Abstract
A wireless device includes at least one slim radiating system having a slim radiating structure and a radio-frequency system. The slim radiating structure includes one or more booster bars. The booster bar has slim width and height factors that facilitate its integration within the wireless device and the excitation of a resonant mode in the ground plane layer, and has a location factor that enables it to achieve the most favorable radio-frequency performance for the available space to allocate the booster bar. The at least one slim radiating system may be configured to transmit and receive electromagnetic wave signals in one or more frequency regions of the electromagnetic spectrum.
Claims
1. A radiation booster bar to enable a radiating system to operate in at least one frequency range of operation, comprising: a dielectric layer having first and second surfaces; a first conductive element on the first surface of the dielectric layer; and a second conductive element on the second surface of the dielectric layer such that the dielectric layer spaces the first and second conductive elements, wherein: the radiation booster bar has an elongated shape with two slim form factors: a slim width factor and a slim height factor, the slim width factor being a ratio between a length and a width of the radiation booster bar, and the slim height factor being a ratio between a length and a height of the radiation booster bar; the slim width factor is greater than 2 and less than 10; the slim height factor is greater than 2 and less than 10; and the radiation booster bar is not resonant within any frequency range of operation of the radiating system.
2. The radiation booster bar of claim 1, wherein the dielectric layer is a single standard layer of dielectric material.
3. The radiation booster bar of claim 1, further comprising at least one via extending through the dielectric layer to electrically connect the first and second conductive elements.
4. The radiation booster bar of claim 1, wherein the slim height factor is greater than 4 and less than 10, and wherein the slim width factor is greater than 3 and less than 10.
5. The radiation booster bar of claim 1, wherein the slim height factor is greater than 4 and less than 10, and wherein the slim width factor is greater than 3.5 and less than 10.
6. The radiation booster bar of claim 1, wherein the slim width factor is greater than 6 and less than 10.
7. The radiation booster bar of claim 1, wherein a location of the radiation booster bar in relation to a ground element is characterized by a location factor defined as a ratio between the width of the radiation booster and a gap spacing the radiation booster bar and a ground element.
8. The radiation booster bar of claim 7, wherein the location factor is between 0.5 and 2.
9. The radiation booster bar of claim 7, wherein the location factor is between 0.3 and 1.8.
10. A radiating system in a wireless device, comprising: a radiating structure comprising: the radiation booster bar of claim 1; a ground plane layer, wherein a location factor is defined as a ratio between the width of the radiation booster bar and a gap spacing the radiation booster bar and the ground plane layer, the location factor providing a frequency bandwidth for the radiation booster bar that covers operating frequency ranges of the radiating system; and a conductive element connected to the radiation booster; and a radio-frequency system coupled to the radiating structure and comprising a matching circuit configured to ensure that the radiating system is impedance-matched at the operating frequency ranges.
11. The radiating system of claim 10, wherein the radiating system is impedance-matched such that an input reflection coefficient is below −4.4 dB.
12. The radiating system of claim 10, wherein the radiation booster bar has a slim width factor of 4, a slim height factor of 5, and a location factor of 0.33.
13. The radiating system of claim 10, wherein the conductive element is L-shaped.
14. The radiation system of claim 10, wherein the conductive element is I-shaped.
15. The radiating system of claim 10, wherein the location factor is between 0. 3 and 1.8.
16. The radiation booster bar of claim 1, wherein: the radiation booster bar is coupled to a test platform comprising a conductive surface acting as ground plane and having sides with a dimension larger than a reference operating wavelength corresponding to a free-space wavelength equivalent to a frequency of 900 MHz; the radiation booster bar is mounted close to and above a central point of the conductive surface and extends perpendicularly from the conductive surface in a monopole configuration; the radiation booster bar is electrically connected to a connector; a ratio between a first resonance frequency of the radiation booster bar in the test platform and a reference frequency of 900 MHz is greater than 3.0; and a radiation efficiency measured for the radiation booster bar in the test platform at the reference frequency of 900 MHz is less than 40%.
17. The radiation booster bar of claim 16, wherein the conductive surface is square with sides measuring 60 centimeters.
18. The radiation booster bar of claim 16, wherein the radiation efficiency measured for the radiation booster bar in the test platform at the reference frequency of 900 MHz is less than 5%.
19. The radiation booster bar of claim 16, wherein the radiation efficiency measured for the radiation booster bar in the test platform at the reference frequency of 900 MHz is less than 20%.
20. The radiation booster bar of claim 1, wherein a maximum size of the radiation booster bar is smaller than 1/15 of a free-space wavelength corresponding to a lowest frequency of operation of the radiating system.
21. A radiation booster bar to enable a radiating system to operate in at least one frequency range of operation, comprising: first and second conducting surfaces; a dielectric layer between the first and second conducting surfaces; and a plurality of vias extending through the dielectric layer and electrically interconnecting the first and second conducting surfaces, wherein the radiation booster bar has a slim width factor within a 10% variation of 3.125 and a slim height factor within a 10% variation of 3.125, and wherein the radiation booster bar is not resonant within any frequency range of operation of the radiating system.
