WO2011110216A1

WO2011110216A1 - An antenna device adapted for simultaneous reception of a first frequency band and a second frequency band

Info

Publication number: WO2011110216A1
Application number: PCT/EP2010/052938
Authority: WO
Inventors: Andrei Kaikkonen; Peter Lindberg; Stefan Irmscher
Original assignee: Laird Technologies Ab
Priority date: 2010-03-09
Filing date: 2010-03-09
Publication date: 2011-09-15
Also published as: DE112010005358T5

Abstract

The present invention relates to an antenna device for a portable radio communication device adapted for simultaneous reception of a first frequency band and a second frequency band. The antenna device comprises radiating means (1) and a low noise amplifier (4), wherein the radiating means is configured to exhibit high impedance for the first frequency band and for the second frequency band, and the low noise amplifier is configured to exhibit high impedance for the first 10 frequency band and for the second frequency band.

Description

AN ANTENNA DEVICE ADAPTED FOR SIMULTANEOUS RECEPTION OF A FIRST FREQUENCY BAND AND A SECOND FREQUENCY BAND FIELD OF INVENTION

The present invention relates generally to antenna devices and more particularly to an antenna device for use in a portable radio communication device, such as a mobile phone. 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, 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 computer or similar devices .

However, the application of internal antennas in a mobile phone puts some constraints on the configuration of the antenna element. In particular, in a portable radio communication device the space for an internal antenna device is limited. These constraints may make it difficult to find a configuration of the antenna device 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 FM radio application. The FM operating band is defined as frequencies between 88- 108 MHz in most of the world and frequencies between 76-90 MHz in Japan. Prior art conventional antenna configurations, such as loop antennas or monopole antennas, fitted within the casing of a portable radio communication device will result in unsatisfactory operation in that the antenna either has too bad performance over a sufficiently wide frequency band or sufficient performance over a too narrow frequency band.

Instead, a conventional FM antenna for portable radio communication devices is usually provided in the headset wire connected to the communication device. This configuration with a relatively long wire permits an antenna length that is sufficient also for low frequency applications. However, if no external antenna is permitted this solution is obviously not feasible.

Further, a portable radio communication device is today many times provided with frequency operational coverage for other frequency bands than FM, such as T-DMB, GSM900, GSM1800, GPS , Bluetooth, WLAN, WCDMA, LTE and GPS. A portable radio communication device has limited space and it is thus desirable to, if possible, add multiple functionality to an antenna device .

When multiple functionalities are added to an antenna device, more components are added increasing cost and space required to accommodate added components, and the power consumption of the portable radio communication device is increased, and it is generally highly desirable to keep costs, size and power consumption of the portable radio communication device as low as possible.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an antenna device for a portable radio communication device adapted for operation at least at a first and a second frequency band, wherein utilized space is limited.

This object, among others, is according to the present invention attained by an antenna device and a portable radio communication device, respectively, as defined by the appended claims.

By reusing power consuming components, such as an amplifier, for multiple functions, power consumption is limited, as well as utilization of space and cost is limited. Reuse of components such as amplifiers generally require addition of other components to maintain desired operating conditions, but if such components are configured as passive components, the increased power consumption of such components is neglectable.

By providing an antenna device antenna device for a portable radio communication device adapted for simultaneous reception of a first frequency band and a second frequency band, wherein the antenna device comprises radiating means and a low noise amplifier wherein the radiating means is configured to exhibit high impedance for the first frequency band and for the second frequency band, and the low noise amplifier is configured to exhibit high impedance for the first frequency band and for the second frequency band, power consumption is limited due to utilization of one low noise amplifier for two separate frequency bands.

By providing an antenna device for a portable radio communication device adapted for simultaneous reception of a first frequency band and a second frequency band, wherein the antenna device comprises radiating means, first filtering means, second filtering means and a low noise amplifier, wherein the first filtering means is configured to high-pass operating frequencies of the second frequency band and to high impedance match the radiating means at the first frequency band, the second filtering means is configured to low-pass operating frequencies of the first frequency band and to high impedance match the radiating means at the second frequency band; the radiating means is connected to the first filtering means, which first filtering means is connected to the second filtering means, which second filtering means is connected to the low noise amplifier, power consumption is also limited due to utilization of one low noise amplifier for two separate frequency bands.

An antenna device according to the present invention is particularly useful wherein the first frequency band is for FM reception and the second frequency band is for T-DMB reception. By preferably realizing the first filtering means as a grounded parallel inductor (or shunt inductor) simple high-impedance tuning/matching is achieved for the first frequency band. By preferably realizing the second filtering means as a series inductor simple high-impedance tuning/matching is achieved for the second frequency band.

Many times is ESD protection required, and in such a case the first filtering means or the second filtering means comprises ESD protection means, preferably realized as two series inductors and two grounded parallel oppositely oriented diodes connected between the two series inductors.

The radiating means is preferably realized as a monopole radiating element, which is particularly useful for FM reception in e.g. a mobile phone. Improved antenna efficiency is preferably provided by arranging the monopole radiating element is off-ground in the portable radio communication device.

