EP2493010A1

EP2493010A1 - An antenna arrangement and a portable radio communication device comprising such an antenna arrangement

Info

Publication number: EP2493010A1
Application number: EP11156253A
Authority: EP
Inventors: Andrei Kaikkonen; Marek Chacinski; Lukasz Grynczel
Original assignee: Laird Technologies AB
Current assignee: Laird Technologies AB
Priority date: 2011-02-28
Filing date: 2011-02-28
Publication date: 2012-08-29
Also published as: CN102655263A

Abstract

The present invention relates to an antenna arrangement for a portable radio communication device comprising a multiple-turn loop NFC antenna element (2) and an FM antenna element (3, 4; 5, 6; 7), wherein the FM antenna element is elongated and positioned at least partly within the multiple-turn loop NFC antenna element.

Description

FIELD OF INVENTION

The present invention relates generally to antenna arrangements and more particularly to an antenna arrangement, comprising a multiple-turn loop NFC antenna element, for a portable radio communication device.

BACKGROUND

Internal antennas have been used for some time in portable radio communication devices. There are a number of advantages connected with using internal antennas compared to protruding antennas, of which can be mentioned that they are small and light, making them suitable for applications wherein size and weight are of importance, such as in mobile phones, PDA, portable computers or similar devices.
However, the application of internal antennas in a mobile phone puts some constraints on the configuration of the radiating elements of the antenna. In particular, in a portable radio communication device the space for an internal antenna arrangement is limited. These constraints may make it difficult to find a configuration of the antenna arrangement that provides for desired use. This is especially true for antennas intended for use with radio signals of relatively low frequencies as the desired physical length of such antennas are large compared to antennas operating with relatively high frequencies.
One specific application operating in a relatively low frequency band is the Near Field Communication (NFC) application. Near Field Communication is e.g. utilized for secure mobile transactions. The NFC operating band is about 13 MHz.
Further, a portable radio communication device is today many times provided with frequency operational coverage for other frequency bands than NFC, such as FM, GSM900, GSM1800, GPS, BT, WLAN, WCDMA and GPS. A portable radio communication device has limited space and it is thus desirable, if possible, to add multiple functionalities to an antenna arrangement. Further, all complementary antennas, i.e. non-cellular antennas such as NFC and FM, are typically allocated to a limited region of a mobile phone. Due to the close proximity of the antennas isolation between the antennas will generally be a problem.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an antenna arrangement for a portable radio communication device providing at least FM and NFC functionality for the portable radio communication device with high FM and NFC antenna efficiency.
This object, among others, is according to the present invention attained by an antenna arrangement and a portable radio communication device, respectively, as defined by the appended claims.
By providing an antenna arrangement for a portable radio communication device comprising a multiple-turn loop NFC antenna element and an FM antenna element, wherein the FM antenna element is elongated and positioned at least partly within the multiple-turn loop NFC antenna element both FM and NFC functionality can be provided with high FM and NFC antenna efficiency.
By preferably providing the FM antenna element positioned completely within the multiple-turn loop NFC antenna element, both antenna elements may e.g. be positioned on the same flex-film, which e.g. facilitates manufacturing and fixing relative positioning between the FM antenna element and the multiple-turn loop NFC antenna element.
By preferably arranging the multiple-turn loop NFC antenna element in a first layer and the FM antenna element a second layer, wherein the first and second layers are arranged in parallel and the FM antenna element is routed perpendicularly across the multiple-turn loop NFC antenna element, the antenna element may be positioned close to each other without to high coupling to each other. To further reduce the coupling between the antenna elements the FM antenna element is preferably narrower across the multiple-turn loop NFC antenna element than within the multiple-turn loop NFC antenna element.
For a well defined positioning relative each other the FM antenna element and the multiple-turn loop NFC antenna element are preferably positioned on opposite sides of a flexible carrier such as a flex-film.
To fulfill NFC requirements for a portable radio communication device a part of the multiple-turn loop NFC antenna element is preferably folded relative the rest of the multiple-turn loop NFC antenna element.
In order to provide both Rx and Tx functionality for FM the antenna arrangement preferably comprises a first and a second FM antenna element positioned parallel relative each other.
For efficient FM Rx function the first FM antenna element is preferably an elongated monopole antenna configured for FM Rx. Advantageously, the elongation of the monopole is along the whole top edge of the ground plane device of the portable radio communication device.
For efficient FM Tx function the second FM antenna element is preferably a half-loop antenna configured for FM Tx.
A portable radio communication device is also provided.
Further preferred embodiments are defined in the dependent claims.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will become more fully understood from the detailed description of embodiments given below and the accompanying figures, which are given by way of illustration only, and thus, are not limitative of the present invention, wherein:

