GB2387971A - Antenna device - Google Patents

Abstract

A Planar Inverted F-Anenna (PIFA) comprises a ground plane 102 and a radiating member 105 extending above and spaced from the ground plane but conductively connected to the ground plane, the radiating member 105 having a cavity 114 within which is located a circuit 110, the circuit being connected to another circuit outside the cavity. The circuit 10 is connected to a printed circuit board 103 by means of a connection arrangement 106. A feed point 12 of the antenna is connected to a feed post 113.

Description

- 1 2387971

AN ANTENNA DEVICE A RIO COI=TION DEVICE

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FIELD OF THE INVENTION

The present invention relates to an antenna device for transmitting and receiving Rú waves in at least a first Frequency band and comprising a support structure and at least one radiating antenna portion carried by the 10 support structure.

The invention also relates to a radio communication device including such an antenna device.

15 3CKGROUND OF THE INVENTION

In _he radio communication systems of today there is an ever increasing demand for making the user devices smaller. This is especially important when it comes to 20 handportable terminals, e.g. portable phones. The design of the handportable terminals must permit the rerminais to be easily and rapidly manufactured at low costs. Still the terminals must be reliable in use and exhibit a good performance.

It is well known that the size of an antenna is criti cal for its performance, see Jcnnsson, Antenna Enginee ring Handbook, McGrawHill 1993, chapter 6. The interac tion between antenna, phone body and the close-by 30 environment, such as e.g. the user himself, will become more important than ever.

This puts requirements on the antenna device to be compact, versatile and to have good antenna performan 35 ce. It must also be robust, stable, easy to mount, easy to connect, and arranged so as to e_rlciently use the

available space. Interest has also been focused on antenna devices mounted inside the housing of hand-

po-table terminals. Thereby, protruding antenna parts are avoided.

The radiating properties of an antenna device for a small-sized structure, e.g. for a handportable termi-

nal, such as a portable phone, depends heavily on the shape and size of the support structure, e.g. a printed 10 circuit board, PCB, of the phone, and also on the phone casing. All radiation properties, such as resonance frequency, input impedance, radiation pattern, impedan-

ce, polarization, gain, bandwith, and near-field pat-

tern are products or the antenna device itself an& its 5 interaction with the PCB and the phone casing. On top of this, objects in the close-by environment affects the radiation properties. Thus, all references to radiation properties made below are intended to be for the whole device in which the antenna is incorporated.

What has been stated above is true also with respect to radio communication systems used in other apparatus than portable phones, such as cordless telephones, telemetry systems, wireless data terminals, etc. Thus, 25 even if the antenna device of the invention is describ-

ed in connection with portable phones it is applicable on a broad scale in various radio communication appara-

tus. 30 As the rate at which new models of portable phones are presented is increasing, the time from start of the development or a new model to the start of production and marketing of the same has been drastically shorten-

ed during the last few years. Further, there is a 35 demand for a reduction of the manufacturing costs at the same time as the technical requirements are in

creasing which necessitates more runc.icns to be in-

cluded in each unit. Further, the di_-eren. parts and urn's must be manufactured to fit well into the method of production. Simple interfaces is one key feature to 5 simplify the assembly of the final product 'rom diffe-

rent parts manufactured at different places.

For all types OI radio communication devices, the part between the antenna and the active components of the RF 10 ront-end is critical for the total performance of the radio communication device. This is because all losses that are introduced here are critical from a system point of view. On the receiver side losses that occur before the Low Noise Amplifier (LNA) regrades the 5 sensitivity of the receiver. On the transmitter side, losses that occur after the Power Amplifier (PA) causes degradation of the transmitted power, forcing the PA to transmit at a higher output level.

20 For portable terminals with energy provided by battery power, these factors are even more critical. Reduced receiver sensitivity causes the device to perform worse in areas with low signal levels. A higher output level from the PA increases the energy consumption from the 25 battery, thereby reducing the available active opera-

ion time.

Modern manufacturing methods for devices, such as portable telephones, is based on modules that are So assembled in a final assembly line. This procedure requires simple and reliable interfaces between the modules. This typically implies that the interfaces have large tolerance=, making them hard to specify tightly. Specifically, this means that the loss in the as interface can be quite large.

In order to obtain improvements in these respects some new principals for designing and assembling the pro-

ducts are necessary. Among them, the method GI- instal-

ling the antenna device and at least some o' the re-

5 quired RF components must be improved.

Resistive losses, for instance/ can be substantially reduced by shorting the connection lines between the antenna elements and the required active analogue lo components, such as filters, amplifiers, etc. This can be obtained by mounting the components close to the antenna elements, and preferably on a common support structure in order to form a separate antenna module.