22. The radiation booster bar of claim 21, wherein a maximum size of the radiation booster bar is smaller than 1/15 of a free-space wavelength corresponding to a lowest frequency of operation of the radiating system.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Embodiments of the invention are shown in the enclosed figures.
(2) FIGS. 1A-1B—Show examples of wireless handheld devices including slim radiating systems according to preferred embodiments of the invention.
(3) FIGS. 2A-2D—Block diagram representations of five examples of slim radiating systems in according with some preferred embodiments of the present invention.
(4) FIG. 3—Shows a perspective view of an example of a slim radiating structure including a booster bar in accordance with the present invention.
(5) FIGS. 4A-4B—Graphs showing bandwidth performances of several slim radiating systems as a function of the booster bar's width and gap dimensions.
(6) FIG. 5—Graph showing bandwidth performances of a slim radiating system as a function of the booster bar's width and gap dimensions for three different depth values.
(7) FIG. 6—Graph showing an example of an acceptable radio-electric frequency behavior for a slim radiating system in accordance with the present invention.
(8) FIG. 7—Shows a perspective view of an example of slim radiating structure including four booster bars in accordance with a preferred embodiment.
(9) FIG. 8—Plan view of an exemplary radio-frequency system coupled to a slim radiating structure in accordance with the present invention.
(10) FIG. 9—Graph showing the radio-electric frequency behavior of a slim radiating system including the slim radiating structure of FIG. 7 and the radio-frequency system of FIG. 8.
(11) FIG. 10—Perspective view of an exemplary slim radiating structure including three booster bars in accordance with a preferred embodiment.
(12) FIG. 11—Plan view of an example of a radio-frequency system coupled to a slim radiating structure in accordance with the present invention.
(13) FIG. 12—Graph showing the radio-electric frequency behavior of a slim radiating system including the slim radiating structure of FIG. 10 and the radio-frequency system of FIG. 11.
(14) FIG. 13—Shows another exemplary slim radiating structure according to the invention.
(15) FIGS. 14A-14B—Show schematic representations of radio-frequency systems in accordance with a preferred embodiment.
(16) FIGS. 15A-15F—Show six preferred matching circuits for some embodiments of the present invention.
(17) FIGS. 16A-16F—Show the impedance transformation of an exemplary slim radiating system as the different stages of a matching circuit in the radio-frequency system are added.
(18) FIG. 17—Shows the reflection coefficient of exemplary slim radiating system of FIG. 16F.
(19) FIG. 18A-18B—Show the impedance and the reflection coefficient of an exemplary slim radiating system comprising a radio-frequency system according to the invention.
(20) FIG. 19—Shows an exemplary radiation booster according to the invention.
(21) FIG. 20—Shows a slim radiating structure and an internal path in the form of a conductive trace in accordance with a preferred embodiment.
(22) FIG. 21A-21B—Show a test platform for the electromagnetic characterization of radiation boosters.
(23) FIG. 22—Shows the radiation efficiency and antenna efficiency of a radiation booster according to the present invention measured with the test platform depicted in FIGS. 21A and 21B.
DETAILED DESCRIPTION
(24) 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.
(25) Illustrative wireless electronic devices including a slim radiating system in accordance with the present invention are shown in FIGS. 1A and 1B. In the particular arrangement of FIG. 1A, the wireless electronic device 100 is a smartphone although it might represent other wireless electronic devices such as for instance a phablet or a tablet. The slim radiating system includes a first booster bar 101, a second booster bar 102, a booster element 110, and a ground element 105 (which may be included in a layer of a multilayer printed circuit board). The booster element 110 comprises two contiguous booster bars: the third booster bar 103 and the fourth booster bar 104. The first booster bar 101 is coupled to a radio-frequency system 109 via a conductive path 106, the second booster bar 102 is coupled to the radio-frequency system 109 via a conductive path 107, and the booster element 110 is coupled to the radio-frequency system 109 via a conductive path 108.
(26) In FIG. 1B there is shown a wireless handheld device 150 in an exploded perspective view, the device comprises a slim radiating structure and a radio-frequency system 153. The slim radiating structure comprises a radiation booster 151 taking the form of a booster bar with an elongated shape, and a ground plane layer 152. The booster bar 151 is coupled to the radio-frequency system via the internal conductive path 154 which, in this particular example, may be a conductive trace.
(27) In the examples of FIGS. 1A and 1B, the booster bars are arranged on a part of the device free of ground plane, so there is no ground plane in the orthogonal projection of the booster bars onto the plane comprising the ground plane layers 105 and 152, respectively. In other embodiments, the orthogonal projection of a booster bar or other radiation booster onto the plane comprising the ground plane layer may be overlapped partially or completely by the ground plane layer.
(28) FIG. 2A shows a block diagram representation of a slim radiating system for an electronic device. The slim radiating system 201a comprises slim radiating structure 202a, radio-frequency system 203a, internal conductive path 204a, and external conductive path 205a. The slim radiating structure is coupled to the radio-frequency system via the internal path 204a, and to other RF circuitry for handling RF wave signals via the external path 205a. A slim radiating system in accordance with this block diagram is configured to operate in at least one frequency region, or in at least two frequency regions, or in at least three frequency regions.
