WO2004091233A1

WO2004091233A1 - An apparatus for signal reception

Info

Publication number: WO2004091233A1
Application number: PCT/SE2004/000569
Authority: WO
Inventors: Carl Gustaf Blom
Original assignee: Perlos Ab
Priority date: 2003-04-09
Filing date: 2004-04-08
Publication date: 2004-10-21
Also published as: CN100362883C; CN1768543A; SE525069C2; WO2004091233A9; SE0301066D0; SE0301066L; EP1616444A1

Abstract

The disclosure relates to an apparatus for receiving signals in the FM and VHF/UHF bands in an electronics unit, such as a cell or mobile telephone which has a reproduction circuit. The reproduction circuit is connected to an antenna unit via a tuner unit. The antenna unit has a fist conductor (11) and a second conductor (13) which are placed in spaced apart relationship to one another and also display a surface spatial extent. The first conductor (11) is connected to the RF input (8) of the reproduction circuit via an extension coil (9) and a tuner unit (3). The second conductor (13) is connected to earth (12) in an unbalanced version and is unearthed in a balanced version.

Description

AN APPARATUS FOR SIGNAL RECEPTION

TECHNICAL FIELD

The present invention relates to an apparatus for receiving signals in the FM and VHF/UHF bands in an electronics unit such as a cell or mobile telephone, comprising a reproduction circuit which is connected to an antenna unit via a tuner unit.

BACKGROUND ART

The terms FM and VHF UHF transmissions are taken in the following description to signify both conventional analog FM and VHF/UHF transmissions and their digital counterparts such as, for example, DAB(Digital Audio Broadcasting) and digital TV.

It is previously known in the art to integrate in a cell or mobile telephone an FM radio which is powered by the standard battery of the mobile telephone and which as a rule employs the loudspeaker of the mobile telephone. ^■ „

FM transmissions employ a frequency band of 88 to 108 MHz. This implies that a quarter wave antenna will be approximately 75 cm in length, and consequently such an antenna cannot be housed within the construction dimensions displayed by a conventional mobile telephone. VHF/UHF transmissions take place at slightly higher frequencies, but the problem is largely the same. This entails that an external antenna must be used, which is often realised in such a manner that use is made of the conductors or the cable that may be included in a so- called hands-free unit connected to the mobile telephone. However, this solution is clumsy and inconvenient and only works when the hands-free unit is available.

Transmissions in the pertinent frequency bands may encompass both TV and radio signals.

PROBLEM STRUCTURE

The present invention has for its object to design the apparatus intimated by way of introduction so that it may be built in interiorly into an electronics unit of small dimensions, such as, for example, a cell or mobile telephone or portable music player (for example MP3). The present invention further has for its object to design the apparatus so that it will be simple and economical to manufacture, that it may be retrofitted in an existing electronics unit without requirements for extra space, and that it does not disturb the normal functions of the electronics unit. Finally, the present invention has for its object to design the apparatus so as to afford the possibility of connecting an external antenna without any reswitching between the antennas needing to be put into effect.

SOLUTION

The objects forming the basis of the present invention will be attained if the apparatus intimated by way of introduction is characterised in that the antenna unit includes a first and a second conductor of spatial extent, disposed in spaced apart relationship to one another, the first conductor being connected, via an extension coil and a tuner unit, to the RF input of the reproduction circuit, while the second conductor is connected to earth in an unbalanced version and is unearthed in a balanced version.

As a result of this design of the apparatus according to the present invention, the, space requirements are reduced by a factor of 100 compared with the more conventional design of the antenna, such as a quarter wave antenna.

According to one preferred embodiment of the present invention, the first and the second conductors also include electrically conductive, for example metalised, surfaces on an inner or an outer casing for the electronics unit produced from dielectric material.

For example, the conductors may also be designed as separate conductive components, for instance metal plates.

