Antenna system for a portable device

Abstract

There is disclosed an antenna system comprising: i) first and second antennas, the second antenna being disposed laterally from the first along a longitudinal axis, and ii) an isolation structure disposed between the first and second antennas. The isolation structure comprises a first resonator element having a first arm with upper and lower ends, the first arm connected to ground at its lower end, and a lateral second arm connected to the upper end of the first arm. At least a portion of the first resonator element is disposed adjacent to a portion of the first antenna such that the first resonator element is strongly coupled to the first antenna.

Claims

1. An antenna system comprising first and second antennas, the second antenna being disposed laterally from the first antenna along a longitudinal axis, and further comprising a first isolation structure disposed between the first and second antennas, the first isolation structure comprising a first resonator element having a first arm with first and second ends, the first arm connected to ground at its first end and extending across the longitudinal axis, and a lateral second arm connected to the second end of the first arm, wherein at least a portion of the first resonator element is disposed adjacent to a portion of the first antenna such that the first resonator element is strongly coupled to the first antenna, wherein the first isolation structure further comprises a second resonator element disposed relative to the first resonator element so as to couple strongly to the first resonator element, and wherein the first and second resonator elements are not directly electrically connected to each other, but are each separately connected to ground, and wherein the second resonator element comprises a lateral elongated element located between the first antenna and the first arm of the first resonator element.

2. The antenna system according to claim 1, wherein a portion of the second arm is located adjacent to and substantially parallel to a portion of the first antenna and spaced apart therefrom, such that the coupling is primarily between the portion of the second arm and the portion of the first antenna.

3. The antenna system according to claim 1, wherein the first resonator element comprises a third arm connected to the lateral second arm at an end of the lateral second arm distal from the first arm and oriented at an angle to the second arm, at least a portion of the third arm being aligned substantially parallel to a portion of the first antenna and spaced apart therefrom it, such that the coupling is primarily between the portion of the third arm and the portion of the first antenna.

4. The antenna system according to claim 1, wherein the portion of the first resonator element is located within a distance of 10 mm of the portion of the first antenna.

5. The antenna system according to claim 1, wherein the first resonator element is strongly coupled to the first antenna such that a resonant condition is created when the first antenna is excited in a first frequency band.

6. The antenna system according to claim 1, further comprising first and second spaced-apart ground planes, the first antenna and the first resonator element being located at least partly in a gap between adjacent edges of the ground planes.

7. The antenna system according to claim 1, wherein at least a portion of the second resonator element is located adjacent to a portion of the first resonator element and spaced apart therefrom, such that the strong coupling is primarily between the portion of the second resonator element and the portion of the first resonator element.

8. The antenna system according to claim 7, wherein the portion of the second resonator element is located within a distance of 10 mm of the portion of the first resonator element.

9. The antenna system according to claim 1, wherein the second resonator element is connected to ground via a short circuit or an impedance.

10. The antenna system according to claim 1, further comprising a first matching network connected to the second resonator element, the first matching network being configured to provide a selectable impedance between the second resonator element and ground.

11. The antenna system according to claim 10, wherein the selectable impedance is selectable from one or more of: an open circuit, a short circuit, a series capacitance, a series inductance, a series LC impedance and a parallel LC impedance.

12. The antenna system according to claim 1, wherein a portion of the second resonator element lies substantially parallel to and spaced apart from a portion of the first resonator element.

13. The antenna system according to claim 1, wherein the first resonator element comprises a third arm connected to the lateral second arm at an end of the lateral second arm distal from the first arm, and an end of the third arm is adjacent to a central portion of the second resonator element to achieve strong coupling between the third arm and the central portion of the second resonator element.

14. The antenna system according to claim 1, further comprising a second isolation structure located between the first isolation structure and the second antenna, the second isolation structure comprising a third resonator element having a first arm with first and second ends, the first arm connected to ground at its first end and extending across the longitudinal axis, and a lateral second arm connected to the second end of the first arm, wherein at least a portion of the third resonator element is disposed adjacent to a portion of the second antenna such that the third resonator element is strongly coupled to the second antenna.

15. The antenna system according to claim 14, wherein the second isolation structure further comprises a fourth resonator element disposed such that the fourth resonator element is strongly coupled to the third resonator element.

16. The antenna system according to claim 15, wherein the first, second, and at least one of the third and fourth resonator elements are configured to provide paths to ground for surface currents on the first, second, third and/or fourth antennas.

17. The antenna system according to claim 14, wherein the first and second isolation structures are substantially mirror images of each other.

18. The antenna system according to claim 14, further comprising a second matching network connected to the fourth resonator element, the second matching network being configured to provide a selectable impedance between the fourth resonator element and ground.

19. The antenna system according to claim 18, further comprising third and fourth antennas located between the first and second isolation structures, and a third isolation structure located between the third and fourth antennas, the third isolation structure comprising a ground plane, at least a portion of the ground plane being located between the third and fourth antennas.