Advantageously, the antenna device is further adapted for simultaneous reception of a third frequency band, wherein the radiating means is configured to exhibit approximately 50 Ω impedance for the third frequency band, and the low noise amplifier is configured to exhibit approximately 50 Ω impedance for the third frequency band. In this way coverage for e.g. GPS operation is possible. Advantageously, the antenna device further comprises third filtering means, fourth filtering means and fifth filtering means, wherein the third filtering means is configured to high-pass the third frequency band and to block the first and second frequency bands and to approximately 50 Ω match the radiating element for the third frequency band, the fourth filtering means is configured to band-pass the third frequency band, the fifth filtering means is configured to high- pass the third frequency band and to block the first and second frequency bands and to approximately 50 Ω match the low noise amplifier for the third frequency band, and the radiating element is connected to the third filtering means, which third filtering means is connected to the fourth filtering means, which fourth filtering means is connected to the fifth filtering means, which fifth filtering means is connected to the low noise amplifier, in order to e.g. provide GPS operation . 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 schematically illustrates a first embodiment of an antenna device according to the present invention. FIG. 2 schematically illustrates a second embodiment of an antenna device 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.

An antenna device for a portable radio communication device according to a first embodiment of the present invention will now be described with reference to Fig. 1. The antenna device is adapted for simultaneous reception of a first frequency band and a second frequency band. The antenna device comprises radiating means 1, first filtering means 2, second filtering means 3, and a low noise amplifier 4. The radiating means 1 is configured to exhibit high impedance for the first frequency band and for the second frequency band. The first filtering means 2 is configured to high-pass operating frequencies of the second frequency band and to tune the radiating means 1 to the first frequency band. The second filtering means 3 is configured to low-pass operating frequencies of the first frequency band and to tune the radiating element to the second frequency band. The low noise amplifier 4 is configured to exhibit high impedance for the first frequency band and for the second frequency band.

The radiating means 1 is connected to the first filtering means 2, which in turn is connected to the second filtering means 3, which in turn is connected to the low noise amplifier 4. The low noise amplifier 4 is in turn connected to a first receiver 7, through first diplex means 5, for the first frequency band and a second receiver 8, through second diplex means 6, for the second frequency band. The first frequency band is preferably for FM reception, and component values in this embodiment are based on that. The second frequency band is preferably for T-DMB reception, and component values in this embodiment are based on that.

The first diplex means 5 is preferably provided with blocking means for the second frequency band. Alternatively, the first diplex means 5 is provided with a series resonance circuit tuned to the FM frequency band, such as a series capacitor of 11 pF and a series inductor of 270 nH. The second diplex means 6 is preferably provided with blocking means for the first frequency band. Alternatively, the second diplex means 6 is provided with a series resonance circuit tuned to the T-DMB frequency band, such as a series capacitor of 3.2 pF and a series inductor of 18 nH.

The first filtering means 2 is preferably realized as a grounded parallel inductor of 330 nH. The second filtering means 3 is preferably realized as a series inductor of 470 nH. Advantageously, the first or second filtering means also includes ESD protection. By arranging the ESD protection between the second filtering means 3 and the LNA 4 it is preferably realized as a series inductor of 51 nH connected to the second filtering means 3, a series inductor of 91 nH connected to the LNA 4, and two parallel and oppositely directed grounded diodes, such as HSMS- 282C, between the two series inductors of the ESD protection. Since both the radiating means and the LNA exhibits high impedance for the first and second frequency bands, losses in the inductors are neglectable .

The radiating means 1 is preferably realized as a monopole radiating element arranged off-ground in the portable radio communication device. The exemplary component values above are based on that the radiating element has a shape of 40x1 mm having a spacing of at least 5 mm to any ground plane means. For adaption to the FM frequency band, the radiating element is preferably a monopole radiating element arranged along a short side of a mobile phone. The monopole radiating element is preferably high-impedance matched at the first frequency band, by means of the grounded inductor of the first filtering means 2 mentioned above, which will make the monopole exhibit high impedance for FM frequency band. The monopole radiating element is preferably high-impedance matched at the second frequency band, by means of the series inductor of the second filtering means 3 mentioned above, which will make the monopole exhibit high impedance for T-DMB.

The low noise amplifier, exhibiting high impedance for the first frequency band, such as FM, and for the second frequency band, such as T-DMB, is preferably realized by having a common source/emitter stage without shunt-shunt feedback, or a common drain/collector stage.

By the term high impedance an impedance of at least 200 Ω is intended. A second embodiment of an antenna device according to the present invention is illustrated in Fig. 2. The second embodiment of the antenna device is identical with the first embodiment of the antenna device described above apart from the following. Simultaneous operation of a third frequency band is added to the antenna device. The antenna device further comprises third filtering means 9, fourth filtering means 10, and fifth filtering means 11.

The third frequency band is preferably for GPS reception, and component values in this embodiment are based on that.

The third filtering means 9 is configured to high-pass operating frequencies of the third frequency band and to block operating frequencies of the first and second frequency bands, preferably comprising at least a series capacitor of 1 pF. The fourth filtering means 10 is configured to band-pass the third frequency band. The fifth filtering means 11 is configured to high-pass operating frequencies of the third frequency band and to block operating frequencies of the first and second frequency bands, preferably comprising at least a series capacitor of 1 pF. The low noise amplifier 4 is configured to exhibit approximately 50 Ω impedance for the third frequency band.

