77GHz high-isolation microstrip array antenna

Abstract

The invention discloses a 77GHz high-isolation microstrip array antenna. The 77GHz high-isolation microstrip array antenna comprises a dielectric substrate, a transmitting antenna, an electromagnetic band gap structure and a receiving antenna, wherein the dielectric substrate is a rectangular flat plate made of Rogers3003 materials, the transmitting antenna comprises three microstrip antenna sub-area arrays and is used for transmitting electromagnetic signals, and the electromagnetic band gap structure is formed by periodically arranging metal units, is arranged between the transmitting antenna and the receiving antenna and is used for inhibiting surface wave coupling between the transmitting antenna and the receiving antenna. The receiving antenna comprises four same microstrip antenna sub-area arrays and is used for receiving echo signals of a target. The antenna has good gain and working bandwidth, has the characteristic of high isolation, and has the advantages of low profile and miniaturization.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and particularly relates to a 77 GHz microstrip array antenna with high isolation. Background Art

[0002] With the rapid development of millimeter-wave radar technology, microstrip array antennas in the 77 GHz band have been widely used in fields such as automotive assisted driving, driverless driving, and the Internet of Things. Due to the advantages of strong beam directivity and high resolution, high-frequency antenna arrays have become the key to achieving high-precision detection. However, the propagation of surface waves between antennas will exacerbate the electromagnetic coupling between array elements, not only reducing the isolation of the antennas, but also possibly affecting their gain and bandwidth performance. The electromagnetic bandgap structure can effectively suppress surface waves without affecting the original bandwidth and gain of the antenna, significantly improving the isolation performance between the transmitting and receiving antennas. This design can effectively utilize the space of the antenna while reducing the coupling effect, meeting the application requirements of low-profile antennas, and providing a feasible technical solution for the performance optimization of millimeter-wave antenna arrays.

[0003] The electromagnetic bandgap is an artificially designed periodic electromagnetic structure that can prevent the propagation of electromagnetic waves within a certain frequency range and is widely used in fields such as antenna design, microwave circuits, and wireless communication. Its principle is similar to the optical bandgap phenomenon in photonic crystals. By designing specific periodic units, the propagation of electromagnetic waves can be suppressed within a specific frequency range, thereby achieving functions such as filtering and reducing coupling interference. The electromagnetic bandgap structure has high-impedance characteristics and in-phase reflection characteristics. By introducing resonant units such as capacitors and inductors into the periodic structure, electromagnetic waves are strongly reflected or absorbed at specific frequencies, making it difficult for the electric or magnetic field energy in the local area to propagate. When electromagnetic waves are vertically incident on a traditional metal plane, the phase of the reflected wave is usually opposite to that of the incident wave, which is called anti-phase reflection. Anti-phase reflection can cause a phase cancellation phenomenon between the incident wave and the reflected wave in the antenna system, which may not be conducive to improving the radiation efficiency of the antenna. However, there is a certain frequency point in the electromagnetic bandgap structure where the reflected wave and the incident wave are in phase, and the surface impedance at this frequency point is relatively high, equivalent to an ideal magnetic conductive surface. By introducing an electromagnetic bandgap structure between antennas, the coupling effect between antennas can be reduced and the performance of the system can be improved. In addition, the electromagnetic bandgap structure is also used in the design of filters. In microwave circuits, high-performance band-pass filters or band-stop filters can be designed using the frequency selection characteristics of the electromagnetic bandgap structure.

[0004] Reference 1 (Hu X, Cui Y, Li R L. Decoupling Network for Coupling Suppression in Series-Fed Millimeter-Wave Antenna Arrays[C]. 2022 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP), 2022: 1-3.) designed a microstrip array antenna for 77 GHz automotive radar and introduced a novel decoupling network between the feed lines, providing an additional coupling path for the antenna to balance the direct coupling between antenna arrays. The port isolation of the antenna was increased by an average of 10 dB in the 77 GHz operating frequency band, with the advantages of low profile and simple structure. Reference 2 (Arumugam S, Palaniswamy S K, Manoharan S. High gain wideband grid array antenna for short range radar and vehicle-to-satellite communications[J]. AEU-International Journal of Electronics and Communications, 2022, 147: 154157.) designed a high gain wideband grid antenna operating at 24 GHz, which can cover 24 GHz short-range radar applications, the Ku band of fixed satellite services, and vehicle-to-satellite broadcast services. By designing the current amplitude of the Taylor distribution, a sidelobe of -16.3 dB was obtained, and by designing an elliptical radiator, a working bandwidth of 3.5% and a peak gain of 14.2 dBi were obtained. Summary of the Invention

[0005] The object of the present invention is to propose a 77 GHz microstrip array antenna with high isolation.

