WO2002031912A1

WO2002031912A1 - Internal antenna arrangement

Info

Publication number: WO2002031912A1
Application number: PCT/SE2001/002241
Authority: WO
Inventors: Jan SJÖHOLM; Tony BJÖRKMAN
Original assignee: Avantego Ab
Priority date: 2000-10-13
Filing date: 2001-10-15
Publication date: 2002-04-18
Also published as: AU2001296131A1

Abstract

The present invention relates to an antenna arrangement comprising an antenna element (12) arranged on a carrier (11). The antenna element (12) comprises a flexible substrate (13) having first and second antenna surfaces, said first antenna surface being provided with a conductive pattern (14). The carrier (11) is made of substantially rigid material having first and second carrier surfaces, said first carrier surface being arranged for receiving said antenna element. The first carrier surface is arranged with a number of elevations (20) provided with substantially plane surfaces for receiving said second antenna surface and eliminating irregularities on said flexible substrate.

Description

TITLE

INTERNAL ANTENNA ARRANGEMENT

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an antenna arrangement comprising an antenna element arranged on a carrier. The antenna element comprises a flexible substrate having first and second antenna surfaces, said first antenna surface being provided with a conductive pattern. The carrier is made of substantially rigid material having first and second carrier surfaces, said first carrier surface being arranged for receiving said antenna element. The invention also relates to a communication device.

BACKGROUND OF THE INVENTION

Wireless phones have traditionally used external antennas (whip and helix) for transmitting and receiving. These antennas radiate outward in all directions. The radiation property is highly desired to ensure good reception.

Recently, over the past two to three years, the mobile phone industry has started considering other antenna alternatives, so-called internal antennas. These antennas are arranged inside the phone on top of a PCB. One method of increasing these parameters is to increase the available antenna volume. As the mobile phone market matures, however, the available antenna volume decreases as users demand smaller and lighter handsets.

In addition, there are multiple phone standards (or frequency bands) throughout the world and even inside single countries (i.e. GSM, DAMPS, CDMA, PCS, UMTS, etc.), increasing the demand for "world-phones". These world-phones are beneficial to both the handset supplier and the end user. The user only needs one phone for vacations and business trips and the handset supplier has better logistics (fewer antenna types required).

A number of flexible antennas are known: WO 99/50927, for example, relates to a problem, how to achieve a lighter and cheaper antenna and a more reliable and simple manufacturing and assembly process. These problems are solved by arranging a first contact to directly contact the radiating element, and by a force enable contact, and to directly contact a feed member so that a conductive connection between the radiating element and the printed circuit board is obtained through the contact. The radiating arrangement is a flexible antenna rolled to a cylinder and arranged inside or outside a carrier extending outwardly from the communication housing. Thus, this invention does not relate to antenna on or inside a communication device.

US 5,841,403 relates to an antenna for a hand-held RF transceiver terminal, includes an antenna element which is encapsulated by material which does not detrimentally effect its antenna performance, but which closely conforms the antenna to the general shape of the terminal without having the antenna extend directly from the terminal. The antenna is arranged on a carrier, separated from the housing, inside the transceiver terminal.

In Japanese Patent Publication No. 4-291502, an antenna has a conduction processing section formed to part of the surface in a rear case of the portable radio equipment as an element part and a ground pattern processing section formed to part on the front side of a printed circuit board as a ground and the element and the ground plate are arranged opposite to each other to form the antenna.

US 6,025,805 relates to radio communications antennas and in particular relates to an antenna for such. An inverted E antenna is disclosed comprising a radiating element and a ground plane. The antenna is suitable for placement in a mobile communications handset. The antenna finds particular applicability in dual mode handsets, where two or more antennas may be located in close proximity. The small dimensions of the antenna relative to the operating wavelength, achieved by folding back an element of the antenna provides a simple solution to such problems as antenna coupling since its small size allows it to be placed as far away as possible within the small confines of a radio communications handset. A method of operating a mobile communications arrangement is also disclosed, the arrangement comprising a microphone, an audio speaker, a transceiver, and an antenna; wherein the antenna is in the form of an inverted E. SUMMARY

Thus, there is a need for an internal antenna, which is easy to manufacture, assemble and which requires small space and easily can be placed inside a housing of a communication device, preferably without a need for modification of the housing.

