Abstract
A radiating system of a wireless device transmits and receives electromagnetic wave signals in a frequency region and comprises an external port, a radiating structure, and a radiofrequency system. The radiating structure includes: a ground plane layer with a connection point; a radiation booster with a connection point and being smaller than 1/30 of a free-space wavelength corresponding to a lowest frequency of the frequency region; and an internal port between the radiation booster connection point and the ground plane layer connection point. The radiofrequency system includes: a first port connected to the radiating structure's internal port; and a second port connected to the external port. An input impedance at radiating structure's disconnected internal port has a non-zero imaginary part across the frequency region. The radiofrequency system modifies impedance of the radiating structure to provide impedance matching to the radiating system within the frequency region at the external port.
Claims
1-20. (canceled)
21. A radiation booster for a wireless electronic device operating in a first frequency region, the radiation booster comprising: an electronic chip component including a surface mount technology (SMT) package; one or more soldering pads to surface mount the SMT package onto a printed circuit board; a conductive part; and a dielectric carrier to provide mechanical support to the conductive part, wherein the radiation booster is smaller than a quarter of a wavelength corresponding to a lowest frequency band of the first frequency region.
22. The radiation booster of claim 21, wherein the radiation booster is smaller than 1/20th of the wavelength corresponding to the lowest frequency band of the first frequency region.
23. The radiation booster of claim 21, wherein the radiation booster is smaller than 1/30th of the wavelength corresponding to the lowest frequency band of the first frequency region.
24. The radiation booster of claim 21, wherein at least 50% of the surface of the radiation booster is placed on one or more planes substantially parallel to a ground plane layer.
25. The radiation booster of claim 24, wherein the at least 50% of the entire conductive part of the radiation booster is placed on one or more planes substantially parallel to the ground plane layer.
26. The radiation booster of claim 21, wherein the radiation booster is configured to connect to a radiofrequency system to provide impedance matching to the first frequency region.
27. The radiation booster of claim 26, wherein the radiation booster has a lowest resonance frequency higher than a highest frequency of the first frequency region when the radiation booster is disconnected from the radiofrequency system providing impedance matching.
28. The radiation booster of claim 21, wherein the radiation booster is configured to connect to a ground plane layer such that there is an overlap between a projection of the radiation booster and the ground plane layer on the printed circuit board.
29. A radiating system for a wireless electronic device, comprising: a ground plane layer on a printed circuit board; a radiofrequency system to provide impedance matching for the radiating system in a first operating frequency region; and a radiation booster smaller than a quarter of a wavelength corresponding to a lowest frequency band of the first operating frequency region, the radiation booster being connected to the ground plane layer such that an overlap exists between a projection of the radiation booster and the ground plane layer on the printed circuit board, the radiation booster comprising: an electronic chip component including a surface mount technology (SMT) package; one or more soldering pads to surface mount the SMT package onto the printed circuit board; a conductive part; and a dielectric carrier to provide mechanical support to the conductive part of the radiation booster.
30. The radiating system of claim 29, wherein the radiation booster is smaller than 1/20th of the wavelength corresponding to the lowest frequency band of the first operating frequency region.
31. The radiating system of claim 29, wherein the radiation booster is smaller than 1/30th of the wavelength corresponding to the lowest frequency band of the first operating frequency region.
32. The radiating system of claim 29, wherein at least 50% of the surface of the radiation booster is placed on one or more planes substantially parallel to the ground plane layer.
33. The radiating system of claim 32, wherein the at least 50% of the entire conductive part of the radiation booster is placed on one or more planes substantially parallel to the ground plane layer.
34. The radiating system of claim 29, wherein the booster has a lowest resonance frequency higher than a highest frequency of the first operating frequency region when the radiation booster is disconnected from the radiofrequency system providing impedance matching.
35. The radiating system of claim 29, wherein a gap is defined in the ground plane layer.
36. The radiating system of claim 35, wherein the gap defined in a ground plane layer has a polygonal shape delimited by a plurality of segments defining a curve.
37. The radiating system of claim 36, wherein the curve is open.
38. A wireless device, comprising: a processing module; a communication module including the radiating system of claim 29; a memory module; a power management module; and a user interface module.
39. The wireless device of claim 38, wherein the wireless device operates in a frequency region above 960 MHz.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0123] Embodiments of the invention are shown in the enclosed figures. Herein shows:
[0124] FIGS. 1A, 1B—(FIG. 1A) Example of an antennaless wireless handheld or portable device including a radiating system according to the present invention; and (FIG. 1B) block diagram of an antennaless wireless handheld or portable device illustrating the basic functional blocks thereof.
[0125] FIG. 2—Schematic representation of a radiating system according to the present invention.
[0126] FIGS. 3A, 3B, 3C—Block diagrams of three examples of radiofrequency systems for a radiating system according to the present invention.
[0127] FIGS. 4A, 4B—Example of a radiating structure for a radiating system, the radiating structure including a radiation booster comprising a conductive part: (FIG. 4A) Partial perspective view; and (FIG. 4B) top plan view.
[0128] FIG. 5—Schematic representation of a radiofrequency system for a radiating system whose radiating structure is shown in FIGS. 4A and 4B.
[0129] FIGS. 6A, 6B, 6C—Typical impedance transformation of the radiofrequency system of FIG. 5 on the input impedance of the radiating structure of FIGS. 4A and 4B: (FIG. 6A) Input impedance at the internal port of the radiating structure when disconnected from the radiofrequency system; (FIG. 6B) Input impedance after connection of the reactance cancellation circuit of the radiofrequency system to the internal port of the radiating structure; and (FIG. 6C) Input impedance at the external port of the radiating system after connection of the broadband matching circuit in cascade with the reactance cancellation circuit.
[0130] FIG. 7—Typical input return losses at the internal port of the radiating structure of FIGS. 4A-4B compared with those at the external port of a radiating system obtained after interconnecting the radiating structure of FIGS. 4A-4B with the radiofrequency system of FIG. 5.
[0131] FIGS. 8A, 8B—Another example of a radiating structure including a radiation booster comprising a conductive part: (FIG. 8A) Partial perspective view; and (FIG. 8B) top plan view.
