Antennaless wireless device capable of operation in multiple frequency regions

Abstract

A radiating system comprises a radiating structure, first and second external ports, and a radiofrequency system. The radiating structure comprises a ground plane layer including a connection point, a single radiation booster including a connection point, and a first internal port defined between the connection points of the single radiation booster and the ground plane layer. The first and second external ports each provide operation in at least one frequency band. The radiofrequency system includes a first port connected to the first internal port of the radiating structure, and second and third ports respectively connected to the first and second external ports.

Claims

1. A radiating system comprising: a radiating structure comprising: a ground plane layer including a connection point; a single radiation booster including a connection point; and a first internal port defined between the connection point of the single radiation booster and the connection point of the ground plane layer; first and second external ports, each providing operation in at least one frequency band; and a radiofrequency system including a first port connected to the first internal port of the radiating structure, and second and third ports respectively connected to the first and second external ports.

2. The radiating system of claim 1, wherein the radiofrequency system comprises a frequency selective element.

3. The radiating system of claim 2, wherein the frequency selective element comprises a bank of filters.

4. The radiating system of claim 2, wherein the frequency selective element comprises a diplexer.

5. The radiating system of claim 1, wherein the radiofrequency system comprises: a first diplexer to separate electrical signals into first and second radiofrequency branches, the first radiofrequency branch providing operation at a first frequency band at the first external port and the second radiofrequency branch providing operation at a second frequency band at the second external port; a first matching network in the first radiofrequency branch to provide impedance matching at the first frequency band; and a second matching network in the second radiofrequency branch to provide impedance matching at the second frequency band.

6. The radiating system of claim 5, wherein the radiofrequency system further comprises: a second diplexer in the first radiofrequency branch that separates the electrical signals at the first radiofrequency branch into two more radiofrequency branches, the radiofrequency system comprising a third radiofrequency branch providing operation at a third frequency band at a third external port.

7. The radiating system of claim 5, wherein the first diplexer comprises a high-pass filter and a low-pass filter.

8. The radiating system of claim 5, wherein the first external port operates at a frequency band in the range from 824 MHz to 960 MHz and the second external port operates at a frequency band in the range from 2400 MHz to 2500 MHz.

9. A radiation booster system comprising: a first radiation booster configured to operate at a first frequency range and including a conductive part and a connection point; and a second radiation booster configured to operate at a second frequency range and including: a gap in a ground plane layer of a radiating structure of a radiating system, the gap being defined by a plurality of segments forming a gap curve; and a connection point located at a first point along the gap curve, wherein: the connection point of the first radiation booster, together with a first connection point of the ground plane layer, defines a first internal port of the radiating structure; the connection point of the second radiation booster, together with a second connection point of the ground plane layer, located at a second point along the gap curve, defines a second internal port of the radiating structure; and a distance between the connection points of the first and second radiation boosters is less than 5% of the free-space wavelength corresponding to a lowest frequency of operation of the radiating system.

10. The radiation booster system of claim 9, wherein the gap curve consists of three segments.

11. The radiation booster system of claim 9, wherein the gap curve is an open curve that intersects a perimeter of the ground plane layer.

12. The radiation booster system of claim 9, wherein the gap of the second radiation booster features a polygonal shape.

13. The radiation booster system of claim 9, wherein at least a part of a first booster box associated with the first radiation booster is contained within a second booster box associated with the second radiation booster.

14. The radiation booster system of claim 13, wherein the first radiation booster box has a projection on a plane containing the ground plane layer that is completely within a projection of the second radiation booster on said plane.

15. The radiation booster system of claim 14, wherein an orthogonal projection of the first and second radiation boosters on said plane containing the ground plane layer is completely inside the perimeter of a ground plane rectangle associated with the ground plane layer.

16. The radiation booster system of claim 9, wherein: a first booster box coincides with an external area of the first radiation booster; a second booster box is a two-dimensional entity defined around the gap of the second radiation booster; and a bottom face of the first booster box is contained within the second booster box.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are shown in the enclosed figures. Herein shows:

(2) FIG. 1(a)—Example of an antennaless wireless handheld or portable device including a radiating system according to the present invention; and FIG. 1(b)—Block diagram of an antennaless wireless handheld or portable device illustrating the basic functional blocks thereof.

(3) FIGS. 2(a)-2(c)—Schematic representations of three examples of radiating systems according to the present invention.

(4) FIGS. 3(a)-3(c)—Block diagrams of three examples of matching networks for a radiofrequency system used in a radiating system according to the present invention.

(5) FIGS. 4(a) and 4(b)—Example of a radiating structure for a radiating system, the radiating structure including a first and a second radiation booster, each comprising a conductive part: FIG. 4(a)—Partial perspective view; and FIG. 4(b)—top plan view.

(6) FIG. 5—Schematic representation of a radiofrequency system for a radiating system whose radiating structure is shown in FIGS. 4(a) and 4(b).

(7) FIG. 6(a)—Schematic representation of a matching network used in the radiofrequency system of FIG. 5; and FIG. 6(b)—Schematic representation of a first and a second band-pass filter and a combiner/splitter used in the radiofrequency system of FIG. 5.

(8) FIGS. 7(a)-7(c)—Typical impedance transformation caused by the matching network of FIGS. 6(a) and 6(b) on the input impedance at the first internal port of the radiating structure of FIGS. 4(a) and 4(b): FIG. 7(a)—Input impedance at the first internal port when disconnected from the matching network of the radiofrequency system; FIG. 7(b)—Input impedance after connection of a reactance cancellation circuit to the first internal port; and FIG. 7(c)—Input impedance after connection of a broadband matching circuit in cascade with the reactance cancellation circuit.

(9) FIGS. 8(a)-8(c)—Typical impedance transformation caused by a matching network similar to that of FIGS. 6(a) and 6(b) on the input impedance at the second internal port of the radiating structure of FIGS. 4(a) and 4(b): FIG. 8(a)—Input impedance at the second internal port when disconnected from the matching network of the radiofrequency system; FIG. 8(b)—Input impedance after connection of a reactance cancellation circuit to the second internal port; and FIG. 8(c)—Input impedance after connection of a broadband matching circuit in cascade with said reactance cancellation circuit.