Therefore, in the initially mentioned antenna arrangement said first carrier surface is arranged with a number of elevations provided with substantially plane surfaces for receiving said second antenna surface and eliminating irregularities on said flexible substrate.

Moreover, said first surface of said substrate is provided with an adhesive agent for adhering said antenna element onto said first surface of said carrier.

Preferably, said carrier is a part of a communications device and the part may be a housing or chassis of the communication device. In one embodiment, said carrier is detachably arranged to said communications device.

Preferably, said conductive pattern is formed as a PIFA and the communication device comprises a ground plane interacting with said antenna element.

To have a larger electrical area in a small volume, the first surface of said carrier is curved between first and second portions. The carrier has a double curved external surface and a single curved internal surface to be able to arrange a thin substrate inside and have a desired exterior form.

The invention also relates to a communications device for receiving and transmitting electromagnetic radiation, comprising a housing inside which is arranged receiving and transmitting and circuitry connected to an antenna arrangement comprising an antenna element arrange on a carrier. The antenna element comprises a flexible substrate having a first and a second surface, said first surface being provided with a conductive pattern. The carrier is made of substantially rigid material having a first and a second surface, said first surface being arranged for receiving said antenna element. The first surface is arranged with a number of elevations, provided with substantially plane surfaces for receiving said antenna element and eliminating irregularities on said substrate. Said surface is part of said housing.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be further described in a non-limiting way with reference to the accompanying drawings in which:

Fig. 1 is a schematic perspective view showing a first embodiment of an antenna arrangement according to the invention with the parts taken apart,

Fig. 2 illustrates the encircled section in fig. 1, in an enlarged view, Fig. 3 is a schematic perspective view showing the first embodiment according to fig. 1 assembled, Fig. 4 is a cross-section along line 1N-IV in fig. 3, and Fig. 5 is a schematic perspective view showing a cellular phone with the antenna arrangement dismounted.

DETAILED DESCRIPTION OF THE EMBODIMENTS

One preferred embodiment of the invention will be described with reference to figs. 1 - 4. The antenna arrangement 10 according to the present invention comprises an antenna element 11 and a carrier member 12. The antenna element 11 comprises a flexible substrate 13, which is provided with a conductive pattern 14 at least on one side. The substrate 11 or the carrier can be provided with an adhesive layer (not shown) to attach the antenna and carrier. The conductive pattern can have any arbitrary form depending on the bandwidth(s); however, a serpentine like shape is illustrated. The conductive pattern can cover substantially the entire substrate and be provided with an eliminated, slit-like (non-conductive) section and in cooperation with a ground plane operate as ground dependent antenna, such as a PIFA (Positive Inverted F Antenna). The shape may also comprise a essentially meander shape, which allows antenna working as a monopol antenna for one or several bands. In ground dependent case, the conductive pattern is provided with feed and ground connections 15 and 16, respectively. It is also possible to provide a straight antenna pattern or the like on the substrate. It can also be arranged to cooperate with a whip antenna element. The conductive pattern is produced through etching, cut out and adhesion or the like. The substrate is preferably made of a thin polymer film or the like.

To provide a stable, substantially plane and robust antenna, the antenna element 11 is adhered onto the carrier 12. The carrier 12 is preferably a plastic member, and in the illustrated embodiment provided with a first substantially plane portion 17 and a second, relative said first portion inclined portion 18, with a slightly curved transition section 19 there between. As it appears from fig. 4, the inner surface of the carrier exhibits a substantially L-shaped formed, while the outer surface is more curved. Thus, it is possible to mount the flexible substrate without a risk for damaging it. The surface of the carrier on which the antenna element is mounted is provided with elevations or ribs 20, with flat surfaces, shown in more detail in fig. 2.