15 This is or specific interest for future Software Radio, SR, architectures where the function of many traditio-

nal RF parts in the terminal are included in the soft-

ware controlling the signal processor. The number of analogue RF parts, especially analogue filters, are No strongly reduced in the software radio architecture.

The ideal SR converts the analogue signal to/from digital data as close as possible to the antenna eie-

ments. However, some components, such as the Low Noise Amplifier(s), TUNA, the filters to reduce strong in 2s terfering signals and noise, the Power AmpliCier(s), PA, and the duplexers to separate transmitting and receiving signals, must still be made as analogue components. Thus, i. would be a great advantage if the radio communication device could be assembled from 30 modules, for instance a complete RF module including all analogue Rr parts and the antenna, and a digital module comprising the signal processor, and a simple interface therebeLween.

35 In more detail a number of advantages can be obtained by such a proposed complete RF module. One is the

reduction of losses mentioned above. Another is the s Kepler RF interface enabled by ceding a lower power face the t_smiter circuitry -I n the d Hi tal module to the RF power ampli ier i n the RF modul, and by ampli 5 Eying the received power before feeding it from the low noise amplify er in the RF module to the receiver cir-

cuitry in the digital module. The proposed position of the interface between an antenna module and a radio module means that losses in the interface is not criti 10 Cal. This reduces the requirements on the tolerances of the interface (e.g. the contact pins) so that a more favourale assembly method can be chosen.

A further advantage can be the simplification of the 15 duplexer, tlplexer, etc. function if more than one antenna is used, e.g. separate receiving and trans-

mitting antennas. To implement this in an efficient way it is necessary that this function is part or a comple-

te RF module. An additional advantage is obtained by a 20 mechanical integration in order to utilize the volume below the antenna element as well as possible. By using the physical area or the antenna module to mount some components needed for processing or the analogue sig-

n3s the total space required is reduced. This is 25 because the positions of the components can be chosen so that they have a minimum impact on the antenna performance. It is an advantage if the interaction between different components can be controlled, both for antenna perfomance and for interference, intermodu 30 ration, etc. Preferably, the antenna structure should conform to the exterior casing or the radio communication. device.

However, the most of the improvement in volume below 35 the antenna element when going from a flat antenna element to an element adapted to the form of the casing

- '. is being obtained already when using an element arang-

ed on a carrier having a single curvature only.

SUMMERY OF THE INVENTION

In this disclosure it is to be understood that the

antenna device of the invention is operable to transmit znd/or receive RF signals. Even if a term is used herein that suggests one specific signal direction it lo is to be appreciated that such a situation can cover that signal direction and/or its reverse.

A main object of the present invention is to provide an antenna device which is easy to manufacture, easy to 15 mount and which enables an efficient use of the avai7--

able space, and has good antenna performance.

An other object is to provide an antenna device in which internal losses due to the resitivity in connec 20 tion lines have been reduced.

A further object or the invention is to provide an antenna device which can be formed as an easily in-

sta7lable antenna module also including processing 2s capacity for analogue RF signals.

An additional object or the invention is to provide an improved antenna device with processing capacity for analogue RF signals which can be formed as a module 30 which via a readily connectable interface can be con-

nected to a signal processor of a software radio mo-

dule. A further object of the invention is to provide an 35 antenna device comprising matching circuits so as to let said antenna means be connectable to a connection

1 ot point having a specific, matched, impedance, for in-

s-ance JO ohm.

A still further object or the invention is to provide 5 an antenna device which is designed as a built-in module. Another object of the invention is to provide an ar-

tenna device which can be adapted to the shape of the 10 casing of the radio communication device it is to be installed in.

These and othe' objects are attained by an antenna 5 device as claimed in claims 1-48.

Claims 31-48 of these claims relate to antenna devices

of the kind generally named Planar Inverted F-Antennas, PIFA, modified in accordance with the present nven 20 Lion. The space occupied by such a modified PIFA is more effectively used since circuitry is accomodated inside the antenna. An other advantage of this design of a PIFA is that such circuitry can be placed in the immediate vicinity of the antenna feeding point, thus 5 avoiding transmission losses.

According to a preferred embodiment of the invention an.

antenna device is provided comprising duplexes, or switch means for combining transmitting and dividing 30 receiving frequencies, filter means for filtering transmitting and receiving frequencies, low-noise amplifier means for amplifying the receiving frequen-

cies and, possibly, powe- amplifie' means for power amplifying the transmission frequencies, as well as a 35 connection device for easy connecting the signal lines to a connection point having a specific impedance, for

instance 50 ohm, and further coupling the signals to OF clrcuitr in the radio communication dev ce.

According to an other embodiment of the invention an 5 antenna device is provided comprising means for secure-

y holding a SIM-card and connecting said SIM-card to circuitry in the radio communication device.