(29) FIG. 2B shows another block diagram of a slim radiating system for an electronic device according to the present invention. The slim radiating system 201b comprises slim radiating structure 202b, radio-frequency system 203b, two internal conductive paths 204b and 205b, and two external conductive paths 206b and 207b. The slim radiating structure is coupled to the radio-frequency system via the internal paths 204b and 205b, and to other RF circuitry for handling RF wave signals via the external paths 206b and 207b. A slim radiating system in accordance with this block diagram is configured to operate in at least two frequency regions, or in at least three frequency regions.
(30) FIG. 2C shows another block diagram of a slim radiating system for an electronic device according to the present invention. The slim radiating system 201c comprises slim radiating structure 202c, radio-frequency system 203c, three internal conductive paths 204c, 205c and 206c, and three external conductive paths 207c, 208c, and 209c. The slim radiating structure is coupled to the radio-frequency system via the internal conductive paths 204c, 205c and 206c, and to other RF circuitry for handling RF wave signals via the external conductive paths 207c, 208c and 209c. A slim radiating system in accordance with this block diagram is configured to operate in at least three frequency regions.
(31) FIG. 2D shows another block diagram of a slim radiating system for an electronic device according to the present invention. The slim radiating system 201d is similar to 201a from FIG. 2A. It comprises slim radiating structure 202a, radio-frequency system 203d, internal conductive path 204a, and two external conductive paths 205d and 206d. The slim radiating structure is coupled to the radio-frequency system via the internal paths 204a, and to other RF circuitry for handling RF wave signals via the external paths 205d and 206d. The radio-frequency system 203d may comprise a matching circuit configured to provide impedance matching in at least two frequency regions, and a diplexer may be connected to said matching circuit and coupled to the external paths. A slim radiating system in accordance with this block diagram is configured to operate in at least two frequency regions. The radio-frequency system 203d is convenient for the interconnection with an RF (radio-frequency) front-end module or RF circuitry that includes separate inputs for signals from the first frequency region and the second frequency region. If such RF front-end module (not illustrated) had one input/output for all the signals, the radio-frequency system 203a from FIG. 2A would be more suitable.
(32) FIG. 3 illustrates a preferred example of a slim radiating structure 301 according to the present invention. The slim radiating structure comprises a booster bar 303 and a ground plane layer 302, the booster bar comprises a single standard layer of dielectric material 306 with a top 304 and a bottom 305 conductive surfaces. The booster bar has a length 310, a width 311 and a height 312. The length of the booster bar is taken along the dimension that is substantially parallel to the ground plane layer in the top or bottom conductive surface, the width is taken along the dimension that is substantially perpendicular to the ground plane layer in the top or bottom conductive surface, and the height is taken as the minimum distance between the top conductive surface and the bottom conductive surface. In some embodiments the booster bar comprises pads on a first and a second surface so that the mounting of the booster can be reversed and top and bottom sides can be interchanged.
(33) The size and shape of the booster bar is characterized by a slim width factor and a slim height form factor. The slim width factor is a ratio between the length and the width of the booster bar, and the slim height factor is a ratio between the length and height of the booster bar, being the slim width factor and the slim height factor preferably larger than 3. In this example, where the booster is configured to operate in one or more frequency bands within the 600 MHz-6 GHz range (e.g. GSM 850 (824-894 MHz), GSM 900 (880-960 MHz), GSM 1800 (1710-1880 MHz), GSM 1900 (1850-1990 MHz), WCDMA 2100 (1920-2170 MHz), CDMA 1700 (1710-2155 MHz), LTE 700 (698-798MHz), LTE 800 (791-862 MHz), LTE 2600 (2500-2690 MHz), LTE 3500 (3.4-3.6 GHz), LTE 3700 (3.6-3.8 GHz), WiFi (2.4-2.5 GHz and/or 4.9-5.9 GHz)), the length is 10 millimeters, the width is 3.2 millimeters and the height is 3.2 millimeters, being the slim width factor 3.125 and the slim height factor 3.125, all those dimensions in these and other embodiments, within a typical tolerance of, for instance +/−1%-3% and in some occasions up to a 10% variation. The booster bar is separated from the ground plane by a gap 313; the gap is taken as the minimum distance between the bottom conductive layer and the ground plane layer. The gap distance plus the booster bar's width 311 is characterized as the depth of the radiation booster. The location of the booster bar in relation to the ground plane layer is characterized by a location factor. The location factor is a ratio between the width of the booster bar and the gap, being the location factor preferably in the range of between 0.5 and 2. In this example, the width is 3.2 mm and the gap is 3.3 mm, being the location factor 0.96 and the depth 6.5 mm, all those dimensions within a typical tolerance of, for instance +/−10% variation.