It is desirable that the antenna element 11 when adhered onto the carrier 12 has so flat surface as possible. However, the surface may be curved as shown in the drawing.

When adhering a flexible, thin film onto a flat surface, usually air bubbles are captured between the film and the flat surface. In the case of the antenna, the air bubbles, which can be captured under the flexible substrate and the carrier will affect and deteriorate the antenna characteristics. By arranging the ribs 20, a substantially flat surface will be provided, which simultaneously prevents formation of irregularities due to captured air bubbles. The antenna may also comprises of a sheet metal adhered to the carrier by means of double sided tape. Also, in this case the ribs will eliminate air bubbles under the tape.

Moreover, the transition section 19 between the first and second portions allows a soft bending angel for the antenna substrate. However, the antenna element does not need to cover the entire inner surface of the carrier. It can just cover the first portion or some parts of it.

The benefit of the antenna arrangement according to the invention is that it can be any part of a housing or chassis of a mobile phone 21 or any other communication device, as shown in fig. 5. It allows the phone manufacturer to produce separate phones and antennas for different demands and systems. In case of ground dependent antenna (according to this example) a ground plane 22 can be separately arranged inside the phone or integrated with the PCB. The feed and ground connectors 15 and 16, of the antenna element when mounted on the phone are arranged to contact (resiliently) connectors 23 and 24 inside the phone, which connect the antenna element to the receiver/transmitter circuitry of the phone. The housing of the phone 21 is provided with an opening 25 at one end arranged with grooves 26 for receiving the carrier of the antenna arrangement 10. The carrier is inserted into the opening and fixed through, for example snap or friction lock. The location of the antenna element is not limited to a detachable part, it can be arranged in any place inside the housing.

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. An antenna arrangement comprising an antenna element (12) arranged on a carrier (11), said antenna element (12) comprising a flexible substrate (13) having first and second antenna surfaces, said first antenna surface being provided with a conductive pattern (14), said carrier (11) being made of substantially rigid material having first and second carrier surfaces, said first carrier surface being arranged for receiving said antenna element, characterised in that said first carrier surface is arranged with a number of elevations (20) provided with substantially plane surfaces for receiving said second antenna surface and eliminating irregularities on said flexible substrate.

2. The antenna arrangement of claim 1, characterised in that at least said first carrier surface or one of surfaces of said substrate is provided with an adhesive agent for adhering said antenna element onto said first surface of said carrier.

3. The antenna arrangement according to any of preceding claims, characterised in that said carrier is a part of a communications device (21).

4. The antenna arrangement of claim 3, characterised in that said part is a housing or chassis of the communication device.

5. The antenna arrangement of claim 3, characterised in that said carrier is detachably arranged to said communications device.

6. The antenna arrangement according to any of preceding claims, characterised in that said conductive pattern is formed as a part of PIFA (Positive Inverted F-Antenna).

7. The antenna arrangement of claim 6, characterised in that said communication device comprises a ground plane (22) interacting with said antenna element.

8. The antenna arrangement according to any of preceding claims, characterised in that said first surface of said carrier is curved between a first and second portions.

9. The antenna arrangement of claim 8, characterised in that the carrier has a double curve external surface and a single curved internal surface.

10. A communications device for receiving and transmitting electromagnetic radiation, comprising a housing inside which is arranged receiving and transmitting and circuitry connected to an antenna arrangement comprising an antenna element (12) arrange on a carrier (11), said antenna element (12) comprising a flexible substrate (13) having first and second substrate surfaces, said first substrate surface being provided with a conductive pattern (14), and said carrier (11) being made of substantially rigid material having first and second carrier surfaces, said first surface being arranged for receiving said antenna element characterised in that said first carrier surface is arranged with a number of elevations (20), provided with substantially plane surfaces for receiving said antenna element (12) and eliminating irregularities on said substrate.

11. The communication device of claim 10, characterised in that said surface is part of said housing.