Description:

F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)

COMPLETE SPECIFICATION
(See section 10 and rule 13)

TITLE
MULTIBAND MIMO ANTENNA APPARATUS FOR 5G AND FUTURE WIRELESS COMMUNICATION

INVENTORS
KANDALA, Anupama Satya Sai Lakshmi, Indian Citizen
104-3-357, Near Sudha Chaitanya Model School, Ganesh Nagar
Morampudi, East Godavari District
Rajahmundry, Andhra Pradesh 533107

KUMAR, Navin, Indian Citizen
21-A, 10th Cross, 3rd Main, Shreyas Colony, J P Nagar
Bengaluru, Karnataka 560078

APPLICANT
AMRITA VISHWA VIDYAPEETHAM
Kasavanahalli, Carmelaram P.O.
Bangalore – 560035, India

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED
 
MULTIBAND MIMO ANTENNA APPARATUS FOR 5G AND FUTURE WIRELESS COMMUNICATION
CROSS-REFERENCES TO RELATED APPLICATION
[0001] None.
FIELD OF INVENTION
[0002] The present disclosure relates to antenna apparatus for wireless communication and more particularly to Multiband Multiple Input Multiple Output (MIMO) antenna apparatus wireless communication.

DESCRIPTION OF THE RELATED ART
[0003] Wireless technologies have evolved rapidly, and the essential characteristics for communication in the wireless environment has shifted from reliable communication to high data rate and low latencies all the while without compromising on the spectral efficiency. In recent years MIMO systems have been used in wireless communication systems to increase data throughput and coverage without compromising on bandwidth or transmit power and thus play an important role in modern wireless communication standards such as 5G.
[0004] 5G spectrum can be classified into three spectral bands, low range frequency, medium range frequency and high range frequency bands. Low frequency band and mid-range frequency band falls under the Sub-6GHz band which is characterized by improved coverage. The high range frequency band falls within the mm wave spectrum. Utilizing both the sub 6 GHz and mm wave spectrum using MIMO antenna apparatus has been considered for achieving a balance between coverage and speed in a communication system. However in such antenna devices the distance between antennas are relatively close, leading to increased mutual coupling between antennas which could compromise the radiation efficiency of the antenna.
[0005] The US patent application US20160049736A1 discloses an antenna apparatus that includes arrays of two types of radiating elements that are arranged in a staggering manner. The Chinese patent CN108565543A describes a MIMO antenna structure and a handheld device. The antenna device includes first antenna unit having slot antenna set on earth plate lower surface and the second antenna element is arranged perpendicular to the upper surface of earth plate, and first antenna unit and the second antenna element are connected with access area respectively, therefore, the isolation of MIMO antenna structure is significantly improved. KR20200137656A describes a dual-band antenna structure covering both 2.4 GHz and 5 GHz,and has a plurality of directional/omnidirectional MIMO antennas that can be implemented on one PCB substrate, and dual-band antenna implementation and band notch characteristics can be realized. WO2020119010A1 discloses an apparatus for antenna placement and antenna arrangement to improve space saving in an antenna system that includes a plurality of antennas. There is a need for an antenna apparatus which could operate at different frequency bands of 5G spectrum while also taking into account isolation, gain and bandwidth.
[0006] MIMO antenna systems and methods are disclosed that is capable of operating in dual frequency bands in the range 2.2GHz - 6.1GHz from the sub-6GHz frequency band and 24.5GHz-41GHz from the mm wave frequency band.