(34) FIG. 4A and FIG. 4B illustrate two examples of the relevance of the location and width of the booster bar in the radio-frequency performance of the slim radiating system; the radio-frequency performance of the slim radiating system is affected by the location of the booster bar with respect to the ground plane layer and the width of the booster bar. FIG. 4A and FIG. 4B plot the potential bandwidths achieved by six slim radiating systems as a function of the booster bar's width and gap dimensions. Curve 401 represents the potential bandwidth of a slim radiating system comprising a booster bar characterized by a height of 2.4 mm and a length of 11.5 mm. Curve 402 represents the potential bandwidth of a slim radiating system that includes a booster bar having a height of 3.2 mm and a length of 9 mm. Curve 403 represents the potential bandwidth of a slim radiating system comprising a booster bar characterized by a height of 2.4 mm and a length of 10.5 mm. Curve 404 represents the potential bandwidth of a slim radiating system comprising a booster bar characterized by a height of 3.2 mm and a length of 7 mm. Curve 405 represents the potential bandwidth of a slim radiating system comprising a booster bar characterized by a height of 2.4 mm and a length of 9 mm. Curve 406 represents the potential bandwidth of a slim radiating system comprising a booster bar characterized by a height of 2.4 mm and a length of 7 mm. As shown in FIG. 4A and FIG. 4B, the potential bandwidth of the slim radiating system depends on the width dimension of the booster bar and the location of the booster bar in relation to the ground plane layer; for each of the curves, there is a region where the most favorable bandwidth values are achieved. In this invention, such region is referred as the effective bandwidth region which corresponds to a range of location factor values that provide the region of most advantageous bandwidth values for the slim radiating system. The preferred values for the location factor are in the range of between 0.5 and 2. Such result is against conventional wisdom as the wider the width of the antenna element, the greater the bandwidth as, for example, in a monopole antenna.
(35) FIG. 5 illustrates another example of the effect of the booster bar's location and width on the radio-frequency performance of a slim radiating system; the radio-frequency performance of the slim radiating system is affected by the location of the booster bar with respect to the ground plane layer and the width of the booster bar. FIG. 5 plots the potential bandwidth achieved by the slim radiating system as a function of the booster bar's width and gap dimensions; the three curves 501, 502 and 503 represent the potential bandwidth of a slim radiating system comprising a booster bar having a height of 3.2 mm and a length of 7 mm. Curve 501 refers to the booster bar having a depth of 7.5 mm, curve 502 corresponds to a depth of 7 mm and curve 503 is for a depth of 6.5 mm. As previously shown in FIGS. 4A and 4B, the potential bandwidth of the slim radiating system depends on the gap that separates the booster bar from the ground plane layer and the width of the booster bar; for each of the curves, there is an effective bandwidth region where the most advantageous bandwidth values are achieved.
(36) One way to characterize the radio-frequency performance of the slim radiating system entails the use of a reflection coefficient plot; a reflection coefficient of less than −4.4 dB is generally acceptable. FIG. 6 illustrates an example of an acceptable radio-frequency performance for a slim radiating system according to the present invention. The slim radiating system comprises a booster bar which is characterized by a width form factor of 3.125, a height form factor of 3.125 and a location factor of 0.96. Curve 601 shows the reflection coefficient of the slim radiating system versus frequency, and line 602 shows an acceptable reference level for the reflection coefficient. In this example, the reflection coefficient is less than −4.4 dB for all the frequencies of the operating frequency region which covers a frequency range of about 824 MHz to about 960 MHz. Such frequency range enables the slim radiating system to be used to cover at least two communication frequency bands such as a band from 824 MHz to 894 MHz and a band from 880 MHz to 960 MHz. These two bands are examples of bands that can be covered by a slim radiating system; other bands may also be handled by the slim radiating system. In another embodiment, a suitable radio-frequency performance for the slim radiating system corresponds to a reflection coefficient of −6 dB or less for all the frequencies of the operating frequency range.
(37) FIG. 7 illustrates a preferred example of a slim radiating structure according to the present invention suitable for a slim radiating system configured to operate in three frequency regions. The slim radiating structure 701 comprises a first booster bar 702, a second booster bar 703, a booster element 704 comprising two adjacent booster bars 705 and 706, and a ground plane layer 707. As shown in FIG. 3, each booster bar comprises a single standard layer of dielectric material with top and bottom conductive surfaces; in this example the dielectric material has a height of 3.2 mm. In this example, the first and second booster bars 702, 703 have a slim width factor of 3.125, a slim height factor of 3.125, and a location factor of 0.96; the booster element 704 has a slim width factor of 6.25, a slim height factor of 6.25 and a location factor of 0.96. In general, any suitable shape may be used for the ground plane layer. FIG. 7 illustrates an example of a slim radiating structure according to the present invention suitable for a slim radiating system configured to operate in three frequency regions. The ground plane layer 707 includes clearance regions that may be used to mount other components of the electronic wireless device, or to adjust the ground plane layer to the shape of the electronic wireless device housing or for SAR purposes. The ground plane rectangle 708 (represented with dashed lines for illustrative purposes only) is characterized as the minimum sized rectangle that encompasses the ground plane layer 707. That is, the ground plane rectangle is a rectangle whose sides are tangent to at least one point the ground plane layer. In accordance with the present invention, a first long side of the ground plane layer refers to a long side of the ground plane rectangle 709 or 710; a second long side of the ground plane layer refers to a second long side of the ground plane rectangle 710 or 709; a first short side of the ground plane layer refers to a first short side of the ground plane rectangle 711 or 712; and a second short side of the ground plane layer relates to a second short side of the ground plane rectangle 712 or 711.