[0132] FIG. 9—Schematic representation of a radiofrequency system for a radiating system whose radiating structure is shown in FIGS. 8A-8B.
[0133] FIGS. 10A, 10B—Typical impedance transformation of the radiofrequency system of FIG. 9 on the input impedance of the radiating structure of FIGS. 8A-8B: (FIG. 10A) Input impedance at the internal port of the radiating structure when disconnected from the radiofrequency system; and (FIG. 10B) Input impedance at the external port of the radiating system.
[0134] FIG. 11—Typical input return losses at the internal port of the radiating structure of FIGS. 8A and 8B compared with those at the external port of a radiating system obtained after interconnecting the radiating structure of FIGS. 8A and 8B with the radiofrequency system of FIG. 9.
[0135] FIGS. 12A, 12B—Example of a radiating structure for a radiating system, the radiating structure including a radiation booster comprising a gap: (FIG. 12A) Partial perspective view; and (FIG. 12B) top plan view.
[0136] FIG. 13—Schematic representation of a radiofrequency system for a radiating system whose radiating structure is shown in FIGS. 12A-12B.
[0137] FIG. 14A-14D—Typical impedance transformation of the radiofrequency system of FIG. 13 on the input impedance of the radiating structure of FIGS. 12A-12B: (FIG. 4A) Input impedance at the internal port of the radiating structure when disconnected from the radiofrequency system; (FIG. 14B) Input impedance after connection of the reactance cancellation circuit of the radiofrequency system to the internal port of the radiating structure; (FIG. 14C) Input impedance after connection of the broadband matching circuit in cascade with the reactance cancellation circuit; and (FIG. 14D) Input impedance at the external port of the radiating system after connection of the fine tuning circuit in cascade with the broadband matching circuit.
[0138] FIG. 15—Typical input return losses at the internal port of the radiating structure of FIGS. 12A-12B compared with those at the external port of a radiating system obtained after interconnecting the radiating structure of FIG. 13 with the radiofrequency system of FIGS. 12A-12B.
[0139] FIGS. 16A, 16B, 16C—Examples of radiation boosters comprising a conductive part.
[0140] FIGS. 17A-17E—Examples of some preferred placements of the radiation boosters of FIGS. 16A-16C with respect to the ground plane layer of a radiating structure.
[0141] FIG. 18—Another example of a radiation booster comprising a conductive part, wherein said conductive part is connected to the ground plane layer of a radiating structure.
[0142] FIGS. 19A-19E—Examples of some preferred placements of the radiation booster of FIG. 18 with respect to the ground plane layer of a radiating structure.
[0143] FIGS. 20A, 20B—Examples of radiation boosters comprising a gap.
[0144] FIGS. 21A-21D—Examples of some preferred placements of the radiation boosters of FIGS. 20A and 20B with respect to the ground plane layer of a radiating structure.
[0145] FIG. 22—Example of a preferred radiating structure including a radiation booster comprising a gap.
[0146] FIGS. 23A, 23B—(FIG. 23A) Example of another preferred radiating structure including a radiation booster comprising a gap; and (FIG. 23B) Detailed view of the radiation booster.
[0147] FIG. 24—Further example of a preferred radiating structure including a radiation booster comprising a gap.
[0148] FIG. 25—Example of a preferred radiating structure including a radiation booster having a substantially planar conductive part.
[0149] FIG. 26—Example of a reconfigurable radiofrequency system for a radiating system comprising a controllable switching matrix and a control circuit.
[0150] FIG. 27—Another example of a reconfigurable radiofrequency system for a radiating system comprising two controllable switching matrices and a control circuit.
[0151] FIG. 28—Radiating structure of a typical wireless handheld or portable device.
DETAILED DESCRIPTION
[0152] 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.
[0153] FIGS. 1A-1B show an illustrative example of an antennaless wireless handheld or portable device 100 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 radiation booster 151 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.
[0154] Referring now to FIG. 1B, it is shown a block diagram of the antennaless wireless handheld or portable device 100 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.
[0155] In FIG. 2 it is depicted a radiating system 200 for an antennaless wireless handheld or portable device according to the present invention. The 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.
[0156] FIG. 3A-3C show the block diagrams of three preferred examples of a radio frequency system 300 comprising a first port 301 and a second port 302.
[0157] In particular, in FIG. 3A the radiofrequency system 300 includes matching network comprising 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 radiofrequency system 301 and another port of the reactance cancellation circuit 305 may be operationally connected to the second port of the radiofrequency system 302.
[0158] Referring now to FIG. 3B, the radiofrequency system 300 includes an alternative matching network comprising 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 radiofrequency system 301, while another port of the broadband matching circuit 332 is operationally connected to the second port of the radiofrequency system 302.
[0159] FIG. 3C depicts a further example of the radiofrequency system 300 including yet another alternative matching network 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 radiofrequency system 301 and a port the fine tuning circuit 362 being connected to the second port of the radiofrequency system 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).
[0160] FIGS. 4A-4B show 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. An antennaless wireless handheld or portable device including such a radiating system may advantageously operate the GSM 850 and GSM 900 cellular communication standards (i.e., two different communication standards).
[0161] The radiating structure 400 comprises a radiation booster 401 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.
[0162] 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.
[0163] In this example, the radiation booster 401 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. In this case, the conductive part of the radiation booster 401 is not connected to the ground plane layer 402. A booster box 451 for the radiation booster 401 coincides with the external area of said radiation booster 401. In FIG. 4B, it is shown a top plan view of the radiating structure 400, in which the top face of the booster box 451 can be observed.
[0164] In accordance with an aspect of the present invention, a maximum size of the radiation booster 401 (said maximum size being a largest edge of the 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. In particular, said maximum size is also advantageously larger than 1/180 times said free-space wavelength.
[0165] In FIGS. 4A-4B, the radiation booster 401 is arranged with respect to the ground plane layer so that the upper and bottom faces of the radiation booster 401 are substantially parallel to the ground plane layer 402. Moreover, said bottom face is advantageously coplanar to the ground plane layer 402. With such an arrangement, the height of the radiation booster 401 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.