20. The antenna system according to claim 19, wherein the portion of the ground plane comprising the third isolation structure takes the form of at least two ground plane extensions that project from an edge of the ground plane and extend between the third and fourth antennas.

21. The antenna system according to claim 19, wherein the ground plane comprises at least two separate ground plane elements.

22. The antenna system according to claim 21, wherein each separate ground plane element is provided with a ground plane extension that extends from an edge of its respective ground plane element, the ground plane extensions forming the third isolation structure.

23. The antenna system according to claim 19, further comprising a meander isolation structure located between the third antenna and the ground plane.

24. The antenna system according to claim 19 formed on a 3D substrate comprising a first upright face, a second upright face and an upper face joining the two upright faces, wherein the first and second antennas and the first isolation structure are provided on the first upright face and the third and fourth antennas and the third isolation structure are provided on the second upright face.

25. The antenna system according to any claim 19, wherein the third and/or fourth antennas are WLAN antennas.

26. The antenna system according to claim 14, further comprising a third antenna located between the first and second isolation structures.

27. The antenna system according to claim 1, wherein at least the first and second antennas are monopole antennas.

28. The antenna system according to claim 1, wherein the first and second antennas are LTE antennas.

29. The antenna system according to claim 1, wherein the first arm of the first resonator element is connected to ground via a selectable impedance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

(2) FIG. 1 shows an embodiment of an antenna system according to the invention comprising a first and second antennas and an isolation structure adjacent to the first antenna.

(3) FIG. 2 shows an embodiment comprising a first and second mirror image isolation structures between the first and second antennas.

(4) FIG. 3 shows an embodiment comprising a first and second isolation structures illustrating regions of strong coupling between the antenna and the first resonator element and between the first and second resonator elements.

(5) FIG. 4 shows an embodiment comprising first and second monopole antennas and mirror image isolation structures between them.

(6) FIG. 5 shows an embodiment of an antenna system configured to be disposed between a first and second ground planes, such as the keyboard and screen components of a portable device case, comprising four antennas, each separated from its neighbour by an isolation structure.

(7) FIG. 6 shows an embodiment of an antenna system comprising a reconfigurable antenna strongly coupled to a resonator structure, the resonator structure being tuneable by means of a matching network.

(8) FIG. 7 shows an embodiment of an antenna system comprising a reconfigurable antenna strongly coupled to a resonator structure, the resonator structure being tuneable by means of a matching network, wherein the antenna is coupled directly to a port.

(9) FIG. 8 shows a further embodiment of an antenna system comprising a reconfigurable antenna, wherein the antenna is coupled directly to a port.

(10) FIG. 9 shows a further embodiment of an antenna system comprising a reconfigurable antenna, wherein the antenna is coupled directly to a port.

(11) FIG. 10A shows a front view of an embodiment of the invention in which a four antenna system is implemented on a 3D substrate adapted to mount in the hinge region of a laptop.

(12) FIG. 10B shows a variation of the embodiment of FIG. 10A.

(13) FIG. 11 is a rear view of the embodiment of FIG. 10A.

(14) FIG. 12 is a top view of the embodiment of FIG. 10A.

(15) FIG. 13 is a bottom view of the embodiment of FIG. 10A.

(16) FIG. 14 is a rear isometric view of the embodiment of FIG. 10A, as mounted between the base and top of a laptop case.

(17) FIG. 15 is a front isometric view of the embodiment as shown in FIG. 14.

(18) FIG. 16 is a rear and lower isometric view of the embodiment as shown in FIG. 14.

(19) FIG. 17 shows the disposition of the antenna system in the hinge region of a laptop computer.

(20) FIG. 18 shows a network diagram of the antenna system including the matching network for the first and second isolation structures.

(21) FIG. 19 shows the radiation characteristics of the first and second LTE antennas at 0.73 GHz.

(22) FIG. 20 shows the radiation characteristics of the first and second LTE antennas at 1.8 GHz.

(23) FIG. 21 shows the radiation characteristics of the first and second LTE antennas at 2.15 GHz.

(24) FIG. 22 shows the radiation characteristics of the first and second LTE antennas at 2.3 GHz.

(25) FIG. 23 shows the radiation characteristics of the first and second LTE antennas at 2.65 GHz.

(26) FIG. 24 shows the radiation characteristics of the first and second WLAN antennas at 2.45 GHz.

(27) FIG. 25 shows the radiation characteristics of the first and second WLAN antennas at 5.5 GHz.

(28) FIG. 26 shows a variation of the embodiment of FIGS. 10 to 16 with an additional 60 GHz WiGig® antenna.

(29) FIG. 27 shows a further variation of the embodiment of FIGS. 10 to 16 with an additional 60 GHz WiGig® antenna and additional isolation structures.

(30) FIG. 28 shows the simulated return loss and isolation characteristics in terms of S-parameters for the embodiment of FIG. 27.

(31) FIG. 29 is a plot showing the total efficiency of the 60 GHz WiGig® antenna of the embodiment of FIG. 27.