[0006] The technical solution for achieving the object of the present invention is: a 77 GHz microstrip array antenna with high isolation, including a dielectric substrate and a transmitting antenna, an electromagnetic bandgap structure, and a receiving antenna disposed on the surface of the dielectric substrate. Among them, the transmitting antenna includes 3 microstrip antenna sub-arrays for transmitting electromagnetic signals, the electromagnetic bandgap structure is disposed between the transmitting antenna and the receiving antenna for suppressing the surface wave coupling between the transmitting antenna and the receiving antenna and improving the antenna isolation, and the receiving antenna includes 4 identical microstrip antenna sub-arrays for receiving the echo signals of the target.

[0007] Preferably, the dielectric substrate is made of Rogers 3003 board material, and the thickness of the dielectric substrate is 0.127 mm.

[0008] Preferably, the transmitting antenna includes two microstrip antenna sub-arrays arranged in a 5×10 unit and one microstrip antenna sub-array arranged in a 2×10 unit; the microstrip antenna sub-array arranged in a 5×10 unit is formed by connecting 5 microstrip antenna sub-arrays in parallel through a one-to-five microstrip power divider, and the microstrip antenna sub-array arranged in a 2×10 unit is formed by connecting 2 microstrip antenna sub-arrays in parallel through a one-to-two microstrip power divider.

[0009] Preferably, the receiving antenna includes 4 microstrip antenna sub-arrays arranged in a 2×10 unit; the microstrip antenna sub-array arranged in a 2×10 unit is formed by connecting 2 microstrip antenna sub-arrays in parallel through a one-to-two microstrip power divider.

[0010] Preferably, taking the 5×10 microstrip antenna sub-array of the transmitting antenna closest to the edge of the dielectric substrate as the coordinate origin, with 1 wavelength λ as the unit, the distances of the remaining 5×10 unit-arranged microstrip antenna sub-array, 2×10 unit-arranged microstrip antenna sub-array of the transmitting antenna, and the 4 2×10 unit-arranged microstrip antenna sub-arrays of the receiving antenna from the origin in the horizontal direction are 3.5λ, 7.5λ, 9.3λ, 12.3λ, 14.3λ, 15.8λ respectively, and the distances from the origin in the vertical direction are 3λ, 0, λ, λ, λ, 0 respectively.

[0011] Compared with the prior art, the significant advantages of the present invention are as follows: The present invention adopts the form of a microstrip antenna, which has the advantages of low profile, low cost, easy integration, etc. By designing rectangular microstrip patch units with unequal widths, the antenna obtains lower side lobes. By designing a specific layout of the transmitting and receiving antennas, the radar angle measurement requirements are realized. By designing an electromagnetic bandgap structure, the surface wave coupling effect between the receiving antenna and the transmitting antenna is effectively suppressed, while maintaining good gain, bandwidth and low-profile characteristics of the antenna while improving the antenna isolation.

[0012] The following further describes the present invention in detail with reference to the accompanying drawings. Description of the Drawings

[0013] Figure 1 It is a three-dimensional structure schematic diagram of a 77 GHz high-isolation microstrip array antenna.

[0014] Figure 2 It is a top view of the transmitting antenna of a 77 GHz high-isolation microstrip array antenna.

[0015] Figure 3 It is a top view of the receiving antenna of a 77 GHz high-isolation microstrip array antenna.

[0016] Figure 4 Schematic diagram of the metal unit structure of the electromagnetic bandgap structure of the present invention.

[0017] Figure 5 Echo loss of the 77 GHz high isolation microstrip array antenna of the present invention.

[0018] Figure 6 Transmission and reception isolation of the 77 GHz high isolation microstrip array antenna of the present invention.

[0019] Figure 7 Azimuth plane antenna radiation pattern of the 77 GHz high isolation microstrip array antenna of the present invention.

