SE516466C2 - Antenna device for multiple frequency bands - Google Patents

Abstract

An antenna device for several frequency bands comprises two radiating elements. The first element is a rod arrangement (22) which radiates in several frequency bands, while the second element (15) includes a pattern of conductor portions disposed on a carrier (4) of insulating material, this element (15) also radiating in several frequency bands. The pattern of conductor portions is designated as a planar, angular helix with a number of galvanically interconnected, substantially straight conductor portions (16, 16', 16''... 17, 17', 17''...). The rod arrangement (22) is placed in association with the carrier (4) in order to be supplied non-galvanically therefrom. Preferably, the carrier (4) is rolled up into a tube or a channel with an axially directed aperture or slot. The carrier (4) has conductor portions in association with the edges (26, 27) which meet along the aperture or slot. The rod arrangement (22) extends axially in the region of the aperture or the slot.

Description

The carrier must be placed close to a further antenna element in the form of a rod device.

In a foil-type antenna, you also want a radiating element, which is as large as possible to the surface relative to the outer edge of the plastic foil, in order for the resulting antenna to have as large an aperture as possible.

A radiating element, which is large relative to the outer edge of the plastic foil, increases the above-described problems of interaction between different portions of the radiating element.

To date, there is no solution to the problem of designing the pattern of electrical conductors forming the radiating element in order to simultaneously arrange a maximum large radiating element on a given area and minimize electrical interaction between different portions of the radiating element.

OBJECTIVE The present invention has for its object to design the antenna initially indicated in such a way that the problems with older technology are eliminated and the antenna has maximum efficiency and very good bandwidth in the frequency bands where it is to be used, this with a far-reaching miniaturization and despite the combination with a rod arrangement. Furthermore, the invention intends to invent the invention object in such a way that it can be manufactured at low costs in a rational manner.

TROUBLESHOOTING The object underlying the invention is achieved if the antenna device initially indicated is characterized in that the pattern of conductor portions is formed as a substantially flat, angular spiral with a number of galvanically interconnected substantially straight conductor portions, and that the rod arrangement is placed in connection to the carrier to be fed non-galvanically from it.

In an advantageous embodiment, it also applies that the carrier is rolled up into a pipe or gutter mold.

By providing the planar and roughly helical, radiating element with a number of substantially straight conductor portions, it has been found that the resulting antenna device will have at least two resonant frequencies. Furthermore, it has been found that the coil does not appreciably affect performance despite the fact that the opposite ends of the radiating element after the coil come close to each other and the rod arrangement. Finally, the small radiating elements of the antenna device can be easily manufactured by an etching method applied to a flexible plastic foil provided with a thin metal layer on one or possibly both sides.

COMPILATION OF DRAWING FIGURES The invention will now be described in more detail with reference to the accompanying drawings. These show: fi g l an exploded view obliquely from below of a part (including a second radiating element) of the antenna device according to the invention, fi g 2 an exploded view of a rod arrangement included in the acquisition object, a first radiating element, fi g 3 a carrier included in the acquisition object with a radiant element, fi g 4 a view corresponding to fi g 3, however of a second embodiment, fi g 5 a view corresponding to fi g 3, however of a third embodiment, fi g 6 a view corresponding to fi g 3, however of a ut fourth embodiment, fi g 7 a view corresponding to ñg 3, however, of a fifth embodiment, and 8 g 8 a view corresponding to 3g 3, however of a sixth embodiment.

PREFERRED EMBODIMENT As indicated above, the object of the invention is primarily intended for use on a so-called mobile telephone, which should be at least of the dual band type so that it covers the EGSM band of 880-960 MHz and at least one of the DCS and PCS bands. bands of 1710-1880 MHz and 1850-1990 MHz, respectively. Ideally, of course, all three frequency bands should be able to be covered.

In the description below, an expression "radiant element" will be used.

Of course, this means that the element must be able to radiate electromagnetic energy within the above-mentioned frequency bands. The term "radiant element" 10 15 20 25 30 40 516 466 ouo u; 4, however, should also be interpreted in such a way that it can receive electromagnetic energy within the said frequency bands.

If fi g 3-8 it should be mentioned that they are represented approximately in scale 1: 1.

In fi g 1, reference numeral 1 refers to a load-bearing part of an antenna device, which is designed to cover at least the GSM band and at least one of the others. The supporting part is made of a suitable plastic material with electrically insulating and non-magnetic properties. The supporting part serves for attachment to the housing of the mobile phone and carries on it two radiating elements, a first radiating element in the form of a rod arrangement 22 (fi g 2) and a small compact second radiating element.