An additional object of the invention is to provide a 10 radio communication device comprising an antenna device manufactured to fulfil the main object of the invention mentioned above. This object is obtained by a radio communication device as claimed in claim 49.

15 An advantage, according to one embodiment of the in-

vention, is that the space occupied by a PTFA is more effectively used since circuitry is accommodated inside the antenna which otherwise would have to be placed in the surrounding areas.

An other advantage, according to one embodiment of the invention, is that circuitry essential for the effec-

tive operation of the antenna can be placed in the immediate vicinity of the antenna feeding point, thus 25 avoiding transmission losses. The feeding point being the point inside said cavity connecting said feeding means to said feeding post.

Another advantage, according to one preferred embodl 30 ment of the invention, is that it is possible to achieve a matched antenna having connector means with a specific impedance, for instance 50 ohm.

The invention is described in greater detail below with 35 reference to the embodiments illustrated in the append-

ed drawings. However, it should be understood that the

detailed description of specific examples, while in-

icaing pre erred embodiments of the invention, are given by way of example only, since various changes and modifications within the scope of the claims will 5 become apparent to those skilled in the art reading this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

10 Figure 1 is a diagrammatic plan view of an embodiment of an antenna device according to the present inven - Lion. Figure la and b is a sectional view and a perspective 15 view of the antenna device of figure la, respectively.

Figure 2 is a diagrammatic plan view of an antenna device comprising a slot antenna element.

20 Figure 3 is a diagrammatic plan view of an antenna device comprising a patch antenna element.

Figure 4 is G diagrammatic perspective view of a curved antenna element in accordance with the present inven 25 Lion.

Figure 5 is a diagrammatic block diagram of an antenna module for transmitting and receiving RF waves accor-

ding to a preferred embodiment or the present inven o Lion.

Figure 6 shows a diagrammatic view of an antenna device according to further embodiment of the invention in a cross-sectonal view.

Figure 7 shows a diagrammatic perspective -view of an

N. antenna device according to a further embodiment of the invention; Figure 8 and 9 snow diagrammatic plan views of antenna 5 devices according to additional embodiments of the invention where part of the top of each antenna device has been lifted away for sake of clarity.

Figure 10-13 show diagrammatic sectional side views of 10 antenna devices according to other embodiments of the invention. Figure 14 shows a diagrammatic top view of an antenna device according to a further embodiment of the in 15 Mention.

Figure 15 shows a diagrammatic perspective, partly ghost view of a GPS antenna device according to an embodiment of the invention.

Figure 16 shows a diagrammatic sectional side view of an additonal embodiment of an antenna device according to the present invention employing a traditional hot-

wire feed.

Figure 17 shows a diagrammatic sectional side view of a further embodiment of an antenna device according to the present invention having a smooth curve line.

3 O DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

W'th reference to Figure 1, a radiating antenna element l on a carrier 2 included in an antenna device for transmitting and receiving RF waves is diagrammatically 35 shown. In this embodiment the antenna element 1 is of meander form. The carrier 2 can be relatively thin and

I,'- q 0t is preferably made from a dielectric polymeric sheet material. The car- e- can be s.i= but can also be flexible so that it can be shaped so as to closely cortcrm to the casing of the radio communication devi 5 ce, for instance a portable telephone, it is to be arranged in.

The antenna element 1 is illustrated as a receiving antenna connected to a Low Noise Amplifier, LNA, 3, but -lo can just as well be a transmitting antenna. The LNA is provided with an output line 14 for amplified RF sig nals. In accordance with the present invention the ENA is 15 mounted very close to and on the same carrier 2 as the antenna element 1. This means that losses in the RF signal path between the antenna element 1 and the LNA 3 are substantially reduced compared to devices in which the LNA is positioned on a Printed Circuit Board, PCB, 20 of the radio communication device spaced from the antenna. It is advantageous to reduce these losses as losses occuring before the LNA degrades the sensitivity or the receiver.

25 In order to reduce the interaction between the antenna element 1 and the [NA 3, or other analogue components mounted on the carrier 2 a shielding can is arranged to surround the LNA at least partly. The shielding can is made of an electrically conductive material and, in 30 accordance with the present invent-on, the feed line 5 of the antenna goes directly into the shielding can 4 wh ch is mounted very close to the antenna element 1.

Thus, the shielding can 4 is functionally integrated with the antenna element 1 and will act as an actively 35 radiating part of the antenna.

tJ 6 Flqures la and b show a sectional view and a perspec-

ive view, respectively, of the antenna device of Figure la.

