CN216288989U

CN216288989U - Gap waveguide feed millimeter wave microstrip antenna unit and array antenna

Info

Publication number: CN216288989U
Application number: CN202122673052.3U
Authority: CN
Inventors: 胡南
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-11-03
Filing date: 2021-11-03
Publication date: 2022-04-12
Anticipated expiration: 2031-11-03

Abstract

The utility model discloses a gap waveguide feed millimeter wave microstrip antenna unit and an array antenna, wherein the antenna unit comprises a metal base plate, a plurality of metal pins are formed on the upper surface of the metal base plate, ridge gap waveguides are formed between the metal pins close to the middle, an upper metal plate is arranged on the upper surfaces of the metal pins, a coupling hole is formed in the center of the upper metal plate, the inner side end part of the ridge gap waveguide is positioned on the lower side of the coupling hole, a dielectric layer is formed on the upper surface of the upper metal plate, a plurality of radiation pieces are formed on the upper surface of the dielectric layer, the radiation pieces are interconnected through microstrip lines, and the microstrip lines are positioned on the upper side of the coupling hole. The array antenna has the advantages of convenience in mechanical assembly, low cost, high gain and the like.

Description

Gap waveguide feed millimeter wave microstrip antenna unit and array antenna

Technical Field

The utility model relates to the technical field of millimeter wave antennas, in particular to a gap waveguide feed millimeter wave microstrip antenna unit and an array antenna.

Background

In recent years, due to the demand for high data rate short-range wireless communication, the development of 60GHz band millimeter wave wireless communication systems has increased. The main challenge in the 60GHz band is the very high radio wave absorption caused by oxygen molecule resonance. An alternative to the solution is to use a high gain antenna with high radiation efficiency. In recent years, attention has been increasingly paid to the development of high-gain broadband millimeter wave antenna arrays having high radiation efficiency. Different planar antenna arrays, such as microstrip and Substrate Integrated Waveguide (SIW) arrays and slot antenna arrays, are two major technologies for millimeter wave applications. The inefficiency of microstrip and SIW antenna arrays imposes many limitations on their practical millimeter wave applications. One major aspect limiting the achievable gain of these antenna arrays is the loss in the feed network. In practice, implementing a high gain array antenna in the millimeter wave band requires a low loss feed network. As a common candidate, fed waveguide slot arrays have been used to achieve high gain and efficiency. At high frequencies, these antennas require precision, high precision and expensive manufacturing.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem of how to provide a gap waveguide feed millimeter wave microstrip antenna unit and an array antenna which are convenient to mechanically assemble, low in cost and high in gain.

In order to solve the technical problems, the technical scheme adopted by the utility model is as follows: a gap waveguide feed millimeter wave microstrip antenna unit which is characterized in that: the metal base plate comprises a metal base plate, wherein a plurality of metal pins are formed on the upper surface of the metal base plate, ridge gap waveguides are formed between the metal pins close to the middle of the metal base plate, the ridge gap waveguides are fixed on the upper surface of the metal base plate, the inner side end parts of the ridge gap waveguides are located in the middle of the metal base plate, the outer side end parts of the ridge gap waveguides are located at the edge parts of the metal base plate, an upper metal plate is arranged on the upper surface of each metal pin, a coupling hole is formed in the center of the upper metal plate, the inner side end parts of the ridge gap waveguides are located on the lower side of the coupling hole, a dielectric layer is formed on the upper surface of the upper metal plate, a plurality of radiation pieces are formed on the upper surface of the dielectric layer, the radiation pieces are interconnected through microstrip lines, and the microstrip lines are located on the upper side of the coupling hole; the height of the ridge gap waveguide is smaller than that of the metal pin; the upper metal plate is fixedly connected with the metal base plate through a support column, so that an air gap is formed between the upper metal plate and the upper surface of the metal pin.

Preferably, the air gap is 0.05 mm.

The further technical scheme is as follows: the whole of the radiation pieces is rectangular, the four radiation pieces are arranged in a circumferential mode, an extension portion is formed on the inner side of each radiation piece, and the extension portions are interconnected through the microstrip lines.