The supporting part has a body part 3, which has two vertically or axially extending holes or bores 23 and 24, respectively, where the bore 23 is intended for mounting a contact device 5 while the bore 24 is intended for receiving the rod arrangement 22.

In Fig. 1, the contact device 5 is shown elevated above the vertical housing 23 and comprises an earth sleeve 6, which is connected to the chassis of the mobile telephone.

Above the ground sleeve 6 there is a fastening part 7, by means of which the contact device 5 is fastened in the bore 23 in the body part 3. On top of the fastening part there is an insulator 8 and a solder pin 9, which later serves for electrical connection of the second radiating element, which is arranged on a carrier 4 made of plastic foil (to be described in detail below).

In the mounted condition of the contact device 5, the connection 6 is located on the underside of the frame part 3 and extends through the hole 23. Although not shown in Fig. 1, the frame part 3 has a cavity 25 inside, in which the carrier 4 is placed in the mounted condition of the antenna. In this state, the solder pin 29 with its upper end is flush with the bottom of the cavity 25.

The carrier 4 according to fi g 1 is rolled up into a tube or sleeve shape and may have a U-shaped, C-shaped or horseshoe-shaped cross-section with a certain distance between the opposite edges 26 and 27 of the wearer. opening or slit.

Figure 2 shows the rod arrangement 22, which is included in the object of invention. In the embodiment shown, it is designed for full-wave resonance in the higher frequency band or bands and half-wave resonance in the lower frequency band (s) of which the GSM band is one. Alternatively, the rod arrangement may be tuned to half-wave resonance in the upper band sequence band and quarter-wave resonance in the lower fi sequence band. It can be seen from the drawing that the rod arrangement extends through a protective hood 1 1, which is intended to fit on the outside of the body part 3 and is snapped onto it by means of grooves and grooves (not shown). In the mounted position, the rod arrangement 22 extends through the housing 24 in the body part 3. This means that the rod arrangement extends axially in the same direction as the opening or slot between the two edges 26 and 27 of the carrier 4. the rod arrangement is completely or partially outside the opening or slot between the two edges. Optionally, it may also be more inclined towards the interior of the carrier 4. The above-described mutual placement of the rod arrangement 22 and the carrier 4, which along their edges 26 and 27 have metallic conductor portions, which will be described in more detail below, means that the rod arrangement is galvanic separate from the radiating element on the carrier 4 and is fed non-galvanically therefrom.

The rod arrangement 22 is displaceable in its longitudinal direction between a position inserted in the mobile telephone and an extended position where it extends up on the top of the protective hood 11.

The rod arrangement 22 has an upper top part 28 with a grip part 29, both of electrically insulating and non-magnetic material. In the retracted position of the rod arrangement, the top part 28 in the ear area for the opening or the slot between the two edges 26 and 27 of the carrier 4 lies so that the radiating element on the carrier 4 is thereby not disturbed.

In the embodiment shown, the antenna rod itself is made telescopically and has an inner rod or wire 30 and a tube 31 lying on top of it. Both the wire 30 and the tube 31 are made of steel in order to obtain good strength and at least a certain fi resilience.

At the lower end of the wire 30 there are arranged fi springs 32 which are retractable in the tube to form an opp connection coupling and an electrical connection with the inside thereof.

The tube 31 has at its lower end a projecting bead 33, which serves to accelerate the rod arrangement 22 in its pulled-up position by co-operation with suitable means inside the bore 24 in the body part 3. 10 15 20 25 30 40 516 466 6 I fi g 3 8 show various alternative embodiments of the radiating element 15, which is applied to the carrier 4.

Figures 3 and 4 show two variants of the flat, approximately helical, radiating element included in the object of invention. This has a supply part 13, which is inserted through the slot 10 in the body part 3, and which has a lower end 14 in the grooves which is intended to be electrically connected to the solder pin 9 on the contact device 5.

Fig. 3 shows that the supply part 13 at its upper end is connected to an outer, straight and substantially vertical conductor 17, which is galvanically connected to a substantially straight, horizontal conductor portion 16 via a marked curved or angled conductor portion 18. The horizontal conductor portion 16 is connected via a second angled guide portion 18 'to a second approximately vertical conductor portion 17', which in turn, in its lower end, via a further angled conductor portion 18 "is connected to an approximately horizontal conductor portion 16 '. An outer" turn " is thus described by an angular, planar and approximately square spiral.The spiral continues inwards in a manner which is completely analogous to that described above and has in the embodiment according to fi g 3 slightly more than three "turns". The curved or angled guide portions 18, 18 ', 18 "etc. have an angle of curvature in the order of 70 ° -10 ° which depends on the shape of the carrier 4.

