A COMPACT DUAL-BAND MIMO ANTENNA FOR MULTI-STANDARD COMMUNICATION IN VEHICULAR ENVIRONMENT

Abstract

The present invention discloses a dual-band, multi-standard MIMO antenna compatible with both metallic and non-metallic car roof-tops. The antenna (100), comprises, a dielectric substrate (70) having plurality of antenna elements (10a, 10b) to transmit and receive signals. The radiating elements (20a, 20b) arranged in Yagi-array configuration generates orthogonal non-overlapping radiation pattern. The ground strips (30a, 30b) utilize asymmetric-coplanar-strip (ACS) for enhanced signal processing. The directors (40a, 40b) and reflectors (50a, 50b) reduce interference and optimize radiation. The shorting pins (60a, 60b) connect the ground strips (30a, 30b) to a shorting strip (110) at the bottom surface of said substrate (70). Further, a plurality of antenna ports (80a, 80b) facilitates connections to multiple coaxial feed lines; and a plurality of split-ring-resonators (SRRs) (90a, 90b) prevents spurious resonance. The said antenna (100) operates across two frequency bands, with meandered portion radiating at 3.5 GHz and the straight monopole radiating at 5.8 GHz.

Specification

Description:FIELD OF INVENTION:
The present invention generally relates to a wireless communication technology. More particularly, the present invention relates to a compact dual-band MIMO antenna for multi-standard communication in vehicular environment, compatible with both metallic and non-metallic car roof-tops.

BACKGROUND AND PRIOR ART:
In the rapidly evolving era of wireless communications, there is a demand for higher data rate, greater reliability, and increased channel capacity leading to development of advanced technologies. As modern wireless devices continue to decrease in size, every component within these devices is compelled to miniaturize as well. Antenna is one among the major components that determine the overall performance of the device, by effectively radiating/receiving electromagnetic energy, which is launched/collected through its feed, to/from free space. MIMO (multiple-input and multiple-output) technology revolutionizes wireless communication by employing multiple antennas at both the transmitter and the receiver ends. MIMO antenna communication systems use multiple antennas to handle multiple signal paths simultaneously, thus communicating data faster than a single antenna communication system.

Modern vehicles are increasingly becoming hubs of connectivity, integrating advanced wireless communication technologies to enhance safety, navigation, entertainment, and communication. By employing MIMO antennas in automotive applications, it facilitates and enhances connectivity, data throughput, overall performance, and above all, the reliability of wireless communication due to incorporation of antenna diversity. Further, this technology also enhances critical communication systems used in vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), etc., put together as vehicle-to-everything (V2X) communication and thus contribute to intelligent transportation system (ITS), used in smart city infrastructure.

US9082307B2 discloses a circular antenna array for vehicular direction-finding applications. The said antenna array comprises a circular disc structure with microstrip antennas arranged radially. It further includes variants like V-shaped and Yagi antennas operating in switched and phased modes within 2.45 GHz band. However, US'307 fails to support maximal ratio combining (MRC) and only support selection combining.

US9083414B2 discloses an LTE MIMO-capable multifunctional vehicle antenna. The said antenna assembly mainly comprises, a primary MIMO antenna, a secondary MIMO antenna, and a global navigation satellite system (GNSS) antenna positioned between the primary and secondary MIMO antennas. Further, said primary MIMO antenna and secondary MIMO antenna comprises, a horizontally-polarized antenna and a vertically-polarized antenna. However, said MIMO antennas does not cover 3.5 GHz 5G band required for CV2X communication and 5.89 GHz DSRC band.

US9093750B2 discloses a multiband MIMO vehicular antenna assembly for a vehicle, comprising at least one cellular antenna configured to be operable over one or more cellular frequencies, at least one satellite antenna configured to be operable over one or more satellite frequencies, and at least one dedicated short-range communication (DSRC) antenna configured to be operable over DSRC frequencies. Further, said dual-band MIMO antenna assembly covers LTE band and DSRC band. However, US'750 requires high precision in machining and bending of metal to achieve desired performance from said antenna.