Fig. 1 is a schematic drawing illustrating an antenna arrangement according to a first embodiment of the present invention.
Fig. 2 is a schematic drawing illustrating an antenna arrangement according to a second embodiment of the present invention.
Fig. 3 is a schematic drawing illustrating an antenna arrangement according to a third embodiment of the present invention.
Fig. 4 is a schematic drawing illustrating an antenna arrangement according to a fourth embodiment of the present invention.
Fig. 5 is a schematic drawing illustrating routing of an antenna arrangement according to a fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, for purpose of explanation and not limitation, specific details are set forth, such as particular techniques and applications in order to provide a thorough understanding of the present invention. However, it will be apparent for a person skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed description of well-known methods and apparatuses are omitted so as not to obscure the description of the present invention with unnecessary details.
In the following description and claims, the term radiating element is used. It is to be understood that this term is intended to cover electrically conductive elements arranged for receiving and/or transmitting radio signals.
An antenna arrangement for a portable radio communication device, such as a mobile phone or similar device, according to a first embodiment of the present invention will now be described with reference to Fig. 1.
The antenna arrangement comprises a multiple-turn loop NFC antenna element 2 arranged in a first layer and a first elongated FM antenna element 3 and a second elongated FM antenna element 4 arranged in a second layer. The first and second layers are arranged substantially in parallel and the second layer is preferably arranged on top of the second layer.
Preferably, the multiple-turn loop NFC antenna element 2 is arranged on a flexible carrier such as a flex-film, which advantageously is arranged on a dielectric carrier, which in turn is mounted to a PCB 1 of the portable radio communication device. The first elongated FM antenna element 3 and the second elongated FM antenna element 4 are preferably arranged on a flex-film, which is e.g. arranged on the dielectric carrier, which the multiple-turn loop NFC antenna element 2 is arranged on, or arranged in a top cap of a cover of the portable radio communication device. When the first and second FM antenna elements 3 and 4 are arranged on the dielectric carrier, the flex-film for all three antenna elements are preferably a common double-sided flex-film, wherein the multiple-turn loop NFC antenna element 2 is arranged on a first side of the double-sided flex-film facing the dielectric carrier and the first and second FM antenna elements 3 and 4 are arranged on a second side of the double-sided flex-film facing away from the dielectric carrier. When the first and second FM antenna elements 3 and 4 are arranged on the top cap of the portable radio communication device they are preferably provided by LDS directly on the top cap instead of arranging a flex-film on the top cap.
The multiple-turn loop NFC antenna element 2 is generally planar, but is preferably partly folded over the top edge of the PCB 1 and a possible dielectric carrier of the portable radio communication device to comply with NFC operation requirements regarding directivity. The PCB 1 generally acts as a ground plane device for the multiple-turn loop NFC antenna element 2 and the FM antenna elements 3 and 4.
The first elongated FM antenna element 3 is preferably configured for receiving FM signals (FM Rx), and the second elongated FM antenna element 4 is preferably configured for transmitting FM signals (FM Tx). The FM antenna element 3 is preferably an elongate monopole antenna over a ground plane device 1 (the PCB) arranged along the whole top edge of the PCB 1 of the portable radio communication device, providing maximum FM performance. The FM antenna element 4 is preferably a half-loop antenna over the ground plane device 1 (the PCB). The second elongated FM antenna element 4 is preferably arranged parallel with the first elongated FM antenna element 3.
For reduced coupling between the multiple-turn loop NFC antenna element 2 and the FM antenna elements 3 and 4 the first and second layers are preferably arranged substantially in parallel and the FM antenna elements 3 and 4 are routed perpendicularly across the multiple-turn loop NFC antenna element 2 and over the empty inner portion of the multiple-turn loop NFC antenna element 2, as illustrated in Fig. 1.
An antenna arrangement according to a second embodiment of the present invention will now be described with reference to Fig. 2. This second embodiment of the present invention is identical to the first embodiment describe above apart from the following.
In order to further reduce the coupling between the FM antenna elements 3 and 4 and the multiple-turn loop NFC antenna element 2, the FM antenna elements 3 and 4 are wider within the multiple-turn loop NFC antenna element 2 than across the multiple-turn loop NFC antenna element 2.
By having a width of the FM antenna elements 3 and 4 across the multiple-turn loop NFC antenna element 2 of at most 0.5 mm coupling is reduced, at the same time assuring that the Rx FM antenna element 3 is arranged along the whole top edge of the PCB of the portable radio communication device, assuring maximum FM performance
For achieving optimal FM performance the FM antenna elements 3 and 4 are preferably configured with a width of at least 1 mm within the multiple-turn loop NFC antenna element 2.
An antenna arrangement according to a third embodiment of the present invention will now be described with reference to Fig. 3. This third embodiment of the present invention is identical to the first embodiment describe above apart from the following.
The FM antenna elements 5 and 6 are arranged completely within the multiple-turn loop NFC antenna element 2. The FM antenna elements 5 and 6 are advantageously also arranged in the same plane as the multiple-turn loop NFC antenna element 2, preferable on a common single-sided flex-film.
The multiple-turn loop NFC antenna element 2 is arranged with three sides of the loop above the PCB 1 of the portable radio communication device and the fourth side folded over the top edge of the PCB 1 or a dielectric carrier mounted between the multiple-turn loop NFC antenna element 2 and the PCB 1, and the FM Rx antenna element 5 is thus not arranged along the whole edge of the PCB 1.
The minimum distance between the multiple-turn loop NFC antenna element 2 and the FM antenna elements 5 and 6 is preferably 1 mm, to ensure isolation there between.
An antenna arrangement according to a fourth embodiment of the present invention will now be described with reference to Fig. 4. This fourth embodiment of the present invention is identical to the third embodiment describe above apart from the following.
The antenna arrangement comprises an FM Rx antenna element only. The multiple-turn loop NFC antenna element 2 is arranged with one side of the loop above the PCB 1 of the portable radio communication device and the three other sides outside the PCB 1, and at least the Rx FM antenna elements 7 is arranged along the whole edge of the PCB 1. The three other sides of the multiple loop antenna element 2 are folded over the top edge and two adjacent side edges of the PCB 1 or a dielectric carrier mounted between the PCB 1 and the multiple loop antenna element 2. A further Tx FM antenna element may however be added to the antenna device similarly to the first to third embodiments described above.
An antenna arrangement according to a fifth embodiment of the present invention will now be described with reference to Fig. 5. This fifth embodiment of the present invention is identical to the fourth embodiment describe above apart from the following.
The routing of the multiple-turn loop NFC antenna element 2 is in this embodiment partly outside the side edges of the PCB 1 and partly above the side edges of the PCB 1. The antenna arrangement comprises a dielectric carrier 8 arranged between the PCB 1 and the antenna elements 2 and 7. The dielectric carrier 8 illustrated in this embodiment, may also be utilized in the first to fourth embodiments described above. The part of the multiple-turn loop NFC antenna element 2 which is in an area in which no FM antenna element 7 is nearby is above the PCB 1, and the part of the multiple-turn loop NFC antenna element 2 which is in an area wherein the FM antenna element 7 is present nearby is routed outside the PCB 1, along a side of the dielectric carrier 8. The routing of the multiple-turn loop NFC antenna element 2 on the top side of the portable radio communication device is along a top side of the dielectric carrier 8.
It will be obvious that the present invention may be varied in a plurality of ways. Such variations are not to be regarded as departure from the scope of the present invention as defined by the appended claims. All such variations as would be obvious for a person skilled in the art are intended to be included within the scope of the present invention as defined by the appended claims.

