WO2004023598A1

WO2004023598A1 - Antenna device

Info

Publication number: WO2004023598A1
Application number: PCT/SE2003/001370
Authority: WO
Inventors: Carl Gustav Blom
Original assignee: Perlos Ab
Priority date: 2002-09-04
Filing date: 2003-09-03
Publication date: 2004-03-18
Also published as: SE0202603D0; SE524871C2; AU2003261687A1; SE0202603L

Abstract

The disclosure relates to an antenna device for a portable radiocommunications apparatus, for example a so-called cell or mobile telephone, which has at least one but preferably several operating frequencies within one frequency range. The frequency range has a width of several times the lower limit frequency of the frequency range, for example 800-2200 MHz. The antenna device has a radiating structure in the form of a continuous conductor. At least a first and a second section of the conductor are connectable to and disconnectable from each other. The interconnection takes place by the intermediary of connecting devices that are controlled by a control unit.

Description

ANTENNA DEVICE

TECHNICAL FIELD

The present invention relates to an antenna device for a portable radiocommunications apparatus, for example a so-called cell or mobile telephone, PDA or laptop, with at least one, but preferably several operating frequencies within a frequency range of a width of several times the lower limit frequency of the frequency range, for example 800-2200 MHz, and comprising a radiating structure in the form of a continuous conductor.

BACKGROUND ART

Within mobile telephony, use is made of numerous different frequency bands within a large, wide frequency range. Thus, EAMPS operates at 824 MHz, while UMTS has an operating frequency of 2200 MHz. In between, there are an additional number of frequency bands that are employed in mobile telephony.

The different operating frequencies are partly geographically determined so that certain operating frequencies are employed in America and others in the Far East. This implies that hitherto it has largely been necessary to adapt a mobile or cell telephone to that geographic region in which it is to be used. This entails in itself a problem since, among other things, the antenna of the mobile or cell telephone must have different appearances depending on the operating frequency selected. In addition, it has hitherto only been possible to a limited extent to employ one and the same mobile telephone in several different places. Thus, in the event of long journeys, it has often been necessary to carry one mobile telephone for one geographic region and another mobile telephone for another geographic region.

Within the technology of amateur radio, there is a commercial antenna device which is marketed under the name "miracle whip antenna". This antenna device comprises a 1.2 m long telescopic antenna rod which is secured on a housing in which is disposed a stepwise variable inductance and a connection to a transceiver device. By alteration of the inductance connected in series with the antenna rod and by adaptation of the length of the antenna rod proper, the antenna device may be caused to operate within a broad frequency band. Possibly, this technology could be scaled down to the frequency ranges which are employed in mobile telephony. However, the length adjustment of the rod antenna involves major problems since such an adjustment would require some form of servo motor which, because of the power needs, is not acceptable in a battery-powered mobile telephone.

Antenna devices are previously known in the art which are composed of a number of radiating components and which are interconnectable or connectable and disconnectable in different combinations.

Mechanical, adjustable components are not relevant in the field of technology under consideration here because of their size and a requirement on some form of electrically powered operating device. Varactors and FET switches entail problems in that they give rise to intermodulation and switches which are based on Pin diode technology are unusable at least in battery-powered applications, because of their power consumption.

PROBLEM STRUCTURE

The present invention has for its object to design the antenna device intimated by way of introduction so that it may operate at a plurality of different operating frequencies within a wide frequency band. The present invention further has for its object to realise an antenna device which is simple and economical in manufacture, and also reliable in operation, as well as displaying extremely low or preferably no power consumption of its own. Finally, the present invention has for its object to realise an antenna device with compact outer dimensions.