(10) FIG. 9(a)—Typical input return losses at the first internal port of the radiating structure of FIGS. 4(a) and 4(b) compared with those after interconnection of the matching network of FIGS. 6(a) and 6(b) to the first internal port of the radiating structure; and FIG. 9(b)—Typical input return losses at the second internal port of the radiating structure of FIGS. 4(a) and 4(b) compared with those after interconnection of a matching network similar to that of FIGS. 6(a) and 6(b) to the second internal port of the radiating structure.

(11) FIG. 10—Typical input return losses at the external port of the radiating system resulting from the interconnection of the radiating system of FIG. 5 to the radiating structure of FIGS. 4(a) and 4(b).

(12) FIGS. 11(a) and 11(b)—Partial perspective views of first and second examples, respectively, of radiating structures comprising two radiation boosters according to the present invention.

(13) FIG. 12—Partial perspective view of another example of a radiating structure comprising two radiation boosters.

(14) FIG. 13—Partial perspective view of a radiating structure comprising two radiation boosters arranged one on top of another in a stacked configuration.

(15) FIGS. 14(a)-14(c)—Partial perspective views of first, second and third examples, respectively, of radiating structures for a radiating system, each radiating structure including a first radiation booster comprising a conductive part and a second radiation booster comprising a gap defined in a ground plane layer.

(16) FIG. 15—Example of a radiating structure for a radiating system according to the present invention, the radiating structure including only one radiation booster.

(17) FIG. 16—Schematic representation of a radiofrequency system for a radiating system whose radiating structure is shown in FIG. 15.

(18) FIG. 17—Radiating structure of a typical wireless handheld or portable device.

(19) FIG. 18—Partial top plan view of a partially-populated PCB showing the layout of the ground plane layer of a radiating structure and the conducting traces and pads of a radiofrequency system.

DETAILED DESCRIPTION

(20) Further characteristics and advantages of the invention will become apparent in view of the detailed description of some preferred embodiments which follows. Said detailed description of some preferred embodiments of the invention is given for purposes of illustration only and in no way is meant as a definition of the limits of the invention, made with reference to the accompanying figures.

(21) FIG. 1 shows an illustrative example of an antennaless wireless handheld or portable device 100 capable of multiband operation according to the present invention. In FIG. 1a, there is shown an exploded perspective view of the antennaless wireless handheld or portable device 100 comprising a radiating structure that includes a first radiation booster 15a, a second radiation booster 151b and a ground plane layer 152 (which could be included in a layer of a multilayer PCB). The antennaless wireless handheld or portable device 100 also comprises a radiofrequency system 153, which is interconnected with said radiating structure.

(22) Referring now to FIG. 1b, it is shown a block diagram of the antennaless wireless handheld or portable device 100 capable of multiband operation advantageously comprising, in accordance to the present invention, a user interface module 101, a processing module 102, a memory module 103, a communication module 104 and a power management module 105. In a preferred embodiment, the processing module 102 and the memory module 103 have herein been listed as separate modules. However, in another embodiment, the processing module 102 and the memory module 103 may be separate functionalities within a single module or a plurality of modules. In a further embodiment, two or more of the five functional blocks of the antennaless wireless handheld or portable device 100 may be separate functionalities within a single module or a plurality of modules.

(23) In FIG. 2, it is shown a schematic representation of three examples of radiating systems for an antennaless wireless handheld or portable device capable of multiband operation according to the present invention.

(24) In particular, in FIG. 2a a radiating system 200 comprises a radiating structure 201, a radiofrequency system 202, and an external port 203. The radiating structure 201 comprises a radiation booster 204, which includes a connection point 205, and a ground plane layer 206, said ground plane layer also including a connection point 207. The radiating structure 201 further comprises an internal port 208 defined between the connection point of the radiation booster 205 and the connection point of the ground plane layer 207. Furthermore, the radiofrequency system 202 comprises two ports: a first port 209 is connected to the internal port of the radiating structure 208, and a second port 210 is connected to the external port of the radiating system 203.

(25) Referring now to FIG. 2b, a radiating system 230 comprises a radiating structure 231, which, in addition to a first radiation booster 204 and a ground plane layer 206, also includes a second radiation booster 234. The radiating structure 231 comprises two internal ports: A first internal port 208 is defined between a connection point of the first radiation booster 205 and a connection point of the ground plane layer 207; while a second internal port 238 is defined between a connection point of the second radiation booster 235 and the same connection point of the ground plane layer 207.

(26) The radiating system 230 comprises a radiofrequency system 232 including three ports: A first port 209 is connected to the first internal port 208; a second port 239 is connected to the second internal port 238; and a third port 210 is connected to the external port of the radiating system 203. That is, the radiofrequency system 232 comprises a port connected to each of the at least one internal ports of the radiating structure 231, and a port connected to the external port of the radiating system 203.

(27) FIG. 2c depicts a further example of a radiating system 260 having the same radiating structure 201 as in the example of FIG. 2a. However, differently from the example of FIG. 2a, the radiating system 260 comprises an additional external port 263.

(28) The radiating system 260 includes a radiofrequency system 262 having a first port 209 connected to the internal port of the radiating structure 208, a second port 210 connected to the external port 203, and a third port 270 connected to the additional external port 263.

(29) Such a radiating system 260 may be preferred when said radiating system 260 is to provide operation in at least one cellular communication standard and at least one wireless connectivity standard. In one example, the external port 203 may provide the GSM 900 and GSM 1800 standards, while the external port 263 may provide an IEEE802.11 standard.

(30) FIG. 3 shows the block diagram of three preferred examples of a matching network 300 for a radiofrequency system, the matching network 300 comprising a first port 301 and a second port 302. One of said two ports may at the same time be a port of a radiofrequency system and, in particular, be interconnected with an internal port of a radiating structure.

(31) In FIG. 3a the matching network 300 comprises a reactance cancellation circuit 303. In this example, a first port of the reactance cancellation circuit 304 may be operationally connected to the first port of the matching network 301 and another port of the reactance cancellation circuit 305 may be operationally connected to the second port of the matching network 302.