[0166] In the radiating structure 400, the radiation booster 401 protrudes beyond the ground plane layer 402. That is, the radiation booster 401 is 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 booster 401 onto the plane containing the ground plane layer 402. The radiation booster 401 is located substantially close to an edge of the ground plane layer 402, in particular to a short edge of the substantially rectangular ground plane layer 402 and, more precisely, the radiation booster 401 is located substantially close to a corner of said ground plane layer 402.
[0167] The radiation booster 401 comprises a connection point 403 located on the lower right corner of the bottom face of the radiation booster 401. In turn, the ground plane layer 402 also comprises a connection point 404 substantially on the upper right corner of the ground plane layer 402. An internal port of the radiating structure 400 is defined between connection point 403 and connection point 404.
[0168] The very small dimensions of the radiation booster 401 result in said radiating structure 400 having 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 its internal port (in absence of a radiofrequency system connected to it) and the highest frequency of the first frequency region is advantageously larger than 4.2.
[0169] With such small dimensions of the radiation booster 401, the input impedance of the radiating structure 400 measured at the internal port features an important reactive component, and in particular a capacitive component, within the frequencies of the first frequency region.
[0170] This can be observed in FIG. 6A, in which curve 600 represents on a Smith chart the typical complex impedance of the antenna structure 400 as a function of the frequency when no radiofrequency system is connected to its internal port. In particular, point 601 corresponds to the input impedance at the lowest frequency of the first frequency region, and point 602 corresponds to the input impedance at the highest frequency of the first frequency region.
[0171] Curve 600 is located on the lower half of the Smith chart, which indeed indicates that said input impedance has a capacitive component (i.e., the imaginary part of the input impedance has a negative value) for all frequencies of the first frequency range (i.e., between point 601 and point 602).
[0172] FIG. 5 is a schematic representation of a radiofrequency system suitable for interconnection with the radiating structure of FIGS. 4A-4B to provide impedance matching to the resulting radiating system in the first frequency region of operation.
[0173] A radiofrequency system 500 comprises a first port 501 to be connected to the internal port of the radiating structure 400, and a second port 502 to be connected to the external port of the radiating system. In this example, the radiofrequency system 500 further comprises a matching network including a reactance cancellation circuit 507 and a broadband matching circuit 508.
[0174] The reactance cancellation circuit 507 includes one stage comprising one single circuit component 504 arranged in series and featuring a substantially inductive behavior in the first frequency region. In this particular example, the circuit component 504 is a lumped inductor. The inductive behavior of the reactance cancellation circuit 507 advantageously compensates the capacitive component of the input impedance of the radiating structure 400.
[0175] Such an effect can be observed in FIGS. 6A-6C, in which the input impedance of the radiating structure 400 (curve 600 in FIG. 6A) is transformed by the reactance cancellation circuit into an impedance having an imaginary part substantially close to zero in the first frequency region (see FIG. 6B). Curve 630 in FIG. 6B corresponds to the input impedance that would be observed at the second port of the radiofrequency system 502 if the broadband matching circuit 508 were removed and said second port 502 were directly connected to a port 503. Said curve 630 crosses the horizontal axis of the Smith Chart at a point 631 located between point 601 and point 602, which means that the input impedance has an imaginary part equal to zero for a frequency advantageously between the lowest and highest frequencies of the first frequency region.
[0176] The broadband matching circuit 508 includes also one stage and is connected in cascade with the reactance cancellation circuit 507. Said stage of the broadband matching circuit 508 comprises two circuit components: a first circuit component 505 is a lumped inductor and a second circuit component 506 is a lumped capacitor. Together, the circuit components 505 and 506 form a parallel LC resonant circuit (i.e., said stage of the broadband matching circuit 508 behaves substantially as a resonant circuit in the first frequency region of operation).
[0177] Comparing FIGS. 6B and 6C, it is noticed that the broadband matching circuit 508 has the beneficial effect of “closing in” the ends of curve 630 (i.e., transforming the curve 630 into another curve 660 featuring a compact loop around the center of the Smith chart). Thus, the resulting curve 660 exhibits an input impedance (now, measured at the second port 502, or equivalently at the external port of the radiating system) within a voltage standing wave ratio (VSWR) 3:1 referred to a reference impedance of 50 Ohms over a broader range of frequencies.
[0178] Alternatively, the effect of the radiofrequency system of FIG. 5 on the radiating structure of FIGS. 4A-4B can be compared in terms of the input return loss. In FIG. 7 curve 700 (in dash-dotted line) presents the typical input return loss of the radiating structure 400 observed at its internal port when the radiofrequency system 500 is not connected to said internal port. From said curve 700 it is clear that the radiating structure 400 is not matched in the first frequency range and that the radiation booster 401 is non-resonant in said first frequency range. On the other hand, curve 710 (in solid line) corresponds to the input return losses at the external port of the radiating system resulting from the interconnection of the radiofrequency system 500 with the radiating structure 400. The radiofrequency system transforms the input impedance of the radiating structure 400, providing impedance matching in the first frequency region. Curve 710 shows how the radiating system exhibits return losses better than −6 dB in the first frequency region (delimited by points 701 and 702 on the curve 710), making it possible for the radiating system to provide operability for the GSM850 and the GSM900 standards.
[0179] Another preferred embodiment of a radiating structure according to the present invention is disclosed in FIGS. 8A-8B, in which a radiating structure 800 comprises a radiation booster 801 and a ground plane layer 802. The radiating structure 800 is to be used in a radiating system capable of operating the GSM 900 cellular communication standard (i.e., the first frequency region extends from 880 MHz to 960 MHz).
[0180] The radiating structure 800 is very similar to the radiating structure 400 already discussed in connection with FIGS. 4A-4B. For example, the dimensions of the ground plane layer 802, and the shape and dimensions of the radiation booster 801, are the same as those of their respective counterparts in the radiating structure 400. Moreover, a ground plane rectangle 850 associated to the ground plane layer 802 and a booster box 851 associated to the radiation booster 801 are defined in the same way as it was done for the example in FIGS. 4A-4B.
[0181] However, the placement of the radiation booster 801 with respect to the ground plane layer 802 is different from what it was shown in FIGS. 4A-4B. While in the radiating structure 400, the radiation booster 401 protrudes beyond the ground plane layer 402; in the radiating structure 800, the projection of the radiation booster 801 onto the plane containing the ground plane layer 802 overlaps completely the ground plane layer 802. This can be observed in the top plan view of the radiating structure 800 in FIG. 8B, in which the projection of the booster box 851 onto the plane of the ground plane layer 802 is inside the ground plane rectangle 851.
