Antenna structure

• US 6,252,554 B1
• Filed: 06/07/2000
• Issued: 06/26/2001
• Est. Priority Date: 06/14/1999
• Status: Expired due to Fees

• Current Assignee: Pulse Finland Oy (Yageo Corporation)
• Original Assignee: Pulse Finland Oy (Yageo Corporation)
• Inventors: Mikkola, Jyrki, Tarvas, Suvi, Isohätälä, Anne
• Primary Examiner(s): Le, Hoanganh
• Assistant Examiner(s): VANNUCCI, JAMES
• Application Number:
  US09/589,309
• Time in Patent Office: 384 Days
• Field of Search: 343/700.MS, 343/702, 455/90
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/244 extendable from a housing along a given path
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 5/40 Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0442 with particular tuning means
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence

Abstract

The invention relates to dual mode antennas particularly suitable for mobile stations. The antenna structure comprises an antenna (211, 201, 202, 212) of the PIFA type which is located within the covers of the mobile station, and a whip element (220) which is movable relating to the PIFA antenna. The PIFA can be a single band or a dual band antenna. When the whip element is extracted its lower end (222) forms a galvanic or capacitive coupling with the radiating element (211) of the PIFA. If the PIFA is a single band antenna the extracted whip element substantially changes the resonant frequency of the PIFA, so that the whip is left as the radiating element at the operating band. If the PIFA is a dual band antenna, then an extracted whip alone, or the whip and the planar element of the PIFA together, functions as the radiating element at one operating band, and at the other operating band the planar element of the PIFA operates as the radiating element. The feeding and the matching of the whip element is arranged by the PIFA without any separate additional components. With the aid of the invention the best properties of both the PIFA and the monopole antenna can be utilised. The structure is further reliable and it has relatively low costs.

Claims

1. An antenna structure of a radio device comprising:

a frames;

a stationary part with reference to said frame; and

a movable part, with reference to said frame, said movable part being locatable substantially within a cover of the device during operation of the device,

said stationary part including a ground plane (201;

301;

401;

501) and a radiating planar element (211;

311;

411;

511), said ground plane and radiating planar element being located within the cover of the device; and

said movable part including a radiating whip element (220;

320;

420;

520),

wherein when said radiating whip element is in an extended position, said radiating whip element is coupled with said planar element, and said coupling provides an electromagnetic feed to said whip antenna.

2. The structure according to claim 1, wherein said coupling is galvanic.

3. The structure according to claim 2, wherein:

said planar element (211;

311;

511) includes a non-conductive gap for obtaining a desired resonant frequency; and

said galvanic coupling spans said gap to change a resonant frequency of the planar element.

4. The structure according to claim 2, wherein a first end of said whip element includes at least a first and a second contact spring (625, 627) connected to said first end of said whip element, and

wherein when said whip element is in an extended position, said first end is located between a stationary dielectric support body (650) of the structure and said planar element (211), and wherein

said first contact spring (625) contacts said dielectric support body and the second contact spring (627) contacts said plane element in order to form a galvanic coupling.

5. The structure according to claim 4, wherein said contact springs (727) are arcuate and located at substantially even intervals on a barrel-like surface at equal distances from the axis of the whip element (720).

6. The structure according to claim 1, wherein said planar element (511) includes a conductive projection (515) toward the ground plane (501) said projection matching the feeding impedance of the whip element (520).

7. An antenna structure according to any of claims 1-6, wherein said stationary part forms an antenna of the PIFA type.