(32) Referring now to FIG. 3b, the matching network 300 comprises the reactance cancellation circuit 303 and a broadband matching circuit 330, which is advantageously connected in cascade with the reactance cancellation circuit 303. That is, a port of the broadband matching circuit 331 is connected to port 305. In this example, port 304 is operationally connected to the first port of the matching network 301, while another port of the broadband matching circuit 332 is operationally connected to the second port of the matching network 302.

(33) FIG. 3c depicts a further example of the matching network 300 comprising, in addition to the reactance cancellation circuit 303 and the broadband matching circuit 330, a fine tuning circuit 360. Said three circuits are advantageously connected in cascade, with a port of the reactance cancellation circuit (in particular port 304) being connected to the first port of the matching network 301 and a port the fine tuning circuit 362 being connected to the second port of the matching network 302. In this example, the broadband matching circuit 330 is operationally interconnected between the reactance cancellation circuit 303 and the fine tuning circuit 360 (i.e., port 331 is connected to port 305 and port 332 is connected to port 361 of the fine tuning circuit 360).

(34) The radiofrequency systems 202, 232, 262 in the example radiating systems of FIG. 2 may advantageously include at least one, and preferably two, matching networks such as the matching network 300 of FIGS. 3a-c.

(35) FIG. 4 shows a preferred example of a radiating structure suitable for a radiating system operating in a first frequency region of the electromagnetic spectrum between 824 MHz and 960 MHz and in a second frequency region of the electromagnetic spectrum between 1710 MHz and 2170 MHz. An antennaless wireless handheld or portable device including such a radiating system may advantageously operate the GSM 850, GSM 900, GSM1800, GSM1900 and UMTS cellular communication standards (i.e., five different communication standards).

(36) The radiating structure 400 comprises a first radiation booster 401, a second radiation booster 405, and a ground plane layer 402. In FIG. 4b, there is shown in a top plan view the ground plane rectangle 450 associated to the ground plane layer 402. In this example, since the ground plane layer 402 has a substantially rectangular shape, its ground plane rectangle 450 is readily obtained as the rectangular perimeter of said ground plane layer 402.

(37) The ground plane rectangle 450 has a long side of approximately 100 mm and a short side of approximately 40 mm. Therefore, in accordance with an aspect of the present invention, the ratio between the long side of the ground plane rectangle 450 and the free-space wavelength corresponding to” the lowest frequency of the first frequency region (i.e., 824 MHz) is advantageously larger than 0.2. Moreover, said ratio is advantageously also smaller than 1.0.

(38) In this example, the first radiation booster 401 and the second radiation booster 405 are of the same type, shape and size. However, in other examples the radiation boosters 401, 405 could be of different types, shapes and/or sizes. Thus, in FIG. 4 each of the first and the second radiation boosters 401, 405 includes a conductive part featuring a polyhedral shape comprising six faces. Moreover, in this case said six faces are substantially square having an edge length of approximately 5 mm, which means that said conductive part is a cube.

(39) In this case, the conductive part of each of the two radiation boosters 401, 405 is not connected to the ground plane layer 402. A first booster box 451 for the first radiation booster 401 coincides with the external area of said first radiation booster 401. Similarly, a second booster box 452 for the second radiation booster 405 coincides with the external area of said second radiation booster 405. In FIG. 4b, it is shown a top plan view of the radiating structure 400, in which the top face of the first booster box 451 and that of the second booster b9x 452 can be observed.

(40) In accordance with an aspect of the present invention, a maximum size of the first radiation booster 401 (said maximum size being a largest edge of the first booster box 451) is advantageously smaller than 1/50 times the free-space wavelength corresponding to the lowest frequency of the first frequency region of operation of the radiating structure 400, and a maximum size of the second radiation booster 405 (said maximum size being a largest edge of the second booster box 452) is also advantageously smaller than 1/50 times said free-space wavelength. In particular, said maximum sizes of the first and second radiation boosters 401, 405 are also advantageously larger than 1/180 times said free-space wavelength.

(41) Furthermore in this example, the first and second radiation boosters have each a maximum size smaller than 1/30 times the free-space wavelength corresponding to the lowest frequency of the second frequency region of operation of the radiating structure 400, but advantageously larger than 1/120 times said free-space wavelength.

(42) In FIG. 4, the first and second radiation boosters 401, 405 are arranged with respect to the ground plane layer 402 so that the upper and bottom faces of the first radiation booster 401 and the upper and bottom faces of the second radiation booster 405 are substantially parallel to the ground plane layer 402. Moreover, the bottom face of the first radiation booster 401 is advantageously coplanar to the bottom face of the second radiation booster 405, and the bottom faces of both radiation boosters 401, 405 are also advantageously coplanar to the ground plane layer 402. With such an arrangement, the height of the radiation boosters 401, 405 with respect to the ground plane layer is not larger than 2% of the free-space wavelength corresponding to the lowest frequency of the first frequency region.

(43) In the radiating structure 400, the first radiation booster 401 and the second radiation booster 405 protrude beyond the ground plane layer 402. That is, the radiation boosters 401, 405 are arranged with respect to the ground plane layer 402 in such a manner that there is no ground plane in the orthogonal projection of the radiation boosters 401, 405 onto the plane containing the ground plane layer 402. The first radiation booster 401 is located substantially close to a first corner of the ground plane layer 402, while the second radiation booster 405 is located substantially close to a second corner of said ground plane layer 402. In particular, said first and second corners are at opposite ends of a short edge of the substantially rectangular ground plane layer 402.

(44) The first radiation booster 401 comprises a connection point 403 located on the lower right corner of the bottom face of the first radiation booster 401. In turn, the ground plane layer 402 also comprises a first connection point 404 substantially on the upper right corner of the ground plane layer 402. A first internal port of the radiating structure 400 is defined between said connection point 403 and said first connection point 404.