 
SUMMARY OF THE INVENTION
[0007] In various embodiments a multiband Multiple Input Multiple Output (MIMO) antenna apparatus configured to operate in a plurality of frequency bands is disclosed. The antenna apparatus includes a substrate that has an inner portion having a circular slot of diameter D on a ground plane and an outer portion. At least four first antenna elements each element placed in a quadrant in the circular slot and configured to operate in sub-6GHzfrequency range andat least four second antenna elements placed in the outer portionand are configured to operate in mm Wave range. In various embodiments the first antenna elements and the second antenna elements are arranged in an alternating manner.
[0008] In various embodiments, the substrate is a polygon comprising 4 to 8 sides. In various embodiments the substrate is Rogers RT 5880 high frequency laminates. In various embodiments the first antenna elements includes an E shaped metal plate integrated with an inverted L shaped metal plate and a first feed line.The E shaped metal plate includes a first vertical plate, a first and a second outer extensions and an inner extension of the vertical plate and the inverted L shaped plate comprising a second vertical plate and a third outer extension at a lower end, wherein the second outer extension is integrated with the third outer extension.
[0009] In various embodiments, the first and the second outer extensions are of equal or different lengths. In various embodiments, the first and the second vertical plates are of equal or different lengths. In various embodiments, the first feed line extends to the edge of the substrate. In various embodiments, the second antenna elements includes two or more concentric arc antenna elements and a circular element placed on a second feed line. In various embodiments, the concentric arc antenna elements have equal or different arc lengths.
[0010] In various embodiments, the first antenna elements are symmetrical to original Cartesian X-Y axis and are aligned at an angle of 90 degrees from each other. The first antenna elements are aligned at an angle of 45 degrees from the second antenna elements.
[0011] In various embodiments, the second antenna elements are symmetrical to the original Cartesian X-Y axis and are positioned at 45 degrees from the original Cartesian X-Y axis and are aligned at an angle of 90 degrees from each other. The second antenna elements are aligned at an angle of 45 degrees from the first antenna elements.
[0012] In various embodiments, each one of the first antenna elements operate infrequencies selected from 2.2GHz, 3.6GHz, 5.0GHz or6.1GHz from the sub-6Ghz frequency band. In various embodiments, the second antenna elements operate in frequencies selected from 24.5GHz, 31.2GHz, 36.5GHz, or 41GHz from the mm Wave frequency band. In various embodiments, the bandwidth is in a range 165MHz to 3.46GHz. In various embodiments, the gain is in a range 6dB to 10dB.

 
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention has other advantages and features, which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:
[0014] FIG. 1 illustrates the structure of the E and inverted L shaped patch designed on top of the substrate with a circular slot of diameter (D) on the ground plane.
[0015] FIG. 2 illustrates the circular arc antenna element.
[0016] FIG. 3 illustrates the antenna apparatus comprising of E and Inverted L shaped patch and circular arc elements arranged in an alternating manner.
[0017] FIG. 4 illustrates thereturn loss at sub-6 GHz range- Radiating at 2.24GHz, 3.58GHz, 5.06 GHz, 6.1GHz frequency.
[0018] FIG. 5A shows the 2D radiation analysis at 2.24GHz operating frequency.
[0019] FIG. 5B shows the 2D radiation analysis at 3.58GHz operating frequency.
[0020] FIG. 5C shows the 2D radiation analysis at 5.06GHz operating frequency.
[0021] FIG. 5D shows the 2D radiation analysis at 6.1GHz operating frequency.
[0022] FIG.6 illustrates thereturn loss of the antenna at 24.5GHz, at operating frequency.
[0023] FIG. 7 illustrates the return loss of the antenna at 31.96 GHz at operating frequency.
[0024] FIG. 8 illustrates the return loss of the antenna at 36.56 GHz at operating frequency.
[0025] FIG. 9 illustrates the return loss of the antenna 40.95 GHz at operating frequency.
[0026] FIG. 10Ashows the 2D radiation analysis at 24.5GHz operating frequency.
[0027] FIG. 10Bshows the 2D radiation analysis at 31.96 GHz operating frequency.
[0028] FIG. 10Cshows the 2D radiation analysis at 36.56 GHz operating frequency.
[0029] FIG. 10D shows the 2D radiation analysis at 40.95 GHz operating frequency.
 

