WO2001065635A1

WO2001065635A1 - Extendable antenna

Info

Publication number: WO2001065635A1
Application number: PCT/SE2001/000208
Authority: WO
Inventors: Ulf Palin; Gunnar Edqvist
Original assignee: Allgon Ab
Priority date: 2000-02-29
Filing date: 2001-02-05
Publication date: 2001-09-07
Also published as: AU2001234268A1; SE517514C2; SE0000657L; SE0000657D0

Abstract

An extendable whip antenna comprising a lower portion (2) mountable through an opening in a holder (3) in a radio communication device, said lower portion (2) comprising at least one rod-like radiating antenna element (4) at least partially covered by a dielectric material. The antenna comprises an engaging portion (6a) constituting an integral part of the lower portion (2), said engaging portion being resiliently engageable with an engaging element (7) in the holder. The engaging portion (6a), is adapted to pass the engaging element (7) during insertion of the lower portion (2) into the holder (3), whereas said engaging portion (6a), mechanically engages with the engaging element (7) when being pulled in the opposite direction, so as to prevent the antenna from being detached from the radio communication device. The engaging portion (6a), could also be adapted to electrically couple the radiating element to said engaging element (7).

Description

EXTENDABLE ANTENNA

Field of the invention

The present invention relates to an extendable whip antenna according to the introductory portion of claim 1. Specifically, the invention concerns an extendable antenna having means for mechanically locking the antenna in its holder, preventing it from being detached once it has been attached to the radio communication device, and/or means for electrically connecting the antenna to the radio communication device.

Background of the invention

A general problem with extendable whip antennas, which are to be assembled with a radio communication device, is the additional assembly steps needed. The assembly steps add to cost and labour needed to accomplish a fully functional device. Typically, the antenna is inserted into an antenna holder in the radio communication device and, once inserted, a separate component, often called a stopper, is attached to the antenna at its lower end, which prevents it from being removed from the holder. The stopper can be attached by using an adhesive or by compressing it such that it attaches to the antenna, or by using other fastening means. Such an antenna, provided with a stopper, is disclosed in e.g. US Pat. No 5,546,094. Extended antennas, which are not retractable, suffer from the same problem as the extendable antenna described above, since once inserted into the antenna holder, it needs to be fastened in its position by attaching a stopper to the antenna.

To establish electrical connection between the radiating antenna element and the RF transceiver in the radio communica- tion device, one or more electrically conductive components are often needed, which mediates the connection from the typically centrally positioned radiating element to a connecting element in the radio communication device, positioned below or beside the antenna. This electrically conductive component may be constituted by a conductive stopper on the antenna, which in that case fulfils both the mechanical retaining function and the electrical conduction function, and suffers from the same problems as above. Manufacturing antennas with such a conductive portion adds additional assembly steps, and the cost of the conductive portion is added to the total cost of the antenna .

US Pat. No 5,945,952 discloses an extendable antenna with an electrically conductive frusto-conical sleeve attached to the lower end of the antenna. The sleeve interacts mechanically and electrically with a collar at the opening in the radio communication device housing for insertion of the antenna. The upper surface of the sleeve is perpendicular to the cylindri- cal surface of the antenna, and the sleeve smoothly decreases in diameter towards the lower end. This design allows the antenna to be inserted into the collar, but once it has been inserted, it cannot be pulled out, since the sleeve engages a locking means in the collar when it is being pulled out. In addition, the sleeve engages an electrical contact means when it engages the mechanical locking means, thus electrically connecting the antenna to the radio communication device RF transceiver. The embodiments disclosed in this document, however, need a separate sleeve component to be attached to the antenna, thus increasing the number of components and the number of assembly steps in the manufacturing process. Summary of the invention

An object of the invention is to provide an extendable antenna which does not suffer from the above-mentioned problems and drawbacks .

