Abstract
The invention relates to a MIMO antenna system for IEEE 802.11 WiFi communications. The invention also relates to a wireless device, such as a wireless access point (AP), a router, a gateway, and/or a bridge, comprising at least one antenna system according to the invention. The invention further relates to a wireless communication system, comprising a plurality of antenna systems according to the invention, and, preferably, a plurality of wireless devices according to the invention.
Claims
1-38. (canceled)
39. Multiple-Input, Multiple-Output (“MIMO”) antenna system for IEEE 802.11 WiFi communications, comprising: a conductive ground plane, a first MIMO pair of first antennas, mounted onto and/or configured to co-act with a top surface of said ground plane, and configured to operate in the 5 GHz frequency band and/or the 2.4 GHz frequency band, and a second MIMO pair of second antennas mounted onto and/or configured to co-act with the top surface of said ground plane, and configured to operate in the 5 GHz frequency band and/or the 2.4 GHz frequency band, and a third MIMO pair of third antennas mounted onto and/or configured to co-act with the top surface of said ground plane, and configured to operate in the 6 GHz frequency band.
40. Antenna system according to claim 39, wherein said first MIMO pair of first antennas and at least a part of said third MIMO pair of third antennas are mutually integrated, wherein a plurality of first antennas is configured to operate in the 6 GHz frequency band.
41. Antenna system according to claim 39, wherein said second MIMO pair of second antennas and at least a part of said third MIMO pair of third antennas are mutually integrated, wherein a plurality of second antennas is configured to operate in the 6 GHz frequency band.
42. Antenna system according to claim 39, wherein the antennas of at least two different MIMO pairs are polarized in different directions.
43. Antenna system according to claim 39, wherein the first antennas of the first MIMO pair are vertically polarized.
44. Antenna system according to claim 39, wherein the second antennas of the second MIMO pair are horizontally polarized.
45. Antenna system according to claim 39, wherein the third antennas of the third MIMO pair are vertically polarized.
46. Antenna system according to claim 39, wherein the first antennas of the first MIMO are configured to operate as dual-band antennas in both the 5 GHz frequency band and the 2.4 GHz frequency band.
47. Antenna system according to claim 39, wherein at least one antenna is mounted on the ground plane.
48. Antenna system according to claim 39, wherein the antenna system comprises a cover configured to at least partially cover the antennas of the antenna system, wherein at least one antenna is affixed to the cover.
49. Antenna system according to claim 39, wherein the first MIMO pair encloses the third MIMO pair, and wherein the third MIMO pair encloses the second MIMO pair.
50. Antenna system according to claim 39, wherein the antennas of each MIMO pair mutually define a MIMO pair related polygonal shape, preferably a convex polygonal shape, more preferably a regular convex polygonal shape, most preferably a equilateral convex polygonal shape, such as a square or diamond shape, and wherein the size and/or orientation of at least two MIMO pair related polygonal shapes mutually differ.
51. Antenna system according to claim 39, wherein the first antennas are configured to operate both in the 5 GHz frequency band and the 2.4 GHz frequency band, and wherein the second antennas are configured to operate solely in the 5 GHz frequency band.
52. Antenna system according to claim 39, wherein at least two second antennas are mounted onto a shared dielectric carrier, such as a plastic carrier.
53. Antenna system according to claim 39, wherein at least one third antenna comprises a bottom section running parallel to the ground plane, and at least one top section, connected to said bottom section, and oriented perpendicularly with respect to said ground plane, wherein the top section comprises an elongated strip, positioned at a distance from the ground plane, and extending parallel to said ground plane, and wherein the top section comprises a cross-strip connected to a center portion of the elongated strip, wherein said cross-strip is orientated towards the bottom section of said third antenna, and wherein said cross-strip is positioned at a distance from the bottom section.