DETAILED DESCRIPTION OF THE EMBODIMENTS
[0030] While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.
[0031] Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of “a”, “an”, and “the” include plural references. The meaning of “in” includes “in” and “on.” Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.
[0032] The present subject matter discloses anantenna apparatus that is configured to operate in a plurality of frequency bands. The antenna apparatus includes 8 antenna elements placed on a single substrate that is in the shape of a polygon. Four antenna elements are structured as the E and inverted L shaped patch and operates in one of thefrequencies 2.2GHz, 3.6GHz, 5.0GHz or 6.1GHz from the sub-6Ghz frequency band and the remaining four antenna elements are structured as concentric arcs and operate in one of the frequencies 24.5GHz, 31.2GHz, 36.5GHz, or 41GHz from the mm Wave frequency band.
[0033] In various embodiments a MIMO antenna apparatus 100 configured to operate in a plurality of frequency bands is disclosed. The antenna apparatus 100 as shown in FIG. 1 includes a single substrate 102 that has an inner portion 104and an outer portion 106. The inner portion 104has a circular slot of diameter D on a ground plane. In various em-bodiments at least four first antenna elements 200are placed in the circular slot. The four antenna elements200 are configured to operate in sub-6GHzfrequency range. In an ex-emplary embodiment each of the first antenna elements200 are placed in a quadrant of the circular slot.In various embodiments at least four second antenna elements300are placed in the outer portion. The second antenna elements 300are configured to operate in mm wave range. In various embodiments the first antenna elements200 and the second antenna elements300 are arranged in an alternating manner as illustrated in FIG. 1.To have minimum correlation between the elements the concentric arcs are placed at the edge-cut corners.
[0034] In various embodiments, the substrate is a polygon comprising 4 to 8 sides.In an exemplary embodiment the substrate is a hexagon with 8 sides. In the hexagonal sub-strate the edges are cut at the corners. The second antenna elements are arranged at the edge-cut corners. The first 200 and the second antenna elements 300are arranged on the substrate102 as illustrated in FIG. 1. In various embodiments, the first feed line 230 ex-tends to the edge of the substrate 108.In various embodiments the substrate is Rogers RT 5880 high frequency laminates.
[0035] In various embodiments the first antenna element200 is constructed as illustrated in FIG. 2. The first antenna element 200 includes an E shaped metal plate 210 integrated with an inverted L shaped metal plate 220 and a first feed line 230.The E shaped metal plate 210 includes a first vertical plate 212, a first and a second outer extension214 and an inner extension of the vertical plate 216. The inverted L shaped plate 220includes a second vertical plate 222 and a third outer extension 224at a lower end. In various em-bodiments the second outer extension 214in the E shaped metal plate 210is integrated with the third outer extension 224 to form the first antenna elements 200.
[0036] In one embodiment, the first 212 and the second vertical plates 222 are of equal lengths. In another embodiment, the first 212 and the second vertical plates 222 are of different lengths. In one embodiment, the first and the second outer extensions 214 are of equal lengths.In another embodiment, the first and the second outer extensions 214 are of different lengths. In various embodiments, the first antenna elements are symmetrical to original Cartesian X-Y axis and are aligned at an angle of 90 degrees from each other.
[0037] In various embodiments, the second antenna elements 300 as illustrated in FIG. 3 includes two or more concentric arc antenna elements 302, 304 and a circular element306 placed on a second feed line 310. In various embodiments, the concentric arc antenna elements 302, 304 have equal or different arc lengths.
[0038] In various embodiments, the second antenna elements 300 are symmetrical to the original Cartesian X-Y axis and are positioned at 45 degrees from the original Cartesian X-Y axis and are aligned at an angle of 90 degrees from each other. The second antenna elements 300 are aligned at an angle of 45 degrees from the first antenna elements 200.
[0039] In various embodiments, each one of the first antenna elements 200 operate in-frequencies selected from 2.2GHz, 3.6GHz, 5.0GHz or6.1GHz from the sub-6Ghz fre-quency band. In various embodiments, the second antenna elements 300 operate in fre-quencies selected from 24.5GHz, 31.2GHz, 36.5GHz, or 41GHz from the mm Wave frequency band. In various embodiments, the bandwidth is in a range 165MHz to 3.46GHz. In various embodiments, the gain is in a range 6dB to 10dB.