[0182] Despite the radiation booster 801 being located above the ground plane layer 802, said radiation booster 801 is not connected to said ground plane layer 802. An internal port of the radiating structure 800 is defined between a connection point of the radiation booster 801 and a connection point of the ground plane layer 802.
[0183] Referring now to FIG. 9, it is depicted a schematic representation of a radiofrequency system 900 suitable for interconnection with the radiating structure 800. The radiofrequency system 900 includes a matching network, a first port 901 (to be connected to the internal port of the radiating structure 800), and a second port 902 (for connection with the external port of a resulting radiating system). The matching network comprises a reactance cancellation circuit 910 and a broadband matching circuit 911, as in the example shown in FIG. 5, but also a fine tuning circuit 912.
[0184] The reactance cancellation circuit 910 is connected to the first port 901 and the fine tuning circuit 912 is connected to the second port 902. The broadband matching circuit 911 is operationally connected between the reactance cancellation circuit 910 and the fine tuning circuit 912, so that said three circuits are connected in cascade.
[0185] The input impedance of the radiating structure 800 measured at its internal port (in absence of the radiofrequency system 900) has an imaginary part featuring an important capacitive component. In FIG. 10A said input impedance is represented by curve 1000, which is clearly located in the lower half portion of the Smith chart for all frequencies of the first frequency region (represented by the interval between point 1001 and point 1002 of the curve 1000). Therefore the reactance cancellation circuit 910 comprises a circuit element 903 having a substantially inductive behavior (in particular being a lumped inductor).
[0186] The broadband matching circuit 911 is similar to the one used for the radiofrequency system 500, and includes one stage substantially behaving as an LC parallel resonant circuit comprising an inductor 904 and a capacitor 905 connected in parallel.
[0187] The fine tuning circuit 912 adds two more stages to the matching network of the radiofrequency system 900. Said two stages form an L-shaped structure having a series inductor 906 and a parallel capacitor 907. In this particular example, the fine tuning circuit 912 provides an additional transformation of the impedance, necessary to attain the required level of impedance matching in the first frequency region.
[0188] FIG. 10B shows the effect of the radiofrequency system 900 on the input impedance of the radiating structure 800, in which curve 1050 correspond to the input impedance observed at an external port of the radiating system obtained from the interconnection of radiating structure 800 and radiofrequency system 900. Thanks to the contributions of the reactance cancellation circuit 910, the broadband matching circuit 911 and the fine tuning circuit 912, the curve 1000 transforms into the curve 1050 which features a loop around the center of the Smith chart.
[0189] The same typical results are shown in FIG. 11 in terms of input return losses. The radiofrequency system 900 transforms curve 1100 (in dash-dotted line), corresponding to the input return loss of the radiating structure 800 observed at its internal port when the radiofrequency system 900 is not connected to said internal port, into curve 1110 (in solid line), corresponding to the input return losses at the external port of the radiating system resulting from the interconnection of said radiofrequency system 900 with the radiating structure 800. Said curve 1110 feature a return loss better than −4 dB for all frequencies of the first frequency region (delimited by points 1101 and 1102 on the curve 1110).
[0190] FIGS. 12A-12B show another preferred example of a radiating structure suitable for a radiating system operating in a first frequency region of the electromagnetic spectrum between 923 MHz and 969 MHz.
[0191] The radiating structure 1200 comprises a radiation booster 2000 and a ground plane layer 2010, having a substantially rectangular shape. In FIG. 12B, it is shown the ground plane rectangle 1250 associated to the ground plane layer 2010, which in this example corresponds to the rectangular perimeter of said ground plane layer 2010. The ground plane rectangle 1250 has a long side and a short side and, in accordance with the present invention, the ratio between said long side and the free-space wavelength corresponding to the lowest frequency of the first frequency region is advantageously larger than 0.16. Moreover, said ratio is advantageously also smaller than 1.2.
[0192] In this example, the radiation booster 2000 comprises a gap defined in the ground plane layer 2010. A closer view of said radiation booster 2000 is provided in FIG. 20A. Said gap of the radiation booster 2000 has a polygonal shape delimited by a plurality of segments (segments 2001, 2002 and 2003) defining a curve. A connection point of the radiation booster 2004 is located at a first point along said curve (in particular a point on segment 2003), while a connection point of the ground plane layer 2011 is located at a second point along said curve (in particular a point on segment 2001). In some examples, according to the present invention, as in this particular example, the connection point of the radiation booster 2004 and the connection point of the ground plane layer 2011 are located on two segments that are at opposite sides of the gap of the radiation booster 2000. An internal port of the radiating structure 1200 is consequently defined between the connection point of the radiation booster 2004 and the connection point of the ground plane layer 2011.
[0193] In this example said gap intersects the perimeter of the ground plane layer, which means that the curve delimiting said gap is open. As it can be seen in FIG. 20A segments 2001 and 2003 intersect the perimeter of the ground plane layer 2010.
[0194] The use of the radiation booster 2000 in the radiation structure 1200 results in a advantageously planar solution, simplifying its integration in a wireless handheld or portable device. In this example, a booster box 1251 for the radiation booster 2000 is substantially planar (i.e., one of its dimensions is substantially close to zero). Furthermore, since the gap of the radiation booster 2000 has a substantially square shape, the booster box 1251 contains the segments 2001, 2002 and 2003.
[0195] In accordance with an aspect of the present invention, a maximum size of the radiation booster 2000 (said maximum size being a largest edge of the booster box 1251) is advantageously smaller than 1/40 times the free-space wavelength corresponding to the lowest frequency of the first frequency region of operation of radiating structure 1200. Additionally, in this example said maximum size is also advantageously larger than 1/250 times said free-space wavelength.
[0196] With such small dimensions of the radiation booster 2000, the radiating structure 1200 features a first resonance frequency at a frequency much higher than the frequencies of the first frequency region and, in consequence, the input impedance of the radiating structure 1200 measured at its internal port (in absence of a radiofrequency system connected to it) has an important reactive component, in particular an inductive component, within the frequencies of said first frequency region. In this case, the ratio between the first resonance frequency of the radiating structure 1200 measured at its internal port (in absence of a radiofrequency system connected to it) and the highest frequency of the first frequency region is advantageously larger than 5.0.
