WO1998048474A1

WO1998048474A1 - An antenna device

Info

Publication number: WO1998048474A1
Application number: PCT/SE1998/000715
Authority: WO
Inventors: Lars Wendel
Original assignee: Lars Wendel
Priority date: 1997-04-21
Filing date: 1998-04-21
Publication date: 1998-10-29
Also published as: SE9701505L; SE9701505D0

Abstract

An antenna device of an electronic unit for receiving and/or transmitting radio waves, said antenna device comprising a helix antenna (1) and a top (2), the antenna (1) being designed for connection with a first end (3) thereof to the electronic unit, the top (2) being designed for connection to a second end (6) of the antenna (1), and the antenna device comprising an arrangement for securing the top to the second end (6) of the antenna, said arrangement comprising a first member (7) of the top (2) and a second member (8) of the antenna (1) and these members are arranged to engage securingly with each other by a relative motion between the top (2) and the antenna (1).

Description

ej/hj

Applicant: Lars WENDEL

AN ANTENNA DEVICE

FIELD OF THE INVENTION AND PRIOR ART

The present invention is related to an antenna device according to the preamble of claim 1 .

The field of the invention comprises antennas for various electronic units as for example mobile phones, computers etc. The antenna device is below described in connection to a mobile phone. This is however not to be regarded restrictingly, but only as an example.

According to prior art, antennas have substantially two different designs, either an elongated pole-like design, or a helix design. The present invention is related to an antenna device with a helix antenna. The antenna is connected by a first end thereof to a seat of a pin of the electronic unit, said pin in turn being connected to a generator of the electronic unit.

Mobile phones are designed for operating within a frequency interval surrounding different, set frequencies. There is for example a 1800 MHz-system, which is related to a frequency interval from 1710 MHz to 1890 MHz. It is desired to design an antenna with a band width as far as possible corresponding to the frequency interval. It is however difficult to obtain an antenna with a band width with such a large frequency interval. It is previously known to arrange a so-called top load on a second end of the antenna in order to increase the band width of the antenna. The capacitance of the antenna device is increased by arranging a top load on the antenna and the band width of the antenna is as a consequence thereof also increased. A problem of antenna devices with top loads according to prior art concerns the difficulty to obtain a desired increase in capacitance by means of the top load. The design of the top load is substantial for the capacitance increase.

A further problem is the connection of the top load to the antenna. Top loads have according to prior art different designs and the top load has according to one design a disc-formed por- tion with a larger diameter than the outer diameter of the helix antenna. The arrangement for securing the top load to the second end of the antenna has a soldering, shrink or similar connection. Such a connection requires a relatively time consuming and complicated operation. It has further not been able to con- nect the top load tightly against the second end of the antenna according to prior art.

SUMMARY OF THE INVENTION

The object of the present invention is to obtain an antenna device for an electronic unit eliminating the above mentioned disadvantages of antenna devices according to prior art.

The object of the invention is achieved by the device according to the invention by that the top has an upper portion extending a distance at least exceeding the inner diameter of the antenna in the radial direction thereof and a lower portion extending in the longitudinal direction of the antenna from the upper portion towards the first end of the antenna, that the arrangement com- prises a first member of the lower portion of the top and a second member of the antenna and that these members are arranged to securingly engage with each other by a relative motion between the top and the antenna. By dimensioning the antenna device with respect to the capacitance thereof, the top may be dimensioned for a certain antenna by determining two parameters, namely the length of the upper portion of the top in the radial direction of the antenna and the length of the lower portion of the top in the longitudinal direction of the antenna. There is further required only a relative motion between the top and the antenna in order to connect them to each other and no further operation in the form of for example soldering. This leads to a simple design and a time save by assembling the antenna device. The upper portion of the top forms a stop against further motion of the top in relation to the antenna during connection thereof due to that the upper portion of the top extends a dis- tance at least exceeding the inner diameter of the antenna in the radial direction thereof, which results in that the connection is fast and easy.