54. Antenna system according to claim 39, wherein the antenna system comprises: a plurality of the first feeding cables, wherein each first feeding cable is connected to a first antenna, a plurality of the second feeding cables, wherein each second feeding cable is connected to a second antenna, and a plurality of the third feeding cables, wherein each third feeding cable is connected to a third antenna, wherein the top surface of the ground plane is provided with a plurality of cable channels, wherein each cable channel is configured to accommodate at least a part of at least one feeding cable, and wherein each cable channel extends from an antenna to a cable feed-through opening applied in the ground plane.
55. Antenna system according to claim 39, wherein the antenna system comprises a plurality of parasitic elements mounted onto the top surface of the ground plane, wherein in between a plurality of adjacent antennas relating to different MIMO pairs, at least one parasitic element, preferably formed by a metallic pin, is positioned.
56. Antenna system according to claim 39, wherein each second antenna comprises: a substantially flat, dielectric substrate, a conductive central feeding point, at least three folded dipole elements applied onto an upper side of said substrate, each folded dipole element comprising: a loop-shaped first conductor including a first curved inner conductor part and a first curved outer conductor part, wherein outer ends of the first inner conductor part are connected to respective outer ends of the first outer conductor part, and a first conductive dipole branch and a conductive second dipole branch, both dipole branches being connected, respectively, to different segments of said first inner conductor part, wherein both dipole branches are also connected to said central feeding point, wherein the conductors of the folded dipole elements are arranged in a substantially circular arrangement.
57. Wireless device, such as a wireless access points (AP), a router, a gateway, and/or a bridge, comprising at least one antenna system according to claim 39.
58. Wireless communication system, comprising a plurality of antennas systems according to claim 39.
Description
[0032] FIGS. 1a-1o show several non-limiting examples of antenna architectures for MIMO antenna systems according to the present invention. Each antenna system 100a-100o comprises a conductive ground plane 107, a first MIMO pair of first antennas 101, mounted onto and/or configured to co-act with a top surface of said ground plane 107, and configured to operate in the 5 GHz frequency band and/or the 2.4 GHz frequency band, and a second MIMO pair of second antennas 102 mounted onto and/or configured to co-act with the top surface of said ground plane 107, and configured to operate in the 5 GHz frequency band and/or the 2.4 GHz frequency band, and a third MIMO pair of third antennas 103 mounted onto and/or configured to co-act with the top surface of said ground plane 107, and configured to operate in the 6 GHz frequency band. In the shown examples, each MIMO pair comprises four antennas 101, 102, 103. Furthermore, in the shown configurations, the first MIMO and the third MIMO pair enclose the second MIMO pair. The antennas 101, 102, 103 of each MIMO pair mutually define a polygonal shape. Adjacent first antennas 101 are positioned in the line of sight with each other. The distance in between a first antenna 101 and an adjacent second antenna 102 exceeds the distance between adjacent second antennas 102. The systems 100a-100o further comprises at least one auxiliary vertically polarized dual-band antenna 106 and an auxiliary vertically polarized single-band antenna 105, preferably mounted onto the ground plane 107. Each auxiliary vertically polarized single-band antenna 105 is positioned at a peripheral edge of the ground plane 107. The auxiliary vertically polarized dual-band antenna 106 can be either positioned at a peripheral edge of the ground plane 107 or at a more central position, preferably enclosed between two adjacent first antennas 101. Where the embodiments of FIGS. 1a-1k show separate first, second and third MIMO pairs, the embodiments of FIGS. 1l-1o show that the first MIMO pair of first antennas 101 and the third MIMO pair of third antennas 103 are mutually integrated. In these embodiments, a plurality of first antennas 101 is configured to operate in the 6 GHz frequency band. For the embodiments shown in FIGS. 1l-1o, also the second MIMO pair of second antennas 102 and the third MIMO pair of third antennas 103 are mutually integrated wherefore a plurality of second antennas is preferably configured to operate in the 5 GHz and/or the 6 GHz frequency band.