EP3840119A1 discloses an automotive MIMO antenna system for 5G base station comprising, a chassis, a printed circuit board fixed to the chassis and defining a main plane, and a dielectric carrier that extends along a main axis perpendicular or tilted relative to said main plane and that has a side face fitted with several antennas electrically connected to the printed circuit board. Further, EP'119 comprises three sets of independent antennas to cover the whole frequency range. However, EP'119 discloses a 3D geometry configuration, which is not very suitable from packaging perspective, of said MIMO antenna, where the feeding mechanism is not evident.

US9666937B2 discloses an dual-band LTE MIMO antenna system for automotive non-metallic rooftops comprising, a first antenna coupled to a first metallic support, wherein the first metallic support forms a ground plane for the first antenna and separates the first antenna from the non-metallic roof; a second antenna coupled to a second metallic support, wherein the second metallic support forms a ground plane for the second antenna and separates the second antenna from the non-metallic roof; a third antenna coupled to the first metallic support; and a fourth antenna coupled to the second metallic support, wherein the third antenna and the fourth antenna form a MIMO antenna pair. However, said antenna according to US'937 is practically restricted to vehicles having non-metallic roof only.

IN202241030472 discloses a microstrip patch antenna for vehicle-to-vehicle communication to operate at 5.9 GHz frequency. However, IN'472 relates to a single band antenna for dedicated short-range communication (DSRC) application only, and is not extended to MIMO implementation. Further, a defected ground structure (DGS) has been used for enhancing the performance of said antenna.

Conventional MIMO antennas for vehicular communication lacks to provide a dual-band MIMO antenna for a shark-fin radome and compatibility with metallic vehicle roofs.

Thus, there is a need of an improved dual-band MIMO antenna which overcomes the drawbacks of frequency range, compactness, compatibility, and diversity reception for effective vehicular communication.

The present invention thus discloses a compact dual-band MIMO antenna for multi-standard communication in vehicular environment, and compatible with both metallic and non-metallic car roof-tops.

SUMMARY OF THE INVENTION:
The present invention relates to a low-loss, low-cost, lightweight, highly-compact, and easy-to-fabricate dual-band MIMO antenna, to enhance the data rates across a given spectral bandwidth, for effective vehicular communication.

It is an object of the present invention to provide a multi-standard MIMO antenna configured to support sub-6 GHz 5G NR communication, DSRC vehicle-to-everything (V2X) communication, and cellular-V2X (C-V2X) communication for vehicles.

It is another object of the present invention to facilitate spatial-pattern diversity by positioning multiple antennas apart from each other, to capture signals from different spatial directions, for improved signal stability and reliability.

It is yet another object of the present invention to enable maximal ratio combining (MRC), to enhance signal reception by combining the signals received from plurality of antennas by weighting them based on the channel gain.

It is yet another object of the present invention to provide an antenna suitable for use in both metallic and non-metallic rooftop of cars.

It is yet another object of the present invention to provide a MIMO antenna with minimal hosting effect on metallic roof of a vehicle.

It is yet another object of the present invention to ensure reliable communication through radiation-pattern-diversity in deep-fading situation of multipath-rich fading channel by using Yagi-Uda type passive antenna array configuration to shape the radiation patterns.

It is yet another object of the present invention to provide common ground to the plurality of the antenna elements for supporting the requirement of diversity combining.

It is yet another object of the present invention to provide a compact MIMO antenna that can fit within the size constraint of a shark fin radome.

Accordingly, the present invention provides an end-fed highly-compact dual-band two-port Yagi-type pattern-diversity antenna mainly comprising, a dielectric substrate; and plurality of antenna elements configured to transmit and receive signals, including radiating elements, ground strips, reflectors, directors printed on the upper surface of said substrate, and shorting pins, split-ring-resonators (SRRs), and a shorting strip on the bottom surface of said substrate. The radiating elements are arranged in Yagi-array configuration to generate orthogonal non-overlapping radiation pattern. The ground strips utilize asymmetric-coplanar-strip (ACS) for enhanced signal processing. Further, the directors and reflectors minimize interference and optimize radiation patterns. The shorting pins connect the ground strips to a main shorting strip, while multiple antenna ports facilitate connections to coaxial feed lines. Additionally, split-ring resonators are incorporated to prevent spurious resonance.