(45) Similarly, the second radiation booster 405 comprises a connection point 406 located on the lower left corner of the bottom face of the second radiation booster 405, and the ground plane layer 402 also comprises a second connection point 407 substantially .on the upper left corner of the ground plane layer 402. A second internal port of the radiating structure 400 is defined between said connection point 406 and said second connection point 407.

(46) In an alternative example, the ground plane layer 402 of the radiating structure 400 may comprise only the first connection point 404 (i.e., only one connection point). In that case the second internal port could have been defined between the connection point 406 of the second radiation booster 405 and said first connection point 404.

(47) The very small dimensions of the first and second radiation boosters 401, 405 result in said radiating structure 400 having at each of the first and second internal ports a first resonance frequency at a frequency much higher than the frequencies of the first frequency region. In this case, the ratio between the first resonance frequency of the radiating structure 400 measured at each of the first and second internal ports (in absence of a radiofrequency system connected to them) and the highest frequency of the first frequency region is advantageously larger than 4.2.

(48) Furthermore, the first resonance frequency at each of the first and second internal ports of the radiating structure 400 is also at a frequency much higher than the frequencies of the second frequency region.

(49) With such small dimensions of the first and second radiation boosters 401, 405, the input impedance of the radiating structure 400 measured at each of the first and second internal ports features an important reactive component, and in particular a capacitive component, within the frequencies of the first and second frequency regions, as it can be observed in FIGS. 7a and 8a.

(50) In FIG. 7a, curve 700 represents on a Smith chart the typical complex impedance at the first internal port of the radiating structure 400 as a function of the frequency when no radiofrequency system is connected to said first internal port. In particular, point 701 corresponds to the input impedance at the lowest frequency of the first frequency region, and point 702 corresponds to the input impedance at the highest frequency of the first frequency regio11.

(51) Curve 700 is located on the lower half of the Smith chart, which indeed indicates that the input impedance at the first internal port has a capacitive component (i.e., the imaginary part of the input impedance has a negative value) for at least all frequencies of the first frequency range (i.e., between point 701 and point 702). Although not represented in FIG. 7a, the input impedance at the first internal port has also a capacitive component for all frequencies of the second frequency region (i.e., curve 700 remains in the lower half of the Smith chart for all frequencies of the second frequency region).

(52) As far as the second internal port of the radiating structure 400 is concerned, curve 800 in FIG. 8a represents the typical complex impedance at said second internal port as a function of the frequency in absence of any radiofrequency system connected to it. Point 801 corresponds to the input impedance at the lowest frequency of the second frequency region, and point 802 corresponds to the input impedance at the highest frequency of the second frequency region.

(53) Curve 800 is also located on the lower half of the Smith chart, indicating that the input impedance at the second internal port has a capacitive component for at least all frequencies of the second frequency range (i.e., between point 801 and point 802). Moreover, despite not being shown in FIG. 8a, the input impedance at the second internal port has also a capacitive component for all frequencies of the first frequency region (i.e., curve 800 remains in the lower half of the Smith chart for all frequencies of the first frequency region).

(54) FIG. 5 presents a schematic of a radiofrequency system 500 to be connected to the two internal ports of the radiating structure 400 in order to transform the input impedance of the radiating structure 400 and provide impedance matching in the first and second regions of operation of the radiating system.

(55) The radiofrequency system 500 comprises two ports 501, 502 to be connected respectively to the first and second internal ports of the radiating structure 400, and a third port 503 to be connected to a single external port of the radiating system.

(56) The radiofrequency system 500 also comprises a first matching network 504 connected to port 501, providing impedance matching within the first frequency region; and a second matching network 505 connected to port 502, providing impedance matching within the second frequency region.

(57) The radiofrequency system 500 further comprises a first band-pass filter 506 connected to said first matching network 504, and a second band-pass filter 507 connected to said second matching network 505. The first band-pass filter 506 is designed to present low insertion loss in the first frequency region and high impedance in the second frequency region of operation of the radiating system.

(58) Analogously, the second band-pass filter 507 is designed to present low insertion loss in said second frequency region and high impedance in said first frequency region.

(59) The radiofrequency system 500 additionally includes a combiner/splitter 508 to combine (or split) the electrical signals of different frequency regions. Said combiner/splitter 508 is connected to the first and second band-pass filters 506, 507, and to the port 503.

(60) FIG. 6b shows a schematic representation of the first and second band-pass filters 506, 507 and the combiner/splitter 508.

(61) The first and second band-pass filters 506, 507 comprise each at least two stages, and preferably at least one of said at least two stages includes an LC resonant circuit. In the particular example shown in FIG. 6b, the first and the second band-pass filter 506, 507 have each two stages in an L-shaped (i.e., parallel—series) arrangement. Furthermore, each of said two stages includes an LC-resonant circuit formed by a Jumped capacitor in parallel with a lumped inductor.

(62) In some examples, the combiner/splitter 508 can be advantageously constructed by directly connecting in parallel the two band-pass filters 506, 507 to the port 503, as it is shown in the example of FIG. 6b. This is possible because in the first frequency region the second band-pass filter 507 does not load the port 503, while in the second frequency region the first band-pass filter 506 does not load the port 503. In other words, it is as if only one of the two matching networks were effectively connected to the port 503 in each frequency region.

(63) FIG. 6a is a schematic representation of the matching network 504, which comprises a first port 601 to be connected to the first internal port of the radiating structure 400 (via the port 501 of the radiofrequency system 500), and a second port 602 to be connected to the first band-pass filter 506 of the radiofrequency system 500. In this example, the matching network 504 further comprises a reactance cancellation circuit 607 and a broadband matching circuit 608.

(64) The reactance cancellation circuit 607 includes one stage comprising one single circuit component 604 arranged in series and featuring a substantially inductive behavior in the first and second frequency regions. In this particular example, the circuit component 604 is a lumped inductor. The inductive behavior of the reactance cancellation circuit 607 advantageously compensates the capacitive component of the input impedance of the first internal port of the radiating structure 400.