[0020] Figure 8 Elevation plane antenna radiation pattern of the 77 GHz high isolation microstrip array antenna of the present invention. Detailed implementation manners

[0021] As Figure 1 shown, a 77 GHz high isolation microstrip array antenna includes a dielectric substrate (1), and a transmitting antenna (2), an electromagnetic bandgap structure (3), and a receiving antenna (4) disposed on the surface of the dielectric substrate (1). Among them, the transmitting antenna (2) includes 3 microstrip antenna sub-arrays for transmitting electromagnetic signals. The electromagnetic bandgap structure is disposed between the transmitting and receiving antennas to suppress surface wave coupling between the transmitting antenna (2) and the receiving antenna (4) and improve antenna isolation. The receiving antenna (4) includes 4 identical microstrip antenna sub-arrays for receiving echo signals of a target.

[0022] In a further embodiment, the transmitting antenna includes two microstrip antenna sub-arrays (21) arranged in a 5×10 unit and one microstrip antenna sub-array (22) arranged in a 2×10 unit. The 5×10 microstrip antenna sub-array (21) is formed by connecting 5 microstrip antenna sub-arrays in parallel through a one-to-five microstrip power divider (211). The 2×10 unit arranged microstrip antenna sub-array (22) is formed by connecting 2 microstrip antenna sub-arrays (211) in parallel through a one-to-two microstrip power divider (221).

[0023] Furthermore, the microstrip antenna sub-array is composed of 10 rectangular microstrip patch units connected in series through microstrip lines, and the widths of the rectangular microstrip patch units of the microstrip antenna sub-array are distributed with the middle being large and gradually decreasing towards both ends.

[0024] Specifically, the rectangular microstrip patch units are uniformly arranged at a spacing of 2.25 mm. The lengths of the rectangular microstrip patch units are all 1.06 mm, and the widths are 0.57 mm, 0.74 mm, 1.05 mm, 1.3 mm, 1.43 mm, 1.43 mm, 1.3 mm, 1.05 mm, 0.74 mm, and 0.57 mm in sequence.

[0025] Specifically, the width of the microstrip line is 0.15 mm.

[0026] In a further embodiment, the electromagnetic bandgap structure (3) is a periodically arranged square metal unit (31), and a "field" - shaped groove is etched on the square metal unit.

[0027] Specifically, the side length of the square metal unit is 1 mm.

[0028] In a further embodiment, the receiving antenna (4) includes 4 microstrip antenna sub - arrays (41) arranged in a 2×10 pattern; the 2×10 - unit - arranged microstrip antenna sub - array is formed by paralleling 2 microstrip antenna sub - line - arrays through a one - to - two microstrip power divider (411).

[0029] In a further embodiment, the transmitting antenna and the receiving antenna include 7 microstrip antenna sub - arrays arranged according to specific positions. Taking the 5×10 microstrip antenna sub - array closest to the edge of the dielectric substrate as the coordinate origin, with 1 wavelength λ as the unit, the distances of the remaining microstrip antenna sub - arrays from the origin in the horizontal direction are 3.5λ, 7.5λ, 9.3λ, 12.3λ, 14.3λ, 15.8λ respectively, and the distances in the vertical direction from the origin are 3λ, 0, λ, λ, λ, 0 respectively.

[0030] By optimizing the width and length of the rectangular microstrip patch units and the width of the microstrip line, the present invention reduces the return loss of the antenna; by optimizing the width and arrangement spacing of the rectangular microstrip patch units, the radiation pattern of the antenna is improved. By optimizing the side length of the square metal unit of the electromagnetic bandgap and the size of the groove etched on the metal unit, the surface wave coupling is effectively reduced, and the isolation between antennas is improved.

[0031] The following further explains the present invention in conjunction with embodiments.

[0032] Embodiment 1

[0033] As Figure 1As shown in the figure, a 77GHz high isolation microstrip array antenna of this embodiment includes a dielectric substrate, a transmitting antenna, an electromagnetic bandgap structure, and a receiving antenna. Among them, the dielectric substrate is a rectangular flat plate made of Rogers3003 material. The transmitting antenna includes 3 microstrip array antennas for transmitting electromagnetic signals. The electromagnetic bandgap structure is composed of a periodic arrangement of metal units and is placed between the transmitting and receiving antennas to suppress the surface wave coupling between the transmitting antenna and the receiving antenna and improve the isolation between the transmitting and receiving antennas. The receiving antenna includes 4 identical microstrip array antennas for receiving the echo signals of the target.

[0034] The simulation software HFSS is used to simulate and optimize the overall antenna to obtain the simulation results of the 77GHz high isolation microstrip array antenna.