The said antenna is a 2x2 MIMO communication antenna configured to exhibit stable electrical characteristics over a broad frequency range, making it suitable for various wireless communication applications.

In a preferred embodiment according to the present invention, said device operates at 5.9 GHz dedicated-short-range-communications (DSRC) band and 3.5 GHz 5G new radio (NR) band, providing pattern-diversity with Envelope Correlation Coefficient (ECC) values of 0.3 and 0.004 at 3.5 and 5.89 GHz, respectively, which are far less than the designated upper limit ECC < 0.5.

The said 2×2 MIMO antenna is constructed using Rogers RO4350B laminate, characterized by a dielectric constant (εr) of 3.48 ± 0.05 and a loss tangent (tan δ) of 0.0037 at 10 GHz, with a thickness of 30 mils (0.762 mm) and is typically coated with 18 μm of copper cladding on both sides.

The fabrication process for the antenna is similar to that used for the widely available FR4 glass-epoxy substrate. The antenna components can be fabricated on the RO4350B substrate either through the classical chemical etching technique or through the modern mechanical milling process. Furthermore, the vias or shorting pin connecting the ground strip to shorting strip at the back are implemented using standard plated through-hole (PTH) technique similar to those utilized in FR4 laminates.

Furthermore, the Yagi-array configuration helps to reduce the ECC between the radiation patterns, and ensures a high port-to-port isolation within a limited footprint area. The arrangement of the Yagi elements allows each antenna element to interact with distinct angular wireless channels, thereby, enhancing the performance of the MIMO antenna.

BRIEF DESCRIPTION OF DRAWINGS:
The figures below show an exemplary embodiment:
Figure 1a illustrates a schematic top side of the proposed dual-band MIMO antenna without shark-fin radome.
Figure 1b illustrates a schematic bottom side of the proposed dual-band MIMO antenna with fabricated prototype in inset.
Figure 1c illustrates a schematic zoom-in view of Split Ring Resonators (SRRs) of figure 1b.
Figure 2a illustrates a simulation model of the proposed dual-band MIMO antenna inside the shark-fin radome and over a large metallic ground plate, which is a representative embodiment of vehicle's metallic roof.
Figure 2b illustrates a fabricated prototype of the proposed dual-band MIMO antenna (after removal of the shark-fin radome) over a large metallic ground plate, which is a representative embodiment of vehicle's metallic roof.
Figure 3a illustrates a 3D polar plot of MIMO antenna inside shark-fin radome with port 1 excited and port 2 terminated in a matched load at 3.5 GHz.
Figure 3b illustrates a 3D polar plot of MIMO antenna inside shark-fin radome with port 1 excited and port 2 terminated in a matched load at 5.89 GHz.
Figure 4 illustrates a graphical representation of S-parameter of the proposed dual-band MIMO antenna with shark-fin radome.

List of reference numerals
Part ref Description
100 Dual-band MIMO antenna
10a First antenna element
10b Second antenna element
20a First radiating element
20b Second radiating element
30a First ground strip
30b Second ground strip
40a First director
40b Second director
50a First reflector
50b Second reflector
60a First shorting pin or via
60b Second shorting pin or via
70 Substrate of antenna
80a First port
80b Second port
90a Split ring resonators (SRRs) for first antenna
90b Split ring resonators (SRRs) for second antenna
110 Shorting strip

DETAILED DESCRIPTION OF THE INVENTION:
The present invention will now be described in detail with reference to optional and preferred embodiments so that various aspects of the invention will be more clearly understood, however, should not be construed to limit the scope of the invention. The following embodiments clearly and completely describes various technical features and advantageous of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. The examples used herein are intended merely to facilitate an understanding of the ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The present invention provides a low-loss, low-cost, lightweight, highly-compact, and easy-to-fabricate dual-band, multi-standard MIMO antenna (100) configured to support sub-6 GHz 5G NR communication, DSRC vehicle-to-everything (V2X) communication, and cellular-V2X (C-V2X) communication for vehicles.