[0197] In the radiating structure 1200, the radiation booster 2000 is located with respect to the ground plane layer 2010 in such a manner that the gap of the radiation booster 2000 intersects an edge of the ground plane layer 2010, in particular a long edge of a substantially rectangular ground plane layer 2010. More precisely, the radiation booster 2000 is located substantially close to the middle point of said long edge.
[0198] FIG. 13 depicts a schematic representation of a radiofrequency system 1300 suitable for interconnection with the radiating structure 1200. The radiofrequency system 1300 includes a matching network, a first port 1301 (to be connected to the internal port of the radiating structure 1200), and a second port 1302 (for connection with the external port of a resulting radiating system). In this example, the matching network comprises a reactance cancellation circuit 1310, a broadband matching circuit 1311, and a fine tuning circuit 1312 connected in cascade.
[0199] The input impedance of the radiating structure 1200 measured at its internal port (in absence of the radiofrequency system 1300) has an imaginary part featuring a significant inductive component, as it can be seen in FIG. 14A. Said input impedance is represented by curve 1400, which is located in the upper half portion of the Smith chart for all frequencies of the first frequency region (represented by the interval between point 1401 and point 1402 of the curve 1400).
[0200] The reactance cancellation circuit 1310 is connected to the first port 1301 and comprises two stages having a substantially capacitive behavior and forming an L-shaped structure with a parallel capacitor 1303 and a series capacitor 1304. The capacitive behavior of the reactance cancellation circuit 1310 advantageously compensates the inductive component of the input impedance of the radiating structure 1200, transforming curve 1400 (FIG. 14A) into curve 1420 (FIG. 14B). Said curve 1420 corresponds to the input impedance that would be observed at the second port 1302 if the broadband matching circuit 1311 and the fine tuning circuit 1312 were removed and said second port 1302 were directly connected to a port 1320. In effect, the curve 1420 crosses the horizontal axis of the Smith Chart (i.e., imaginary part of the input impedance equal to zero) at a point 1421 located between point 1401 and point 1402.
[0201] The broadband matching circuit 1311 is connected in cascade after the reactance cancellation circuit 1310 and is similar in topology to the ones already discussed in connection with FIG. 5 and FIG. 9. Again, the broadband matching circuit 1311 includes one stage substantially behaving as an LC parallel resonant circuit comprising a capacitor 1305 and an inductor 1306 connected in parallel.
[0202] The broadband matching circuit 1311 further transforms the input impedance of the antenna structure and converts curve 1420 into curve 1440, said curve 1440 being the input impedance that would be observed at the second port 1302 if the fine tuning circuit 1312 were removed and said second port 1302 were directly connected to a port 1321. Curve 1440 features a compact loop that unfortunately is shifted towards the upper half of the Smith chart. If said loop were centered on the center of the Smith chart, impedance matching would be obtained over a much broader range of frequencies.
[0203] Finally, the fine tuning circuit 1312 is connected in cascade between the broadband matching circuit 1311 and the second port 1302, and includes one stage having a substantially capacitive behavior for all frequencies of the first frequency region. In particular said stage comprises a series circuit element (lumped capacitor 1307). The fine tuning circuit 1312 provides the additional transformation of the input impedance necessary to re-center the loop of curve 1440 on the center of the Smith chart. In FIG. 14D, curve 1460 represents the input impedance measured at the second port 1402, or equivalently at the external port of the radiating system. Said curve 1460 attains the level of VSWR required to provide operability to the radiating system in its first frequency region.
[0204] Referring now to FIG. 15, it is shown there a comparison between the typical input return losses observed at the internal port of the radiating structure 1200 when the radiofrequency system 1300 is disconnected (see curve 1500 in dash-dotted line) and the typical input return losses at the external port of the radiating system resulting from the interconnection of said radiofrequency system 1300 with the radiating structure 1200 (see curve 1510 in solid line). The presence of radiofrequency system 1300 improves substantially the return losses of the radiating structure 1200 for all frequencies of the first frequency region (delimited in the figure by points 1501 and 1502 on the curve 1510).
[0205] FIGS. 16A-16C show three preferred examples of radiation boosters comprising a conductive part. Each of the radiation boosters 1600, 1630, 1660 may advantageously excite a radiation mode on a ground plane layer 1610. In these examples, the radiation boosters 1600, 1630, 1660 are preferably not connected to the ground plane layer 1610.
[0206] FIG. 16A depicts a radiation booster 1600 including a conductive part featuring a polyhedral shape comprising a plurality of faces. More precisely, said conductive part takes the shape of a cube having six substantially square faces. Nevertheless, other polyhedral shapes are also possible.
[0207] In this particular example, two of the faces of the radiation booster (namely, the top face 1601 and the bottom face 1602) are substantially parallel to the ground plane layer 1610, which may facilitate the integration of the radiation booster 1600 into a wireless handheld or portable device by mounting said radiation booster 1600 on a PCB of the wireless device, and in particular the PCB that also comprises the ground plane layer 1610. However, in other examples, the radiation booster 1600 may not be substantially parallel to the ground plane layer 1610.
[0208] In this case, a booster box associated to said radiation booster 1600 coincides with the external surface of the radiation booster 1600. Since the smallest dimension of said booster box is not smaller than the 90% of the largest dimension of said booster box, the radiation booster 1600 takes full advantage of being a three-dimensional structure that occupies a volume.
[0209] The radiation booster 1600 also comprises a connection point 1603 advantageously located substantially close to a corner of the radiation booster 1600, said corner being in particular also a corner of the bottom face 1602. Said connection point 1603 defines together with a connection point of the ground plane layer 1611 an internal port of a radiating structure.
[0210] FIG. 16B shows radiation booster 1630 that includes a conductive part also featuring a polyhedral shape. In this example, said conductive part takes the form of a parallelepiped having substantially a square top face, a bottom face and four substantially rectangular lateral faces. However, other shapes for the top and bottom faces are also possible (such as for instance, but not limited to, triangle, pentagon, hexagon, octagon, circle, or ellipse) and/or for the lateral faces. Furthermore, the conductive part of the radiation booster could also have been shaped as a cylinder having circular or elliptical top and bottom faces. The conductive part of the radiation booster 1630 is mounted with respect to the ground plane layer in such a way that the top and bottom faces of the conductive part of said radiation booster 1630 are substantially parallel to the ground plane layer 1610.