(38) FIG. 8 shows an example of a radio-frequency system 805 coupled to a slim radiating structure 801 via internal conductive paths 802, 803 and 804. An example of a suitable slim radiating structure 801 to be coupled to the radio-frequency system 805 is the slim radiating structure shown in FIG. 7. The radio-frequency system 805 comprises a first matching circuit 806, a second matching circuit 807, and a third matching circuit 808. The first matching circuit 806 is configured to ensure that the slim radiating system is impedance-matched at a first frequency region to other circuitry coupled via external conductive path 809. The second matching circuit 807 is configured to provide impedance matching at a second frequency region for other circuitry coupled to external conductive path 810. The third matching circuit 808 is configured to guarantee that the slim radiating system is matched in impedance at a third frequency region at the external conductive path 811. The first, second and third matching networks are therefore configured to ensure an acceptable reference level for the reflection coefficient over an entirety of the first, second and third operating frequency ranges. Each of the first, second and third matching circuits comprises a network of passive components such as inductors and capacitors, which are arranged with a suitable architecture like, for instance, an inductor plus an LC network. Other suitable matching circuits may be used to ensure that the slim radiating system is matched in impedance at the operating frequency ranges; other suitable matching circuits may comprise a network of passive and/or active components, which may be arranged with other suitable architectures.
(39) FIG. 9 illustrates the radio-frequency performance of the slim radiating system resulting from the interconnection of the slim radiating structure 701 to the radio-frequency system 805. Curve 901 shows the reflection coefficient of the slim radiating system versus frequency at a terminal in the external path 809, curve 902 shows the reflection coefficient of the slim radiating system versus frequency at a terminal in the external path 810, curve 903 shows the reflection coefficient of the slim radiating system versus frequency at a terminal in the external path 811, and line 904 shows an acceptable reference level for the reflection coefficient. In this example, the reflection coefficient 901 is less than −4.4 dB for all the frequencies of a first operating frequency region 905, the reflection coefficient 902 is less than −4.4 dB for all the frequencies of a second operating frequency region 906, and the reflection coefficient 903 is less than −4.4 dB for all the frequencies of a third operating frequency region 907. The first operating frequency region 905 of the slim radiating system covers a first frequency range of about 698 MHz to about 798 MHz, the second operating frequency region 906 of the slim radiating system covers a frequency range of about 824 MHz to about 960 MHz, and the third operating frequency region 907 of the slim radiating system covers a third frequency range of about 1710 MHz to about 2690 MHz. The first frequency range enables the slim radiating system to be used to cover at least three communication bands such as a band from 699 MHz to 746 MHz, a band from 746 MHz to 787 MHz, and a band from 758 MHz to 798 MHz. The second frequency range enables the slim radiating system to cover at least two communication frequency bands such as a band from 824 MHz to 894 MHz and a band from 880 MHz to 960 MHz. The third frequency range enables the slim radiating system to cover at least five communication frequency bands such as a band from 1710 MHz to 1880 MHz, a band from 1850 MHz to 1990 MHz, a band from 1920 MHz to 2170 MHz, a band from 2300 MHz to 2400 MHz, and a band from 2496 MHz to 2690 MHz. Other desirable communication frequency bands may also be handled by the slim radiating system.
(40) FIG. 10 illustrates another example of a slim radiating structure in accordance to the present invention; the slim radiating structure is suitable for a slim radiating system that is configured to operate in at least two frequency regions. The slim radiating structure 1001 comprises a first booster element 1002 including a first booster bar 1003 and a second booster bar 1004 adjacent to the first booster bar; the slim radiating structure 1001 further comprises a third booster bar 1005, and a ground plane layer 1006. As shown in FIG. 3, each booster bar may be formed by a single standard layer of dielectric material with top and bottom conductive surfaces. In this example, the dielectric material has a height of 2.4 mm; the first booster element 1002 has a slim width factor of 8, a slim height factor of 10, and a location factor of 0.375; the third booster bar 1005 has a slim width factor of 4, a slim height factor of 5 and a location factor of 0.375.
(41) FIG. 11 shows an example of a radio-frequency system 1101 coupled to a slim radiating structure 1102 via internal conductive paths 1103 and 1104. An example of a suitable slim radiating structure 1102 to be coupled to the radio-frequency system 1101 is illustrated in FIG. 10. The radio-frequency system 1101 comprises a matching circuit being configured to ensure that the slim radiating system is impedance-matched to other circuitry coupled via external conductive path 1105 at a first frequency region and a second frequency region. The matching network is therefore configured to ensure an acceptable reference level for the reflection coefficient over an entirety of the first and second operating frequency ranges. The matching circuit comprises a network of passive components such as inductors, capacitors and transmission lines, which are arranged with a suitable architecture as shown in FIG. 11. Other suitable matching circuits may be used to ensure that the slim radiating system is impedance matched at the operating frequency ranges; other suitable matching circuits may comprise a network of passive and/or active components, which may be arranged with other suitable architectures.
