WO2002037603A1

WO2002037603A1 - Antenna arrangement

Info

Publication number: WO2002037603A1
Application number: PCT/SE2001/002438
Authority: WO
Inventors: Jari Paananen; Gunnar Engblom
Original assignee: Avantego Ab
Priority date: 2000-11-06
Filing date: 2001-11-06
Publication date: 2002-05-10
Also published as: AU2002212929A1

Abstract

The invention relates to a ground dependent antenna arrangement (10) of the type that comprises a substantially planar antenna element (14) and a ground plane (15) distanced from said antenna element. Said element arrangement comprises a carrier body (11) comprising a main portion (12) and a connection portion (13) extending from said main portion, said body being provided with a layer of said antenna element (14) and a layer of ground plane (15). The antenna is arranged to be connected at one end of a carrier (20) by means of said connection portion so that said antenna element and ground plane extend out from said end of said carrier (20) in a direction of a longitudinal axes of said carrier.

Description

ANTENNA ARRANGEMENT

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a ground dependent antenna arrangement of the type that comprises a substantially planar antenna element and a ground plane distanced from said antenna element.

BACKGROUND OF THE INNENTION

PIFAs (Planar Inverted F- Antenna) comprise of a substantially planar antenna element parallel to a carrier member or printed circuit board (PCB) of a communication device, on which carrier a ground plane is arranged. The radiator can be made with different patterns consisting of non-conductive gaps etc, to obtain a desired electrical length, multiband or other characteristics.

In some embodiments a shielding arrangement is provided comprising a conductive box parallel to the radiator element, in which the conductive box (together with the PCB) comprises the ground plane. It is also possible to integrate the radiator element as a part of the shielding box.

The design of the radiator element usually results in an insufficient distance between the radiator element and the ground plane. Moreover, the size of the radiator is usually not sufficient enough to optimise the non-conductive gap pattern.

Since the radiator is a substantive part of the antenna and affects the antenna efficiency, its design is very significant, while the length and form of the ground plane is not affected through the design of the radiator element. The prior art describes a number of antennas:

JP11355034, for example, considers an antenna element formed of a metallic part and a support body. The metallic part is formed of a metallic board and a feeding point and a ground contact point are formed at the end parts of the metallic part. The support body is formed of an insulator or a dielectric and holds the metallic part accurately in prescribed form. The metallic part is fixed to the support body to form them into one body. A slit, whose thickness is similar to or slightly thicker than that the circuit board, is installed in the support body. The antenna element is fixed to the circuit board by inserting the circuit board into the slit. The feeding point and the ground contact point are connected to the feeder terminal and ground terminal of the circuit board to constitute the objective deformed inverted F antenna.

GB 2 345 208 A relates to a radio device comprising an antenna and a PCB. The antenna is unitary structure and is edge mounted onto the PCB.

WO 01/299925 relates to an expansion card and an antenna structure for this expansion card for wireless data transmission. The card comprises a card part to be placed inside an expansion card interface of an electronic device, and which antenna part for receiving and transmitting of signals comprises at least one electroconductive, radiating antenna plane and a ground plane arranged parallel to the same, at a distance, as well as a dielectric between said planes. For improving the antenna properties, the antenna structure is placed in a housing part which is connected to the end of the card part and which comprises a cover structure and a bottom structure, for extending said antenna structure at least partly outside said interface, wherein the antenna plane is arranged on the side of the cover structure, the ground plane is arranged on the side of the bottom structure, and said dielectric arranged is a free clearance.

EP 892459 Al relates to small-sized antenna systems, especially planar antenna structures operating on several frequency bands. The antenna structure comprises a radiating antenna element with at least two lips. Thus, the antenna structure has two basic resonance frequencies, which are defined by the dimensions of the lips of the antenna element, gaps between them, and the other dimensions of the antenna structure. The radiating antenna structure is connected to the ground plane at least at one place. The radiating antenna element comprises at least two connection points, which are used for connecting the feed lines of the transmitter and receiver, and for connecting special tuning elements. The resonance frequencies of the antenna structure may be adjusted by connecting the said tuning elements to the connection points and antenna feed lines so that the antenna structure is operable on more than two frequency bands. The switches may be conventional semiconductor switches, such as FET switches or PIN diodes. Various optionally connectable tuning element or antenna feed arrangements may be used for carrying out an antenna arrangement which may be tuned in on all reception and transmission bands of an arrangement with several frequency ranges and mobile phone systems.