[0040] The advantages of the system includesignificant isolation, gain and bandwidth achieved in multiple frequency bands with a single antenna configuration. A simple an-tenna design with similar elements covering a large frequency range as described here remains undisclosed in the art.The antenna system has wide commercial application for 5G mobile phone as well as base station (5GgNB) and future generation mobile. The system is also suitable for 5th and 6th Generation of WiFi (Wireless local area network –WLAN).
[0041] EXAMPLES
[0042] Example. 1: Construction of the MIMO Antenna:
[0043] An antenna having 8 antennas elements on a single substrate was designed. The antenna was able to radiate/receive 8 bands of frequency. Out of 8 bands, 4-bands belong to sub-6GHz (FR1) while other 4 bands in mm wave(FR2) from 26GHz to 41GHz on the same patch. Frequency covered: [(2.2GHz, 3.6GHz, 5.0GHz, 6.1GHz)], and [(24.5GHz, 31.2GHz,36.5GHz, 41GHz)]. The E and Inverted-L shaped patch as shown was designed on the top layerof the substrate with a circular slot of diameter (D) on the ground plane. The dimensions of E and Inverted-L shaped antenna element are shown in Table. 1.
Table 1: Dimensions of E and Inverted-L Shaped Antenna Element
Parameter Value (mm)
FL 19.56
FW 2.15
HL 18.15
Le 19.5
L1 7.35
L2 8.5
LI 16
[0044] The dimensions of concentric arcs antenna system is shown in Table. 2.
Table 2: Dimensions of E and Inverted-L Shaped Antenna Element
Parameter Value (mm)
A2 9
A1 6
V1 2.54
R 3
Lf1 12.76
Wf1 2.15
Lsub, Wsub 120
The antenna elements were arranged alternatively. The design is able to offer significant gain, bandwidth in all 8 frequencies. While thebandwidth varies from 165MHz to 3.46GHz, the gain varies from 6dB to 10dB.
FIG. 4 illustrates thereturn loss at low frequency ranges, S11 at sub-6 GHz range- Radiating at 2.24GHz, 3.58GHz, 5.06 GHz, 6.1GHz frequency. FIG. 5A-FIG. 5D shows the 2D radiation analysis at 2.24GHz, 3.58GHz, 5.06 GHz, 6.1GHz frequency. FIG. 6-FIG. 8 are simulation results showing the return loss of the antenna at 24.5GHz, 31.96 GHz, 36.56 GHz, and 40.95 GHz of operating frequencies respectively.The X-axis represents operation frequency and the Y-axis represents the magnitude of return loss in dB. While, FIG.6 shows the return loss of approximately -16.80dB at 24.5GHz and wide bandwidth of 3.16GHz, FIG.7 depicts the improved return loss of -27.5dB at frequency 31.96GHz.and bandwidth of 1.97GHz. Similarly, FIG.8 shows a return loss of -15.5dB at operating frequency of 36.56GHz.with 2.26GHz of bandwidth. From this, it is clear that the designhas significant performance in terms of bandwidth, gain, etc.FIG. 10A-FIG. 10D shows the 2D radiation analysis at 24.5GHz, 31.96 GHz, 36.56 GHz, and 40.95 GHz operating frequencies respectively. The high frequency analysis of the designed antenna is given in Table. 3. Table. 4 contains a summary of the antenna performance and prior art.
Table 3: High Frequency Analysis of the Designed Antenna
S. No Center Fre-quency (GHz) Bandwidth
(GHz) Peak Di-rectivity (dBi) Peak Gain (dBi) ECC Isolation
(port 5-port 6) dB
1 24.5 3.46 7.94 8.10 0.003249 24.6
2 31.96
1.97 10.08 10.27 0.002525 20.9
3 36.57 2.26 8.85 9.02 0.00009 20.3
4 40.95 1.45 9.33 9.55 0.009173 23.43
Table. 4: Summary of Performance of the Antenna
Reference MIMO Support Size Freq (GHz) Gain at mm-wave (dB) No. of Ports Isolation at mm-wave
Sub-6 mm-wave
This work Yes Yes Yes 120x
120x
1.57 Sub-6:2.24, 3.58, 5.06, 6.1
5G FR2:24.5, 31.96, 36.57, 40.95 10.27 8
4-low
4-high >20dB
Single-layered MIMO antenna system
Yes Yes Yes 104x
104x 0.51 Sub-6 : 2.45, 2.6, 5.2
5G FR2: 24.5, 28 11 8
4-low
4-high >16dB
MIMO for 5G&4G
Yes No Yes 80x80x 1.57 5G FR2: 28, 33, 38; FR1: 1.8, 2.6 12 4
4-high >20dB
The single-layered MIMO antenna system disclosed in "Multiband MIMO Microwave and Millimeter Antenna System Employing Dual-Function Tapered Slot Structure," M. Ikram et al. in IEEE Transactions on Antennas and Propagation, vol. 67, no. 8, pp. 5705-5710, Aug. 2019, doi: 10.1109/TAP.2019.2922547, the supports frequencies ofWLAN (2.45 GHz, 5.2 GHz), 4G LTE (2.6 GHz) and 5G (24 GHz, 28 GHz) bands. This is a tapered slot. The performance of the single-layered MIMO antenna system in comparison with the claimed antenna is lesser Gain at lower frequency and lesser isolation.
[0045] In our work, design is different, supported frequency is more, gain is high in both the bands, isolation is high. The MIMO antenna for 5G&4G disclosed in "MIMO Antenna System for Multi-Band Millimeter-Wave 5G and Wideband 4G Mobile Communications,", Al Abbas et al in IEEE Access, vol. 7, pp. 181916-181923, 2019, doi: 10.1109/ACCESS.2019.2958897 has a tapered design. For 5G inmmWave, the supported frequency is 28, 37, 39GHz while the supported frequency is 1.8 and 2.6GHz for 4G.The performance of the MIMO for 5G&4G antenna is S11 is lesser than -10dB for mmWave and lesser than -6dB for 2GHz band. Thus, for lower frequency, the antenna is not considered to have good gain. The gain is much less around 3.4dB.In theclaimed antenna thesupported frequencies are more, S11 parameters are much lesser than -10dB and gain is much higher.
[0046] While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material the teachings of the invention without departing from its scope, which should be as delineated in the appended claims.