The said MIMO antenna (100) is a 2x2 MIMO communication antenna configured to exhibit stable electrical characteristics over two frequency bands. The said antenna (100) is constructed using Rogers RO4350B laminate coated with copper cladding on both sides, and the fabrication process is similar to that used for the widely available FR4 glass-epoxy substrate. In an embodiment, the antenna components can be fabricated on the RO4350B substrate either through the classical chemical etching technique or through the modern mechanical milling process. Furthermore, the vias or shorting pin connecting the ground strip to shorting strip at the back are implemented using standard plated through-hole (PTH) technique similar to those utilized in FR4 laminates.

Furthermore, the Yagi-array configuration helps to reduce the ECC between the radiation patterns, and ensures a high port-to-port isolation within a limited footprint area. The arrangement of the Yagi elements allows each antenna element to interact with distinct angular wireless channels, thereby, enhancing the performance of the MIMO antenna.

Referring to figure 1a, illustrates a schematic top-side view of the proposed dual-band MIMO antenna (100). The said antenna (100) comprises, a dielectric substrate (70) having plurality of antenna elements (10a, 10b) including radiating elements (20a, 20b), ground strips (30a, 30b), reflectors (50a, 50b), directors (40a, 40b) configured to transmit and receive signals. The said radiating elements (20a, 20b) are arranged in Yagi-array configuration to generate orthogonal non-overlapping radiation pattern. The said ground strips (30a, 30b) utilize asymmetric-coplanar-strip (ACS) for enhanced signal processing. The said directors (40a, 40b) are positioned beside said radiating elements (20a, 20b) to reduce interference and optimize radiation patterns. The said reflectors (50a, 50b) are positioned between said plurality of radiating elements (20a, 20b) to isolate, reduce interference and optimize the radiation pattern of the antenna elements (10a, 10b). The shorting pins or vias (60a, 60b) connect the ground strips (30a, 30b) to a shorting strip (110) placed at the bottom surface of said dielectric substrate (70). Further, a plurality of antenna ports (80a, 80b) facilitates connections to multiple coaxial feed lines.

Referring to figure 1b, illustrates the bottom-side view of the antenna (100) comprising, a shorting strip (110) to short the ground strips (30a, 30b), plurality of antenna elements (10a, 10b); and a plurality of split-ring-resonator (SRR) (90a, 90b) to prevent spurious resonance printed on the bottom surface of said dielectric substrate (70). Further, figure 1c illustrates the zoom-in view of said split ring resonator (SRRs) (90a, 90b).

Referring to figure 2a, 2b, illustrates a simulation model and fabricated prototype of the proposed dual-band MIMO antenna (100) inside the shark-fin radome and over a large metallic ground plate.

Referring to figure 3a and 3b, illustrates a 3D polar plot of MIMO antenna inside shark-fin radome with port 1 excited and port 2 terminated in a matched load at 3.5 GHz and 5.89 GHz, respectively. As illustrated, the said dual-band MIMO antenna (100) shows partial pattern diversity at the lower frequency band and almost complementary radiation patterns at the upper frequency band, which makes the two ports of the MIMO antenna see two substantially different radio channels. The said MIMO antenna (100) provides a peak gain of 3.29 dBi at 3.5 GHz, and a peak gain of 7.67 dBi at 5.89 GHz. The pattern diversity further helps to achieve the envelope correlation coefficient (ECC) of around 0.3 at 3.5 GHz and 0.004 at 5.89 GHz.

Referring to figure 4 illustrates a graphical representation of S-parameter of the proposed dual-band MIMO antenna (100) with shark-fin radome. The said dual-band MIMO antenna (100) provides a 10-dB return loss (RL) bandwidth (BW) of around 240 MHz at the lower band, and around 390 MHz BW at the upper band with isolation better than around 18.16 dB across both the bands.