It is an object of one aspect of the invention to provide an extendable, or non-rectractable extended antenna, which can simply be inserted into a radio communication device, and is prevented from being pulled out of the radio communication device after insertion, without having to add a separate component, after the antenna has been assembled with the radio communication device. This is achieved by providing the dielectric material covering the antenna with one or more engaging portions, e.g. in the form of barbs, or recesses or through- holes in the antenna. These engaging portions are designed such that they resiliently interact with an engaging element in the radio communication device opening for insertion of the antenna. The engaging portions have one part, which allows the antenna to slide into the radio communication device, and a substantially transverse surface which lockingly engage the locking means .

Another object of the invention is to provide an antenna, which does not need an additional conductive portion to be assembled with the antenna, to electrically connect the rod-like radiating antenna element to the radio communication device. This is achieved by fully or partially exposing the radiating element, at the lower end surface of the antenna or using a recess at or a hole through the lower end portion of the antenna, which reaches the radiating element. The exposed radiating element can then engage with a conducting element in the radio communication device, thus electrically connecting the radiating element to the RF transceiver in the radio communication device. Optionally, the radiating element may be partially exposed only, so as to capacitively couple the radiating element to the transceiver.

The two aspects of the invention, i.e. the mechanical locking function and the electrical connection function, can be achieved simultaneously simply by adding both a mechanical locking portion, and, independently, an electrical connection portion, each interacting with associated engaging elements in the opening in the radio communication device for insertion of the antenna. More advantageously, the two functions are combined using a single portion, which fulfills both functions. Such an embodiment solves the object of achieving an extend- able antenna comprising a single portion which mechanically locks the antenna to the radio communication device when it has been inserted, preventing it from being disengaged, and concurrently electrically connects it to the radio communication device, constituting an integral part of the antenna, i . e . no additional components need to be added after manufacturing of the antenna. The engaging portion can mechanically engage a mechanical locking element in the opening, and engage a separate electrical connection element, or the two functions can be achieved with a combined mechanical locking and elec- trical connection means.

It is generally an object of the present invention to provide an antenna which can simply be inserted into the radio communication device, and is prevented from being pulled out after insertion, or an antenna which does not need an additional conductive portion to be assembled with the antenna, to electrically connect the radiating antenna element to the radio communication device, or an antenna which has both these advantageous properties.

Brief description of the drawings

Fig. 1 is a perspective view of an extendable antenna according to the invention, and are associated holder (located in a non-illustrated radio communication device) .

Fig. 2a shows the lower end of an antenna with one embodiment of the engaging portion (left) for mechanically locking the antenna, and a corresponding holder (right) .

Fig. 2b shows a second embodiment of the engaging portion (left) and a corresponding holder (right) .

Fig. 2c shows a third embodiment of the engaging portion (left) and a corresponding holder (right) .

Fig. 2d shows a fourth embodiment of the engaging portion in a top view (top left) , a cross-sectional side view (bottom left) and a cross-sectional side view of a corresponding holder (right) .

Fig. 3a shows a first embodiment of the engaging portion for electrically connecting the antenna to the radio communication device in a top view (top left) , a cross-sectional side view (bottom left) , and a cross-sectional side view of a corresponding holder (right) .

Fig. 3b shows a second embodiment of the engaging portion in top view (top left) , a cross-sectional side view (bottom left) , and a cross-sectional side view of a corresponding holder (right) .

Fig. 3c shows a third embodiment of the engaging portion in top view (left) , and a cross-sectional top view of a corresponding holder (right) .

Fig. 3d shows a fourth embodiment of the engaging portion in top view (top left) , a cross-sectional side view (bottom left) , and a cross-sectional side view of a corresponding holder (right) .

Description of preferred embodiments

Fig. 1 shows one embodiment of the extendable whip antenna

(left) , with the lower end portion (to the right) comprising an engaging portion 6a for preventing the antenna from being pulled out from an associated holder (right) once it has been inserted into the holder, and a further engaging portion 4 for electrically connecting the antenna to the radio communication device RF transceiver. The holder is provided with corresponding engaging elements 7 for lockingly engaging the engaging portion 6a, and further engaging elements (not shown) for electrically connecting the engaging portion 4. The lower end portion of the antenna is the one facing the holder in the drawing, whereas the opposite or top portion of the antenna in some cases may contain an auxiliary antenna element, which typically is electrically engaged only when the antenna is in its retracted position. Such an auxiliary antenna element, which could be a helix or meander antenna, may alternatively be provided at the upper end of the antenna or, optionally, the radio communication device may be provided with such an auxiliary antenna, possibly at least partially surrounding a portion of the whip antenna, and it will not be discussed any further.

