Planar antenna structure and radio device

• US 7,501,983 B2
• Filed: 01/07/2004
• Issued: 03/10/2009
• Est. Priority Date: 01/15/2003
• Status: Active Grant

• Current Assignee: Cantor Fitzgerald Securities (Cantor Fitzgerald, L.P.)
• Original Assignee: Pulse Finland Oy (Yageo Corporation)
• Inventors: Mikkola, Jyrki
• Primary Examiner(s): Wong; Don
• Assistant Examiner(s): Lie; Angela M
• Application Number:
  US10/753,885
• Publication Number:
  US 20040145527A1
• Time in Patent Office: 1,889 Days
• Field of Search: 343/702, 343/700.MS, 343/718, 343/725, 343/846, 343/745
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 19/005 Patch antenna using one or more coplanar parasitic elements
• CPC Class Codes: H01Q 5/335 at the feed, e.g. for impedance matching
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• 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 9/0457 electromagnetically coupled to the feed line

Abstract

A planar antenna structure intended to be used in small portable radio devices and a radio device using an antenna structure according to the invention. The radiating element (340) of the antenna is a conductive part in the cover of the radio device or a conductive coating attached to the cover. The radiating element is fed electro-magnetically by a parallel planar feed element (330) connected to the antenna port and located near the radiating element, between it and the ground plane (310). Between the feed element and antenna port there is a feed circuit (320) to provide matching for the antenna and, if necessary, forming an additional operating band. The radiating element need not be shaped to set the resonating frequencies or match the antenna. Instead, it can be designed relatively freely, based on the desired external appearance of the device, for example. Moreover the antenna requires relatively little space within the device.

Claims

1. A planar antenna structure for a radio device having at least one operating band comprising:

a ground plane;

a radiating element galvanically isolated from the ground plane and other conductive parts of the radio device;

a feed element having an antenna feed point, wherein the feed element is only electromagnetically coupled to the radiating element so as to transfer energy to the radiating element and receive energy from the radiating element;

a feed circuit that couples the antenna feed point to an antenna port of the radio device, wherein the feed circuit includes a reactive component and also couples the antenna feed point to the ground plane;

the feed circuit including a feed circuit board between the feed element and the ground plane, the feed circuit board including a feed conductor which galvanically connects said feed point to the antenna port;

wherein the feed conductor and the ground conductor are meandering strip conductors, which have certain inductances which act as the reactive component, and

a ground conductor which electromagnetically connects the feed conductor to the ground plane at a point along the feed conductor;

whereby said at least one operating band is set to a desired range on the frequency axis so as to match the antenna.

2. A planar antenna structure according to claim 1, wherein the radiating element, when installed, follows the contours of the outer surface of the radio device as regards its shape and position.

3. A planar antenna structure according to claim 2, wherein the radiating element is a rigid conductive piece belonging to a cover of the radio device.

4. A planar antenna structure according to claim 3, wherein said conductive piece is an extrusion piece.

5. A planar antenna structure according to claim 1, further comprising a dielectric layer above the ground plane, the dielectric layer including a radiating element on one surface of said dielectric layer and a feed element on the opposing surface thereof.

6. A planar antenna structure according to claim 5, wherein a plate formed by said dielectric layer, radiating element and feed element is arranged to be attached to an inner surface of a non-conductive cover of the radio device.

7. A planar antenna structure according to claim 2, wherein the radiating element is a conductive layer on an outer surface of the cover of the radio device, and the feed element is a conductive layer on an inner surface of the cover of the radio device.

8. A planar antenna structure according to claim 2, wherein at least one of the radiating element and the feed element is located inside the cover of the radio device.

9. A planar antenna structure according to claim 1, further comprising at least one radiating parasitic element.

10. A radio device comprising:

a planar antenna structure, which has at least one operating band and comprises;

a ground plane;

a radiating element galvanically isolated from the ground plane and other conductive parts of the radio device;

a feed element having an antenna feed point, wherein the feed element is only electromagnetically coupled to the radiating element so as to transfer energy to the radiating element and receive energy from the radiating element; and

a feed circuit that couples the antenna feed point to an antenna port of the radio device, wherein the feed circuit includes a reactive component and also couples the antenna feed point to the ground plane;

the feed circuit including a feed circuit board between the feed element and the ground plane, the feed circuit board including a feed conductor which galvanically connects said feed point to the antenna port;

wherein the feed conductor and the ground conductor are meandering strip conductors, which have certain inductances which act as the reactive component/and

a ground conductor which electromagnetically connects the feed conductor to the ground plane at a point along the feed conductor;

whereby said at least one operating band is set to a desired range on the frequency axis so as to match the antenna.

11. A planar antenna structure for a radio device having at least one operating band comprising:

a ground plane;

a radiating element galvanically isolated from other conductive parts of the radio device;

a feed element, wherein the feed element is electromagnetically coupled to the radiating element to transfer energy to the radiating element and receive energy from the radiating element;

a feed circuit including a feed circuit board between the feed element and the ground plane, wherein the feed circuit includes a reactive component;

the feed circuit board including a feed conductor and a ground conductor, wherein the feed conductor and the ground conductor are meandering strip conductors, which have certain inductances to form said reactive component;

the ground conductor configured to electromagnetically couple the feed conductor to the ground plane at a point in the feed conductor; and

the radio device including an antenna port;

wherein the feed circuit also connects an antenna feed point in the feed element to the antenna port;

whereby at least two operating band are provided.