(42) FIG. 12 illustrates the radio-frequency performance of the slim radiating system resulting from the interconnection of the slim radiating structure 1001 to the radio-frequency system 1101. Curve 1201 shows the reflection coefficient of the slim radiating system versus frequency at a terminal in the external path 1105, and line 1202 shows an acceptable reference level for the reflection coefficient. In this example, the reflection coefficient 1201 is less than −4.4 dB for all the frequencies of the first and second frequency regions. The first operating frequency region of the slim radiating system covers a first frequency range of about 698 MHz to about 960 MHz, and the second operating frequency region of the slim radiating system coves a frequency range of about 1710 MHz to about 3800 MHz. The first frequency range enables the slim radiating system to be used for covering at least five communication bands such as a band from 699 MHz to 746 MHz, a band from 746 MHz to 787 MHz, a band from 758 MHz to 798 MHz, a band from 824 MHz to 894 MHz, and a band from 880 MHz to 960 MHz. The second frequency range enables the slim radiating system to cover at least seven communication frequency bands such as a band from 1710 MHz to 1880 MHz, a band from 1850 MHz to 1990 MHz, a band from 1920 MHz to 2170 MHz, a band from 2300 MHz to 2400 MHz, a band from 2496 MHz to 2690 MHz, a band from 3400 MHz to 3600 MHz, and a band from 3600 MHz to 3800 MHz. Other desirable communication frequency bands may also be handled by the slim radiating system.
(43) Another example of a slim radiating structure is shown in FIG. 13. The slim radiating structure 1300 comprises ground plane layer 1302 on a printed circuit board 1307, and radiation booster 1301 characterized by a slim width factor between 1 and 2, and a slim height factor between 1 and 2. The radiation booster 1301 is separated from the ground plane layer by a gap and is characterized by a location factor between 0.5 and 2, preferably between 0.5 and 1. The ground plane layer may be inscribed in ground plane rectangle 1306 (in dashed lines for illustrative purposes only), and the radiation booster may be inscribed in booster box 1305 (in dashed lines for illustrative purposes only).
(44) A wireless electronic device comprising a slim radiating system that includes slim radiating structure 1300 may advantageously provide penta-band operation: two frequency bands in the first frequency region, like for example the frequency bands corresponding to the GSM 850 and GSM 900 cellular communication standards (i.e. the first frequency region comprising the 824 MHz to 960 MHz frequency range), and three frequency bands in the second frequency region, like for example the frequency bands corresponding to the GSM 1800, GSM 1900 and WCDMA 2100 cellular communication standards (i.e. the second frequency region comprising the 1710 MHz to 2170 MHz frequency range). In another example, a device according to the present invention could provide triple-band or quad-band operation with at least two frequency bands in the first frequency region, and at least another two frequency bands in the second frequency region, wherein first and second frequency regions do not overlap in frequency. Such device could operate, for instance but not limited to, the GSM 850 and GSM 900 cellular communication standards, and the GSM 1800 and GSM 1900 cellular communication standards.
(45) FIG. 14A illustrates a radio-frequency system 1400 that comprises a first port 1401, a second port 1402, and a matching circuit 1403. Such radio-frequency system is particularly convenient to be used in the slim radiating system of FIG. 2A. Port 1401 may be connected to an internal conductive path (for instance 204a), and port 1402 may be connected to an external conductive path (for instance 205a). The matching circuit 1403 may be configured to provide impedance matching in at least one frequency region, or in at least two frequency regions, or in at least three frequency regions.
(46) FIG. 14B illustrates another radio-frequency system 1410 comprising a first port 1411, a second port 1412, a third port 1413, a matching circuit 1414, a diplexer 1415, and a conductive path 1416 connecting the matching circuit to the diplexer. In reception, the diplexer 1415 is configured to split the signal from conductive path 1416 in a first signal extracted at port 1412, preferably comprising the frequencies corresponding to the first frequency region, and in a second signal extracted at port 1413, preferably comprising the frequencies corresponding to the second frequency region; in transmission, diplexer 1415 combines signals from ports 1412 and 1413 and are extracted in conductive path 1416. The matching circuit 1414 provides impedance matching to the slim radiating system in the first and second frequency regions. Ports 1412 and 1413 may be respectively connected to first and second external paths as shown in FIG. 2D.
(47) FIGS. 15A to 15F show preferred matching circuits configured to provide impedance matching in at least two frequency regions.
(48) FIG. 15A shows matching circuit 1500 comprising first and second ports 1501 and 1502, and a circuit including five stages forming a ladder topology (series-parallel-series-parallel-series). The first stage, which is connected to port 1501, is an inductor in series 1503, the second stage is a shunted inductor 1504, the third stage is a capacitor in series 1505, the fourth stage is an inductor in parallel 1506, and the fifth stage is a capacitor in series 1507, said fifth stage being connected to the second port 1502.