According to a preferred embodiment of the invention, said sec- ond member of the antenna is formed by an upper part of the antenna being elastic in the radial direction thereof, which results in an embracing holding force upon an object with a larger outer diameter than the inner diameter of the upper part of the antenna when the object is brought into the same, and an out- wardly pressing force in the radial direction upon an object having an opening with a smaller inner diameter than the outer diameter of the antenna when the object is brought onto the antenna.

According to another preferred embodiment of the invention, said first member of the lower portion of the top being insertable into the upper antenna part and being formed by a cylindrical mantle surface with a diameter equal to or larger than the inner diameter of the upper antenna part. By dimensioning the above- mentioned parameter regarding the length of the lower portion of the top in the longitudinal direction of the antenna, only the length of the cylindrical surface in the longitudinal direction of the antenna is needed to be determined. A diameter of the object at least somewhat larger than the inner diameter of the an- tenna results in a sufficient contact with the antenna and a suffi- cient holding effect. It is further relatively simple to manufacture a cylindrical surface.

According to another preferred embodiment of the invention, the upper portion of the top having a disc-like form, and according to a further preferred embodiment of the invention, the upper portion of the top having a larger diameter than the inner diameter of the antenna. By dimensioning the above-mentioned parameter regarding the length of the upper portion of the top in the radial direction of the antenna, only the diameter of the upper portion of the top is needed to be dimensioned.

According to another preferred embodiment of the invention, the upper portion of the top being arranged to contact the antenna when the first member of the top and the second member of the antenna are in a secured engagement with each other, a shorter total length of the antenna device is achieved compared to what has been possible according to prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the enclosed drawings a more close description of embodiment examples of the invention follows hereunder. In the drawings;

Fig 1 is an exploded view of the device according to a first preferred embodiment of the invention.

Fig 2 is a side view of the device according to the first pre- ferred embodiment of the invention, the antenna being connected to a pin, which in turn is intended to be connected to a generator of the electronic unit, as well as connected to a top. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Fig 1 is an exploded view of the device according to the invention comprising a helix antenna 1 and a top 2. The antenna 1 is with a first end 3 thereof designed to be connected to a seat 4 of a pin 5, which in turn is intended to be connected to the generator of an electronic unit. The top is designed to be connected to a second end 6 of the antenna 1 . The antenna device comprises an arrangement for securing the top 2 to the second 6 of the antenna 1 . The arrangement comprises a first member 7 of the top 2 and a second member 8 of the antenna 1 and these members are arranged to securingly engage with each other by a relative motion between the top 2 and the antenna 1.

Said members 7, 8 may within the scope of the inventive claims have several different designs. Said first member 7 of the top 2 is according to a first preferred embodiment of the arrangement formed by a cylindrical mantle surface with a diameter equal to or larger than the inner diameter of the upper part 9 of the antenna. Since the antenna 1 is elastic in the radial direction thereof, a sufficient physical contact is obtained, and as a consequence thereof also a sufficient electrical contact, when the antenna 1 is brought into a compressed or extended condition in the radial direction thereof. By forming the cylindrical mantle surface with a diameter somewhat larger than the inner diameter of the upper part 9 of the antenna, it is possible to obtain holding of the top by means of the upper part 9 of the antenna clamping around the first member 7 of the top 2 when the top 2 and the antenna 1 are in engagement with each other. The insertion of said first member 7 of the top 2 into the upper part 9 of the antenna may take place in a plurality of ways, for example by a displacing movement, turning movement, or by a to and fro motion. The top 2 has an upper portion 13 extending a distance at least exceeding the inner diameter of the antenna in the radial direction thereof and a lower portion 14 extending a distance in the longitudinal direction of the antenna from the upper portion towards the first end of the antenna. The upper portion 13 of the top 2 thereby forms a stop to the connecting motion between the top and the antenna. Thus, the top is brought into the antenna substantially in the longitudinal direction thereof until the upper portion thereof will contact the upper part of the antenna.

The upper portion 13 of top 2 may have a plurality of different designs. According to the first preferred embodiment of the invention, the upper portion of the top having a substantially disclike form, i.e. a relatively flat design. Since the upper portion contacts the antenna in an active condition, the addition of the upper portion to the length of the antenna device will result in an insignificant length increase thereof, which is very advantageous from a space saving point of view.