In a preferred embodiment according to the present invention, a dual-band multiple-input-multiple-output (MIMO) antenna (100) for vehicular communication, comprises,
a low loss dielectric substrate (70) for printing a plurality of antenna elements (10a, 10b) including radiating elements, ground strips, directors, reflectors on the upper surface; and a shorting strip, shorting pins, and split-ring-resonators (SRRs) on the bottom surface of said substrate (70);
a plurality of radiating elements (20a, 20b) arranged in a Yagi-array configuration to generate orthogonal non-overlapping radiation pattern in the first and second antenna elements (10a, 10b);
a plurality of ground strips (30a, 30b) comprising, asymmetric-coplanar-strip (ACS) for flexible signal processing for MIMO communication;
a plurality of directors (40a, 40b) positioned beside said plurality of radiating elements (20a, 20b), configured to reduce interference and enhance performance by improving directivity and non-overlapping nature of radiation from the plurality of antenna elements (10a, 10b);
plurality of reflectors (50a, 50b) positioned between said plurality of radiating elements (20a, 20b), configured to isolate said first antenna element (10a) and second antenna element (10b) to reduce interference and direct the radiation pattern of the said antenna elements in the opposite directions;
plurality of shorting pins or vias (60a, 60b) configured to connect the ground strips (30a, 30b) to a shorting strip (110) placed at the bottom surface of said dielectric substrate (70);
a plurality of antenna ports (80a, 80b) configured to connect said antenna elements (10a, 10b) to plurality of coaxial feed lines, to facilitate maximal ratio combining-based diversity reception and signal processing for MIMO communication; and
a plurality of split-ring-resonators (SRRs) (90a, 90b) printed on the bottom surface of said substrate (70), configured to prevent spurious resonance;
wherein said shorting strip (110) printed on the bottom surface of said substrate (70) is connected to said ground strips (30a, 30b), to facilitate a common ground for the plurality of the antenna elements (10a, 10b);
wherein said first antenna element (10a) and second antenna element (10b) is configured for both transmission and reception of signals across multiple frequency bands;
wherein said plurality of reflectors (50a, 50b) is positioned in close proximity to said plurality of radiating elements (20a, 20b) to form a resonant system for improving impedance matching and radiation efficiency;
wherein said antenna (100) is perpendicularly mounted on both non-metallic and metallic vehicle roofs, to ensure minimal interaction with metallic surfaces and preserve its original radiation characteristics while exhibiting a dipole-like radiation pattern, thereby maintaining the integrity of the antenna's driven pattern diversity.

In a same preferred embodiment, shown in figure 2 (a) and (b), the antenna (100) is a printed monopole antenna configured for pattern diversity and to exhibit minimal disruption to the original radiation pattern.

In a same preferred embodiment according to the present invention, said dielectric substrate (70) is selected from Rogers RO 4350B laminate to enhance the manufacturability of the antenna compared to other high-performance substrates, while maintaining cost-effectiveness.

In a same preferred embodiment according to the present invention, said dielectric substrate (70) is made of Rogers RO 4350B laminate material, with thickness of 30 mils (0.762 mm), having relative permittivity (ε_r)≈ 3.48 ± 0.05 and loss tangent 〖(tan〗⁡〖δ)〗≈ 0.0037 at 10 GHz, to ensure minimal signal loss and effective operation at a wide range of frequencies.

In a same preferred embodiment according to the present invention, said dielectric substrate (70) made of Rogers RO 4350B laminate material is coated with 18 μm of copper cladding on both sides.

In a same preferred embodiment according to the present invention, said plurality of antenna elements (10a, 10b) is driven by said asymmetric-coplanar-strip (ACS).

In a same preferred embodiment according to the present invention, said antenna (100) is fed at one end using a SMA-connector.

In a same preferred embodiment according to the present invention, said plurality of reflectors (50a, 50b) is placed close to said radiating elements (20a, 20b) at 0.04λ0 to form a resonant system, where λ0 is the free-space wavelength at 5.9 GHz.