SUMMARY

The main object of the present invention is to introduce a ground plane dependent antenna module, which solves the problems related to known antennas,

The advantageous obtained through the antenna arrangement according to the present invention are:

• Lower height over the PCB plane, • Additional surface for antenna pattern (non-conductive gap), which allows to introduce a pattern in a projected surface to meet the demands for multiband antennas,

• Possibility of partly forming the ground plane for optimising the RF efficiency. Thus, it is possible to arrange, e.g., slits and meander patterns on the ground plane to affect the electrical length or other characteristics of the ground plane,

• Ability to integrate the antenna module with other components, such as speaker, buzzer, vibrator, Infra Read links, etc.,

• Freedom to design the module adaptable to the design of the communication device, e.g. having double curved surfaces, etc., • Possibly to optimise the ground plane to optimise the antenna efficiency.

Thus, the initially mentioned antenna arrangement comprises a carrier body comprising a main portion and a connection portion extending from said main portion. The body is with a layer of said antenna element and a layer of ground plane. The antenna is arranged to be connected at one end of a carrier by means of said connection portion and that said antenna element and ground plane extend out from said end of said carrier in a direction of a longitudinal axes of said carrier. The antenna element and ground plane form a two separate planes and that the carrier between said planes. The antenna element and/or ground plane is/are arranged with non-conductive gap. Preferably, the body is made of a plastic or dielectric material and includes a gap for distancing said antenna element and ground plane.

In one embodiment, the body is substantially h-shaped with main portion and a tail portion, and that said tail portion is connected to said carrier. The antenna element can extend above and under said tail portion. Preferably an antenna pattern/gap may also extend above and under said tail portion. Said body includes inserted layers of conductors acting as ground plane and/or antenna element. Said layers are applied through metalhstaion, plating, electrolysis, etc.

The ground plane can be connected to a ground plane of a communication device, which is optimised for the device and preferably covers one side of the PCB.

The invention also refers to a commumcation arrangement including an antenna arrangement according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be further described in non-limiting way under reference to the accompanying drawings in which:

Fig. 1 is a schematic planar view of the antenna arrangement according to the invention provided on a carrier inside a commumcation,

Fig 2 is a cross-sectional view along line H-II in fig 1, and

Fig 3 is a cross-sectional view of a part of an antenna arrangement according to another embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An exemplary embodiment of an antenna arrangement according to the invention is shown schematically in figs. 1 and 2. The antenna module 10 according to the invention comprises a body 11, which can be connected to a carrier 20, which in this case is a Printed Circuit Board (PCB). The PCB carries different electrical components 21.

The body 11 is substantially h-shaped with a main substantially U-shaped portion 12 and a tail portion 13. Preferably, the body is made of a plastic or dielectric material. With substantially h-shape is meant a structure comprising of a first plane, a portion substantially perpendicular to said first plane along the first planes longitudinal axis, and a second plane connected to said portion and substantially parallel to said first plane and covering at least part of said first plane. Thus the tail potion is the part not covered by the second plane. However, the body 11 may also be formed substantially H-shaped.

The antenna elements, i.e. the radiator 14 and ground plane 15 are applied onto the body 11 by metallization, plating, electrolysis etc., in a suitable and known way.

The tail portion 11 of the antenna module extends over the PCB 20. The radiator 15 provided with a non-conductive gap 16, which provides the antenna with desired electrical length and other characteristics, known for a skilled person. The gap is provided, e.g. through material exclusion.