[0211] As in the example of FIG. 16A, a booster box associated to the radiation booster 1630 also coincides with the external surface of the radiation booster 1630. However in the case of FIG. 16B, the smallest dimension of the booster box associated to the radiation booster 1630 is much smaller than the 70% of the largest dimension of said booster box. Therefore, although the radiation booster 1630 is not planar (i.e., two dimensional), it does not take full advantage of being a three-dimensional structure either.
[0212] The radiation booster 1630 further comprises a connection point 1631, located substantially close to a corner of the radiation booster 1630, which defines together with the connection point of the ground plane layer 1611 an internal port of a radiating structure.
[0213] In FIG. 16C it is shown a radiation booster 1660 including also a conductive part. Said conductive part comprises a conductive polygonal shape 1661 being substantially square and arranged substantially parallel to the ground plane layer 1610 at a predetermined height with respect said ground plane layer 1610. In other examples, the conductive polygonal shape 1661 may be shaped differently (for instance, as a polygon having a different number of sides of the same or different lengths, or as a circle or an ellipse).
[0214] Said conductive part further comprises a conductive strip 1662 having a substantially elongated shape and featuring two ends: A first end of the conductive strip 1662 is connected to the conductive polygonal shape 1661; and a second end of the conductive strip 1662 includes a connection point 1663, which together with the connection point of the ground plane layer 1611 defines an internal port of a radiating structure. In this example, the conductive strip 1662 is arranged substantially perpendicular to the ground plane layer 1610.
[0215] A radiating structure resulting from the combination of any of the radiation boosters 1600, 1630, 1660 in FIGS. 16A-16C with the ground plane layer 1610, features an input impedance (measured at the internal port of the radiating structure in absence of radiofrequency system) having an imaginary part with an important capacitive component. Therefore, such radiating structure could be advantageously interconnected with a radiofrequency system such as those in FIG. 5 or FIG. 9.
[0216] Referring now to FIGS. 17A-17E, it is shown some preferred placements of the radiation boosters of FIGS. 16A-16C with respect to a ground plane layer of a radiating structure.
[0217] In particular, FIG. 17A presents a radiating structure 1700 comprising the radiation booster 1660 and the ground plane layer 1610. The ground plane layer 1610 features a substantially rectangular shape having a long edge 1701 and a short edge 1702. In this example, the radiation booster 1660 is arranged substantially centered with respect to the ground plane layer 1610. That is, the radiation booster 1660 is substantially close to the point of the ground plane layer 1610 defined by the intersection of a first line 1703 (perpendicular to the long edge 1701 and crossing said long edge 1701 at its middle point) and a second line 1704 (perpendicular to the short edge 1702 and crossing said short edge 1702 at its middle point). Therefore, in this example the projection of the radiation booster 1660 on the plane containing the ground plane layer 1610 completely overlaps the ground plane layer 1610.
[0218] FIG. 17B shows a radiating structure 1720 similar to that of FIG. 17A, but in which the radiation booster 1660 has been arranged with respect to the ground plane layer 1610 in such a manner that the radiation booster is substantially close to the middle point of the long edge 1701. Consequently, in this radiating structure 1720 approximately only 50% of the area of the projection of the radiation booster 1660 on the plane containing the ground plane layer 1610 overlaps the ground plane layer 1610. A radiating structure such as the one in FIG. 17B may be advantageous when it is required to excite a radiation mode on the ground plane layer 1610 in which the currents are substantially aligned with respect the short edge 1702.
[0219] FIGS. 17C and 17D present two additional radiating structures comprising the radiation booster 1630 located substantially close to the short edge 1702. In the case of the radiating structure 1740, the radiation booster 1630 is advantageously located on a corner of the ground plane layer 1610, said corner being defined by the intersection of the long edge 1701 and the short edge 1702. On the other hand, in the radiating structure 1760 the radiation booster is located substantially close to the middle point of the short edge 1702.
[0220] Finally, FIG. 17E shows a radiating structure 1780, which resembles the radiating structure in FIG. 17D, but using the radiation booster 1600 instead. In this example, it is advantageous to protrude the radiation booster 1600 beyond the short edge 1702, avoiding any overlapping between the projection of the radiation booster 1600 on the plane of the ground plane layer 1610 and the ground plane layer 1610.
[0221] Although FIGS. 17A-17E present some examples of radiating structures using a radiation booster as those described in FIGS. 16A-16C, other possible embodiments according to the present invention would result from replacing the particular radiation booster shown in FIGS. 17A-17E by any of the other radiation boosters shown in FIGS. 16A-16C.
[0222] Referring now to FIG. 18, it is shown another example of a radiation booster. Radiation booster 1800 includes a conductive part comprising a plurality of conductive strips. In the figure, said conductive part comprises three conductive strips, although in other examples said conductive part may comprise more or fewer than three conductive strips. As depicted in FIG. 18, a first conductive strip 1801 and a third conductive strip 1803 are arranged substantially perpendicular to a ground plane layer 1810. A second strip 1802 is arranged substantially parallel to the ground plane layer 1810 and connected to the other two conductive strips, so that a first end of the second conductive strip 1802 is connected to a first end of the first conductive strip 1801 and a second end of the second conductive strip 1802 is connected to a first end of the third conductive strip 1803.
[0223] In this example, said conductive part of the radiation booster 1800 is connected to the ground plane layer 1810. For that purpose, a second end of the third conductive strip 1803 is connected to the ground plane layer 1810.
[0224] The radiation booster comprises a connection point 1804 located on a second end of the first conductive strip 1801, said connection point 1804 defining together with a connection point of the ground plane layer 1811 an internal port of a radiating structure 1820. Such a radiation booster 1800 may be advantageous when it is desired to have a radiating structure that features an input impedance at the internal port 1820 (in absence of a radiofrequency system) having a positive imaginary part for all the frequencies of the first frequency region (i.e., said imaginary part being an inductive component).