(32) FIG. 30 is a schematic view of a further embodiment comprising first and second antenna systems arranged at opposite ends of a main PCB of a mobile handset.

(33) FIG. 31 shows an antenna system at one end of the main PCB of the FIG. 30 embodiment.

(34) FIGS. 32 and 33 show a variation of the FIG. 30 embodiment with a first resonator element formed as part of a frame or casing of the mobile handset.

(35) FIGS. 34 and 35 show another variation of the FIG. 30 embodiment with parts of an antenna and a second resonator element formed as part of a frame or casing, as well as the first resonator element.

(36) FIG. 36 is an S-parameter simulation plot for the embodiment of FIG. 30.

(37) FIG. 37(a) is an S-parameter simulation plot for a configuration as shown in FIG. 37(b).

(38) FIG. 38(a) is an S-parameter simulation plot for a configuration as shown in FIG. 38(b).

(39) FIG. 39(a) is an S-parameter simulation plot for a configuration as shown in FIG. 39(b).

(40) FIG. 40(a) is an S-parameter simulation plot for an embodiment as shown in FIG. 40(b), which is similar to the embodiment of FIGS. 11 and 14.

(41) FIG. 41(a) is an S-parameter simulation plot for a configuration as shown in FIG. 41(b), which is similar to the configuration of FIG. 40(b) but with the second resonator element removed.

(42) FIG. 42(a) is an S-parameter simulation plot for a configuration as shown in FIG. 42(b), which is similar to the configuration of FIG. 40(b) but with less coupling between the antenna and the second resonator element.

(43) FIG. 43(a) is an S-parameter simulation plot for a configuration as shown in FIG. 43(b), which is similar to the configuration of FIG. 40(b) but with less coupling between the antenna and the first resonator element.

(44) FIG. 44(a) is an S-parameter simulation plot for the configurations shown in FIGS. 44(b) and 44(c), which are similar to the configuration of FIGS. 30 and 31, but with the second resonator element removed.

DETAILED DESCRIPTION

(45) Referring to FIGS. 1 to 5, a reconfigurable antenna system comprises:

(46) i) a first antenna 24 and a second antenna 26, the second antenna being spaced apart laterally from the first, and

(47) ii) an isolation structure 28 disposed on the substrate between the first and second antennas, comprising a first resonator element 30 having a vertical first arm 31 connected to ground at its lower end 35 and a lateral second arm 32 connected to the upper end of the vertical first arm, wherein at least a portion 33 of the first resonator element is disposed adjacent to a portion 150 of the first antenna such that the first resonator element is strongly coupled to the first antenna, the coupling region in which coupling will be strong being indicated as 152.

(48) The first and second antennas have feed points 93, 96, and may be mounted adjacent to a ground plane 124, such as forming part of a portable device.

(49) In this embodiment the first resonator element 30 comprises a third arm 33 connected to the lateral second arm at the end of the lateral second arm distal from the vertical first arm and oriented at a right angle to it, at least a portion of the third arm being arranged alongside a portion 150 of the first antenna and spaced apart from it, such that the coupling is primarily between the said portion of the third arm and the said portion of the first antenna, as indicated by the region 152. The third arm 33 may be directed upwardly away from the edge of the groundplane 124, or may be directed downwardly as shown, towards the edge of the groundplane 124. The third arm 33 may be aligned substantially parallel to at least a portion 150 of the first antenna 24, or may be angled relative thereto.

(50) In some embodiments the third arm 33 is omitted and a portion of the second arm 32 is located adjacent to and parallel to a portion of the first antenna and spaced apart from it, such that the coupling is primarily between the said portion of the second arm and the said portion of the first antenna. The second arm 32 may be widened or flared outwardly towards the portion 150 of the first antenna 24.

(51) The first resonator element 30 may include additional meanders or sections angled relative to each other, for example to allow the first resonator element 30 to take a desired pathway across the substrate without interfering with other structures on the substrate.

(52) The distance between the coupling portion of the first resonator element and the antenna may be selected according to the frequency band and the electrical properties of the materials used to form the antenna system, and may be 10 mm or less, such as 8 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, 1 mm or less.

(53) Referring to FIG. 2, in another embodiment the antenna system further comprises a second isolation structure 48 having the same features as the first, located between the first isolation structure 28 and the second antenna 26, the first and second isolation structures being substantially mirror images of each other.

(54) Referring to FIG. 3, an embodiment of a reconfigurable antenna system comprises:

(55) i) a first antenna 24 and a second antenna 26, the second antenna being spaced apart laterally from the first, and

(56) ii) a first isolation structure 28 disposed on the substrate between the first and second antennas, comprising: a first resonator element 30 having a vertical first arm 31 connected to ground at its lower end 35 and a lateral second arm 32 connected to the upper end of the vertical first arm, and a third arm 33 connected to the lateral second arm 32 at the end of the lateral arm distal from the vertical arm 31, the third arm 33 being aligned substantially parallel to the vertical arm and spaced apart from it, and a second resonator element 40 comprising a lateral elongated element located adjacent to portions of the first resonator element.