In a same preferred embodiment according to the present invention, said MIMO antenna (100) is mounted on a structure selected from shark fin radome.

In a same preferred embodiment according to the present invention, said MIMO antenna (100) is a 2x2 configuration MIMO antenna having two antennas both at the transmitter and receiver.

In a same preferred embodiment according to the present invention, said antenna elements (10a, 10b) operates across two frequency bands, with meandered portion radiating at 3.5 GHz and straight monopole radiating at 5.8 GHz.

In a same preferred embodiment according to the present invention, said antenna (100) is configured to support multiple standards including sub-6 GHz 5G communication, DSRC vehicle-to-everything (V2X) communication, and cellular-V2X (C-V2X) communication.

In an embodiment according to the present invention, the RO4350B substrate is fabricated using chemical etching and mechanical milling techniques to enhance reliability by minimizing unwanted material removal often seen with softer substrates.

In an embodiment according to the present invention, the two-sided PCB fabrication utilizes a highly automated CNC milling process, eliminating the need for specialized craftsmanship of chemical etching's mask alignment, thereby streamlining production, reducing costs and ensuring high quality.

In an embodiment according to the present invention, the antenna incorporates two vias that connect the first ground to the shorting strip located on the backside, utilizing standard plating through hole (PTH) vias in RO4350B laminates for straightforward manufacturing, in contrast to the complex processes required for high-performance substrates like PTFE polymers.

In an embodiment according to the present invention, the use of Rogers RO4350B improves the antenna's performance while providing a reliable, yet economically viable solution for mass production, making the invented antenna suitable for various applications in wireless communication, including consumer electronics and industrial systems.

In a further preferred embodiment according to the present invention, said dual-band MIMO antenna (100) provides a peak gain of 3.29 dBi at 3.5 GHz, and peak gain of 7.67 dBi at 5.89 GHz.

In a further preferred embodiment according to the present invention, said antenna (100) achieves an envelope correlation coefficient (ECC) of 0.3 at 3.5 GHz, and 0.004 at 5.89 GHz.

In a further preferred embodiment according to the present invention, said MIMO antenna (100) is mounted on the roof of a vehicle such that the printed-monopoles stand perpendicular to the vehicle's roof.

In a further preferred embodiment according to the present invention, the dimensions of said antenna (100) is approximately 23x30 mm2 footprint area.

In a further preferred embodiment according to the present invention, the below table. 1, mentions the dimensions of the proposed dual-band MIMO antenna (100).

Table-1: Dimensions of the proposed dual-band MIMO antenna (unit: mm).
LSUB WSUB g LG LR L1 L2 L3
23 30 0.6 9.15 21.3 19 2.45 3
L4 L5 L6 L7 L8 L9 L10 L11
7.5 8 5.5 6.5 3 3.342 8.6 7.643
L12 L13 W1 W2 W3 W4 W5 W6
7.77 2.14 2 2 3 2.5 0.5 0.58
W7 W8 α1 α2 L14 L15 L16 L17
1 0.5 16.7O 5.31O 2.45 2.3 8.5 9.8
W9 W10 W11 WR a b c d e
4.5 0.6 0.7 2.1 0.3 3.4 0.15 0.2 2.3

The advantages of the MIMO antenna (100) of the present invention are as follows:
supports multiple standards like DSRC, C-V2X, sub-6 GHz 5G NR, etc.
provides flexible diversity combining and MIMO communication
compact and suitable for use in both metallic and non-metallic roof-top of cars.