(49) In FIG. 15B there is shown matching circuit 1510 comprising six stages that form an alternative ladder topology (series-parallel-series-parallel-series-parallel). The first stage (in series) is connected to the first port 1501 of the matching circuit, and the sixth stage comprising an inductor in parallel 1511 is connected to the second port 1502 of the matching circuit.
(50) FIG. 15C depicts another preferred matching circuit 1520 comprising two stages: the first stage comprises a capacitor in parallel 1521, and the second stage comprises an inductor in series 1522. A preferred range of capacitor values for shunted capacitor 1521 of matching circuit 1520 is 0.01 pF to 30 pF.
(51) FIG. 15D shows another preferred matching circuit 1530 comprising a series inductor 1531 connected to port 1501 and to a series LC resonator formed by inductive component 1532a and capacitive component 1532b. The LC resonator is connected to an LC resonator in parallel, comprising inductor 1533a and capacitor 1533b, and to a series capacitor 1534. The series capacitor is connected to second port 1502 of the matching circuit 1530. This matching circuit comprises a single branch formed by four stages (series-series-parallel-series).
(52) FIG. 15E shows a fifth preferred matching circuit 1540 comprising: inductor 1541 in series connected to port 1501, inductor 1542 in parallel, capacitor 1543 in series, inductor 1544a and capacitor 1544b in parallel forming a parallel LC circuit, and capacitor 1545 in series connected to port 1502.
(53) FIG. 15F illustrates another preferred matching circuit 1550 that is similar to matching circuit 1540 with the difference that capacitor 1545 is connected to inductor in series 1551 forming a series LC circuit, and said inductor being connected to port 1502 instead of capacitor 1545 as in FIG. 15E.
(54) Inductors 1503, 1531 and 1541 corresponding to the first stage of matching circuits 1500, 1510, 1530, 1540 and 1550 may preferably have a value in the range of 0.1 nH to 80 nH.
(55) Matching circuits 1500, 1510, 1520, 1530, 1540, and 1550 are suitable for being used as matching circuit 203a and 203d shown in FIGS. 2A and 2D.
(56) FIG. 16A shows the impedance 1600 of a slim radiating system comprising a radiation booster, measured at its internal conductive path, when it is disconnected from a radio-frequency system as disclosed in the present invention. Points 1601 and 1602 from said impedance correspond to the lowest and highest frequencies of a first frequency region (in this example, said frequencies are 824 MHz and 960 MHz); and points 1603 and 1604 correspond to the lowest and highest frequencies of a second frequency region (for this particular example, said frequencies are 1710 MHz and 2170 MHz). The impedance 1600 has a substantially large negative reactance, namely the impedance in the first frequency region is capacitive, for the entire range of frequencies limited by points 1601 and 1602, and is also capacitive for the frequencies of the second frequency region. The first resonant frequency of said slim radiating structure is at a frequency above the highest frequency of the second frequency region (as indicated by point 1604).
(57) FIGS. 16B to 16F show the evolution of the impedance of slim radiating system of FIG. 16A after the slim radiating system is connected to a radio-frequency system comprising a matching circuit like 1500 as the stages are added successively to the matching circuit. FIG. 16B shows the impedance 1610 when the matching circuit only comprises the first stage (an inductor in series). In FIG. 16C, the impedance 1620 of the slim radiating system is shown after adding the inductor in parallel (corresponding to the second stage) to the matching circuit. The impedance 1630 from FIG. 16D is obtained after the series capacitor from the third stage is added. The impedance 1640 from FIG. 16E is obtained after the shunted inductor from the fourth stage is added. And with the addition of the fifth stage corresponding to another capacitor in series, the impedance 1650 of the slim radiating system is obtained. In addition to the impedance 1650 as shown in FIG. 16F, the reflection coefficient 1700, when the slim radiating structure is connected to a radio-frequency system comprising the five-stage ladder matching network is also shown in FIG. 17. In this particular example, the operating frequency range for the radiating system covers a first frequency region at least comprising the range of frequencies delimited by points 1701 and 1702 (824 MHz and 960 MHz respectively), and a second frequency region at least comprising the range of frequencies delimited by points 1703 and 1704 (1710 MHz and 2170 MHz respectively), wherein said points establish a minimum level of reflection coefficient for a good radio-frequency performance for this particular example, although in other embodiments said minimum level could be, for example, −4.4 dB.
(58) A ratio between the lowest frequency of the second frequency region and the lowest frequency of the first frequency region is, for this particular case, greater than 1.5 and even greater than 2.0. In addition, a ratio between the first resonant frequency of the slim radiating structure measured at an internal path, when disconnected from the radio-frequency system, and the lowest frequency of the first frequency region is greater than 1.3, also greater than 2.0, and even greater than 2.4.