Since the upper portion 13 of the top 2 has a diameter at least larger than the inner diameter of the upper part 9 of the antenna, the above-mentioned stop function of the upper portion of the top is obtained. By forming the upper portion of the top in the form of a circular disc, the above-mentioned stop function as well as a relatively easy form to manufacture are obtained. Since the capacitance increase of the antenna device by adding the top is dependent on the forming of the top, the top should have an easy form for the dimensioning operation, which is also obtained by the circular disc. The upper portion 13 of the top 2 may however have a plurality of different formings within the scope of the claims, such that for example rectangular, oval or triangular cross-sections, or in the form of an elongated element having a length larger than the inner diameter of the upper part of the antenna, etc. According to the first preferred embodiment of the invention, said first member 7 of the top 2 having a cylindrical mantle surface and is intended to be brought into the antenna pressing the upper part of the antenna in the radial direction. The first mem- ber 7 may however have a plurality of different formings in order to obtain such a pressure. The first member 7 may for example have a form different from a cylindrical mantle surface, i.e. a form different from a continuous contact surface, and instead have an intermittent contact surface against the antenna. An intermittent contact surface is in this context related to an interrupted contact surface in the circumferential direction of the antenna.

According to a second preferred embodiment of the arrange- ment, the lower portion of the top 2 being tubular and arranged with a smaller inner diameter than the outer diameter of the upper part 9 of the antenna. The first member of the top 2 is formed by an inner surface of the tubular lower portion in the radial direction thereof. By applying said first member of the top 2 onto the upper part 9 of the antenna compressing the same, a holding effect of the top 2 in relatin to the antenna 1 is obtained due to that the upper part 9 of the antenna is pressing outwards in the radial direction against the inner surface of the tubular lower portion. The application of said first member of the top 2 on the upper part 9 of the antenna may take place in a plurality of different ways, for example by a displacing motion while in some way compressing the upper part 9 of the antenna, by a turning motion or similar. The lower portion of the top 2 has within the scope of the inventive claims a form different from tu- bular, but the first member should be arranged to compress the antenna in the radial direction thereof. The first member 7 of the top 2 may for this purpose have an intermittent forming in the circumferential direction of the antenna, i.e. being interrupted in the circumferential direction of the antenna. It is sufficient with some kind of gripping portion of the first member 7 of the top 2 in order to obtain holding around the upper part of the antenna, i.e. that at least two sections on opposite sides of the upper part of the antenna are extending from the upper portion of the top and gripping around the upper part of the antenna.

The wire forming the helix antenna has preferably a continuous cross-section along the total length of the antenna.

According to a preferred embodiment of the antenna 1 , the outer diameter thereof is changing in the longitudinal direction in the rest condition, i.e. in a non-loaded condition, in order to have a constant outer diameter in the longitudinal direction of the antenna when it is connected to the electronic unit in an active condition with the top 2 secured thereto.

According to a third and forth preferred embodiment of the arrangement, said first member of the top having a helix groove corresponding to the forming of the upper part 9 of the antenna in order to engage securingly with the upper part of the antenna by the relative motion in the form of a turning motion. This helix groove is according to the third embodiment formed in the cylindrical mantle surface of the lower portion of the top 2, which in similarity to the first preferred embodiment of the arrangement has a larger outer diameter than the inner diameter of the upper part 9 of the antenna 1 , and according to the forth embodiment formed in the inner surface in the radial direction of the tubular lower portion. According to the forth embodiment of the arrangement, the top being intended to be brought onto the upper part of the antenna in similarity to the second preferred embodiment of the arrangement and for this purpose the tubular lower portion having a smaller inner diameter than the outer diameter of the upper antenna part.

Since the top 2 is arranged with a recess 15, which is open towards a lower end of the lower portion 14, the connection of the upper antenna part 9 with the top may take place by applying the top onto the upper part of the antenna. It is in order to ob- tain a sufficient holding force advantageous that the recess has a circular cross-section with a smaller diameter than the outer diameter of the upper part of the antenna.