The angle of curvature may be different for different angled portions in one and the same radiating element.

The embodiment according to fi g 4 follows the same principles but is made in right turns in contrast to what applies in fi g 3. Another difference is that the embodiment according to fi g 4 is slightly lower and elongated in the horizontal direction and therefore fills a much larger part of the wearer's 4 yta. It can be expected that this larger surface area gives the finished antenna a larger aperture and thus a better radiation capability.

The angular spiral radiating elements 15 described above are both fed from the outside at the periphery.

It has been found that radiating elements according to fi g 3 and 4 have at least two resonant frequencies. The higher resonant frequency is in principle determined by the height of the spiral, i.e. in fi g 3 of the length of the vertical conductor portions 17 and 17 '. The shorter these are, the higher the resonant frequency and vice versa. The lower resonant frequency is determined by the total length of all conductor portions 16, 17, 16 ', 17', etc., i.e. "the total wire length included in the coil". In practice, this means that with a given height, the width of the spiral, i.e. the length of the horizontal conductor portions 16, determines the lower resonant frequency. By analogy with the above, the shorter these are, the higher the resonant frequency and vice versa. In the embodiment form according to fi g 3, the resonant fi sequences are in the order of 900 MHz and 1800 MHz, while in the embodiment form according to Fig. 4 it becomes approximately 800 MHz and 1900 MHz (the figures in scale 1: 1). The higher value of the higher resonant frequency is due to the fact that the height of the spiral in fi g 4 is slightly smaller than that in fi g 3. Furthermore, of course the resonant frequencies will be affected by the plastic material in the carrier 4 but of course also by the material in the body part 3 and the protective hood 1 1. The effect of these plastic materials means that the resonant frequencies decrease slightly.

Because the radiating element in the embodiment according to fi g 4 has a larger surface area than that which applies in the embodiment according to ñg 3, a greater efficiency can be expected for the embodiment according to fi g 4.

In fi g 5 a modified embodiment of the radiating element according to fi g 3 is shown. together.

The position of the short circuit 19 in the radiating element 15 does not appreciably affect the higher resonant frequency but can be used to tune the resonant frequency in the lower frequency band. The further out in the coil the short circuit is located, ie in electrical terms the closer it is located to the supply part 13, the higher the resonant frequency in the lower frequency band compared to if the short circuit 19 did not exist. Conversely, the resonant frequency becomes lower in the lower frequency band the further towards the center of the radiating element 15 where the short circuit 19 is placed. In the extreme case with the short circuit 19 maximally offset inwards, the difference in resonant frequency is close to zero with an identical radiating element without short circuit. Thus, if a radiating element according to fi g 3 is dimensioned to the nominal frequency bands, the element will probably resonate at too low frequencies after mounting on the frame part 3 has taken place and the protective hood 11 has been fitted. It is then possible to place a short circuit 19 in such a position along the spiral that the said reduction of the resonant frequency is compensated.

Another argument for using a short circuit 19 is that the outer distance of the antenna determines its aperture. This means that with a large outer dimension, ie a large total "wire length" in the angular spiral, its lower resonant frequency tends to be too low. By using the short circuit 19, the lower resonant frequency fl can be superimposed up to the correct value with maintained outer reaches and thus with maintained aperture.

In an embodiment with a short circuit 19 in the coil, the portion of the coil located inside the short circuit can be regarded as a top load for the portion of the coil located outside the short circuit.

The embodiment according to Fig. 5 also differs from the embodiment according to fi g 3 by the presence of a blindly closing conductor portion 20. This conductor portion 20 is located in the end of the outermost vertical conductor portion 17 facing away from the feed part 13 in the radiating element 15 and is approximately perpendicular to the first vertical conductor portion 17 and can thus be seen as an extension of the first horizontal conductor portion 18. The effect of the blindly closing and projecting conductor portion 20 is that an optimization takes place of the resonance in the higher frequency band, so that this resonance is amplified while the width is increased, even to the extent that both the DCS and PCS tapes can be covered.

The presence of the blindly closing conductor portion 20 does not significantly affect the resonance in the lower frequency band.

Possibly, the outermost, vertical conductor portion 17 between the feed portion 13 and the blind-closing conductor portion 20 can be considered as a separate radiating element in the higher sequence band. In this case, the blindly closing conductor portion 20, possibly together with the spiral itself, forms a top load for the radiating element in the high frequency band.

Alternatively, the first vertical conductor portion 17 and the projecting conductor portion 20 may be considered as an angular, planar spiral with less than one revolution, in about 5 and a half revolutions.