[0225] FIGS. 19A-19E present some preferred placements of the radiation booster 1800 with respect to the ground plane layer 1810. The ground plane layer 1810 features a substantially rectangular shape having a long edge 1901 and a short edge 1902.
[0226] In FIG. 19A it is shown a radiating structure 1900 in which the radiation booster 1800 is arranged substantially close to the long edge of the ground plane layer 1901. More precisely, the radiation booster 1800 is substantially close to the middle point of said long edge 1901. Moreover, the second conductive strip 1802 of the radiation booster 1800 is oriented substantially parallel to the short edge of the ground plane layer 1902, so that the first conductive strip 1801 is closer to the long edge 1901 than it is the third conductive strip 1803. Such an arrangement has turned out to be advantageous to enhance the coupling of energy between the radiation booster and the ground plane layer.
[0227] FIG. 19B presents another example of a radiating structure 1920 in which the radiation booster 1800 is also arranged substantially close to the long edge 1901 as in the previous case. However, now the radiation booster 1800 is advantageously located on a corner of the ground plane layer (said corner being defined by the intersection of the long edge 1901 and the short edge 1902), and its second conductive strip 1802 is oriented substantially parallel to the long edge of the ground plane layer 1901. That is, the radiation booster 1800 is arranged in such a manner that the first conductive strip 1801 is closer to said corner of the ground plane layer 1810 than it is the third conductive strip 1803.
[0228] FIG. 19C shows a further radiating structure 1940 including the radiation booster 1800 still arranged in such a way that its second conductive strip 1802 is oriented substantially parallel to the long edge of the ground plane layer 1901, as in FIG. 19B. However, now the radiation booster 1800 is placed substantially close to the short edge of the ground plane layer 1902, and more precisely approximately on the middle point of said short edge 1902. Additionally, the first conductive strip of the radiation booster 1801 is closer to the short edge 1902 than it is the third conductive strip 1803.
[0229] Another possible placement of the radiation booster 1800 is as indicated in the radiating structure 1960 shown in FIG. 19D, in which the radiation booster 1800 is substantially centered on the ground plane layer 1810. As in previous examples, it is preferred arranging said radiation booster 1800 so that its second conductive strip 1802 is aligned substantially parallel to the long edge of the ground plane layer 1901.
[0230] FIG. 19E presents a somewhat different radiating structure comprising a radiation booster inspired in the one shown in FIG. 18. A radiating structure 1980 comprises a radiation booster 1890 including a conductive part having three conductive strips 1891, 1892, 1893. Unlike the previous examples, the radiation booster 1890 is coplanar to the ground plane layer 1810, making it possible to embed the radiation booster 1890 and the ground plane layer 1810 in a same PCB.
[0231] Conductive strip 1891 includes a connection point that together with a connection point of the ground plane layer 1810 defines an internal port of the radiating structure 1895. Conductive strip 1893 is connected to the ground plane layer 1810. Conductive strip 1892 connects conductive strip 1891 with conductive strip 1893.
[0232] As it can be observed, the radiation booster 1890 protrudes beyond the short edge of the ground plane layer 1902, so that there is no ground plane in the projection of said radiation booster 1890 on the plane containing the ground plane layer 1810. Moreover, the radiation booster 1890 is advantageously located on a corner of the ground plane layer 1810 (in particular, the corner defined by the intersection of the long edge 1901 and the short edge 1902) and the conductive strip 1893 is closer to said corner than it is the conductive strip 1891.
[0233] Although FIGS. 19A-19E present some examples of radiating structures using a radiation booster as that described in FIG. 18, other possible embodiments according to the present invention would result from reorienting the radiation booster 1800 to have its second conductive strip 1802 aligned with respect to a given edge of a ground plane layer 1810, or from replacing the radiation booster 1800 with its coplanar equivalent (such as radiation booster 1890).
[0234] In FIGS. 20A-20B there are shown two examples of radiation boosters comprising a gap. The radiation booster 2000 in FIG. 20A has already been discussed in connection with the radiation structure of FIGS. 12A-12B. An alternative radiation booster is depicted in FIG. 20B, in which a radiation booster 2050 comprises a gap delimited by a plurality of segments defining a closed curve (i.e., a curve that does not intersect the perimeter of the ground plane layer 2010). In this example, segments 2051-2054 delimit a gap having a polygonal shape (in fact, the shape of a square).
[0235] The radiation booster 2050 comprises a connection point 2055 located at a first point along the curve delimiting said gap. In particular said connection point 2055 is located on a point of segment 2053. The ground plane layer 2010 also includes a connection point 2011, said connection point 2011 being located at a second point along said curve, and more precisely on a point of segment 2051. Although not always required, the connection point of the radiation booster 2055 and the connection point of the ground plane layer 2011 are advantageously located on segments at opposite sides of said gap of the radiation booster 2050 (segment 2053 and segment 2051 respectively).
[0236] Of course, FIG. 20A and FIG. 20B just present a couple of examples of a radiation booster. Other possible examples may include a different number of segments to delimit the gap (such as for instance two, three, four, five, six or more) and/or said segments could be straight, curved or a combination thereof.
[0237] FIGS. 21A-21D present some preferred placements for the radiation boosters 2000 and 2050 with respect to the ground plane layer 2010. The ground plane layer 2010 features a substantially rectangular shape having a long edge 2101 and a short edge 2102.
[0238] In FIG. 21A it is shown a radiating structure 2100 similar to the one shown in FIGS. 12A-12B but in which the radiation booster 2050 is used instead. Said radiation booster 2050 is arranged substantially close to the long edge of the ground plane layer 2101. In particular, the radiation booster 2050 is substantially close to the middle point of said long edge 2101. In this example, the segments 2051 and 2053 (i.e., the segments containing the connection points) are arranged so that they are substantially parallel to the short edge of the ground plane layer 2102. Such an arrangement is advantageous to properly excite a radiation mode on the ground plane layer 2010.