(57) In this embodiment the first resonator element 30 is strongly coupled to the first antenna as before, and also strongly coupled to the second resonator element 40 in the region 154 and also, optionally, in the region 156 also. The degree of coupling between the first and second resonator elements may be chosen by selecting the spacing of the first and second resonator elements in these regions.

(58) The antenna system may further comprise a second isolation structure 48 located between the first isolation structure and the second antenna, the second isolation structure comprising:

(59) a third resonator element 50 having a vertical first arm 51 connected to ground at its lower end 55 and a lateral second arm 52 connected to the upper end of the vertical first arm, and a third arm 53 connected to the lateral second arm 52 at the end of the lateral arm distal from the vertical arm 51, the third arm 53 being aligned substantially parallel to the vertical arm and spaced apart from it, and

(60) a fourth resonator element 60 comprising a lateral elongated element located adjacent to portions of the third resonator element.

(61) In this embodiment the first 28 and second 48 isolation structures are substantially mirror images of each other.

(62) The second and fourth resonator elements are each connected via an impedance Z1, Z2 to ground, by means of a first and second matching networks 70, 170 connected to the second and fourth resonator elements 40, 60 and configured to provide a selectable impedance between the respective resonator elements and ground. The selectable impedance may comprise two or more capacitors selectable by way of an RF switch, for example an SP4T switch. Optionally, one switch position may consist of an “open” position, or direct connection to ground. In one exemplary embodiment, an SP4T switch may be used to switch between three capacitors: 68 pF, 2.4 pF and 0.5 pF, as well as to a direct connection to ground. This allows switching between four modes, and enables the antenna to cover a low-band LTE frequency range of 700 to 960 MHz. The matching networks are described in more detail in reference to FIG. 18 below.

(63) The isolation structures 28, 48 together with matching networks 70, 170 each form an isolation system 140. The first antenna 24 may be connected via an antenna matching network 142 to a first TX and/or RX port 144. The second antenna 26 may be connected via an antenna matching network 146 to a second TX and/or RX port 148.

(64) In these embodiments, the electrical length of the respective antenna 24, 26 and the tuning is being changed by the coupling with the respective second resonator 40, 60 so as to optimise or at least improve performance in the LTE low band (or other bands as appropriate). As such, the isolation structures 28, 48 act both as isolators and also as antenna elements.

(65) Referring to FIG. 4, a further embodiment comprises features as described for FIG. 3, in which the first and second antennas are monopole antennas each having a first arm 94 and second arm 95 on each side of a feed point 93. The first resonator element is disposed adjacent to the arm 95 of the antenna to achieve strong coupling in the region 152, and close to the centre of the second resonator element 40 to achieve strong coupling in the region adjacent to the said centre, indicated by 154. Further, one end of the second resonator element may optionally be disposed adjacent to the first arm of the first resonator element, to achieve coupling as indicated by 156. The other end of the second resonator element may be disposed adjacent to the antenna 24, to achieve coupling at that end region also.

(66) Referring to FIG. 5, a schematic diagram is shown of the placement of multiple antennas and isolation structures between two ground planes 122, 124, in which the antennas are isolated from each other by the isolation structures 28, 48. First and second antennas 24, 26 are isolated from each other by isolation structures 28 and 48, which are tuned by means of matching networks 70, 170. The antenna system comprises a third 84 and a fourth 86 antennas located between the first and second isolation structures, and a third isolation structure 88, located between the third and fourth antennas, the third isolation structure comprising a ground plane.

(67) Referring to FIG. 6, an embodiment of a reconfigurable antenna system comprises

(68) i) a first antenna 24,

(69) ii) a first resonator element 30, having a first arm 31 connected to ground at its first end and a second arm 32 connected to the first arm at its second end distal from the first end, the second arm being at an angle to the first, such as a right angle, wherein at least a portion of the first resonator element, here a third arm 33 connected to the second arm and parallel to the first arm, is disposed adjacent to a portion 150 of the first antenna such that the first resonator element is strongly coupled to the first antenna as indicated in the region 152,

(70) iii) a second resonator element 40 disposed adjacent to the first resonator element such that the second resonator element is strongly coupled to the first resonator element, as indicated in the region 154, and

(71) iv) a first matching network 70 connected to the second resonator element, the matching network being configured to provide a selectable impedance between the second resonator element and ground.

(72) The first and second resonator elements together form a resonator structure, portions of which are strongly coupled to the antenna.

(73) Strong coupling between the first resonator element and the antenna, and between the first resonator element and the second resonator element, is defined as described above and may be achieved by means of the dimensions of the resonator elements and their disposition adjacent to one another and spaced a suitable distance from one another.

(74) The said portion of the first resonator element is located within a distance of 10 mm of the said portion of the first antenna, or a lesser distance, as described above.