5 The antenna device which forms a readily installable module can easily be fitted in the casing of a radio communication device and its output is connected to additional receiver circuitry by means of a simple interface. As the received RF signals are amplified 10 before they are passed through the interface the design of the interface is not as critical as it is in cases where it should handle un-amplified RF signals to be fed to a LNA positioned on a PCB of the radio communi-

cation device, for instance.

Figure 2 illustrates a slot antenna element 6 including a conductive sheet 7 provided with a RF radiating slot 8. In this embodiment the antenna element operates as a transmitting antenna and RF signals are supplied from a 20 Power Amplifier, PA, 9 which feeds the antenna element with amplified RF signals across the slot 8. This is indicated by means of a contact point 10 between the signal feed line 11 and the conductive sheet 7 in which the slot 8 is provided.

The shielding can 4 surrounding the PA 9 is mounted as an integrated part directly on the antenna element 6 and in galvanic contact with the conductive sheet 7.

Thus the shielding can operates as a part of the con 30 ductive sheet 7.

The PA 9 is supplied with transmitting RF signals via an input line 15 connected to transmitting curcuitry of a radio communication device via a simple interface 35 (not shown). The design of the, interface is simplified because it has not to be designed for handling ampli

l -red high power RF signals. The position of the PA on the antenna element 6 and after the terrace a so reduces losses of the amplified signals which is impor-

tant. Otherwise such losses require the PA to transmit 5 at a higher output level. This should increase the energy consumption from the battery powering the PA and should accordingly reduce the available active opera-

ion time of the radio communication device.

-lo figure 3 illustrates a RF transmitting antenna device corresponding to that of figure 2 but in which the slot antenna element has been replaced by a patch antenna element 16. The same reference numerals as in figure 2 have been used on corresponding parts. The PA 9 feeds 15 the patch 16 with RF signals via a feed post 10 which passes through an opening 17 in the parch, and down towards a ground plane (not shown). The PA 9 and the shielding can 4 are mounted directly on the patch 16 and the shielding can is galvanically connected to the 20 patch -6. Thus, the shielding can 4 is integrated with the patch 16 and will operate as an actively radiating part thereof. The shielding can can also be formed by a part of the patch i6 itself so that a cavity is formed between the patch and a supporting carrier, not shown.

25 In that case the PA 9 is positioned in said cavity.

The above mentioned antenna elements have only been shown as representing preferred examples and the in-

vention is not limited to the use of any specific form 30 or any specific way of feeding an antenna element.

ur.he-, only one analogue RF component or circuit has been shown to be integrated with the respective antenna element and shielded by a shielding can. However, in accordance with the present invention any or all ana 35 rogue RF components of the receiving and the trans-

mi.ting circuitry of a radio communication device can

be mounted together with the antenna element to form an easily manufactured antenna module which is readily installable in a radio communication device.

5 Figure 4 shows an antenna device in accordance with the present invention formed as a curved antenna module 26. The curvature has been adopted to the design of the radio onnunication device in which the antenna module is intended to be arranged. The module shown in the lo figure is shaped to fit into a portable phone. The carrier can be a flexible substrate which is easily -

adoptable to any design of a casing. A meandering antenna element 27 is provided on the concave surface -of the carrier and connected to a shielding can 28 in 15 which one or more analogue RF components are mounted.

The shielding can is connected to and functionally integrated with the antenna element. The components in the can 28 can be readily connected to the remainder circuitry of a radio communication device via a simple 20 interface (not shown). The meander element can be replaced by any other radiating antenna element, such as a patch element or a slot element, or a combination o- different kinds of antenna elements.

25 As an alternative to being prov deaf on the concave suer-ace of the carrier the antenna element can be provided on the convex surface as well. Further, a first portion of the radiating antenna element can be on the concave surface and a second portion can be on to the convex surface.

The shielded analogue components or some of them can be mounted on the convex surface, preferably in recesses.

Antenna elements and components on opposite sides of 5 the carrier can be interconnected by means of connect-

ing lines passing through holes in the carrier.

it? The carrier 26 can be excluded and the antenna element and the shielding can be provided directly on the inner surface or to- nstance the back part of a divided casing or a portable telephone. The antenna element can 5 be composed of a thin electrically conductive film which can be adhered to the desired surface.

The shielding can has been shown as a closed box pro-

vided with openings required for connection lines.

10 However, the box can be replaced by a shield in the form of a tunnel or the like. The walls of the shield need not be completely closed, but can be provided with openings provided the greatest dimension of the open-

ngs is substantially smaller than A/2 of the RF fre 15 quency used.

Figure 5 illustrates a preferred RF antenna module according to the present invention. The module 30 comprises separated RF transmitter (TX) 31 and RF 20 receiver (RX) 32 sections.