The top 2 may be detachably arranged on the antenna 1 , which leads to an easy dismounting of the same from the antenna.

The antenna wire is according to a preferred embodiment of the invention formed by spring steel, which has sufficient elastic properties in the radial direction. By silvering the antenna, i.e. applying a silver layer, the antenna will receive sufficient electrical conductive properties.

The antenna device is in fig 2 shown in a first preferred em- bodiment. In this embodiment, the first member 7 of the top 2 being inserted into the upper part 9 of the antenna, the upper portion 13 of the top 2 being arranged contacting the antenna 1 , and the seat 4 of the pin 5 being inserted into the lower part 12 of the antenna 1 .

The connection of the antenna 1 to the seat 4 of the pin 5 may be formed in the same way as the connection between the antenna 1 and the top 2. This will be further explained below.

The antenna device comprises a second arrangement for securing the first end 3 of the antenna 1 to the pin 5. This second arrangement comprises a first member 10 of the seat 4 and a second member 1 1 of the antenna 1 and these members are arranged to engage securingly with each other by a relative mo- tion between the antenna 1 and the pin 5.

Said second member 1 1 of the antenna is formed by a lower part 12 of the antenna 1 being resilient in the radial direction thereof. Said first member 10 of the pin 5 is formed to effect the lower part 12 of the antenna in the radial direction by the relative motion between the antenna 1 and the pin 5 towards the engaging condition for storing potential energy in order to hold the an- tenna 1 in the secured condition.

Said first member 10 of the pin 5 is substantially tubular.

Said first member 10 of the pin 5 is according to a first embodi- ment insertable into the lower part 12 of the antenna and has a larger outer diameter than the inner diameter of the lower part 12 of the antenna.

Said first member of the pin 5 is according to a second embodi- ment applicable onto the lower part 12 of the antenna and has a smaller inner diameter than the outer diameter of the lower part 12 of the antenna.

The lower part 12 of the antenna has, according to one embodi- ment, a reduced inner diameter in the longitudinal direction of the antenna 1 when the antenna 1 is in a rest condition. The lower part 12 of the antenna has, according to another embodiment, an increased outer diameter in the longitudinal direction of the antenna 1 when the antenna 1 is in the rest condition.

Said first member 10 of the pin 5 has, according to another embodiment, a helix groove in the surface of the first member 10 intended to interact with the lower part 12 of the antenna 1 , said groove corresponding to the forming of the lower part 12 of the antenna, in order to securingly engage with the lower part of the antenna by a turning motion.

The antenna 1 is according to a further embodiment detachably connected to the pin 5. A casing covering the antenna device may be provided to protect the same. It is further possible to mould the antenna device with a plastic and/or rubber material. The antenna device would for such moulding be located in a space in a tool, and the mate- rial being injected into the space. A non-rigid and homogeneous unit may in this way be obtained. However, there is a risk that the antenna device will be directed obliquely, bent or in some other way deformed by the injection of the material. It is for this purpose advantageous to be able to fix or control the antenna device during the injection of material. A solution to this problem is to provide a recess in the top, said recess being open at least upwards, and preferably formed through the total top, i.e. also through the lower portion. It is in this way possible to centre or control the antenna device during the injection by inserting a centering element into the recess.

It is evident that the embodiments discussed hereinabove and illustrated in the drawings only are examples and that the invention may be realised in other ways without leaving the scope of the inventive claims. Thus, a plurality of modifications within the scope of the invention and the following claims are obvious for a man skilled in the art after having been presented to the inventive idea without departing from said inventive idea by any such modifications.

It is for example within the scope of the inventive claims to arrange the top 2 in relation to the antenna 1 and the antenna 1 in relation to the pin 5 securing each other by a bayonet catch.

The present invention is further not restricted to be used for a specific frequency interval, but may for example be used for a frequency interval surrounding 900 MHz and alternatively for a frequency interval surrounding 1800 MHz. The above discussed dimensioning of the top in order to achieve the desired increase in capacitance may be accomplished regarding only one or both of said parameters.