SOLUTION

The objects forming the basis of the present invention will be attained if the antenna device intimated by way of introduction is characterised in that at least a first and a second section of the conductor are, by means of connecting devices controlled by a control unit, connectable an disconnectable to and from each other, respectively. 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 shows a first embodiment of a radiating device according to the present invention;

Fig. 2 shows a second embodiment of a radiating device according to the present invention;

Fig. 3 shows a third embodiment of a radiating device according to the present invention;

Fig. 4 shows a fourth embodiment of a radiating device according to the present invention;

Fig. 5 shows a fifth embodiment of a radiating device according to the present invention; and

Fig. 6 shows a sixth embodiment of a radiating device according to the present invention;

DESCRIPTION OF PREFERRED EMBODIMENT

For some time, there have been on the market a group of components that are produced using MEMS technology (Micro Electro Mechanical Systems) and that comprise switches, capacitances - both fixed and variable - as well as inductances that are also fixed and variable. The components are physically small, of the order of magnitude of 0.5 to 1 or a few mm, but in certain cases even smaller, and can readily be integrated in larger units.

The mass of the moving parts is extremely slight, for which reason these components, on the one hand, require extremely slight energy for their operation and, on the other hand, can be made ultra-rapid. This does not give rise to intermodulation problems. Operation of the MEMS components can be electrostatic or electromagnetic. The electrostatic operation requires a relatively high voltage of 10V or more, but, on the other hand, consumes no current. The electromagnetic operation consumes a certain amount of current but, on the other hand, needs no high voltage.

The objects of the present invention may be attained by alterations in the radiator or radiating structure that transmits and receives RF energy.

Two fundamentally different basic variations are possible, namely first a radiating structure that has a number of radiating components that, by means of connecting devices controlled by a control unit, may be connected and disconnected to and from a radiating component respectively, which in turn is directly or indirectly connected to a supply conductor and, secondly, a radiating structure in the form of a continuous conductor where at least a first and a second section of the conductor are, by means of connecting devices controlled by a control unit, connectable and disconnectable to and from each other, respectively.

Combinations of these two in principle different variations are also possible, as well as combinations with switchable or modifiable matching networks.

The connecting devices are preferably of the MEMS type and may be designed for galvanic connection, capacitative connection or inductive connection. Variations where a varying degree of connection exist may be relevant in all embodiments.

Fig. 1 shows a first embodiment which, in electric terms, may be likened to a rod antenna of variable length.

It will be apparent from the Drawing that a coaxial cable 41 has a supply point 43 on an elongate radiating component 42 in the form of an electric conductor. The connection between the coaxial cable 41 and the conductor 42 is permanent.

The antenna device according to Fig. 1 includes further radiating components in the form of conductors 44, 45 and 46. These conductors 44-46 are also elongate in configuration and are, in one practical version, arranged considerably more proximal one another in the longitudinal direction of the antenna device than is intimated on the Drawing. Between adjacent conductors, there are disposed connecting devices 47, 48 and 49 which are shown on the Drawing as switches.

In Fig. 1, all switches 47-49 are open, but if the switch 47 is closed, this will have as a result that the effective length of the antenna device is, doubled compared with if the switch 47 is open. This will have as a result that the resonance frequency of the antenna device is halved.

By closing the switch 48 as well, there will be realised a further extension of the antenna device, and so the resonance frequency falls even further. In a corresponding manner, the resonance frequency will be even lower if the conductor 46 is also connected in to the antenna device by closing the switch 49.

In the Figure, the conductors 42 and 44-46 are shown as having different lengths, which implies that the frequency modification steps will be of different sizes when the switches are closed. Naturally, the conductors may also have the same length and of course they may be both more and fewer in number.

The embodiment according to Fig. 1 may be modified in that a second array of conductors is provided in addition to the conductors 42 and 44-46. In such instance, one conductor in the second array may be connected to the coaxial cable 41. Between the individual conductors 42 and 44-46 in the one array and at least some of the conductors in the second array there are bridge connections with switches.