The foregoing descriptions are merely specific embodiments of the present invention, but are not intended to limit the protection scope of the present invention. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
, Claims:
A dual-band multiple-input-multiple-output (MIMO) antenna (100) for vehicular communication, comprising,
a dielectric substrate (70) for printing a plurality of antenna elements (10a, 10b) including radiating elements, ground strips, reflectors, directors, on the upper surface; and a shorting strip, shorting pins, split-ring-resonators (SRRs), on the bottom surface of said substrate (70);
a plurality of radiating elements (20a, 20b) arranged in Yagi-array configuration to generate orthogonal non-overlapping radiation pattern in the first and second antenna elements (10a, 10b);
a plurality of ground strips (30a, 30b) comprising, asymmetric-coplanar-strip (ACS) for flexible signal processing for MIMO communication;
a plurality of directors (40a, 40b) positioned beside said plurality of radiating elements (20a, 20b), configured to reduce interference and enhance performance by improving directivity and non-overlapping nature of radiation from the plurality of antenna elements (10a, 10b);
a plurality of reflectors (50a, 50b) positioned between said plurality of radiating elements (20a, 20b), configured to isolate said first antenna element (10a) and second antenna element (10b) to reduce interference and direct the radiation pattern of the said antenna elements in the opposite directions;
a plurality of shorting pins or vias (60a, 60b) configured to connect the ground strips (30a, 30b) to a shorting strip (110) placed at the bottom surface of said dielectric substrate (70);
a plurality of antenna ports (80a, 80b) configured to connect said antenna elements (10a, 10b) to plurality of coaxial feed lines, to facilitate maximal ratio combining-based diversity reception and signal processing for MIMO communication; and
a plurality of split-ring-resonators (SRRs) (90a, 90b) printed on the bottom surface of said substrate (70), configured to prevent spurious resonance;
wherein said shorting strip (110) printed on the bottom surface of said substrate (70) is connected to said ground strips (30a, 30b), to facilitate a common ground for the plurality of the antenna elements (10a, 10b);
wherein said first antenna element (10a) and second antenna element (10b) is configured for both transmission and reception of signals across multiple frequency bands;
wherein said reflectors (50a, 50b) is positioned in close proximity to said radiating elements (20a, 20b) to form a resonant system for improving impedance matching and radiation efficiency;
wherein said antenna (100) is perpendicularly mounted on both non-metallic and metallic vehicle roofs, to ensure minimal interaction with metallic surfaces and preserve its original radiation characteristics while exhibiting a dipole-like radiation pattern, thereby maintaining the integrity of the antenna's driven pattern diversity.

The MIMO antenna (100) as claimed in claim 1, wherein said antenna (100) is a printed monopole antenna configured for pattern diversity and to exhibit minimal disruption to the original radiation pattern.

The MIMO antenna (100) as claimed in claim 1, wherein said dielectric substrate (70) comprises Rogers RO 4350B laminate, with thickness of 30 mils (0.762 mm), having relative permittivity ε_r≈ 3.48 and loss tangent tan⁡δ≈ 0.004, to ensure minimal signal loss and effective operation at a wide range of frequencies.

The MIMO antenna (100) as claimed in claim 1, wherein said dielectric substrate (70) is coated with 18 μm of copper cladding on both sides.

The MIMO antenna (100) as claimed in claim 1, wherein said plurality of antenna elements (10a, 10b) is driven by said asymmetric-coplanar-strip (ACS).

The MIMO antenna (100) as claimed in claim 1, wherein said antenna (100) is end-fed using a SMA-connector.

The MIMO antenna (100) as claimed in claim 1, wherein said plurality of reflectors (50a, 50b) is placed close to said radiating elements (20a, 20b) at 0.04λ0 to form a resonant system, where λ0 is the free-space wavelength at 5.9 GHz.

The MIMO antenna (100) as claimed in claim 1, wherein said MIMO antenna (100) is mounted on a structure selected from shark fin radome.

The MIMO antenna (100) as claimed in claim 1, wherein said MIMO antenna (100) is a 2X2 configuration MIMO antenna having two antennas both at the transmitter and receiver.

The MIMO antenna (100) as claimed in claim 1, wherein said antenna elements (10a, 10b) operates across two frequency bands, with meandered portion radiating at 3.5 GHz and the straight monopole radiating at 5.8 GHz.

The MIMO antenna (100) as claimed in claim 1, wherein said antenna (100) is configured to support multiple standards including sub-6 GHz 5G communication, DSRC vehicle-to-everything (V2X) communication, and cellular-V2X (C-V2X) communication.

Documents