(65) Such a reactance cancellation effect can be observed in FIG. 7b, in which the input impedance at the first internal port of the radiating structure 400 (curve 700 in FIG. 7a) is transformed by the reactance cancellation circuit 607 into an impedance having an imaginary part substantially close to zero in the first frequency region (see FIG. 7b). Curve 730 in FIG. 7b corresponds to the input impedance that would be observed at the second port 602 of the first matching network 504 (when disconnected from the first band-pass filter 506) if the broadband matching circuit 608 were removed and said second port 602 were directly connected to a port 603. Said curve 730 crosses the horizontal axis of the Smith Chart at a point 731 located between point 701 and point 702, which means that the input impedance at the first internal port of the radiating structure 400 has an imaginary part equal to zero for a frequency advantageously between the lowest and highest frequencies of the first frequency region.

(66) The broadband matching circuit 608 includes also one stage and is connected in cascade with the reactance cancellation circuit 607. Said stage of the broadband matching circuit 608 comprises two circuit components: a first circuit component 605 is a lumped inductor and a second circuit component 606 is a lumped capacitor. Together, the circuit components 605 and 606 form a parallel LC resonant circuit (i.e., said stage of the broadband matching circuit 608 behaves substantially as a resonant circuit in the first frequency region of operation).

(67) Comparing FIGS. 7b and 7c, it is noticed that the broadband matching circuit 608 has the beneficial effect of “closing in” the ends of curve 730 (i.e., transforming the curve 730 into another curve 760 featuring a compact loop around the center of the Smith chart). Thus, the resulting curve 760 exhibits an input impedance (now, measured at the second port 602 when disconnected from the first band-pass filter 506) within a voltage standing wave ratio (VSWR) 3:1 referred to a reference impedance of 500 hms over a broader range of frequencies.

(68) In this particular example, the second matching network 505 of the radiofrequency system 500 has the same configuration as that of the first matching network 504 shown in FIG. 6a: A reactance cancellation circuit that includes one stage comprising one single circuit component arranged in series and featuring a substantially inductive behavior in the first and second frequency regions; and a broadband matching circuit connected in cascade with the reactance cancellation circuit and that includes also one stage, said stage comprising two circuit components that form a parallel LC resonant circuit so that said stage behaves substantially as a resonant circuit in the second frequency region of operation. Said second matching network also comprises a first port to be connected to the second internal port of the radiating structure 400 (via the port 502 of the radiofrequency system 500), and a second port to be connected to the second band-pass filter 507.

(69) Despite the fact that the first and second matching networks 504, 505 have the same configuration, the different frequency ranges in which each matching network is to provide impedance matching makes the actual values of the circuit components used in each matching network be possibly different.

(70) The effect of the reactance cancellation circuit of the second matching network 505 on the input impedance at the second internal port of the radiating structure 400 is shown in Figure Sb, in which the input impedance at said second internal port (curve 800 in Figure Sa) is transformed into an impedance having an imaginary part substantially close to zero in the second frequency region. Curve 830 in FIG. 8b corresponds to the input impedance that would be observed at the second port of the second matching network 505 (when disconnected from the first band-pass filter 507) if said second matching network 505 had only a reactance cancellation circuit operationally connected between its first and second ports. Said curve 830 crosses the horizontal axis of the Smith Chart at a point 831 located between point 801 and point 802, which means that the input impedance at the second internal port of the radiating structure 400 has an imaginary part equal to zero for a frequency advantageously between the lowest and highest frequencies of the second frequency region.

(71) Finally, the broadband matching circuit of the second matching network 505 transforms the curve 830 in FIG. 8b into another curve 860 (in FIG. 8c) that features a compact loop around the center of the Smith chart. Thus, the resulting curve 860 exhibits an input impedance (now, measured at the second port of the second matching network 505 when disconnected from the second band-pass filter 507) within a VSWR 3:1 referred to a reference impedance of 500 hms over a broader range of frequencies.

(72) Alternatively, the effect of the first and second matching networks of the radiofrequency system of FIG. 5 on the radiating structure of FIG. 4 can be compared in terms of the input return loss. In FIG. 9a curve 900 (in dash-dotted line) presents the typical input return loss of the radiating structure 400 observed at its first internal port when the radiofrequency system 500 is not connected to said first internal port. From said curve 900 it is clear that the radiating structure 400 is not matched in the first frequency region and that the first radiation booster 401 is non-resonant in said first frequency region. On the other hand, curve 910 (in solid line) corresponds to the input return losses at the second port 602 of the first matching network 504 (when disconnected fro the first band-pass filter 506).

(73) Likewise, in FIG. 9b curve 950 (in dash-dotted line) presents the typical input return loss of the radiating structure 400 observed at its second internal port when the radiofrequency system 500 is not connected to said second internal port. From said curve 950 it is clear that the radiating structure 400 is not matched in the second frequency region and that the second radiation booster 405 is non-resonant in said second frequency region. On the other hand, curve 960 (in solid line) corresponds to the input return losses at the second port of the second matching network 505 (when disconnected from the second band-pass filter 507).

(74) The first and second matching networks 504, 505 of the radiofrequency system 500 transform the input impedance of the first and second internal ports of the radiating structure 400 to provide impedance matching respectively in the first and second frequency regions. Indeed, curve 910 exhibits return losses better than −6 dB in the first frequency region (delimited by points 901 and 902 on the curve 910), while curve 960 exhibits return losses better than −6 dB in the second frequency region (delimited by points 951 and 952 on the curve 960).

(75) Finally, the frequency response of the radiating system resulting from the interconnection of the radiating system of FIG. 5 to the radiating structure of FIG. 4 is shown in FIG. 10, in which the curve 1000 corresponds to the return loss observed at the external port of the radiating system. The return loss curve 1000 exhibits a better than −6 dB behavior in the first frequency region (delimited by points 1001 and 1002 on said curve 1000) and in the second frequency region (delimited by points 1003 and 1004), making it possible for the radiating system to provide operability for the GSM850, GSM900, GSM1800, GSM1900 and UMTS standards.

(76) The radiating structure of FIG. 4 and the radiofrequency system of FIG. 5 could be advantageously provided on a common layer of a PCB, as it is shown in FIG. 18, in which on a layer of a PCB 1800 it is provided a ground plane layer 1802 and the conducting traces and pads of the radiofrequency system that make it possible to interconnect a first and a second radiation booster to an external port 1810, which is connected to an integrated circuit chip 1804 performing radiofrequency functionality.