Fig. 4 shows a second embodiment of a radiating structure which comprises radiating components of which a first radiating component 50 is, by the intermediary of a supply point 51, connected to a coaxial cable 52. The first radiating component 50 is a conductor which is elongate in configuration and from which there extend out laterally three branch conductors 53, 54 and 55. The radiating component 50 with its branch conductors 53-55 is manufactured as a single continuous conductor. To each one of the branch conductors 53-55, additional conductors 56-58 may be connected either individually or in combinations by means of connecting devices 59-61 in the form of switches. As an alternative to the switches 59-61, use may also be made - as was intimated above - of connecting devices for capacitative and/or inductive connection with fixed or variable degrees of connection.

It will be apparent from Fig. 4 that the additional conductors 56-58 are of different lengths while, on the other hand, the branch conductors 53-55 are shown has having the same length, although this is not necessary.

In the embodiment according to Fig. 4, one or some of the conductors 56-58 may be permanently connected to the conductor 50. Between the conductors 56-58, there may also be provided connecting bridges with switches. Further, there may be connecting bridges with switches disposed between the conductors 53-55.

Fig. 5 shows a third embodiment of a radiator which has three mutually discrete and separate conductors 62, 63 and 64. The conductor 62 is in the form of a rectangular or square plate and has a supply point 65 by the intermediary of which it is connected to a coaxial cable 66. The conductors 63 and 64 are disposed about the central or core conductor 62 and are approximately in the form of square frames or rectangular frames which have apertures 67 and 68 for passage of the coaxial cable 66. At least one connecting device 69 is disposed between the core conductor 62 and the centrally disposed conductor 63. Correspondingly, at least one connecting device 70 is provided for interconnecting the centrally located conductor 63 and the outermost conductor 64.

The connecting devices 69 and 70 are shown as switches, but they may also be designed for capacitative or inductive connection between the conductors. Further, the positioning of the connecting devices 69 and 70 is shown only for purposes of exemplification, for which reason the positioning may be totally different than that shown on the Drawing. It is also possible to employ more than two connecting devices.

Also in this embodiment, use may be made of more connecting bridges than those shown on the Drawing at 60 and 70, for example connecting bridges which, via switches, close the apertures 67 and 68. Further, the supply via the coaxial cable may be connected to more than the innermost core conductor 62. Fig. 2 shows an in principle slightly different embodiment of the antenna device according to the present invention. In this embodiment, there is a single continuous conductor 71 which is in the form of an approximately C-shaped frame with approximately right-angled corners. The frame has an aperture 72 which is bridgeable or connectable via a connecting device 73 shown in the form of a switch. With the connecting device 73 closed, the conductor 71 will have the configuration of a closed, square annulus while, with the connecting device 73 open, it will have the previously described open, square C-shape.

The conductor 71 has a supply point 74 and an earth point 75 by the intermediary of which it is connected to a coaxial cable 76.

Fig. 3 shows yet a further embodiment of the antenna device according to the present invention. In this embodiment, use is made of a conductor 77 in the form of a meander which, in its one end, has a supply point 78 by the intermediary of which it is connected to a coaxial cable 79. A winding in the meander-shaped conductor 77 may be short-circuited by means of a connecting device 88 in the form of a switch.

The illustrated positioning of the connecting device is only made for purposes of exemplification, for which reason the positioning may be between any whatever of two adjacent sections of the meander 77. Naturally, more connecting devices may be employed, which are intended for interconnecting other, adjacent sections of the meander.

Fig. 6 shows yet a further embodiment of the antenna device according to the present invention. In this embodiment, use is made of a conductor 81 in the form of a square, planar helix which, in its outer end, has a supply point 82 by the intermediary of which it is connected to the core conductor in a coaxial cable 83.

Also in this embodiment, adjacent sections of the conductor 81 are connectable to one another by the intermediary of connecting devices 84 and 85 which are designed as switches.