(75) The said portion of the second resonator element is located within a distance of 10 mm of a portion of the first resonator element, thereby achieving strong coupling between the resonator elements.

(76) Referring to FIGS. 6 to 8, in these embodiments the second resonator element comprises an elongated element aligned substantially parallel to the second arm 32 of the first resonator element, and is located between the first antenna and the first arm 31 of the first resonator element.

(77) Referring to FIG. 7 and FIG. 8, in these embodiments the first resonator element comprises a third arm 33 connected to its second arm, and the end of the said third arm is adjacent to the centre of the second resonator element 40 to achieve strong coupling between the said third arm and the central portion of the second resonator element. The coupling may be defined by the distance between the end of the third arm and the second resonator element. This distance may be made smaller than the width of the third arm, as shown in FIGS. 7 and 8.

(78) Referring to FIG. 9, in a further embodiment at least a portion of the second resonator element 40 is substantially parallel to and spaced apart from a portion of the first resonator element 30, and further is substantially parallel to and spaced apart from a portion of the antenna 24. The arrangement in FIG. 9 promotes strong coupling between the arm 95 of the antenna and both of the first and the second resonators. The total length along the conductive portion of the antenna, that along the first resonator element and that along the second resonator element may each be selected to suit the frequency band in which the antenna is configured to operate.

(79) Referring to FIG. 6, in some embodiments the antenna system comprises an antenna matching network 142 and the antenna is connected via the matching network to a port 144, for example a port for one or both of transmitting and receiving functions.

(80) Referring to FIGS. 7 to 9, in some embodiments the first antenna is connected directly to a port without an intervening matching network.

(81) The said selectable impedance in the matching network 70 may be selectable between an open circuit, a short circuit, a series capacitance, a series inductance, a series LC impedance and a parallel LC impedance. An example of a matching network is described with reference to FIG. 18.

(82) In this way the embodiments in FIGS. 7 to 9 provide a reconfigurable antenna operable over a wide frequency band or in a range of frequency bands that may be selected by means of the matching network 70 connected to the second resonator element 40, which determines the frequency band in which strong coupling occurs between the antenna and the resonator structure comprising the first and second resonator elements, in which the antenna may be coupled directly to a port and hence to one of a receiver, a transmitter or a combined transmitter/receiver, without passing through an antenna matching network as is typical in the prior art.

(83) In some embodiments the antenna system further comprises a second antenna disposed such that the first and second resonator elements are located between the first and the second antennas, the antennas and first and second resonator elements being as shown in the embodiments in FIGS. 6 to 9.

(84) In some embodiments the said antenna system comprises:

(85) a first antenna having adjacent to it a first resonator structure comprising a first resonator element and a second resonator element,

(86) a second antenna having adjacent to it a second resonator structure comprising a third resonator element and a fourth resonator element,

(87) wherein the second and fourth resonator elements are connected to ground via an impedance, such as a selectable impedance,

(88) and wherein each antenna is connected directly to a port without an antenna matching network between the antenna and the port.

(89) In this way the configurable antenna systems of the invention may be combined together to provide MIMO functionality with tuneable frequency band for each antenna, together with isolation between the first and second antennas.

(90) Referring to FIGS. 10 to 16, an embodiment of a reconfigurable antenna system 10 is disposed on an elongated substrate 11 having a first face 12, a second face 14, elongated top 16 and bottom 18 sides, and left 20 and right sides 22, the antenna system comprising:

(91) i) first 24 and second 26 antennas, the second antenna 26 being spaced apart laterally from the first 24, and

(92) ii) an isolation structure 28 disposed on the substrate between the first and second antennas, comprising: a first resonator element 30 having a vertical first arm 31 connected to ground at its lower end 35 and a lateral second arm 32 connected to the upper end of the vertical first arm, and a second resonator element 40 comprising a lateral elongated element located between the first antenna and the vertical arm of the first resonator element.

(93) In this embodiment, the antenna system further comprises a second isolation structure 48 located between the first isolation structure and the second antenna, the second isolation structure comprising:

(94) a third resonator element 50 having a vertical first arm 51 connected to ground at its lower end 55 and a lateral second arm 52 connected to the upper end of the vertical first arm, and

(95) a fourth resonator element 60 comprising a lateral elongated element located between the second antenna and the vertical arm of the third resonator element.

(96) In this embodiment the first 28 and second 48 isolation structures are substantially mirror images of each other.

(97) Referring to FIG. 18, the second resonator elements is connected via an impedance to ground, by means of a first matching network 70 connected to the second resonator element 40 and configured to provide a selectable impedance between the respective second resonator element and ground. The matching network 70 comprises a switch 72 operable to connect the second resonator to ground via four circuits 74a-74d, each comprising an impedance, such as an open circuit, a short circuit, a series capacitance, a series inductance, a series LC impedance or a parallel LC impedance. Preferably each of the four circuits 74a-74d comprises a different impedance. The circuits each comprise a first port, connected to the switch 72 as shown, and a second port, connected to ground. The switch 72 is configured to be operated by a digital input from a digital interface 75 forming part of, and/or controlled by, the portable device. The first antenna 24 may be connected via an antenna matching network 76 to a first port 78.