The substantially U-shaped main section 12 of the antenna module is defined by distancing the radiator part from the ground plane part. However, the antenna element and the ground plane can be interconnected, e.g. at the end of the tail portion 13. The gap 22 can be empty (field with air) or a distancing dielectric material.

The ground plane can be applied both inside and/or outside the gap 22. The ground plane is separated from the antenna element and connected to a ground plane 18 of the PCB. The ground plane can be connected to a ground plane of the communication device, which is optimised for the device and preferably covers one side of the PCB.

The radiator, as shown but not necessarily, can extend all the way over the tail portion and also under the tail portion, which can connect to a feed connection 17 of the communication device. Also, the gap pattern can follow the radiator under the tail portion.

Also, the ground plane can be provided with a non-conductive gap 19 as shown in the drawings.

Using metallised carrier, it is possible to insert layers 14' inside the carrier and arrange parallel or substantially perpendicular extensions of the radiator/ground planes. The parallel layers can also carry patterns as described above. The layers may be connected capacitivaly.

The branches of the antenna element and/or the ground plane, including the gaps/slits for capacitive coupling, can be formed in three dimensions, so that the gaps/slits can be build in the depth direction, e.g. two substantially parallel surfaces substantially perpendicular to remaining pattern planes or two substantially parallel surfaces parallel to the other planes. In this way, a more robust construction can be obtained.

The invention is not limited the shown embodiments but can be varied in a number of ways without departing from the scope of the appended claims and the arrangement and the method can be implemented in various ways depending on application, functional units, needs and requirements etc.

Claims

1. A ground dependent antenna arrangement (10) of the type that comprises a substantially planar antenna element (14) and a ground plane (15) distanced from said antenna element, characterised in that said antenna arrangement comprises a carrier body (11) comprising a main portion (12) and a connection portion (13) extending from said main portion, said body being provided with a layer of said antenna element (14) and a layer of ground plane (15) and that the antenna is arranged to be connected at one end of a carrier (20) by means of said connection portion and that said antenna element and ground plane extend out from said end of said carrier (20) in a direction of a longitudinal axes of said carrier.

2. The antenna arrangement of claim 1, characterised in that said antenna element and ground plane form a two separate planes and that the carrier between said planes.

3. The antenna arrangement of claim 1 or 2, characterised in that said antenna element and/or ground plane is/are arranged with non-conductive gap (16, 19).

4. The antenna arrangement according to one of claims 1-3, characterised in that said body (11) is made of a plastic or dielectric material.

5. The antenna arrangement according to claim 1, characterised in that said body includes a gap for distancing said antenna element and ground plane.

6. The antenna arrangement according to any of claims 1-5, characterised in that said body is substantially h-shaped with main portion and a tail portion, and that said tail portion is connected to said carrier.

7. The antenna arrangement according to any of claims 1-6, characterized in that said antenna element extends above and under said tail portion.

8. The antenna arrangement according to claim 7, characterized in that an antenna pattern/gap extends above and under said tail portion.

9. The antenna arrangement according to any of claims 1-8, characterized in that said body includes inserted layers of conductors acting as ground plane and/or antenna element.

10. The antenna arrangement according to any of claims 1-9, characterized in that said layer are applied through metalhstaion, plating, electrolysis, etc.

11. The antenna arrangement according to any of claims 1-10, characterized in that ground plane can be connected to a ground plane of a communication device, which is optimised for the device and preferably covers one side of the PCB.

12. A communication arrangement including an antenna arrangement according to any of claims 1-11.

13. A method of saving space in a communication arrangement having a ground dependent antenna arrangement (10) of the type that comprises a substantially planar antenna element (14) and a ground plane (15) distanced from said antenna element, characterised by providing said antenna arrangement as a carrier body (11) comprising a main portion (12) and a connection portion (13) extending from said main portion, said body being provided with a layer of said antenna element (14) and a layer of ground plane (15) and connecting said body at one end of a carrier (20) by means of said connection portion so that said antenna element and ground plane extend out from said end of said carrier (20) in a direction of a longitudinal axes of said carrier.