The antenna module 30 is the high frequency (HF) part or a soft ware radio communication device (not shown) for transmitting and receiving radio waves. Thus, 25 antenna module 30 comprising all analogue components is preferably arranged to be electrically connected, via a relatively simple interface, to a digital signal pro-

cessor of the radio communication device.

30 The antenna module 30 is preferably supported on a carrier 33 which may be a flexible substrate, a MID (molded interconnection device) or a PCB. Such an antenna module PCB may either be mounted, particularly releasably mounted, together with a PCB of the radio 35 communication device side by side in substantially the same plane or it may be attached to a dielectric sup

1-- porting means mounted e.g. on the radio device COB such that it is substantially parallel with it, but elevated here ram. The antenna module COB can also be substan-

tially perpendicular to the PCB of the radio communica-

5 Lion device, or it can have a three-dimensional form.

The transmitter section 31 includes an input line 34 for receiving a digital signal from a digital trans-

mitting source of the radio communication device. The 10 input line 34 is connected to a digital to analogue (D/A) converter 35 for converting the digital signal to an analogue signal. The converter 35 is further connec-

ted to a power amplifier (PA) 36 for application of the frequency converted signal. An unconverted knot shown' 15 for upconvertng the frequency or the analogue signal to the desired RF frequency can be arranged between the D/A and the PA. Power amplifier 36 is further connected to a transmitter antenna element 37. A filter (not shown) may be arranged in the signal path before or 20 after the power amplifier.

A device 38 for measuring a reflection coefficient, e.g. voltage standing wave ratio (VSWR), in the trans-

mitter section is connected between power amplifier 36 25 and the transmitter antenna element 37.

A switching device39, preferably a switching matrix of MEMS (Microelectromechanical System switches), is connected between the SWR and the transmitting antenna 30 structure 37, which is switchaole between a plurality of (at least two) antenna configuration states, each of which is distinguished by a set of radiation related parameters, such. as resonance frequency, input impedan-

ce, bandwidth, radiation pattern, gain, polarization, 35 and near-field pattern.

The receiver section 32 includes a receiving antenna e emen_ JO for receiving Rr waves and So' generating an RF slgna2 in dependence hereof. The receiving antenna element 40 is switchable between a plurality of (at s leas. two) antenna configuration states, each of which is distinguished by a set of radiation related parame ers, such as resonance frequency, input impedance, bandwidth, radiation pattern, gain, polarization, and nea---ield pattern. A switching device 4' is arranged 1O in proximity thereof for selectively switching the antenna element between.the antenna configuration states. The switching of the antennas between a plura lity of antenna configuration states is further detail ed in our co-pending Swedish patent application No. 35 9903942-2 "An antenna device for transm sting ancl/or receiving RF waves", filed on October 29, 1999, which application hereby is incorporated by reference.

The antenna element 40 is further connected to one or several low noise amplifiers (LNA) 42 for amplifying 20 Cue received RF signal.

OR reception diversity is used the signal outputs from the low noise amplifiers 42 are combined in a combiner 43. The diversity combining can be of switching type, 25 or be a weighted summation of the signals. Two or more diversity branches can be used. A downconverter (not shown) for downconverting the frequency of the signal can be connected before an analogue to digital (A/D) converter 44 ror-converting the received signal to a 30 digital signal. The digital signal is output on an output line 45 to digital processing circuitry of the radio communication device. The diversity function can, alternatively, be included in the d gital part. This requires separate receiver circuits for each diversity 35 branch.

According to the embodiment of the invention shown in Figure 5 the transmitter section 31 and its antenna element 37, and the receiver section 32 and its antenna element 40 are arranged on a common carrier 33 to form 5 an easily manufactured and readily installable antenna module. The module comprises all analogue components and is intended to be connected to a digital processor unit via a rather simple interface (not shown).

lo In order to avoid disturbances between the components of the transmitter section and the components of the receiver section, andbetween the components and the antenna elements, shield-Leg cans 46 and 47 are arranged to shield the components of the respective section. The is shielding cans are connected to the antenna elements as has been described earlier.

Each shielding can 46, 47 can be divided into two or more compartments by partition walls 48, 49 to avoid 20 disturbances between components in each section.

The invention may wel', be used for modifications of antenna devices of the kind generally named planar Inverted F-Antennas, PIFA, and some preferred embodi 25 meets of such modified PIFA elements are shown in the Figures 6-17.

Figure 6 shows an antenna in a cross-sectional view according to a preferred embodiment of the invention 30 where a PCB (Printed Circuit Board) is denoted 101. A ground plane means 102 is located on one side of the PCB 101 and on the other side is a circuit layout 103 located. An antenna support structure 104 is coated with a conductive layer 105. The support structure 104 35 is connectable to a connector means 106. The connector means 106 may for instance consist of metallic hooks

- 107 with spring action Lo grip the support Lo firmly fix the support structure iO4 in position and elec-

trically couple the ground plane means 102 to the con-

ductive coating 105. The coupling means 1C6 further 5 comprises male connector means 108 arranged for co-

operating with female connector means 109 located and fixed in connection with said support structure 104.