(98) Where present, the fourth resonator element 60 forming part of the second isolation structure 50 may be connected to a second matching network 170 having the same configuration as the first matching network 70. Preferably the second matching network 170 comprises a switch 172 and circuits 174a-174d as for the first matching network, the impedance in each circuit 174a-174d being the same as that in the corresponding circuit 74a-74d, the switches 72, 172 being operable together by the digital interface 75 to select the same impedance between the second resonator element 40 and ground as between the fourth resonator elements 60 and ground. The second antenna 26 may be connected via an antenna matching network 176 to a second port 178.

(99) In this embodiment the first matching network is connected to the second resonator element at a connection point 42 adjacent to the first antenna 26, and the second matching network is connected to the fourth resonator element at a connection point 62 adjacent to the first antenna 26.

(100) In this embodiment the first resonator element 30 comprises a third arm 33 connected to the lateral second arm 32 at the end of the lateral arm distal from the vertical arm 31, the third arm 33 being aligned substantially parallel to the vertical arm and spaced apart from it, and the end 36 of the said third arm 33 is adjacent to the centre of the second resonator element 40.

(101) In this embodiment the first resonator element 30 comprises a fourth lateral arm 34 connected to the base 35 of the vertical arm 31, the first resonator element being grounded at the end 37 of the fourth arm distal from the vertical arm. It will be noted that the shape of the first resonator element 30 allows a WLAN antenna, for example, to be placed on the substrate above the fourth arm, while the fourth arm allows the first resonator element to be long enough to isolate in, for example, the LTE frequency band>>

(102) In this embodiment the antenna system comprises third 84 and a fourth 86 antennas located between the first 28 and second 48 isolation structures, and a third isolation structure 88, located between the third and fourth antennas, the third isolation structure comprising a ground plane 90, at least a portion of the ground plane being located between the third and fourth antennas. The said third isolation structure further comprises meander isolation structures 92 located between the third and fourth antennas 84, 86 and the ground plane 90. Instead of a single, wide ground plane 90 as shown in FIG. 10A, the third isolation structure may be formed as two relatively narrow ground plane strips 90a, 90b extending upwardly and generally parallel to each other between the third 84 and fourth 86 antennas. This is shown in FIG. 10B. The ground plane strips 90a, 90b may extend from a common ground plane 90, or the ground plane 90 may be split into two (or more) separate ground plane components.

(103) In this embodiment the first and second antennas are configured as LTE antennas, operable to transmit and/or receive in frequency bands between 0.73 GHz and 2.35 GHz. The antennas may be substantially identical and may be mirror images of each other, or they have minor differences, which may help to improve bandwidth. The first antenna 24 comprises a first arm 94, and a second arm 95, extending to either side of a feed point 93. The second antenna 26 comprises a first arm 97, a second arm 98, extending to either side of a feed point 96, and a slot 99 formed in the first arm.

(104) In this embodiment the third and/or fourth antennas are WLAN antennas configured to operate in the WiFi frequency bands of 2.4 GHz and 5.5 GHz. Each antenna comprises an inverted L, having a vertical arm 100, a lateral arm 101, and a feed point 102 at the base of the vertical arm.

(105) The antenna system may comprise further antennas, for example first and second GPS antennas 104, 106, having a folded shape and feed points 105, 107.

(106) As seen most clearly in FIGS. 14 to 16, the embodiment is formed on a 3D substrate 11 comprising a first vertical face 12, a second vertical face 14 and an upper face 13 joining the two vertical faces, wherein the first and second antennas 24, 26 and the one or more isolation structures 28, 48 are provided on the first vertical face 12 and the third and fourth antennas 84, 86 are provided on the second vertical face 14. The first and second antennas are wrapped over the top surface 13 to provide the correct dimensions on a limited height of the first face. The isolation structures are also wrapped from the first face, over the top face, to the second face. In particular, the first and second resonator elements, 30, 50 are wrapped such that the second arm 32, 52 is located on the upper face 13. The third isolation structure 88 extends over both the first and second faces, and the upper face.

(107) FIGS. 14 to 16 show the disposition of the antenna system in the hinge region 120 of a laptop computer that comprises a first conductive sheet component 122 (a metallic screen case) located adjacent to the top side of the substrate and a second conductive sheet component 124 (a metallic base) located adjacent to the bottom side of the substrate.

(108) The antenna system may form part of a portable device having a conductive first and second case components hinged together, the antenna system being located in the gap between the first and second case components, such as in the hinge region. The antenna system may form part of a hinge component that attaches the two case components.

(109) It is a feature of the antenna system of the invention that no conductive connections are needed between the screen and base parts of the mobile device cover, and hence the hinges do not have to be conductive. Further, no electrical connections need to be made to the mobile device cover. The electrical connections to the antenna system 10 are made by RF coaxial cables 130, which may be routed conveniently from the side of the substrate as shown in FIG. 14. This is a great advantage of the antenna system of the invention over the prior art, and allows the system to be mounted between two hinges placed close to the edges of the mobile device, as shown in FIG. 8.