The positioning of the connecting devices 84 and 85 shown on the Drawing is merely for purposes of exemplification, for which reason totally different positionings may be relevant, as well as only one connecting device, but also more than two. For controlling the antenna devices according to Figs. 1 - 6, use is made of a control unit which may be integrated in the radiating structure or be formed as a separate unit. The control unit receives control signals that may be of two in principle different types, namely control signals that reflect the operational status in the transceiver circuits of the mobile telephone, and control signals that reflect the effects of the ambient surroundings on the mobile telephone. As examples of the first type of control signal, mention might be made of frequency (transmitted and received, respectively) and operational status (e.g. GSM, PCS, DCS, AMPS or UMTS). As examples of the second type of control signal, mention might be made of RSSI (receiver signal strength indicator), the transmitter's VSWR (voltage standing wave ratio), BER (bit error rate) and C/N (carrier/noise).

The software in the control unit controls so that one of the parameters or a combination of them is optimised. By such means, the combination of connecting devices is entered which gives that resonance frequency which in turn gives optimum operation in view of operational status and the actual ambient conditions.

For different operational statuses according to the foregoing, pre-set values are programmed in. If the telephone is employed for GSM, the above-described switches are thus set in preprogrammed positions that give optimum function across the GSM region when the telephone is employed in normal speech mode. If any of the control signals, for example RSSI shows a low value, the control unit takes over and tests that combination of statuses which gives the best resonance frequency for the relevant frequency being employed.

If possible, conventional radiating structures are made for adaptation to 50Ω. The actual impedance that the telephone displays can however vary and deviate from 50Ω, but is most generally transformed to this value. With the control unit according to the present invention, the impedance can be adapted to the relevant impedance that the circuits of the telephone display before the impedance transformation to 50Ω.

Claims

WHAT IS CLAIMED IS:

1. An antenna device for a portable radiocommunications apparatus, for example a so- called cell or mobile telephone, with at least one, but preferably several operating frequencies within a frequency range of a width of several times the lower limit frequency of the frequency range, for example 800-2200 MHz, and comprising a radiating structure in the form of a continuous conductor (71; 77; 81), characterised in that at least a first and a second section of the conductor (71; 77; 81) are, by means of connecting devices (73; 88; 84, 85) controlled by a control unit, connectable and disconnectable to and from each other, respectively.

2. The antenna device as claimed in Claim 1, characterised in that the connecting devices (73; 88; 84, 85) are disposed for galvanic connection.

3. The antenna device as claimed in Claim 1, characterised in that the connecting devices (73; 88; 84, 85) are disposed for inductive connection.

4. The antenna device as claimed in Claim 1, characterised in that the connecting devices (73; 88; 84, 85) are disposed for capacitative connection.

5. The antenna device as claimed in any of Claims 1 to 4, characterised in that the connecting devices (73; 88; 84, 85) are of the MEMS type.

6. The antenna device as claimed in any of Claims 1 to 5, characterised in that the control unit at least has input signals that reflect the operational status in the transceiver circuits of the mobile telephone.

7. The antenna device as claimed in any of Claims 1 to 6, characterised in that the control unit at least has input signals that reflect the effects of the ambient surroundings on the mobile telephone.

8. An antenna device for a portable radiocommunications apparatus, for example a so- called cell or mobile telephone, with at least one but preferably several operating frequencies within a frequency range of a width of several times the lower limit frequency of the frequency range, for example 800-2200 MHz, comprising a radiating structure with a number of separate radiating components (42, 44-46; 50, 56-58; 62-64), characterised in that a first radiating component (42, 50, 62) has a connection (43, 51, 65) to a power supply conductor (41, 52, 66); and that a number of additional radiating components (44-46; 56-58; 63, 64) are, by means of connecting devices (47-49; 59-61; 69, 70) controlled by a control unit, directly or indirectly connectable and disconnectable to the first radiating component; and that, within at least some of the radiating components, there are bridge connections provided with connecting devices which unite different sections of one and the same component.