[0033] FIG. 2 shows a further possible embodiment of a Multiple-Input, Multiple-Output (“MIMO”) antenna system for IEEE 802.11 WiFi communication according to the present invention. The MIMO antenna system 200 comprises a conductive ground plane 207, a first MIMO pair of vertically polarized first antennas 201, possibly mounted onto a top surface of said ground plane 107, and configured to operate in the 5 GHz frequency band and/or the 2.4 GHz frequency band, and a second MIMO pair of horizontally polarized second antennas 202 configured to operate in the 5 GHz frequency band. The system 200 further comprises a third MIMO pair of third antennas 203 mounted onto and/or configured to co-act with the top surface of said ground plane 207, and configured to operate in the 6 GHz frequency band. The first MIMO pair comprises in the shown embodiment four first antennas 201, the second MIMO pair comprises four second antennas 202 and the third MIMO pair comprises four third antennas 203. The four first antennas 201 are positioned in a substantially square configuration. The same applied to the four second antennas 202 whereas the four third antennas 203 have a substantially diamond shaped orientation. The antenna system 200 further comprises two auxiliary vertically polarized dual-band antennas 206 and an auxiliary vertically polarized single-band antenna 205 mounted onto the ground plane 207. In order to clarify the measurement results, all the antennas have a letter indication, which is useful for explanation of the experimental data shown in further figures. The top surface of the ground plane 207 may be provided with a plurality of cable channels, wherein each cable channel is configured to accommodate at least a part of at least one feeding cable (not shown).
[0034] FIG. 3 shows a perspective view of the antenna system 200 as shown in FIG. 2 in combination with a cover 250 which configured to at least partially cover the antennas 201, 202, 203, 205, 206 of the antenna system 200. It is conceivable that at least one antenna 201, 202, 203, 205, 206 is mounted onto the cover 250. The cover 250 is configured to protect the antennas 201, 202, 203, 205, 206 of the antenna system 200. The cover 250 can also be referred to as radome 250. In the shown embodiment the cover 250 is made of molded plastic.
[0035] FIGS. 4a-9f are related to the first antennas A-D as shown in the previous figures. If a dotted line is indicated in the figure, the measured value should be below this threshold line. If an uninterrupted line is shown, the measured value should be above this threshold line.
[0036] FIGS. 4a and 4b show a graph of the Voltage Standing Wave Ratio (VSWR) in relation to the frequency expressed in GHz. A performance requirement is that the VSWR is below 1.80:1 for the first antennas in the 2.4 GHz frequency band and below 1.70:1 for the first antennas in the 5 GHz frequency band. The measurements are carried out for four first antennas (A-D) used in an antenna system according to the present invention, which is shown in the previous figures. It can be seen that both for the 2.4 GHz frequency band (FIG. 6a) and the 5 GHz frequency band (FIG. 6b) the results are below the requirement which is indicated with the dotted line. The tests are performed by using a Vector Network Analyser in the 2.4 and 5 GHz operational frequency ranges.
[0037] FIGS. 5a and 5b show a graph of the efficiency (expressed in %) across the used frequency bands. The uninterrupted line indicates the minimum efficiency requirement, which should be above 63% in the 2.4 GHz frequency band and above 61% in the 5 GHz frequency band. It can be observed that the total efficiency of all the first antennas used in the antenna system fulfils the requirement for both frequency bands.
[0038] FIGS. 6a and 6b show a graph of the peak realized gain level (PRG) in both the 2.4 GHz frequency band (FIG. 6a) and the 5 GHz frequency band (FIG. 6b). It can be seen that in the low frequency band values below 4.0 dBi are measured, and that in the high frequency band values below 5.9 dBi are measured. These values are below the maximal level of 6.0 dBi specified by Federal Communications Commission (FCC) regulation.
[0039] FIGS. 7a and 7b show a graph of the parasitic mutual coupling level measured between the dual band antennas A-D in said frequency ranges. The desired isolation value of above 20 dB is achieved for all antenna combinations.