(110) FIGS. 19 to 22 show the radiation characteristics of the antennas in certain embodiments, showing radiative efficiency in desired frequency bands and good isolation between them, in particular between the first and second LTE antennas and the third and fourth WLAN antennas. The good isolation is in part owing to a degree of directionality of the radiation pattern caused by the isolation structures: the left hand LTE antenna (the first antenna) having a degree of directionality to the left and the right hand LTE antenna to the right, and the left hand WLAN antenna (the third antenna) having a more pronounced degree of directionality to the left and the right hand WLAN antenna (the fourth antenna) to the right, as directed by the efficient isolation structures between them.

(111) FIG. 19 shows the radiation characteristics of the first and second LTE antennas at 0.73 GHz; FIG. 20 shows the radiation characteristics of the first and second LTE antennas at 1.8 GHz; FIG. 21 shows the radiation characteristics of the first and second LTE antennas at 2.15 GHz; FIG. 22 shows the radiation characteristics of the first and second LTE antennas at 2.3 GHz, FIG. 23 shows the radiation characteristics of the first and second LTE antennas at 2.65 GHz, FIG. 24 shows the radiation characteristics of the first and second WLAN antennas at 2.45 GHz and FIG. 25 shows the radiation characteristics of the first and second WLAN antennas at 5.5 GHz.

(112) FIG. 26 shows a further development of the embodiment of FIGS. 10 to 16, with an additional 60 GHz WiGig® antenna 200 mounted on its own substrate 201 which is conformed to the surface of the main substrate 11 and located at a central part of the main substrate 11 between WLAN antennas 84 and 86. The 60 GHz antenna 200 has a feed point 202, and is driven against the groundplane 90. Also shown in FIG. 26 are GPS antennas 104, 106.

(113) FIG. 27 shows a variation of the FIG. 26 embodiment in which the GPS antennas 104, 106 are replaced by additional isolation structures 203, 204 in the form of L or inverted-L shaped resonators connected to the groundplane 90. The additional isolation structures 203, 204 help to isolate the 60 GHz antenna 200 from the first and second LTE antennas which are not visible in FIGS. 26 and 27, being disposed on the other side of the substrate 11.

(114) FIG. 28 shows the simulated return loss and isolation characteristics in terms of S-parameters for the embodiment of FIG. 27. It can be seen that the embodiment of FIG. 27 is in effect a five port antenna system, with ports 1 and 2 for the first and second LTE antennas, ports 3 and 4 for the first and second WLAN antennas, and port 5 for the 60 GHz WiGig® antenna.

(115) FIG. 29 is a plot showing the total efficiency of the 60 GHz WiGig® antenna of the embodiment of FIG. 27.

(116) FIG. 30 shows a main PCB 500 of a mobile handset. The main PCB 500 includes a groundplane (not shown) and serves as a platform for various electronic components of the handset. The main PCB 500 is of generally rectangular shape, and has first and second opposed ends 501, 502. A first antenna system comprising a first antenna 503, a first resonator element 504 and a second resonator element 505 is arranged at the first end 501 of the PCB 500. In this particular example, the first antenna 503 is configured as a monopole antenna, but other types of antennas may be employed. The first antenna 503 is driven against the groundplane of the PCB 500 by a feed 506. In this embodiment, the first antenna 503 is shown as a self-supporting structure, for example stamped or cut from a sheet of metal. The first antenna 503 is positioned generally at the left of the first end 501 of the PCB 500, and extends laterally generally parallel to the edge of the first end 501. The first antenna 503 includes a lateral portion 507 that extends towards the right of the first end 501 of the PCB 500. The first resonator element 504 comprises a generally L shaped self-supporting conductive component with a first arm 508 connected to the groundplane on the right hand side of the PCB 500, and a second arm 509 extending generally parallel to the edge of the first end 501 of the PCB 500. The distal end of the second arm 509 is located parallel to and adjacent to the lateral portion 507 of the first antenna 503 so as to allow strong coupling therebetween. The second resonator element 505 is located between the first antenna 503 and the first resonator element 504 on the first end of the PCB 500. The second resonator element is connected to ground, for example by way of a selectable impedance, such as a short circuit, an open circuit, a fixed or variable capacitance, or a fixed or variable impedance. The second resonator element 505 is a self-supporting conductive component shaped so that its distal end portion 510 is located adjacent and generally parallel to the second arm 509 of the first resonator element 504 so as to couple strongly therewith.

(117) A second antenna system, essentially similar or identical to the first antenna system, is arranged at the second end 502 of the main PCB 500, with like parts being labelled as for the first antenna system with the addition of a prime. It can be seen that the first and second antenna systems are arranged about the main PCB 500 with 2.sup.nd order rotational symmetry—the main PCB 500 can be rotated through 180° in its plane and the first and second antenna systems will be swapped and look similar or identical.