In the illustrated embodiment, the lower end portion of the antenna is rectangular in cross-section, and comprises two separate rod-like antenna wires. Alternatively it could assume any desired symmetrical or asymmetrical cross-sectional shape, and may contain any number of antenna wires . The wires may also assume any arbitrary cross-sectional shape and dimension, but they typically have a cross-sectional dimension much smaller than the outer dimension of the lower end portion of the antenna allowing some resiliency for the antenna. Thus, the lower end portion of the antenna comprises at least one electrically conducting wire which, at least when the antenna is in its extended position, acts as the electromagnetically active antenna element, optionally in conjunction with additional components . The conductive wire is surrounded by an insulating, preferably resilient material, such as thermoplastic material. A non-centro- symmetric cross-sectional shape is ad- vantageous if the antenna comprises more than one wire, all of which must be connected to associated connectors in the radio communication device. The embodiment of the antenna shown in the figure is extendable and retractable, and the knob at the upper end of the antenna whip acts as a stopper, preventing the antenna from being retracted further into the radio communication device housing. This knob could also comprise an additional antenna element.

In all drawing figures, the holder is shown as a separate com- ponent, to be attached to the radio communication device, but this is for reason of simplicity only. The engaging element, whether electrical or mechanical in function, or both, could be constituted by one or several components in the radio com- munication device itself. This engaging element could be arranged on a circuit board in the radio communication device, in the opening of the radio communication device for receiving the antenna, or, for some embodiments of the engaging portion, it could simply be constituted by the opening itself. The detailed function of each embodiment of the holder is to engage with the corresponding engaging portion of the antenna whip when the antenna is located in its extended position, where the word "engage" is to be understood as being mechanical, electrical, or both in character, depending on the particular embodiment of the engaging portion, and will not be discussed further henceforth.

In figs 2a-2d there are shown different embodiments of the engaging portion on the lower portion of the antenna, and corresponding holders. The figures are intended to illustrate the mechanical locking function of the antenna according to the invention, that is the function which prevents the antenna from being pulled out of the holder once it has been inserted into the receptacle. The additional electrical function of each illustrated engaging portion, or the presence of an additional engaging portion for that purpose, has been left out in order to simplify the understanding of the figures. Nor are the wires shown, for the same reason.

Figures 2a-2c show the exterior surface of the lower end portion of the antenna. The inner surface of the corresponding holder may be circular symmetric around the centre axis. Figures 2a and 2b show embodiments using barbs as the engaging portion. In fig. 2a, the barbs are arranged at a distance from the lower end of the antenna, and in fig. 2b they are arranged at the very end. The barbs have a surface facing away from the holder, this surface being substantially perpendicular to the surface of the antenna and serving as a stop surface for preventing the antenna from being pulled out of the holder by engaging the recess portion 7 in the engaging element. The barbs also have a surface facing the holder with a small slope, for allowing the antenna to be inserted into the holder. Naturally, the barbs could be replaced by any other pro- tuding element, which has the same locking function as the barbs. In both figures, the resiliency of the region of the barbs has been increased by moulding the antenna (2a) with a through-hole or a recess between the barbs (2b) . This structure is primarily intended for allowing the barbs, and the corresponding portion of the antenna, to resiliently flex inwards when the barbs are pushed into the holder. If the dielectric material covering the antenna is sufficiently elas- tic, such a structure would be unnecessary. The hole or recess could also be dimensioned to expose the wires, and these in turn will engage with an electrical engaging element in the holder. Barbs could be added to any of the engaging portion disclosed, adding strength to the retention strength, assuming that corresponding engaging elements are provided. Fig. 2c shows an embodiment using a recess as the engaging portion. Here, the surface which lockingly engages with the holder when the antenna is pulled out is the surface situated closest to the lower end of the antenna.