Claims

1. An antenna arrangement for a portable radio communication device comprising a multiple-turn loop NFC antenna element (2), characterized in that said antenna arrangement comprises an FM antenna element (3, 4; 5, 6; 7), wherein said FM antenna element is elongated and positioned at least partly within said multiple-turn loop NFC antenna element.

2. The antenna arrangement according to claim 1, wherein said multiple-turn loop NFC antenna element (2) is arranged in a first layer and said FM antenna element (3, 4) is arranged in a second layer, wherein said first and second layers are arranged substantially in parallel and said FM antenna element is routed perpendicularly across said multiple-turn loop NFC antenna element.

3. The antenna arrangement according to claim 2, wherein said FM antenna element is wider within said multiple-turn loop NFC antenna element than across said multiple-turn loop NFC antenna element.

4. The antenna arrangement according to claim 2 or 3, comprising a multiple-layer flexible carrier, wherein said FM antenna element and said multiple-turn loop NFC antenna element are positioned on opposite sides of said flexible carrier.

4. The antenna arrangement according to claim 1, wherein said FM antenna element (5, 6; 7) is positioned completely within said multiple-turn loop NFC antenna element.

6. The antenna arrangement according to any of claims 1-5, wherein a part of said multiple-turn loop NFC antenna element is folded relative a plane of the rest of said multiple-turn loop NFC antenna element.

7. The antenna arrangement according to any of claims 1-6, comprising a first (3; 5) and a second (4; 6) FM antenna element positioned parallel relative each other.

8. The antenna arrangement according to claim 7, wherein said first FM antenna element (3; 5) is an elongated monopole antenna configured for FM Rx.

9. The antenna arrangement according to claim 7 or 8, wherein said second FM antenna element (4; 6) is a half-loop antenna configured for FM Tx.

10. A portable radio communication device, characterized in that it comprises an antenna arrangement according to any of claims 1-9.

11. The portable radio communication device according to claim 10, comprising a ground plane device (1) having an edge over which said multiple-turn loop NFC antenna element is folded.

12. The portable radio communication device according to claim 11, wherein said FM antenna element is positioned along said edge of said ground plane device.

13. The portable radio communication device according to claim 12 when dependent on claim 8, wherein said first FM antenna element is positioned along said edge.

14. The portable radio communication device according to any of claims 11-13, comprising a top cap, wherein said FM antenna element and said multiple-turn loop NFC antenna element is arranged separately in said top cap and on said ground plane device.