The radiating means 1 is connected to the third filtering means 9. The third filtering means 9 is in turn connected to the fourth filtering means 10, which in turn is connected to the fifth filtering means 11, which in turn is connected to the low noise amplifier 4. The low noise amplifier 4 is in turn connected to a third receiver 13, through third triplex means 12, for reception of the third frequency band. The first and second diplex means 5 and 6 is thus now considered as first and second triplex means 5 and 6.

The third triplex means 12 is preferably provided with blocking means for the first and second frequency bands. Alternatively, the third triplex means 12 is provided with a series resonance circuit tuned to the GPS frequency band, such as series capacitor of 2 pF and a series inductor of 5.1 nH.

The third filtering means 9 preferably comprises at least a series capacitor of 1 pF. Advantageously, the third filtering means 9 is also configured to 50 Ω- match the radiating means 1 to the fourth filtering means 10 for the third frequency band, preferably realized as a grounded parallel inductor of 3.3 nH arranged between the series capacitor and the fourth filtering means 9. The fourth filtering means 10 is preferably a standard 50 Ω-matched band-pass filter for the GPS frequency band.

The fifth filtering means 11 preferably comprises at least a series capacitor of 1 pF. Advantageously, the fourth filtering means is also configured to 50 Ω- match the LNA 4 to the fourth filtering means 10 for the third frequency band, preferably realized as a series inductor of 12 nH and a grounded parallel inductor of 20 nH arranged between the series capacitor and the fourth filtering means.

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 device for a portable radio communication device adapted for simultaneous reception of a first frequency band and a second frequency band, wherein said antenna device comprises radiating means (1) and a low noise amplifier (4), characterized in that said radiating means is configured to exhibit high impedance for said first frequency band and for said second frequency band, and said low noise amplifier is configured to exhibit high impedance for said first frequency band and for said second frequency band.

2. An antenna device for a portable radio communication device adapted for simultaneous reception of a first frequency band and a second frequency band, wherein said antenna device comprises radiating means (1), first filtering means (2), second filtering means (3) and a low noise amplifier (4), characterized in that said first filtering means (2) is configured to high- pass operating frequencies of said second frequency band and to high impedance match said radiating means (1) at said first frequency band, said second filtering means (3) is configured to low-pass operating frequencies of said first frequency band and to high impedance match said radiating means ( 1 ) at said second frequency band; said radiating means (1) is connected to said first filtering means (2), which first filtering means (2) is connected to said second filtering means (3), which second filtering means (3) is connected to said low noise amplifier (4).

3. The antenna device according to claim 1 or 2, wherein said first frequency band is for FM reception.

4. The antenna device according to any of claims 1-3, wherein said second frequency band is for T-DMB reception .

5. The antenna device according to any of claims 2-4, wherein said first filtering means comprises a grounded parallel inductor.

6. The antenna device according to any of claims 2-5, wherein said second filtering means comprises a series inductor .

7. The antenna device according to any of claims 2-6, wherein said first filtering means or said second filtering means comprises ESD protection.

8. The antenna device according to claim 7, wherein said ESD protection comprises two series inductors and two grounded parallel oppositely oriented diodes connected between said two series inductors.

9. The antenna device according to any of claims 2-8, wherein said radiating means comprises a monopole radiating element.

10. The antenna device according to claim 9, wherei said monopole radiating element is arranged off ground.

11. The antenna device according to any of claims 1- 10, further adapted for simultaneous reception of a third frequency band, wherein said radiating means is configured to exhibit approximately 50 Ω impedance for said third frequency band, and said low noise amplifier is configured to exhibit approximately 50 Ω impedance for said third frequency band.

12. The antenna device according to claim 11, comprising third filtering means (9), fourth filtering means (10) and fifth filtering means (10), wherein said third filtering means is configured to high-pass said third frequency band and to block said first and second frequency bands and to approximately 50 Ω match said radiating element for said third frequency band, said fourth filtering means is configured to band-pass said third frequency band, said fifth filtering means is configured to high-pass said third frequency band and to block said first and second frequency bands and to approximately 50 Ω match said low noise amplifier for said third frequency band, and said radiating element is connected to said third filtering means, which third filtering means is connected to said fourth filtering means, which fourth filtering means is connected to said fifth filtering means, which fifth filtering means is connected to said low noise amplifier.

13. A portable radio communication device, characterized in that it comprises an antenna device according to any of claims 1-10 and a first receiver (7) for reception of said first frequency band and a second receiver (8) for reception of said second frequency band, wherein both receivers are connected to said low noise amplifier through diplex means (5, 6).

14. A portable radio communication device, characterized in that it comprises an antenna device according to claim 11 or 12 and a first receiver (7) for reception of said first frequency band, a second receiver (8) for reception of said second frequency band, and a third receiver (13) for reception of said third frequency band, wherein all receivers are connected to said low noise amplifier through triplex means ( 5 , 6 , 12 ) .