The male connector means are connected to the circuit layout diagram 103 for Further coupling to circuitry lo located elsewhere on the PCB 101.

The support structure 104 has a cavity, or a substan-

tially confined space 114. Since the support structure 104 is substantially completely surrounded with a 15 conductive coating IDS, which is coupled to a ground plane means 102, the space 114 constitutes a Faraday cage. This space 114 is thus shielded from magnetic and electric radiation and is therefore particularly suit-

able for housing analogue RF circuitry 110 of the 20 antenna device.

The RF circuitry 110 -s connected through the female connector means 109 and the male connector means 108 to circuitry located elsewhere on he PCB 101. A feeding 25 line 111 is also connected to the female connector means 109, for furthe- connection through the male connector means 108 to circuitry (not shown) located on the PCB 101. It is thus clea- that the male and female connector means 109, 108 may, in their turn, have one 30 or more individual connector means for connecting different signals. The connector means lOB, 109 may constitute an interface between analogue circuits in the cavity and digital processor circuits elsewhere on the PCB 101.

The feeding line is further connected to a feeding point 112 which is connected to a conductive feeding

post 113. The conductive feeding post 113 is extending down cowards the ground plane means to constitute a capacitive coupling with said ground plane means 102.

So is a planar inverted F-antenna construed having an 5 inner shielded space suitable for mounting analogue RF components. The shielding conductive layer is complete-

1y integrated with a radiating antenna surface.

Figure 7 shows a diagrammatic perspective view of an 10 othe' embodiment of the invention. A support structure 201 is shown in "look through" fashion to reveal the arrangement inside the antenna means. An interface connector means 202 firmly grips and connects the support structure 201 to a PCB 203. A ground plane 15 means 204 on the top side of the PCB is connected, through the coupling means 202, to a conductive coating 205 on the support structure 201. First, second and third connector means, 206, 207 and 208 are coupling first, second and third cicuitry 209, 210 and 211 20 located in a cavity 212, de ined by said support struc-

ture 201, to circuitry (not shown) located outside said cavity 212. The cavity with its surrounding conductive coating defines a Faraday cage.

25 A feeding point 213 is corrected to said second and third circuitry 210 and 211, which divides the signal in receiving and transmitting signals. The feeding point is connected to the conductive coating 205 as is a conductive post 214, extending downwards towards the 30 ground plane means 204 and substantially across the complete width of the support structure 201. The feed-

ing point is connected to the conductive Feeding post, and the conductive feeding post may be connected to the ground plane means or may define a capacitive coupling 95 with said ground plane means.

_,r) Figure 8 shows z diagrammatic view according to a Further embodiment o the invention in top view where Ace top part has been cut away. A support structure of c dielectric material 301 has a conductive coating 302.

5 Circuitry 303 is connected through first and second connection means 304, 305. Circuitry 303 is any ana lcgue circuitry which is conveniently positioned inside said support structure 301. The first and second con nection means may be any means for electrically con 1O necting one or several signals to said first and second circuitry 302 and 303, such as twisted pai- cable, serialize, micro stripline, coplanar wave guide etc. A reed line 306 is connected, at one end to coupling means (not shown) for further connection to F.F cir 1-, cuitry and, at the other end to a feeding point 307 which is connected to a conductive post 30C,, shown with a dotted circle is extending down towards a ground plane means (not shown) making a capacitive coupling with the same.

Mu Figure 9 shows a diagrammatic view according to a rurtner embodiment of the invention in tap view where the top part has been cut away. In this embodiment a feeding point 402 is connected to a duplexes 401. The 25 feeding point 402 is located above, and connected to, an elongated conductive post 403 indicated by dotted lines which extends down towards a ground plane means (not shown). The dupioxer 401 separates transmitting and receiving RP signals and couples the receiving 30 signal to a filter 404, a low-nose amplifier 405 and Further through interface means (not shown) to the receiving circuitry (not shown) located in a portable radio communication device too. shown). Similarly the RF transmitting signal is received from the transmit 35 ting circuitry of the radio communication device, coupled to a filter 406, to the duplexer 401 and fed

through the feeding point 402. Possibly, also matching means migh' be included in the arrangement. Thus a planar inverted F-antenna is achieved, which supplies a connection with separated transmitting and receiving 5 signals, comprising amplification for the receiving signal at the closest possible location to the receiv ing point of the antenna, which is matched to a 50 ohm impedance. 10 In figure 10, a diagrammatic sectional side view of a -urther embodiment according to the invention is dis closed. A support 5Q1 is mounted on a PCB 502 having a ground plane means 503 on the surface facing the sup ort 501 and a circuit layout 504 on the opposite 15 surface. Said support having a conductive coating 505 on a first side, orthogonal to said ground plane means 503, and on a second side substantially facing said ground plane means. Said conductive coating being electrically coupled to said ground plane means 503.