As a result of these characterising features, the major advantage will be afforded that the space requirements interiorly in the electronics unit are in principle non-existent.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail hereinbelow, with reference to the accompanying Drawings. In the accompanying Drawings: Fig. 1 is a block diagram of an FM radio function;

Fig. 2 is a schematic diagram of the antenna device included in the apparatus according to the present invention;

Fig. 3 is a scnematic view showing the positioning ot the antenna device according to the present invention;

Fig. 4 shows one example of a circuit diagram for a passive tuner unit; and

Fig. 5 shows one example of a circuit diagram for an active tuner unit.

DESCRIPTION OF PREFERRED EMBODIMENT

In the following description, use will be made of a mobile telephone as one example of an electronics unit where the present invention may be put into effect. Other examples are mobile terminal units of different types, such as PDA (Personal Digital System), portable music players (e.g. MP3 players) etc.

In the following description, the reproduction circuit is exemplified concretely by means of an FM radio circuit, but other practical applications, such as the reception of TV signals, are naturally also possible. In such instance, the reproduction circuit is adapted to the practical application in question. Correspondingly, the present invention is also applicable to other frequencies. Principally, the present invention is conceived for use in the frequency range of 70 to 800 MHz.

Referring to the Drawings, in Fig. 1, reference numeral 1 relates to a battery which may be the standard battery of the terminal unit or the mobile telephone, but which may also be a battery specifically provided for the FM radio function. Reference numeral 2 relates to a reproduction circuit in the form of an FM radio circuit which may be of standard type, for example a circuit manufactured by Philips and marketed under the designation TEA5767. In order that the signal-to-noise relationship will be as favourable as possible, it should be set in the mono mode. The stereo mode may also be used in those cases where there are possibilities for stereo listening, for example via a headset. In future possibilities for RDS (Radio Data System), this function may also be included in the reception. Such a circuit generates a control or excitation voltage of between approx. 0.5 and 3 volts which is proportional to the frequency in question. According to the present invention, this voltage is used for controlling a tuner circuit 3 which is connected between the FM radio circuit 2 and an antenna device 5.

The FM radio circuit has an output which is connected to the standard loudspeaker 4 of the mobile telephone, which hence normally operates in mono mode. The invention may also be employed in stereo applications (including future RDS), for example when listening may be put into effect using two integral loudspeakers or via a headset.

Finally, in Fig. 1, reference numeral 6 relates to the output for the control voltage of the FM radio circuit 2, which reference numeral 7 relates to a corresponding input on the tuner unit 3.

Antennas may generally be designed according to known principles with balanced and unbalanced design. The term balanced design is taken to signify that both branches of the antenna are disconnected from earth while unbalanced design means that the one branch of the antenna is earthed.

Fig. 2 shows a schematic diagram of the antenna device 5 and it will be apparent that the antenna device has a connection 8 for RF supply, an extension coil 9 and a radiator 10 with a capacitative end loading 11. Advantageously, the connection 8 is connected to the RF input of the FM radio circuit via the tuner unit 3.

The antenna device 5 further includes an earth connection 12 and a counterweight 13 in the unbalanced version. The earth connection is omitted in the balanced version.

The end loading 11 and the counterweight 13 should have as large surface area as possible and their longitudinal extent should be from a few centimetres up to approximately 10 cm. The larger the area of the end loading 11, the lower will be the inductance value of the extension coil 9.

Fig. 3 shows by means of broken lines 14 an apparatus casing for the mobile telephone, which also displays an antenna 15 intimated by broken lines. It will further be apparent from Fig. 3 that the antenna device of the FM radio circuit is located at as great a distance as possible away from the antenna 15 of the mobile telephone, i.e. at the end of the casing facing away from the antenna 15. Furthermore, the end loading 11 and the counterweight 13 are disposed as far away from one another as possible and, in the illustrated embodiment, along opposing side edges of the casing 14. Finally, the antenna device 5, primarily the end loading 11 and -5- the counterweight 13 should be disposed as far away as possible from the earth plane of the mobile telephone.