(59) FIGS. 18A and 18B show the impedance and reflection coefficient of another exemplary embodiment. Such embodiment corresponds to a slim radiating system comprising a slim radiating structure featuring an impedance similar to that of FIG. 16A, and a radio-frequency system according to the present invention. The radio-frequency system comprises a six-stage matching circuit in a ladder topology, like for example matching circuit 1510 from FIG. 15B. The impedance 1800, when the slim radiating structure is connected to such radio-frequency system, is shown in FIG. 18A. In said figure, points 1801 and 1802 refer to the lower and higher frequencies of a first frequency region (824 MHz and 960 MHz respectively), and points 1803 and 1804 refer to the lower and higher frequencies of a second frequency region (1710 MHz and 2170 MHz respectively). The reflection coefficient 1810 of FIG. 18B corresponds to the slim radiating system of FIG. 18A. The operating frequency range for a slim radiating system according to this particular embodiment at least covers a first frequency region including the first range delimited by points 1811 and 1812 (824 MHz and 960 MHz), and a second frequency region including the second range delimited by points 1813 and 1814 (1710 MHz and 2170 MHz).
(60) FIG. 19 shows a radiation booster 1900 comprising conducting surfaces 1901 and 1902, a dielectric material 1904 (shown transparent for illustrative purposes only), and a plurality of vias 1903 electrically interconnecting the two conducting surfaces 1901 and 1902 (in other examples, said conducting surfaces may be interconnected by just one via). Said radiation booster is a booster bar featuring a slim width factor of 3.125, and a slim height factor of 3.125. The booster bar 1900 may be used, for example, in slim radiating structure 1300 instead of radiation booster 1301.
(61) A booster bar such as 1900 is configured to be used in slim radiating systems according to the present invention, and in particular in each and every embodiment of the present invention. As such, a slim radiating system comprising a slim radiating structure, a radio-frequency system and at least one external conductive path, wherein the slim radiating structure comprises a radiation booster like, for example, 1900 and a ground plane layer, may be configured to transmit and receive electromagnetic wave signals in at least one frequency region, or in at least two frequency regions. The radio-frequency system comprises a matching circuit configured to provide impedance matching to the slim radiating system in said at least one or at least two frequency regions at the at least one external path.
(62) FIG. 20 shows a slim radiating structure comprising a radiation booster (e.g. booster bar) 2001, a ground plane layer 2002. There is also shown a conductive element 2003 that may advantageously function as an internal conductive path. The conductive element 2003 is connected to radiation booster 2001, advantageously tuning the input impedance of the radiation booster prior its connection to a radio-frequency system (not shown). The conductive element may improve the efficiency of the slim radiating system comprising said slim radiating structure, or make the slim radiating system operable in more frequency bands in at least one frequency regions or in at least two frequency regions. In this example, the booster bar features a height of 2.4 mm, a slim width factor of 4, a slim height factor of 5, and a location factor of 0.33. Although the conductive element 2003 is L-shaped, in other examples the conductive element may take other forms as well such as a straight I.
(63) The electrical length of conductive element 2003 may be shorter than 10% of the free-space wavelength corresponding to the lowest frequency of the first frequency region, and preferably it may be shorter than 5% of said free-space wavelength.
(64) FIG. 21A schematically shows, in a 3D perspective, a test platform for the characterization of radiation boosters. The platform comprises substantially square conductive surface 2101 and connector 2102 (for instance an SMA connector) electrically connected to the device or element 2100 to be characterized. The conductive surface 2101 has sides with a length larger than the reference operating wavelength corresponding to the reference frequency. For instance, at 900 MHz, said sides are at least 60 centimeters long. The conductive surface may be a sheet or plate made of copper, for example. The connector 2102 is placed substantially in the center of conductive surface 2101.
(65) In FIG. 21B the same test platform of FIG. 21A is schematically represented in a 2D perspective wherein the conductive surface 2101 is partially drawn. In this example, the element that is to be characterized 2100 in FIG. 21A corresponds to booster bar 1900 from FIG. 19, which is arranged so that its largest dimension is perpendicular to conductive surface 2101, and one of the first or second conductive surfaces (1901 or 1902 of FIG. 19) is in direct electrical contact with connector 2102 (for clearer interpretation of the orientation of radiation booster 1900, via holes 1903 connecting the first and second conductive surfaces of the radiation booster are also drawn in FIG. 21B). The radiation booster 1900 lies on a dielectric material (not shown) attached to the conductive surface 2101 so as to minimize the distance between radiation booster 1900 and surface 2101. Said dielectric material may be a dielectric tape or coating, for example.
(66) FIG. 22 shows a graph of the radiation efficiency and antenna efficiency measured in a test platform like the one shown in FIG. 21A and FIG. 21B, when the element 2100 to be characterized is radiation booster 1900. In this particular example, the radiation efficiency measured 2201 (represented with a solid line) at 900 MHz is less than 5%, and the antenna efficiency measured 2202 (represented with a dashed line) at 900 MHz is less than 1%.
(67) The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. So even though that in the illustrative examples described above in connection with the figures some particular designs of booster bars with specific values for the slim width factor, the slim height factor, and the location factor have been used, many other designs of boosters bars in accordance with the invention having for example different slim width factor, slim height factor, and/or location factor could have been equally used in the slim radiating structures.