[0239] FIG. 21C presents a radiating structure 2140 also comprising the radiation booster 2050 as in FIG. 21A, but in which said radiation booster 2050 is arranged substantially centered with respect to the ground plane layer 2010. That is, the radiation booster 2050 is substantially close to the point of the ground plane layer 2010 defined by the intersection of a first line 2103 (perpendicular to the long edge 2101 and crossing said long edge 2101 at its middle point) and a second line 2104 (perpendicular to the short edge 2102 and crossing said short edge 2102 at its middle point). Again, in the radiation structure 2140, the segments 2051 and 2053 (i.e., the segments containing the connection points) are arranged so that they are substantially parallel to the short edge of the ground plane layer 2102.
[0240] FIG. 21B presents another radiating structure 2120 including the radiation booster 2000 placed intersecting the short edge of the ground plane layer 2102 approximately on the middle point of said short edge 2102. Alternatively, the radiating structure 2160 in FIG. 21D includes the radiation booster 2000 arranged intersecting another long edge of the ground plane layer 2105. Now the radiation booster 2000 is advantageously located substantially close to a corner of the ground plane layer (said corner being defined by the intersection of the long edge 2105 and the short edge 2102).
[0241] FIG. 22, FIGS. 23A-23B, and FIG. 24 present some further examples of radiating structures including a radiation booster comprising a gap.
[0242] Referring now to FIG. 22, a radiating structure 2200 comprises a radiation booster 2201 and a substantially rectangular ground plane layer 2202. In this example, the radiation booster 2201 comprises a gap having a meandering shape. Said gap is delimited by a plurality of segments defining a curve that comprises more than ten (10) segments and that intersects the perimeter of the ground plane layer 2202 (i.e., the curve is open).
[0243] FIG. 24 presents another example of a radiating structure 2400 comprising a radiation booster 2401 and a ground plane layer 2402. The radiation booster 2401 includes a gap having a U-shape. Said gap is delimited by a plurality of segments defining a curve that intersects the perimeter of the ground plane layer 2402 (i.e., the curve is open). In this example said curve comprises seven (7) segments.
[0244] A further example is depicted in FIGS. 23A-23B, in which a radiating structure 2300 having a radiation booster 2301 and a substantially rectangular ground plane layer 2302. The radiation booster 2301 comprises an inner gap 2303, an outer gap 2305 and a conductive strip 2304 separating said inner gap 2303 from said outer gap 2305. The conductive strip 2304 features a shape inspired in a Hilbert curve. The inner gap 2303 is delimited by segments 2310-2312 and by a plurality of segments of the conductive strip 2304, defining a curve that intersects the perimeter of the ground plane layer 2302.
[0245] The radiation booster 2301 comprises a connection point 2306 located at a first point along said curve, said first point being at an end of the conductive strip 2304. The ground plane layer 2302 also comprises a connection point 2307 located at a second point along said curve delimiting the inner gap 2303, and in particular said second point being substantially close to an end of segment 2310.
[0246] In these examples, the radiation boosters 2201, 2301, 2401 are arranged with respect to the ground plane layer 2202, 2302, 2402 in such a manner that said radiation boosters 2201, 2301, 2401 are located substantially close to a long edge of the ground plane layer 2202, 2302, 2402, and in particular substantially centered with respect to said long edge. Such an arrangement is particularly advantageous when the input impedance of a radiating structure an has an inductive component. However, other placements for the radiation boosters 2201, 2301, 2401 are also possible.
[0247] Moreover, a connection point of these radiation boosters 2201, 2301, 2401 is preferably located on a point of a first segment of the curve delimiting the gap of said radiation boosters 2201, 2301, 2401, said first segment intersecting the perimeter of the ground plane layer 2202, 2302, 2402. Likewise, a connection point of the ground plane layer is preferably located on a point of a second segment of said curve, said second segment being opposite to said first segment and said second segment also intersecting the perimeter of the ground plane layer 2202, 2302, 2402.
[0248] These radiating structures 2200, 2300, 2400 feature an input impedance (measured at their internal port when disconnected from a radiofrequency system) having an imaginary part with an inductive component. Therefore, such radiating structures could be advantageously interconnected with a radiofrequency system such as the one shown in FIG. 13.
[0249] A further radiating structure is depicted in FIG. 25, in which a radiating structure 2500 comprises a radiation booster 2501 and a substantially rectangular ground plane layer 2502. The radiation booster 2501 includes a conductive part having a substantially square conductive polygonal shape 2503 and being coplanar to the ground plane layer 2502. The arrangement of the radiation booster 2501 with respect to the ground plane layer is similar to that of the example in FIGS. 4A-4B.
[0250] FIG. 26 and FIG. 27 are two examples of radiofrequency systems comprising switching matrices.
[0251] Referring now to FIG. 26, it is shown a radiofrequency system 2600 comprising a switching matrix 2604, a first matching network 2605 and a second matching network 2606. The radiofrequency system 2600 further comprises a first port 2601 for interconnection with the internal port of a radiating structure.
[0252] The switching matrix 2604 is connected between said first port 2601 and the first and second matching networks 2605, 2606 and allows selecting which one of the first and second matching networks 2605, 2606 is operationally connected to the first port 2601. The radiofrequency system 2600 also includes a control circuit 2607 that acts on the switching matrix 2604 to select which one of the first and second matching networks 2605, 2606 is selected at any given time.
[0253] In this example, the radiofrequency system 2600 comprises a second port 2602 and a third port 2603 connected to the first matching network 2605 and to the second matching network 2606 respectively.
[0254] An alternative example is presented in FIG. 27, in which a radiofrequency system 2700 comprises a first switching matrix 2704, a first matching network 2705, a second matching network 2706, and a second switching matrix 2708. The radiofrequency system also includes a first port 2701 for connection to an internal port of a radiating structure and a second port 2702, which may become an external port of a radiating system for a wireless handheld or portable device. The first switching matrix 2704 is connected between the first port 2701 and the first and second matching networks 2705, 2706, while the second switching matrix 2708 is connected between the first and second matching networks 2705, 2706 and the second port 2702.
[0255] A control circuit 2707 included in the radiofrequency system 2700 acts on the first and second switching matrices 2704, 2708 to select which one of the first and second matching networks 2705, 2706 is operationally connected to the first port 2701 and the second port 2702.
[0256] Although the radiofrequency systems 2600, 2700 have been described as comprising two matching networks, other possible radiofrequency systems according to the present invention could include three, four or more matching networks selectable by one or more switching matrices.