The execution form according to fi g 6 differs from the execution form according to fi g 4 mainly in that the spiral is slightly narrower than that which applies in fi g 4.

Furthermore, in accordance with what applies according to fi g 5, there is a short circuit 19.

An outer conductor portion 16 included in the radiating element 15 is connected both to the supply part 13 and to a blind-closing conductor portion 21. In this embodiment, the blind-closing conductor portion 21 has been given the shape of a "square, flat spire" with slightly smaller than one lap. Theoretically, this could correspond to a "spiral antenna" which is tuned to the higher frequency band. It is also conceivable that the blind-closing conductor portion 21 is analogous to the above-described blind-closing conductor portion 20. The embodiments according to fi g 7 differ from the embodiment according to fi g 4 by the presence of both a short circuit 19 as a blindly closing conductor portion 20. However, in this figure the short circuit unites three conductor portions with each other.

In the embodiment according to fi g 8, the blindly closing joint portion 21 is connected to the angular spiral half a turn into it, ie after the second straight conductor portion 16, which in this case is the first horizontal conductor portion. The blind-closing conductor portion 21 is L-shaped and adjoins the periphery of the coil so that it extends along the first horizontal conductor portion 16, rimmed the corner 18 between it and the first vertical conductor portion 17 and at least partially along it. Also in this embodiment there is a short circuit 19, which is located a maximum far towards the center of the spiral.

ALTERNATIVE EMBODIMENTS It has been assumed above that the short circuit 19 is located on the same side of the carrier 4 as all other conductor sections and that it consists of the same metal layer as the conductor sections. However, instead of a galvanic short circuit, it is possible to use a capacitive short circuit which in that case is located on the opposite side of the carrier 4.

A capacitive short circuit 19 can also be located on the same side of the carrier 4 as the straight conductor portions 16, 16 ', 16 "and 17, 17', 17" etc. and be caused by nearby conductor portions in the area of the capacitive short circuit 19 having little mutual distance.

In the alternatives in the short circuit 19, the portions of the radiating element 15 which are located inside the short circuit can be given a design deviating from the helical shape. The portions of the radiating element located inside the short circuit 19 function in this context as a top load for the radiating element in the lower frequency band.

It has been described above how the carrier 4 is rolled or wrapped externally around a body part 3. As an alternative, the carrier 4 can in more or less rolled-up condition be arranged inside a cavity or recess in the body part. The cavity can be cylindrical, conical, etc. and can have a circular, oval, elliptical or arm-shaped cross-section. . ||| »| In a further embodiment of the invention, the carrier 4 is flat as shown in the drawings. In this alternative, it can be fixed on a flat body part or even fixed on the inside of the cover, which the mobile phone is provided with.

As an alternative to a telescopic rod arrangement, a fixed length rod arrangement can be used. This can be particularly advantageous at M2 and M4 resonance in the high and low frequency bands, respectively. Finally, a spiral rod arrangement can also be used.

Claims (7)

10 15 20 25 30 35 516 466 l 1 PATENT REQUIREMENTS An antenna device for fl your frequency bands comprising a first element radiating in fl your frequency bands in the form of a rod arrangement (22), a second element (15) radiating in fl your frequency bands with a pattern of conductor portions arranged on a tube or gutter rolled carrier (4) of insulating material, the pattern of conductor portions being formed as a substantially planar, angular spiral with a number of galvanically interconnected, substantially straight conductor portions (16, 16 ', 16 "17, 17', 17" ...), characterized in that the rolled-up carrier (4) has an axially directed opening or slot, that the carrier has guide portions in connection with the edges (26, 27) which meet each other along the opening or slot and that the rod arrangement (22) extends axially in the area of the opening or slot to be fed non-galvanically from the carrier. Antenna device according to claim 1, characterized in that the rod arrangement (22) is displaced inwards towards the interior of the coiled carrier (4). Antenna device according to claim 1 or 2, characterized in that the rod arrangement (22) is displaced outwards from the interior of the coiled carrier (4). Antenna device according to any one of claims 1-3, characterized in that the second radiating element (15) is galvanically connected to at least one transiver in the apparatus on which the antenna device is located. Antenna device according to any one of claims 1-4, characterized in that the angular spiral is fed at its periphery. Antenna device according to any one of claims 1-5, characterized in that two adjacent conductor portions in the angular spiral are connected (19) to each other. Antenna device according to any one of claims 1-6, characterized in that a freely closing conductor portion (20, 21) is connected to an outer conductor portion (16, 16 ', 16 "17, 17', 17". ..) in the angular spiral.