Claims

1. An antenna device for an electronic unit and for receiving and/or transmitting radio waves, said antenna device com- prising a helix antenna (1 ) and a top (2), the antenna (1 ) being designed for connection with a first end (3) thereof to the electronic unit, the top (2) being designed for connection to a second end (6) of the antenna (1 ), and the antenna device comprising an arrangement for securing the top to the second end (6) of the antenna, characterized in that the top (2) has an upper portion (13) extending a distance at least exceeding the inner diameter of the antenna in the radial direction thereof and a lower portion (14) extending in the longitudinal direction of the antenna from the upper portion towards the first end of the antenna, that the arrangement comprises a first member (7) of the lower portion of the top and a second member (8) of the antenna and that these members are arranged to securingly engage with each other by a relative motion between the top and the antenna.

2. A device according to claim 1 , characterized in that said second member (8) of the antenna (1 ) is formed by an upper part (9) of the antenna (1 ) being elastic in the radial direction thereof.

3. A device according to claim 2, characterized in that said first member (7) of the top (2) is formed to effect the upper antenna part (9) in the radial direction by the relative motion between the top (2) and the antenna (1 ) towards the secured position in order to store potential energy for keeping the top

(2) in the secured position.

4. A device according to any preceding claim, characterized in that said first member (7) of the lower portion (14) of the top (2) is insertable into the upper antenna part (9) and is formed by a cylindrical mantle surface with a diameter equal to or larger than the diameter of the upper antenna part (9).

5. A device according to any of the claims 1 -3, characterized in that said first member of the lower portion of the top (2) forms an intermittent contact surface against the antenna in the circumferential direction thereof when the top is connected to the antenna (1 ) in an active position.

6. A device according to any preceding claim, characterized in that the upper portion (13) of the top (2) has a disc-like form.

7. A device according to claim 6, characterized in that the upper portion (13) of the top (2) has a larger diameter than the inner diameter of the antenna (1 ).

8. A device according to any preceding claim, characterized in that the upper portion (13) of the top (2) is designed for contacting the antenna (1 ) when the first member (7) of the top (2) and the second member (8) of the antenna (1 ) are arranged in a secured engagement with each other.

9. A device according to any preceding claim, characterized in that the top has a recess (15), which is open towards a lower end of the lower portion (14),

10. A device according to claim 9, characterized in that the recess (15) extends through the top (2) in the longitudinal direction of the antenna and is open towards an upper surface of the upper portion (13).

1 1. A device according to claim 9 or 10, characterized in that the recess has a substantially circular cross-section with a smaller diameter than the outer diameter of the upper an- tenna part (9).

12. A device according to any preceding claim, characterized in that the cross-section of the antenna wire is constant along the total length of the antenna (1 ).

13. A device according to any preceding claim, characterized in that the antenna has an outer diameter changing in the longitudinal direction thereof in a rest position, so that the antenna (1 ) will have a constant outer diameter in the longitudinal direction thereof when the antenna (1 ) with the top (2) in the secured position is connected to the electronic unit in an active position.

14. A device according to any preceding claim and at least claim 2 and claim 4, characterized in that the upper antenna part (9) has a reduced inner diameter in the longitudinal direction of the antenna (1 ) when the antenna (1 ) is in the rest position.

15. A device according to any of the claims 1 -12 and at least claim 2 and claim 1 1 , characterized in that the upper antenna part (9) has an increased outer diameter in the longitudinal direction of the antenna (1 ) when the antenna (1 ) is in the rest position.

16. A device according to any of the claims 2-15, characterized in that said first member (7) of the top (2) has a helix groove in the surface of the lower portion (14) of the top corresponding to the forming of the upper part (9) of the antenna (1 ) and intended for interaction with the upper part (9) of the antenna (1 ) in order to engage securingly with the upper part

(9) of the antenna (1 ) by a relative motion in form of a turning motion.

17. A device according to any preceding claim, characterized in that the top (2) is removably arranged on the antenna (1 ).

18. A device according to any preceding claim, characterized in that the antenna is formed by spring steel.

19. A device according to any preceding claim, characterized in that the antenna wire is provided with a silver layer.