(77) The first radiation booster 401 in FIG. 4 could be mounted on a first area 1801 of the PCB 1800 (delimited with a dash-dotted line) and the connection point 403 of the first radiation booster 401 be electrically connected (e.g., soldered) to a mounting pad 1803. Analogously, the second radiation booster 405 could be provided on a second area 1805 (also delimited with a dash-dotted line on the PCB 1800), and the connection point 406 of said second radiation booster 405 be electrically connected to a mounting pad 1806.

(78) A plurality of pads 1807 is provided in order to mount the circuit components 1811, 1812 of the matching networks and band-pass filters of the radiofrequency system 500. The pads 1807 are laid out adjacent to an edge of the ground plane layer 1802 to facilitate mounting shunted circuit components 1812.

(79) Furthermore, conducting traces 1808, 1809 allow routing the signals between the mounting pads 1803, 1806 and the external port 1810. In particular, conducting trace 1808 together with the ground plane layer 1802 defines a coplanar transmission line. In an example, said transmission line features a characteristic impedance of 50 Ohms. In another example, the conducting trace 1808 is designed so that said transmission line cooperates with a band-pass filter of the radiofrequency system to present high impedance to the external port 1810.

(80) Referring now to FIG. 11, it is shown a partial perspective view of two examples of radiating structures for a radiating system of a wireless handheld or portable device comprising two radiation boosters.

(81) In particular, FIG. 11a presents a radiating structure 1100 comprising a first radiation booster 1101, a second radiation booster 1105, and a ground plane layer 1102. The radiating structure 1100 comprises two internal ports: a first internal port being defined between a connection point of the first radiation booster 1103 and a first connection point of the ground plane layer 1104; and a second internal port being defined between a connection point of the second radiation booster 1106 and a second connection point of the ground plane layer 1107.

(82) The ground plane layer 1102 features a substantially rectangular shape having a short edge 1110 and a long edge 1111. In this example, the first radiation booster 1101 is substantially close to a first corner of the ground plane layer 1112 and the second radiation booster is substantially close to a second corner of the ground plane layer 1113. Since the ground plane layer is substantially rectangular, the first and second corners 1112, 1113 are advantageously in common with two corners of the ground plane rectangle associated to said ground plane layer 1102. Moreover, said two corners 1112, 1113 are at opposite ends of the short edge of the ground plane layer 1110 (which coincides in this example with a short side of the ground plane rectangle).

(83) In the radiation structure 1100, the first radiation booster 1101 is arranged substantially close to the short edge 1110, while the second radiation booster 1105 is arranged substantially close to the long edge 1111. The short edge 1110 and the long edge 1111 are advantageously perpendicular and meet at the corner 1113 of the ground plane layer 1102.

(84) A radiating structure such as that in FIG. 11a may be particularly interesting when it is necessary to achieve higher isolation between the two internal ports of the radiating structure. The enhancement in isolation is due not only to the separation between the two radiation boosters (which is maximized along the short edge of the ground plane layer), but also to their relative orientation with respect to the edges of the ground plane layer (which may excite two radiation modes on the ground plane layer having substantially orthogonal polarizations).

(85) FIG. 11b shows a radiating structure 1150 similar to that of FIG. 11a, but in which its ground plane layer 1152 has been modified with respect to that in FIG. 11a to include two cut-out portions in which metal has been removed from the ground plane layer 1152. A first cut-out portion 1153 has been provided where the ground plane layer 1102 had its first corner 1112, while a second cut-out portion 1154 has been provided where the ground plane layer 1102 had its second corner 1113.

(86) Despite the fact that the ground plane layer 1152 is irregularly shaped compared to the rectangular ground plane layer 1102), it has a ground plane rectangle 1151 equal to that associated to the ground plane layer 1102.

(87) The first radiation booster 1101 can now be provided on the first cut-out portion 1153, while the second radiation booster 1105 can be provided on the second cut-out portion 1154. That is, with respect to the example in FIG. 11a, the radiation boosters 1101, 1105 have been receded towards the inside of the ground plane rectangle 1151, so that the orthogonal projection of the first and second radiation booster 1101, 1105 on the plane containing the ground plane layer 1152 is completely inside the perimeter of the ground plane rectangle 1151. Such a ground plane layer and arrangement of the radiation boosters with respect to the ground plane layer are advantageous to facilitate the integration of the radiating structure within a particular handheld or portable wireless device.

(88) In FIG. 12, it is presented another example of a radiating structure for a radiating system according to the present invention. The radiating structure 1200 comprises two radiation boosters: a first radiation booster 1201 and a second ration booster 1203, each again comprising a conductive part. The radiating structure 1200 further comprises a ground plane layer 1202 (shown only partially in FIG. 12), inscribed in a ground plane rectangle 1204. The ground plane rectangle 1204 has a short side 1205 and a long side 1206.

(89) The first radiation booster 1201 is arranged substantially close to said short side 1205, and the second radiation booster 1203 is arranged substantially close to said long side 1206. Moreover, the first and second radiation boosters 1201, 1203 are also substantially close to a first corner of the ground plane rectangle 1204, said corner being defined by the intersection of said short side 1205 and said long side 1206.

(90) In this particular case, the first radiation booster 1201 protrudes beyond the short side 1205 of the ground plane rectangle 1204, so that the orthogonal projection of the first radiation booster 1201 on the plane containing the ground plane layer 1202 is outside the ground plane rectangle 1204. On the other hand, the second radiation booster 1203 is arranged on a cut-out portion of the ground plane layer 1202, so that the orthogonal projection of the second radiation booster 1203 on said plane containing the ground plane layer 1202 does not overlap the ground plane layer. Moreover, said projection is completely inside the perimeter of the ground plane rectangle 1204.