In terms of production, the casing 14 may be both an inner casing for the mobile telephone and its outer casing. The conductors between the connections 8 and 12, the extension coil 9

10 which is suitably in meandering configuration, and the end loading 11 and counterweight 13 may be produced by metalisation on the casing 14, provided that this is manufactured from a non-magnetic and electrically insulating material. For example, manufacture of the above- mentioned components may be put into effect using so-called MID techniques. This positioning of the antenna device 5 on the casing 14 entails that the antenna device will

15 approach very closely to a hand which holds the mobile telephone, a situation that could disturb its operation. Normally, this is not a problem, since the mobile telephone, in FM reception, generally lies free, for example on a table.

The conductors 11 and 13 may also be designed as separate metal plates.

20

According to the present invention, the extension coil 9 may be realised as a discrete inductor which is disposed on the casing 14.

Alternatively, the extension coil 9 may also be disposed on a circuit card in the mobile 25 telephone. In such instance, this circuit card suitably also carries the tuner circuit 3. This version is particularly appropriate when the extension coil 9 consists of the primary winding in a transformer included in the tuner unit (as will be described in greater detail hereinbelow).

The tuner units 3 shown in Figs. 4 and 5 serve the purpose of realising, on the one hand, a 30 frequency tuning controlled by the control or excitation voltage from the FM radio circuit, as well as an impedance adaptation between the antenna unit 5 and the FM radio circuit..

Fig. 4 illustrates a preferred embodiment of a circuit diagram for a passive tuner unit 3. It will be apparent from the Figure that the counterweight 13 has an earth connection 12 and that there is disposed, between the extension coil 9 and the earth connection, a primary winding 17 included in a transformer TR. The secondary winding 19 included in the transformer TM is connected with its one end to earth 12 while the opposing end of the winding is connected to a conductor 19 which, via a capacitance 20, is in communication with a connection 16 which -§- connects the tuner unit 3 with the FM radio circuit.2 (see Fig. 1).

The control or excitation voltage from the FM radio circuit 2 is supplied to the tuner unit 3 via the input 7 and a resistor 20 which is also connected to two counterconnected varicap diodes

22. The two sides of the varicap diodes facing away from one another are connected to earth 0 at 12 and to the conductor at 19, respectively. The capacitance of the varicap diodes 22 varies as a function of the control or excitation voltage via the input 7, in which event different capacitance values give different sensitivity regions within the FM band.

The transformer TR is an autotransformer and is disposed for impedance adaptation to the 15 antenna 10. The primary winding of the transformer, i.e. the winding 17, constitutes a part of the extension coil 9, but can, in a different embodiment, also constitute the whole of this coil. In such an embodiment, the extension coil designated 9 is omitted.

Fig. 5 shows one preferred embodiment of a circuit diagram for an active tuner unit 3. In this 0 embodiment, the two counter-connected varicap diodes 22 are connected in parallel across the primary winding 17 of the transformer TR. Between the varicap diodes 22 and via a resistor

23, the tuner unit 3 has its input 7 for control voltage. Like the above-described embodiment, the end of the primary winding 17 facing away from the antenna 15 is connected to earth at the connection 12.

25

The secondary winding 24 of the transformer TR is connected to an amplifier 25 which, on the one hand, has a connection to earth 12 and, on the other hand, a connection 26 for supply voltage. The amplifier 25 has an output which, via a capacitance 27, is connected to the output 16 from which the FM radio circuit 2 is supplied.

30

The embodiment of the tuner unit 3 illustrated in Fig. 5 realises, in addition to frequency tuning and impedance adaptation, also an amplification of the output signal, which improves the signal-to-noise relationship. The tuner unit may, in certain applications, be simplified and the tuning frequency be set at the centre of the frequency band.

The amplifier 25 is of standard type with low noise factor and an amplification of approx. 10 *£=

If, in some situation, even better reception were to be desired than that which may be obtained using the antenna device 5 according to the invention, this may be achieved by connection of an external antenna to the connection 16 (see Figs. 1, 4 and 5). The external antenna connected in this manner will then assume the functions of the antenna device 5 and the tuner unit 3 without any disconnection or reconnection needing to be put into effect. Nor will the external antenna disturb the normal function of the mobile telephone.