[0040] FIGS. 8a-8f show the normalized radiation patterns for antennas A-D. It can be observed that the radiation patterns of the antennas substantially overlap for each measurement. Hence the radiation pattern can be qualified as quasi uniform, meaning that the antenna system according to the present invention provides uniform radio coverage without radiation nulls and/or blind spots for both the 2.4 and 5 GHz frequency band. This is supported by the results of the normalized aggregated radiation patterns for antennas A-D as shown in FIGS. 9a-9f.
[0041] FIGS. 10-15c are related to the second antennas E-H as shown in the previous figures. If a dotted line is indicated in the figure, the measured value should be below this threshold line. If an uninterrupted line is shown, the measured value should be above this threshold line.
[0042] FIG. 10 shows a graph of the Voltage Standing Wave Ratio (VSWR) in relation to the frequency expressed in GHz. A performance requirement is that the VSWR is below 1.75:1. The measurements are done for four second antennas (E-H) used in an antenna system according to the present invention, which is shown in the previous figures. It can be seen that the results measured in the 5 GHz frequency band are below the requirement which is indicated with the dotted line.
[0043] FIG. 11 shows a graph of the total efficiency (expressed in %) across the 5 GHz frequency band, which meets the requirements indicated within the uninterrupted lines for all antennas E-H.
[0044] FIG. 12 shows a graph of the peak realized gain level (PRG) in the 5 GHz frequency band. It can be seen that in this frequency band values below 5.6 dBi are measured. These values are below the maximal level of 6.0 dBi specified by Federal Communications Commission (FCC) regulation.
[0045] FIG. 13 shows the isolation between the single-band 5 GHz antennas in the second MIMO pair. A graph of the parasitic mutual coupling level measured between the single-band band antennas E-H is shown. The desired isolation value of above 20 dB is achieved for all the antenna combinations.
[0046] FIGS. 14a-14c show the normalized radiation patterns for antennas E-H. It can be observed that the radiation patterns of the antennas substantially overlap for each measurement. Hence the radiation pattern can be qualified as quasi uniform, meaning that the antenna system according to the present invention provides uniform radio coverage without radiation nulls and/or blind spots in the 5 GHz frequency band. This is supported by the results of the normalized aggregated radiation patterns for antennas E-H as shown in FIGS. 15a-15c.
[0047] FIGS. 16-24 are related to the third antennas I-L as shown in the previous figures. If a dotted line is indicated in the figure, the measured value should be below this threshold line. If an uninterrupted line is shown, the measured value should be above this threshold line.
[0048] FIG. 16 shows a graph of the Voltage Standing Wave Ratio (VSWR) in relation to the frequency expressed in GHz. A performance requirement is that the VSWR is below 1.71:1. The measurements are done for four third antennas (I-L) used in an antenna system according to the present invention, which is shown in the previous figures. It can be seen that the results measured in the 6 GHz frequency band are below the requirement which is indicated with the dotted line.
[0049] FIG. 17 shows a graph of the total efficiency (expressed in %) across the 6 GHz frequency band, which meets the requirements indicated with the uninterrupted line for all antennas I-L.
[0050] FIG. 18 shows a graph of the peak realized gain level (PRG) in the 6 GHz frequency band. It can be seen that in this frequency band values below 5.8 dBi are measured. These values are below the maximal level of 6.0 dBi specified by Federal Communications Commission (FCC) regulation.
[0051] FIG. 19 shows the isolation between the single-band 6 GHz antennas in the third MIMO pair. A graph of the parasitic mutual coupling level measured between the third antennas I-L is shown. The desired isolation value of above 20 dB, in particular above 23.4 dB, is achieved for all the antenna combinations.
[0052] FIGS. 20a-20c show the normalized radiation patterns for antennas I-L. It can be observed that the radiation patterns of the antennas substantially overlap for each measurement. Hence the radiation pattern can be qualified as quasi uniform, meaning that the antenna system according to the present invention provides uniform radio coverage without radiation nulls and/or blind spots in the 6 GHz frequency band.