(91) However, in another example both the first and the second radiation boosters could have been arranged on cut-out portions of the ground plane layer, so that the radiation boosters are at least partially, or even completely, inside the perimeter of the ground plane rectangle associated to the ground plane layer of a radiating structure. And yet in another example, both the first and the second radiation boosters could have been arranged at least partially, or even completely, protruding beyond a side of said ground plane rectangle.

(92) The radiating structure 1200 may be advantageous to facilitate the interconnection of the radiation boosters 1201, 1203 to a radiofrequency system, since the connection points of said radiation boosters (not indicated in FIG. 12) are much closer to each other, that they are for example in the radiating structures of FIG. 11.

(93) FIG. 13 presents another example of a radiating structure comprising two radiation boosters, in which one radiation booster is arranged one on top of the other radiation booster forming a stacked configuration.

(94) The radiating structure 1300 comprises a first and a second radiation booster 1301, 1305 and a ground plane layer 1302. The first radiation booster 1301 comprises a substantially planar conducting put having a polygonal shape (in this example a square shape) and a first connection point 1303 located substantially on the perimeter of said conducting part. The second radiation booster 1305 also comprises a substantially planar conducting part having a polygonal shape and a second connection point 1306 located substantially on the perimeter of said conducting part. Said first and second connection points 1303, 1306 define together with a connection point of the ground plane layer 1302 (not shown in the figure) a first and a second internal port of the radiating structure 1300.

(95) In the example of the figure, the shape and dimensions of the two radiation boosters 1301, 1305 are substantially the same, although in other examples the boosters may have different shapes and/or sizes, although preferably they will be substantially planar.

(96) The first radiation booster 1301 is substantially coplanar to the ground plane layer 1302 of the radiating structure 1300, and is arranged with respect to said ground plane layer 1302 such that the first radiation booster 1301 is substantially close to a short edge 1304 of the ground plane layer 1302 and protrudes beyond said short edge 1304.

(97) The second radiation booster 1305 is advantageously located at a certain height h above the first radiation booster 1301, such that the orthogonal projection of the second radiation booster 1305 on the plane containing the ground plane layer 1302 overlaps a substantial portion of the orthogonal projection of the first radiation booster 1301 on said plane. A substantial portion may preferably refer to at least 50%, 60%, 75% or 90% of the area of the orthogonal projection of the first radiation booster 1301. In the example of the figure, the portion overlapped corresponds to 100% of the area of the orthogonal projection of the first radiation booster 1301. This overlapping between the radiation boosters of a radiating structure is advantageous for achieving a very compact arrangement.

(98) Furthermore, in order to facilitate the integration of the first and second boosters 1301, 1305, the height h is preferably not larger than a 2% of the free-space wavelength corresponding to the lowest frequency of the first frequency region of operation of the radiating system comprising the radiating structure 1300. In this example, said height h is about 5 mm, although in other examples it could be even smaller.

(99) FIG. 14 provides three examples of radiating structures for a radiating system capable of operating in a first and in a second frequency region according to the present invention that combine a radiation booster comprising a conductive part with another radiation booster comprising a gap defined in the ground plane layer of the radiating structure. In particular, in FIG. 14a a radiating structure 1400 comprises a first radiation booster 1401 and a second radiation booster 1405. Both radiation boosters 1401, 1405 cooperate with a ground plane layer 1402 (shown partially in the figure).

(100) The first radiation booster 1401 comprises a conducting part and is similar to the radiation boosters already described in connection with the example of FIG. 4. That is, the conductive part of the first radiation booster 1401 features a polyhedral shape comprising six faces. Moreover, since in this case said six faces are substantially square, said conductive part is a cube. Said first booster comprises a connection point 1403 that defines together with a first connection point of the ground plane layer 1404 a first internal port of the radiating structure.

(101) The second radiation booster 1405 comprises a gap defined in the ground plane layer 1402. Said gap is delimited by a plurality of segments (more precisely, 3 segments in the examples shown in FIG. 14) defining a curve, which in this case is open as the curve intersects the perimeter of the ground plane layer 1402 (in particular a long edge 1409 of said ground plane layer 1402). Furthermore, the gap of the second radiation booster 1405 features a polygonal shape, which in this example is substantially square. This second radiation booster 1405 comprises a connection point 1406 located at a first point along said curve. A second connection point of the ground plane layer 1407 is located at a second point along said curve, said second point being different from said first point. A second internal port of the radiating structure 1400 is defined between the connection point 1406 and the second connection point of the ground plane layer 1407.

(102) In FIG. 14a, the first radiation booster 1401 is arranged with respect to the ground plane layer 1402 so that the upper and bottom faces of the first radiation booster 1401 are substantially parallel to the ground plane layer 1402. Moreover, the bottom face of the first radiation booster 1401 is advantageously coplanar to the ground plane layer 1402. Thus, the first radiation booster 1401 is substantially coplanar to the second radiation booster 1405.

(103) In the radiating structure 1400, the first radiation booster 1401 protrudes beyond a short edge 1408 of the ground plane layer 1402, and is located substantially close to said short edge 1408, and more precisely substantially close to an end of said short edge 1408. The second radiation booster 1405 is located substantially close to a long edge 1409 of the ground plane layer 1402, said long edge 1409 being substantially perpendicular to said short edge 1408. More specifically, the second radiation booster 1405 is located near an end of the long edge 1409, said end being in common with an end of the short side 1408.

(104) In accordance with an aspect of the present invention, a maximum size of each of the first and second radiation boosters 1401, 1405 is advantageously smaller than 1/30 times the free-space wavelength corresponding to the lowest frequency of the first frequency region of operation of the radiating structure 1400. Furthermore in this example, at least the first radiation booster 1401 has a maximum size smaller than 1/30 times the free-space wavelength corresponding to the lowest frequency of the second frequency region of operation of the radiating structure 1400.

(105) The very small dimensions of the first and second radiation boosters 1401, 1405 result in the radiating structure 1400 having at each of the first and second internal ports a first resonance frequency at a frequency much higher than the frequencies of the first frequency region. According to the present invention, the ratio between the first resonance frequency of the radiating structure 1400 measured at each of the first and second internal ports (in absence of a radiofrequency system connected to them) and the highest frequency of the first frequency region is advantageously larger than 3.5. Said first resonance frequency at each of the first and second internal ports of the radiating structure 1400 is also at a frequency much higher than the frequencies of the second frequency region.