The FM radio circuit 2 is usually mounted on the circuit card of the mobile telephone together with the tuner unit 3. In the case of the active tuner unit, the amplifier 25 can be positioned in the tuner unit 3, as shown in Fig. 5, or be integrated in the FM radio circuit 2.

DESCRIPTION OF ALTERNATIVE EMBODIMENTS

In addition to by metalisation, the conductors 11 and 13, as well as the extension coil 9, may also be produced as electrically conductive surfaces with the aid of other solutions, such as conductive plastic material or a conductive surface which is applied on a circuit card or a flexible film, a so-called flexfilm. The conductive surface may be integrated in an existing casing or some other existing, non-conductive component which is included in the electronics unit and even on an existing circuit card or an existing flexfilm. A further variation possibility is that both the inside and the outside of the outer casing of the electronics unit may be utilised for applying the conductive surface.

The conductive surfaces may also be designed as separate components, such as metal plates, conductive plastic, circuit card or flexfilm. The component may then be placed at a suitable position in the electronics unit. For optimum function, the positioning should be as close to the outer casing of the electronics unit as possible, and as far away as possible from any other eventual radiators which are included in the electronics unit. In a manner corresponding to that described above for the conductive surfaces, the separate components may also be applied on the inside or outside of the outer casing.

As was mentioned above, the present invention is not restricted to FM radio reception, since -5- the antenna may readily be adapted to the desired frequency band find be employed within other practical applications, such as TV reception.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for receiving signals in the FM and VHF/UHF bands in an electronics unit such as a cell or mobile telephone, comprising a reproduction circuit (2) which is &otmected- Q-an- t nfla-um1^5^ characterised in_thfllihe_antenna unit_

(5) includes a first (11) and a second (13) conductor of spatial extent, disposed in spaced apart relationship to one another, the first conductor (11) being connected, via an extension coil (9) and a tuner unit (3), to the RF input (8) of the reproduction circuit, while the second conductor (13) is connected to earth (12) in an unbalanced version and is unearthed in a balanced version.

2. The apparatus as claimed in Claim 1, characterised in that the first (11) and the second (13) conductors include electrically conductive surfaces on an inner or outer casing (14) for the electronics unit produced from dielectric material.

3. The apparatus as claimed in Claim 1, characterised in that the first (11) and the second (13) conductors include electrically conductive surfaces on existing, non-conductive components, in addition to the casing (14) of the electronics unit.

4. The apparatus as claimed in Claim 2 or 3, characterised in that the electrically conductive surfaces are metalised surfaces.

5. The apparatus as claimed in Claim 1, characterised in that the first (11) and the second (13) conductors comprise separate conductive components.

6. The apparatus as claimed in Claim 5, characterised in that the separate conductive components are metal plates.

7. The apparatus as claimed in any of Claims 1 to 6, characterised in that the extension coil (9) comprises a meander-configured metalisation on an inner or outer casing (14) for the electronics unit produced from dielectric material.

8. The apparatus as claimed in any of Claims 1 to 7, characterised in that the first (11) and the second (13) conductors are disposed at maximum displacement to the end of the casing (14) of the electronics unit facing away from the electronics unit's own antenna device (15).

9. The apparatus as claimed in any of Claims 1 to 8, characterised in that the first (11) ^ -and l^-second-.Cl )-x mduc-lJors are elong-tte^and-dis Ωssd^l g φpαsm^

(14) of the electronics unit.

10. The apparatus as claimed in any of Claims 1 to 9, characterised in that the tuner unit (3) is operable under the action of a control voltage from the reproduction circuit (2).

10

11. The apparatus as claimed in Claim 10, characterised in that the tuner unit (3) is a passive tuner unit.

12. The apparatus as claimed in Claim 10, characterised in that the tuner unit (3) is an 15 active tuner unit.

13. The apparatus as claimed in any of Claims 1 to 12, characterised in that an amplifier is integrated in the reproduction circuit (2).