[0053] FIGS. 21a-21c show the results of the normalized aggregated radiation patterns for antennas I-L.
[0054] FIG. 22 shows the isolation between the first MIMO pair and the second MIMO pair. A graph of the parasitic mutual coupling level measured between the dual-band antennas A-D and the single-band antennas E-H is shown. The desired isolation value of above 43 dB is achieved for all the antenna combinations in the 5 GHz frequency band.
[0055] FIG. 23 shows the isolation between the first MIMO pair and the third MIMO pair. A graph of the parasitic mutual coupling level measured between the dual-band antennas A-D and the single-band antennas I-L is shown. The desired isolation value of above 34.9 dB is achieved for all the antenna combinations in the 5 GHz and 6 GHz frequency bands.
[0056] FIG. 24 shows the isolation between the second MIMO pair and the third MIMO pair. A graph of the parasitic mutual coupling level measured between the dual-band antennas E-H and the single-band antennas I-L is shown. The desired isolation value of above 35.1 dB is achieved for all the antenna combinations in the 5 GHz and 6 GHz frequency bands.
[0057] FIG. 25 shows a non-limiting example of a possible embodiment of a third antenna 303 according to the present invention. The third antenna 303 as shown is a metal-stamped antenna 303. The antenna 303 has a three-dimensional configuration and is configured to operate in the 6 GHz frequency band. The base part 303a of the antenna 303 is configured to be mounted onto, for example, a ground plane and the extended part 303b extends with respect to base part 303a in an upward direction. The base part 303a comprises two receiving spaces 304 for receiving at least part of a connection element. Both the base part 303a and the extended part 303b have a substantially flat configuration. The extended part 303b has a substantially horizontally oriented elongated upper part which is connected to the base part 303a via an L-shaped leg. The extended part 303b, and in particular the elongated upper part, further comprises a downward leg. The downward leg and the L-shaped leg are positioned at a distance from each other, in particular such that they enclose an open space.
[0058] It will be apparent that the invention is not limited to the working examples shown and described herein, but that numerous variants are possible within the scope of the attached claims that will be obvious to a person skilled in the art.
[0059] The above-described inventive concepts are illustrated by several illustrative embodiments. It is conceivable that individual inventive concepts may be applied without, in so doing, also applying other details of the described example. It is not necessary to elaborate on examples of all conceivable combinations of the above-described inventive concepts, as a person skilled in the art will understand numerous inventive concepts can be (re)combined in order to arrive at a specific application.
[0060] The ordinal numbers used in this document, like “first”, and “second”, are used only for identification purposes. Expressions like “horizontal”, and “vertical”, are relative expressions with respect to a plane defined by the ground plane. The verb “comprise” and conjugations thereof used in this patent publication are understood to mean not only “comprise”, but are also understood to mean the phrases “contain”, “substantially consist of”, “formed by” and conjugations thereof.
[0061] It is imaginable that the MIMO antenna system according to the appended claims as filed is not configured to operate in the 2.4 GHz, 5 GHz, and 6 GHz frequency band, but is configured to operate in the frequency band of 24 GHz-300 GHz, in particular 30 GHz-100 GHz (“mmWave Communication”), and/or in the frequency band 100 GHz-10 THz (“Terahertz Communication”). This latter MIMO antenna systems are sometimes also referred to as Ultra-Massive MIMO (UM-MIMO) antenna systems, and fulfil the needs of applications and devices requiring high speed transmission. Technologies in this higher frequency bands (up to 10 THz) include, for example, ultra-fast short-range wireless communications, remote sensing, biological detection, basic material research, enhanced indoor wireless communications, vehicular communications, drone-to-drone communications, device-to-device (D2D) communications, and nano-communications. It is conceivable that the MIMO antenna system according to the invention is configured to operate both in the 2.4, 5, and 6 GHz frequency band, as well as in the one or more of the aforementioned frequency bands of 24 GHz-300 GHz, in particular 30 GHz-100 GHz, and/or 100 GHz-10 THz.