(106) With such small first and second radiation boosters 1401, 1405, the input impedance of the radiating structure 1400 measured at the first internal port features an important capacitive component within the frequencies of the first and second frequency regions, and the second internal port features an important inductive component within the frequencies of the first and second frequency regions.

(107) The radiating structure 1430 shown in FIG. 14b is a modification of the radiating structure 1400 of FIG. 14a, in which the arrangement of the first and second radiation boosters 1401, 1405 with respect to the ground plane layer 1402 is different.

(108) In particular, the second radiation booster 1405 has been translated and rotated with respect to the case shown in FIG. 14a. The second radiation booster 1405 is now located substantially close to the short edge 1408 of the ground plane layer 1402, and more precisely substantially close to an end of said short edge 1408. Given that the first radiation booster 1401 is also located substantially close to said end of the short edge 1408, the first and second radiation boosters 1401, 1405 are arranged near a same corner of the ground plane layer 1402, which facilitates the interconnection of the radiation boosters with a radiofrequency system.

(109) Furthermore, the second radiation booster 1405 has undergone a 90 degree clockwise rotation, so that the curve delimiting the gap of said second radiation booster 1405 intersects now the short edge 1408 of the ground plane layer 1402. Such an orientation makes it possible for the second radiation booster 1405 to excite a radiation mode on the ground plane layer 1402 having a polarization substantially orthogonal to the polarization of the radiation mode excited on the ground plane layer 1402 by the first radiation booster 1401.

(110) Referring now to FIG. 14c, it is shown another example of a radiating structure that constitutes a further modification of the two previous ones. More specifically, the position of the first radiation booster 1401 has been modified with respect to the position it had in the case of FIG. 14b, so that the first radiation booster 1401 has a projection on the plane containing the ground plane layer 1402 that is completely within the projection of the second radiation booster 1405 on said same plane. Moreover, the orthogonal projection of the first and second radiation boosters 1401, 1405 on said plane containing the ground plane layer 1402 is completely inside the perimeter of the ground plane rectangle 1462 associated to the ground plane layer 1402. Such an arrangement leads to very compact solutions.

(111) The first radiation booster 1401 is advantageously embedded within the second radiation booster 1405, because at least a part of a first booster box associated to the first radiation booster 1401 is contained within a second booster box 1461 associated to the second radiation booster 1405. In this particular example, the first booster box coincides with the external area of the first radiation booster 1401, while the second booster box 1461 is a two-dimensional entity defined around the gap of the second radiation booster 1405. The bottom face of the first booster box is thus contained within the second booster box 1461.

(112) FIG. 15 shows another radiating structure 1500 for a radiating system capable of operating in a first and in a second frequency region of the electromagnetic spectrum when an appropriate radiofrequency system is connected to said radiating structure 1500.

(113) As in the previous examples, the radiation structure 1500 comprises a substantially rectangular ground plane layer 1502 and a first radiation booster 1501. However, there is no second radiation booster. That is, the radiating structure 1500 has only one radiation booster.

(114) The first radiation booster 1501 protrudes beyond the ground plane layer 1502 (i.e., there is no ground plane in the orthogonal projection of the radiation booster 1501 onto the plane containing the ground plane layer 1502). Moreover, said first radiation booster 1501 is advantageously located substantially close to a corner of the ground plane layer 1502, said corner being defined by the intersection of a short edge 1505 and a long edge 1506 of the ground plane layer 1502.

(115) The first radiation booster 1501 comprises a connection point 1503, which defines together with a connection point of the ground plane layer 1504 an internal port of the radiating structure 1500.

(116) In this example, the first radiation booster 1501 (i.e., a same radiation booster) in cooperation with a radiofrequency system advantageously excites at least two different radiation modes on the ground plane layer 1502 responsible for the operation of the resulting radiating system in said first and second frequency regions of the electromagnetic spectrum.

(117) FIG. 16 shows an example of a radiofrequency system suitable for interconnection with the radiating structure of FIG. 15, The radiofrequency system 1600 comprises a first diplexer 1603 to separate the electrical signals of a first and a second frequency regions of operation of a radiating system, a first matching network 1605 to provide impedance matching in said first frequency region, a second matching network 1606 to provide impedance matching in said second frequency region, and a second diplexer 1604 to recombine the electrical signals of said first and second frequency regions.

(118) Each of the first and second matching networks 1605, 1606 may be as in any of the examples of matching networks described in connection with FIG. 3.

(119) The first diplexer 1603 is connected to a first port 1601, while the second diplexer 1604 is connected to a second port 1602. In a radiating system, an internal port of a radiating structure (such as for instance the internal port of the radiating structure 1500) may be connected to said first port 1601, while an external port of the radiating system may be connected to said second port 1602.

(120) The use of diplexers in the radiofrequency system is advantageous to separate the electrical signals of different frequency regions and transform the input impedance characteristics in each frequency region independently from the others.

(121) Even though that in the illustrative examples described above in connection with the figures some particular designs of radiation boosters have been used, many other designs of radiation boosters having for example different shape and/or dimensions could have been equally used in the radiating structures.

(122) In that sense, although the first and second radiation boosters in FIGS. 4, 11, and 12, and the first radiation booster in FIGS. 14 and 15, have a volumetric geometry, other designs of substantially planar radiation boosters could have been used instead.

(123) Also, even though that some examples of radiating structures (such as for instance, but not limited to, those in FIG. 4, 11, 12 or 15) have been described as comprising radiation boosters having a conductive part, other possible examples could have been constructed using radiation boosters comprising a gap defined in the ground plane layer of the radiating structure.

(124) In the same way, despite the fact that the first and second radiation boosters in FIGS. 4 and 11-13 have been chosen to be equal in topology (i.e., a planar versus a volumetric geometry), shape and size, they could have been selected to have different topology, shape and/or size, while preserving for example the relative location of the radiation boosters with respect to each other and with respect to the ground plane layer.