(118) FIG. 31 shows the first antenna system at the first end 501 of the main PCB 500 in close-up. It can be seen how the components are arranged to promote strong coupling between the lateral portion 507 of the first antenna 503 and the distal end of the second arm 509 of the first resonator element 504, and between the distal end portion 510 of the second resonator element 505 and the distal end of the second arm 509 of the first resonator element 504.

(119) FIGS. 32 and 33 show an alternative configuration of the general embodiment of FIGS. 30 and 31. In this embodiment, a frame 511 surrounds the main PCB 500. The frame 511 may be a part of the casing or housing of a mobile handset, and conveniently serves as a substrate for the first resonator element 504.

(120) A further variation is shown in FIGS. 34 and 35. Here, the frame 511 serves as a substrate not just for the first resonator element 504, but also for the antenna 503 and for the distal end portion 510 of the second resonator element 505. In the particular embodiment shown in FIGS. 34 and 35, the antenna 503 is configured as a PIFA, with a feed pin 512 connected to the feed 506 and a shorting pin 513 connected to ground. The antenna 503 and the second arm 509 of the first resonator element 504 may be disposed in different planes on the frame 511, for example being parallel to each other but spaced apart by a thin dielectric separation layer 514. This allows strong coupling to be maintained between the antenna 503 and the first resonator element 504. The distal end portion 510 of the second resonator element 505 runs parallel to the second arm 509 of the first resonator element 504 on the frame 511, allowing strong coupling therebetween.

(121) FIG. 36 is an S-parameter plot for the embodiment of FIG. 30, showing the S11 return loss for both an open circuit and a short circuit connection of the first resonator element to ground, as well as the S21 isolation between antennas 503 and 503′ for both the open circuit and short circuit configurations.

(122) FIGS. 37(a) and 37(b) show a comparative example where the second arm 509 of the first resonator element 504 is shortened so that it does not couple strongly with the lateral portion 507 of the antenna 503. The S11 return loss plot in FIG. 37(a) shows that the antenna system no longer works effectively.

(123) FIGS. 38(a) and 38(b) show a comparative example where the second resonator element 505 is configured so that it still couples strongly with the first resonator element 504, but less strongly (or even negligibly) with the first antenna 503. The S11 return loss plot in FIG. 38(a) shows that the antenna system surprisingly still works reasonably well.

(124) FIGS. 39(a) and 39(b) show a comparative example where the second resonator element 505 is configured so that it does not couple strongly with the first resonator element 504. The S11 return loss plot in FIG. 39(a) shows that the antenna system cannot be tuned effectively.

(125) FIGS. 40(a) and 40(b) show an example corresponding to the embodiment of FIGS. 11 and 14, mounted in a hinge region of a laptop computer, with a first antenna 24, a first resonator element 30 and a second resonator element 40. The S-parameter plot in FIG. 40(a) shows good performance, with the low frequency band being tuneable from 700 to 960 MHz.

(126) FIGS. 41(a) and 41(b) show a comparative example similar to that of FIG. 40(b), except with the second resonator element 40 removed. While tuning is still possible by adjusting the connection of the first resonator element 30 to ground by using an RF switch, for example an SP4T (single pole 4-throw) switch, isolation between antennas 24 and 26 is not good.

(127) FIGS. 42(a) and 42(b) show a comparative example similar to that of FIG. 40(b), except with the second resonator element 40 configured so as to couple less strongly with the antenna 24. The S-parameter plot in FIG. 42(a) shows that the antenna system is still effective, and that the operational frequency band is shifted to higher frequencies.

(128) FIGS. 43(a) and 43(b) show a comparative example similar to that of FIG. 40(b), except with the first resonator element 30 configured so as to couple less strongly with the antenna 24. The S-parameter plot in FIG. 43(a) shows that the antenna system is still effective, and that the operational frequency band is shifted to higher frequencies.

(129) FIG. 44(a) shows an S-parameter plot for the variations shown in FIGS. 44(b) and 44(c). FIG. 44(b) is similar to the embodiment of FIGS. 30 and 31, except that the second resonator element 505 has been removed. The first arm 508 of the first resonator element 504 is connected to ground by a short circuit at 600. FIG. 44(c) shows the same general arrangement, except that the first arm 508 of the first resonator element 504 is connected to ground by a variable impedance at 601. An equivalent antenna system is provided at the bottom end 502 of the main PCB 500 as in FIG. 31. FIG. 44(a) shows the S11 return loss for the antenna 503 in both short circuit 600 and variable impedance 601 configurations, as well as the S21 isolation between the antennas 503 and 503′. Even without the second resonator element 505, the antenna system can be made to work, with tuning being possible by adjusting the variable impedance 601. It will be noted, however, that the isolation between antennas 503 and 503′ is not as good as for the embodiment of FIGS. 30 and 31.

(130) Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

(131) Features, integers, or characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

(132) The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.