Fig. 2d shows an embodiment of the engaging portion realised by a hole through the lower part of the antenna. The lowermost surface of the hole should be at a large enough angle relative to the surface of the antenna to lockingly engage the holder, while other aspects of the shape of the hole is of less importance. In this embodiment, again, the engaging portion may be dimensioned to expose the wires, and with a suitable construction of the engaging element, it could both electrically con- nect the wires to the RF transceiver and lock the antenna mechanically.

Figs 3a-d illustrate the electrical function of different em- bodiments of the engaging portion, and the electrically conductive elements are shown by solid, thick lines. The extension of the engaging elements through the holder is not illustrated. Neither is the mechanical locking function of the engaging portion shown, nor the presence of additional enga- ging portion for that purpose, but in figs 3b-d it is obvious that the engaging element may mechanically lock the antenna. It should be understood that the engaging portion may also have a mechanical locking function, or that a second engaging portion may be arranged elsewhere. In each of these figures, the wires are illustrated as being fully exposed, giving direct electrical connection to the RF transceiver. By leaving a thin coating of dielectric material on the wire, and properly selecting the thickness of the coating, the wires will still electrically couple to the transceiver, although capacitively, which may be preferred for such reasons as impedance matching and corrosion resistance.

The embodiment of the engaging portion shown in fig. 3a simply comprises a exposed portion of the wires at the lower end of the antenna. The actual design of the antenna end with free wire ends may comprise a portion of the antenna end extending as far as the wires, to protect the wires from bending forces. Extending portions may also surround the wires on all sides, as long as the wires are exposed enough to allow them to en- gage the engaging elements in the holder. Assuming the person inserting the antenna into the holder knows how to orient the antenna, or if the antenna cross-section is asymmetric, such that each wire has only one possible position in the recep- tacle, except for length-wise movement, this embodiment has an additional advantage, as compared to the others. This advantage is that the exposed wire ends may be inserted directly so as to make contact with the circuit board when the antenna is in its retracted position, with no need for contact clamps or other resilient contact elements which act on the side of the wire .

The embodiments shown in figs 3b-d expose the wires by way of a recess arranged on the upper side of the antenna, on the lateral sides of the antenna, and in the form of a hole through the antenna, respectively. Assuming that the surfaces of the recess located closest to the holder, as illustrated in the figures, and the engaging elements are properly designed, the engaging portion may concurrently perform the mechanical locking function.

Although the invention has been described in conjunction with a number of preferred embodiments, it is to be understood that various modifications may still be made without departing from the scope of the invention as defined by the appended claims. One such possible modification is to add engaging portion at other positions along the lower end portion of the antenna, serving to electrically connect the antenna to the RF trans- ceiver, and/or to hold, although not lock, the antenna in positions other that fully extended. Another modification is for a non retractable extended antenna, in which case the lower end of the holder 3 could be closed at its lower end.

Claims

1. An extendable whip antenna comprising at least one rodlike radiating element (4) at least partially covered by a dielectric material, said whip antenna comprising a lower por- tion (2) mountable through an opening in a holder (3) in a radio communication device, characterised in that the lower portion (2) , at its lower end portion, comprises an engaging portion (6a, 6b, 6c) constituting part of the lower portion (2), said engaging portion being resili- ently engageable with an engaging element (7) in the holder.

2. An extendable whip antenna according to claim 1, characterised in that said engaging portion (6a, 6b, 6c) , is adapted to pass the engaging element (7) during insertion of the lower portion (2) into the holder (3) , whereas said engaging portion (6a, 6b, 6c) , mechanically engages with the engaging element (7) when being pulled in the opposite direction, so as to prevent the antenna from being detached from the radio communi- cation device.

3. An extendable whip antenna according to claim 2, characterised in that said engaging portion comprises a recess (6a) in the lower portion said recess having a lower transverse surface adapted to engage with for example a catch in said engaging element (7) .