 
, Claims:WE CLAIM:
1. A multiband multiple input multiple output (MIMO) antenna apparatus (100) configured to operate in a plurality of frequency bands comprising:
a substrate(102) comprising an inner portion (104) having a circular slot of di-ameter D on a ground plane and an outer portion (106);
at least four first antenna elements (200)each element placed in a quadrant in the circular slot (104) and configured to operate in sub-6GHzfrequency range; and
at least four second antenna elements (300) placed in the outer portion (106) and configured to operate in mm wave range, wherein
the first antenna elements (200) and the second antenna elements (300) are arranged in an alternating manner.
2. The antenna apparatus (100) as claimed in claim 1, wherein the substrate is a polygon comprising 4 to 8 sides.
3. The antenna apparatus (100) as claimed in claim 1, wherein the substrate is Rogers RT 5880 high frequency laminates.
4. The antenna apparatus (100) as claimed in claim 1, wherein the first antenna ele-ments (200) comprise an E shaped metal plate (210) integrated with an inverted L shaped metal plate (220) and a first feed line (230), the E shaped metal plate (210) comprising a first vertical plate (212), a first and a second outer extensions (214) and an inner exten-sion of the vertical plate (216) and the inverted L shaped plate (220) comprising a second vertical plate (222) and a third outer extension (224) at a lower end, wherein the second outer extension (214) is integrated with the third outer extension (224).
5. The antenna apparatus (100) as claimed in claim 3, wherein thefirst and the sec-ond outer extensions (214) are of equal or different lengths.
6. The antenna apparatus (100) as claimed in claim 3, wherein the first (212) and the second vertical plates (222) are of equal or different lengths.
7. The antenna apparatus (100) as claimed in claim 3, wherein the first feed line (230) extends to the edge of the substrate (108).
8. The antenna apparatus (100) as claimed in claim 1, wherein the second antenna elements (300) comprise two or more concentric arc antenna elements (302, 304) and a circular element(306) placed on a second feed line (310).
9. The antenna apparatus (100) as claimed in claim 8, wherein the concentric arc antenna elements (302, 304) have equal or different arc lengths.
10. The antenna apparatus (100) as claimed in claim 1, wherein the first antenna ele-ments (200)are symmetrical to original Cartesian X-Y axis and are aligned at an angle of 90 degrees from each other.
11. The antenna apparatus (100) as claimed in claim 1, wherein the first antenna ele-ments (200) are aligned at an angle of 45 degrees from the second antenna elements (300).
12. The antenna apparatus (100) as claimed in claim 1, wherein the second antenna elements (300) are symmetrical to the original Cartesian X-Y axis and are positioned at 45 degrees from the original Cartesian X-Y axis and are aligned at an angle of 90 degrees from each other.
13. The antenna apparatus (100) as claimed in claim 1, wherein the second antenna elements (300) are aligned at an angle of 45 degrees from the first antenna elements (200).
14. The antenna apparatus (100) as claimed in claim 1, wherein each one of the first antenna elements (200) operate infrequencies selected from 2.2GHz, 3.6GHz, 5.0GHz or6.1GHz from the sub-6GH z frequency band.
15. The antenna apparatus (100) as claimed in claim 1, wherein the second antenna elements (300) operate in frequencies selected from 24.5GHz, 31.2GHz, 36.5GHz, or 41GHz from the mm Wave frequency band.
16. The antenna apparatus (100) as claimed in claim 1, wherein the bandwidth is in a range 165MHz to 3.46GHz.
17. The antenna apparatus (100) as claimed in claim 1, wherein the gain is in a range 6dB to 10dB.

Sd.- Dr V. SHANKAR IN/PA-1733
For and on behalf of the Applicants