20 Said coating 505 is in electrical contact on all sides with a stiff conductive metallic sheet 506 forming an integrated part of the radiating antenna and defining together with said conductive coating a shielded space 507 having one open side 508. Inside said space is a 25 first circuit 509 located. A feedline 510 is r-eeding RF signals to a feed point 511. Said feed point 5il is in conductive contact with a conductive post 542 extending down towards said ground plane means 503 for achieving capacitive coupling.

Figure 11 shows a diagrammatic cross-sectional side -view of a further embodiment according to the inven ion. The embodiment in figure 11 is somewhat similar o the embodiment shown in figure 10. The main diffe 35 rence being that a stiff conductive metallic sheet 601 has a protruding part 602 extending substantially

- ( parallel to a ground plane means 603 at a first distan ce 604 -am the ground plane means. Said first distance is dir Cement from a second distance 605 from a conduc tive coating 606 to the ground plane means 603. By 5 designing the planar inverted F-antenna to have sur faces substantially parallel to the ground plane means 603 but at different distances, the antenna can more precisely be tuned to different resonance frequencies ro' multi band operation. A post 607 is exceeding from 10 the conductive coating 606 to the ground plane means 603. Figure 12 shows a diagramma c cross-sectional side view of an antenna according to the invention. In this 15 embodiment a shielded space 701, for mounting circuitry 703 and 704, is formed in the par' of the PIFA which is extending orthogonal to a ground plane means 702. A stiff conductive metallic sheet 705 is shielding the space 701 and extending substantially parallel to the 20 ground plane means 702. An insulated feed line 706 is exendlng on the sheet 705 for feeding RF energy to a feed point 707.

Figure 13 shows a diagrammatic cross-sectional side 25 view of a further embodiment according to the inven tion. A first and second feed point 801 and 802 are fed with RF signals from a firs_ and second feed line 803 and 804, respectively. The first and second feed line 803 and 804 may be feeding transmitting and receiving 30 RF signals respectively, or may be feeding signals from two different systems, such as GSM and PCN, respec tively. Figure Id shows a diagrammatic cross-sectional top view 35 of the embodiment described in connection with figure 13. The same reference numerals are used in figure 14

as in figure 13.

Figure 15 shows a diagrammatic view of another embodi-

ment according to the invention. In this embodiment a 5 UPS antenna is formed using an almost square, but somewhat rectangular, conductive portion lQO1 which is red with an offset from the center, marked with an X, lQ02, to produce a circular polarized RF signal. A shielded cavity 100 is formed in the support structure 10 for mounting of analogue circuits 1004. An edge load 1005 is present to adjust the antenna to the preferred characteristics. The load 1005 make an impedance con-

nection between the conductive portion 1001 and a ground plane means (not shown).

Figure 16 shows a diagrammatic cross-sectional view or a further embodiment according to the invention where a hotwire 1101 is forming the conductive post and is arranged for feeding RF signals to the antenna accord 20 ing to traditional methods. A shielded cavity 1102 is formed inside a support structure 1103 and is arranged for housing circuits 1104 in similar ways as been described earlier.

25 Figure 17 shows a diagrammatic cross-sectional view of a preferred emDodimen. according to the invention where the antenna has a smooth curving to follow a contour OI a portable cellular phone. A conductive portion 1201 is arranged on a support and Is shielding a cavity 1202.

30 Circuitry (not shown) on a circuit board 1203, having a ground plane means 1204 arranged thereupon, is coupled to ana2ogue circuitry 1205 arranged inside said cavity through coupling means 1206 as has previously been described. as For manufacturing purposes, or other purposes, it could

- - be beneficial to design the cavity as a box having a lid or a hood, or, more generally, as a box having one open side which can, at a convenient time, be covered.

5 The conductive portion or coating defining and shield-

ing said cavity need not necessarily be tight but may instead be formed as a net or may comprise a number of holes, as long as the holes is substantially smaller than 1/4, that is, one quarter of the current wave lo length. This will seal the circuitry inside the cavity from the radiation emitted from the antenna device. The cavity can also be filled with a dielectricum.

The invention being thus described, it will be obvious 15 that tee same may be varied in many ways. Such varia-

tions are not to be regarded as a departure from the spirit and scope of the invention, and all such modifi-

cations as would be obvious to one skilled in the art are intended to be included within the scope of the 20 follow ng claims.