4. An extendable whip antenna according to claim 2, charac- terised in that said engaging portion comprises a hole (6b) through the lower portion having a lower transverse surface adapted to engage with for example a catch in said engaging element (7) .

5. An extendable whip antenna according to claim 2, characterised in that said engaging portion comprises a catch (6c) , such as a barb, on the lower portion having an upper transverse surface adapted to engage with for example a recess in said engaging element (7) .

6. An extendable whip antenna according to claim 2, charac- terised in that said engaging portion comprises a recess (6a) having a lower transverse surface adapted to engage with said engaging element (7) , and a catch (6c) having an upper transverse surface adapted to engage with said engaging element (7) .

7. An extendable whip antenna according to claim 2, characterised in that said engaging portion comprises - a hole (6b) through the lower portion having a lower transverse surface adapted to engage with said engaging element ( 7) , and a catch (6c) having an upper transverse surface adapted to engage with said engaging element (7) .

8. An extendable whip antenna according to claim 1, characterised in that said engaging portion (6a, 6b) , is arranged such that the radiating element (4) is electrically engageable with said engaging element (7) , such that the radiating element (4) is electrically coupled to said engaging element (7) .

9. An extendable whip antenna according to claim 8, charac- terised in that said engaging portion comprises a recess (6a) in the lower portion, exposing a portion of the radiating element (4) .

10. An extendable whip antenna according to claim 8, characterised in that said engaging portion comprises a hole (6b) through the lower portion, exposing a portion of the radiating element (4) .

11. An extendable whip antenna according to claim 9, characterised in that said recess (6a) is located at the lower end surface of the lower portion.

12. An extendable antenna according to any of claims 2, 3, 6 or 7, characterised in that said engaging element (7) is electrically conductive, and that the radiating element (4) is exposed in the engaging portion (6a, 6b) , such that electrical coupling between the the radiating element (4) and the engaging element (7) is obtained when the engaging portion (6a, 6b) mechanically engages the engaging element (7) .

13. An extendable antenna according to any of claims 2-7, characterised in that said engaging portion (6a, 6b) is engageable with two engaging elements (7, 7a), the first engaging element (7) being electrically conductive, and that - the radiating element (4) is exposed in said engaging portion, obtaining electrical coupling between the radiating element (4) and said first engaging element (7) , when said engaging portion mechanically engages the second engaging element ( 7a) .

14. An extendable antenna according any of claim 3-7, characterised in that - the lower portion, at its lower end, comprises an auxiliary engaging portion (6a, 6b) constituting an integral part of the dielectric material, said auxiliary engaging portion (6a, 6b) being adapted to be electrically couple the radiating element (4) to an auxili- ary engaging element (7a) , when said engaging portion (6a, 6b) mechanically engage the engaging element (7) .

15. An extendable antenna according to claim 14, characterised in that said auxiliary engaging portion comprises a re- cess (6a) in the lower portion, exposing the radiating element (4) .

16. An extendable antenna according to claim 14, characterised in that said auxiliary engaging portion comprises a hole (6b) through the lower portion, exposing the radiating element (4) .

17. An extendable antenna according to claim 15, characterised in that said recess is located at the lower end of the lower portion.

18. An extendable antenna according to any of claims 1-17, characterised in that said lower portion comprises two or more radiating elements (4) .

19. An extendable antenna according to any of claims 8-17, characterised in that said radiating element is only being partially exposed so as to establish a capacitive connection between the radiating element and the electrically conductive engaging element (7, 7a) .

20. An extendable antenna according to claim 18, characte- rised in that at least one of said radiating elements is only being partially exposed so as to establish a capacitive connection between the at least one radiating element and the electrically conductive engaging element (7, 7a) .

21. An extendable antenna according to any of claims 8-20, characterised in that said lower portion has an essentially constant cross-section.

22. An extendable antenna according to any of claims 8-21, characterised in that said lower portion (2) has essentially the same cross-section as the holder (3) opening.

23. A radiocommunication device comprising: a housing, a transceiver circuit, a user interface and a de- vice for receiving an antenna, characterised in that an antenna according to any of claims 1-20 arranged in the antenna receiving device.