[0035] This embodiment simulates the 77GHz high isolation microstrip array antenna. As Figure 5 shown, the return loss of the antenna is less than -10dB in the range of 74.6GHz - 78.2GHz. As Figure 6 shown, the isolations of the transmitting and receiving antennas at the 77GHz frequency point are 64.5dB, 70.8dB, 84.5dB, and 79dB respectively. As Figures 7 - 8 shown, the gain of the 77GHz high isolation microstrip array antenna at the 77GHz frequency point is 20.8dBi. The 3dB beam width in the horizontal plane is 18.5°, the beam width in the elevation plane is 10.5°, and the sidelobe levels are -13dB and -18.4dB respectively.

Claims

1. A 77GHz high isolation microstrip array antenna, characterized in that: The invention comprises a dielectric substrate (1), and a transmitting antenna (2), an electromagnetic bandgap structure (3), and a receiving antenna (4) arranged on the surface of the dielectric substrate (1), wherein the transmitting antenna (2) comprises three microstrip antenna sub-arrays for transmitting electromagnetic signals, the electromagnetic bandgap structure (3) is arranged between the transmitting antenna (2) and the receiving antenna (4) for suppressing surface wave coupling between the transmitting antenna (2) and the receiving antenna (4) and improving antenna isolation, and the receiving antenna (4) comprises four identical microstrip antenna sub-arrays for receiving echo signals of a target.

2. The 77 GHz high isolation microstrip array antenna according to claim 1, characterized in that: The dielectric substrate is made of Rogers 3003 plate, and the thickness of the dielectric substrate is 0.127 mm.

3. The 77 GHz high isolation microstrip array antenna according to claim 1, characterized in that: The transmitting antenna includes two microstrip antenna sub-arrays with 5×10 units and one microstrip antenna sub-array with 2×10 units; the microstrip antenna sub-array with 5×10 units is composed of five microstrip antenna sub-arrays connected in parallel through a one-to-five microstrip power divider, and the microstrip antenna sub-array with 2×10 units is composed of two microstrip antenna sub-arrays connected in parallel through a one-to-two microstrip power divider.

4. The 77 GHz high isolation microstrip array antenna according to claim 3, characterized in that: The receiving antenna includes four microstrip antenna sub-arrays arranged with 2×10 units; the microstrip antenna sub-arrays arranged with 2×10 units are formed by connecting two microstrip antenna sub-arrays in parallel through a one-to-two microstrip power divider.

5. The 77 GHz high isolation microstrip array antenna according to claim 4, characterized in that: Taking the 5×10 microstrip antenna sub-array closest to the edge of the dielectric substrate of the transmitting antenna as the coordinate origin, and taking 1 wavelength λ as the unit, the remaining 5×10 unit microstrip antenna sub-array of the transmitting antenna, the 2×10 unit microstrip antenna sub-array and the four 2×10 unit microstrip antenna sub-arrays of the receiving antenna are at horizontal distances from the origin of 3.5λ, 7.5λ, 9.3λ, 12.3λ, 14.3λ, and 15.8λ, respectively, and their vertical distances from the origin are 3λ, 0, λ, λ, λ, and 0, respectively.

6. The 77 GHz high isolation microstrip array antenna according to claim 5, characterized in that: The rectangular microstrip patch units are evenly arranged at a spacing of 2.25 mm. The lengths of the rectangular microstrip patch units are all 1.06 mm, and the widths are 0.57 mm, 0.74 mm, 1.05 mm, 1.3 mm, 1.43 mm, 1.43 mm, 1.3 mm, 1.05 mm, 0.74 mm, and 0.57 mm, respectively.

7. The 77 GHz high isolation microstrip array antenna according to claim 5, characterized in that: The microstrip antenna sub-array is composed of 10 rectangular microstrip patch units connected in series through microstrip lines, and the width of the rectangular microstrip patch units is large in the middle and gradually decreases towards both ends.

8. The 77 GHz high isolation microstrip array antenna according to claim 5, characterized in that: The width of the microstrip line is 0.15 mm.

9. The 77 GHz high isolation microstrip array antenna according to claim 1, characterized in that: The electromagnetic band gap structure is a periodically arranged square metal unit, and field-shaped grooves are etched on the square metal unit.

10. The 77 GHz high isolation microstrip array antenna according to claim 7, characterized in that: The side length of the square metal unit is 1 mm.

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