Claims (1)

1. An antenna device for receiving and transmitting RF signals in at least a first frequency band comprising: 5 - a support structure (104), a ground plane means (102), at least a first radiating conductive portion (105) extending above said ground plane means at a first distance from said ground plane means and being 10 electrically coupled to said ground plane means, - a conductive feeding post (113) extending between said first radiating conductive portion and said ground plane means, characterized in, that 15 - said first radiating conductive portion is forming at least a first cavity (114) comprising at least a first opening, - coupling means (106) being arranged for connecting a second circuit to at least one first circuit (110) 20 arranged inside said cavity through said first opening.

   2. An antenna device according to claim 1, comprising: a ground plane means (102), at least a first conductive portion (105) forming at 25 least one radiating antenna portion, and extending above said ground plane means at a first distance from said

   ground plane means and being electrically coupled to said ground plane means, and a conductive feeding post (113) extending between said first radiating conductive portion and said ground 5 plane means, wherein said first radiating conductive portion forms at least a first radiation shielding cavity comprising at least a first opening, said first circuit is arranged inside said cavity, 10 and - said coupling means are arranged for connecting said first circuit to said circuits of the radio communication device through said first opening.

   15 3. An antenna device according to claim 2, wherein at least a first feeding means (111) is extending through said opening and being coupled to said conductive feeding post at a feeding point (112) above said ground plane means, 20 - said feeding means being arranged for being coupled to RF circuitry for feeding RF signals to said feeding point. 4. An antenna device according to claim 2, wherein 25 _ said conductive post is a hotwire (1101) for feeding RF signals from RF circuitry to a feeding point on said

   radiating conductive portion above said ground plane means. 5. An antenna device according to any of claims 2 to 4, 5 wherein - said first radiating conductive portion extending at least partly substantially parallel over said ground plane means.

   10 6. An antenna device according to claim 3 or claim 5, wherein said conductive post extending towards said ground plane means from said first radiating conductive portion.

   15 7. An antenna device according to any of claims 2 to 6, wherein said ground plane means having a second opening adapted to fit to said at least first opening, said coupling between said first radiating 20 conductive portion and said ground plane means being achieved by coupling substantially the complete rim of said at least first opening to substantially the complete rim of said second opening in said ground plane means.

   25 8. An antenna device according to any of claims 2 to 7, wherein

   ! 29

   said coupling between said first radiating conductive portion and said ground plane means being achieved through metallic hooks coupled to said ground plane means and exerting a contact force on said first 5 conductive portion, - said hooks further being arranged for fixedly holding said support structure.

   9. An antenna device according to any of claims 2 to 8, 10 wherein said coupling means comprises at least a first connector member arranged on said support and at least a second connector member arranged on a circuit board, said first connector member having means for 15 connecting said radiating conductive portion to said ground plane means.

   10. An antenna device according to any of claims 2 to 9, wherein 20 - said first radiating conductive portion having a first portion substantially parallel to said ground plane means arranged at a first distance (604) to said ground plane means and a second portion substantially parallel to said ground plane means and arranged at a second 25 distance (605) from said ground plane means.

   ( 30 11. An antenna device according to any of claims 2 to 9, wherein said first circuit being selected from a group of analogue circuits including the following circuits: low 5 noise amplifier, power amplifier, de-coupler, coupler, multiplexer, diplexer, SIM-card, logical circuits' balun circuits, diod, sensing device and phasing circuits.

   12. An antenna device according to any of claims 2 to 10 11, wherein a second feeding means being arranged for feeding RF signals to a second feeding point, - said second feeding point being in electric contact with said at least partly parallel portion, 15 - a second conductive post, electrically coupled to said at least partly parallel portion, extending towards said ground plane means and arranged in proximity of said second feeding point.

   20 13. An antenna device according to any of claims 2 to 12, wherein said conductive post has a circular cross-section.

   14. An antenna device according to any of claims 2 to 25 13, wherein

   ! 31 said conductive post has an elongated cross-section extending from one side of said at least partly parallel portion to the opposite side.

   5 15. An antenna device according to any of claims 2 to 14, wherein said conductive post has a mechanical interface with said ground plane means so as to make an electrical conductive connection.

   16. An antenna device according to any of claims 2 to 14, wherein said conductive post couples capacitively to said ground plane means.

   17. An antenna device according to any of claims 2 to 16, wherein - said antenna being operative in at least a first frequency band corresponding to at least one of the GSM, 20 PCN, and/or GPS communication bands.

   18. An antenna device according to any of claims 2 to 17, wherein said cavity is filled with a dielectricum.

   19. A radio communication device comprising an antenna device according to any of claims 1 to 18.