) when the antenna element is in its extended position, and the second connector (6) and matching circuit (2) are connected to the inner circuit when the antenna element is in its retracted position.
Claim 7
Independent Claim
46 words
A system according to any preceding claim, wherein the antenna element (1) has an elongated antenna rod (1b), and a top load (1a) at an extreme end of the antenna rod, and the top load locates outside the housing (8) when the antenna element is retracted.
Claim 8
Dependent Claim
29 words
A system according to claim 7, wherein the top load (1a) is a coil (1a-1) with its axis substantially coincident with the longitudinal direction of the antenna rod (1b).
Claim 9
Dependent Claim
25 words
A system according to claim 7, wherein the top load is a flat conductive plate (1a-2) mounted at the extreme end of the antenna rod(1b).
Claim 10
Dependent Claim
39 words
A system according to claim 7, wherein the top load (1a) has two coils (A,B) connected in series with eachother so that a junction (J) of the coils is connected to the extreme end of the antenna rod (1b).
Claim 11
Independent Claim
85 words
A system according to any of claims 5 to 10, wherein the second matching circuit comprises a conductive linear means (15) extending from a negative terminal of the second connector (6); the antenna rod (1b) and the conductive linear element forming a balanced pair cable with an electrical length of approximately a quarter wavelength of the operating frequency of the transceiver; and a third connector (14) connected to the conductive linear means and grounded, which contacts the antenna rod when the antenna rod is retracted.
Claim 12
Dependent Claim
31 words
A system according to claim 11, wherein the conductive linear means (15) is a hollow cylindrical tube, and the antenna rod (1b) and the hollow tube operate as a coaxial cable.
Claim 13
Independent Claim
48 words
A system according to any preceding claim, wherein the antenna rod (1b) has a chip (5a,6a) for engaging with the connector (5,6), and the chip and the connector have a concave surface and a convex surface for engagement with eachother in a snap fix of the antenna rod.
Claim 14
Dependent Claim
23 words
A portable transceiver including a retractable antenna system according to any of the preceding claims connected to an inner circuit of the transceiver.
References Cited (Backward Citations)
No citation records indexed.
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