The further technical scheme is as follows: the microstrip line comprises a central feeder line positioned in the middle and lateral feeder lines positioned at two ends of the central feeder line, and four lateral feeder lines are arranged and are respectively connected with the extending parts on the radiating fins.

The further technical scheme is as follows: the coupling hole is opposite to the medium plate between the extending parts.

Preferably, the radiation pieces have a length of 1.6mm, a width of 1.25mm and a thickness of 18 μm, and the center-to-center distance between adjacent radiation pieces is 2.45 mm in both the x and y directions.

The utility model also discloses a gap waveguide feed millimeter wave microstrip array antenna, which is characterized in that: the antenna comprises 16 millimeter wave microstrip antenna units, and the connection between the antenna units is realized by connecting a power divider with ridge gap waveguides in the antenna units.

The further technical scheme is as follows: a via hole is formed in the center of a metal base plate in the array antenna, an input waveguide is formed in the via hole, the input waveguide is connected with the power divider, and an input signal is distributed to ridge gap waveguides in the antenna unit for transmission through the power divider.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: in the array antenna, the waveguide can be realized without metal contact between the upper surface (metal pins) and the lower surface (upper metal plate), and the antenna with mechanical assembly design is simplified, so that the production cost of the antenna is reduced. In addition, the array antenna provided by the application is tested through experiments, when the working frequency is 57.5-67.2GHz, the antenna has 15.5% of impedance bandwidth, the reflection coefficient is lower than-10 dB, the gain is higher than 21.5dBi, the side lobe level of an E surface and an H surface is lower than-13 dB, and the RGW fed antenna array can be widely applied to microstrip antennas.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 1 is a schematic structural diagram of an antenna unit according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a center feed line and a side feed line in an embodiment of the present invention

Fig. 3 is a side view of an antenna unit according to an embodiment of the present invention;

FIG. 4 is a graph of the reflection coefficient of an antenna unit embodying the present invention;

fig. 5 is a schematic partial sectional view of an array antenna according to an embodiment of the present invention;

FIG. 6 is an enlarged schematic view of the structure at A in FIG. 5;

FIG. 7 is a simulation and measurement of | S11

FIG. 8 is a plot of simulated directivity and measured gain for the array antenna and 100%, 90%, 80%, and 70% efficiency lines in an embodiment of the present invention;

FIG. 9a is the array antenna radiation pattern (E-plane-58 GHz) in an embodiment of the present invention;

FIG. 9b is the array antenna radiation pattern (H-plane-58 GHz) in an embodiment of the present invention;

FIG. 9c is the array antenna radiation pattern (E-plane-62 GHz) in an embodiment of the present invention;

FIG. 9d is the array antenna radiation pattern (H-plane-62 GHz) in an embodiment of the present invention;

FIG. 9E is the array antenna radiation pattern (E-plane-67 GHz) in an embodiment of the present invention;

FIG. 9f is the array antenna radiation pattern (H-plane-67 GHz) in an embodiment of the present invention;

wherein: 1. a metal base plate; 2. a metal pin; 3. a ridge gap waveguide; 4. an upper metal plate; 5. a coupling hole; 6. a dielectric layer; 7. a radiation sheet; 8. an air gap; 9. a center feed line; 10. a lateral feeder line; 11. a power divider; 12. an input waveguide.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

As shown in fig. 1-3, an embodiment of the present invention discloses a gap waveguide feed millimeter wave microstrip antenna unit, including a metal base plate 1, where the upper surface of the metal base plate 1 is formed with a plurality of metal pins 2, and the specific number of the metal pins 2 may be set as required; a ridge gap waveguide 3 is formed between the metal pins 2 close to the middle, the ridge gap waveguide 3 is fixed on the upper surface of the metal base plate 1, the inner side end of the ridge gap waveguide 3 is located in the middle of the metal base plate 1, and the outer side end of the ridge gap waveguide 3 is located at the edge part of the metal base plate 1; the upper surface of metal pin 2 is provided with upper metal sheet 4, the center of upper metal sheet 4 is formed with coupling hole 5, just the medial extremity position of ridge clearance waveguide 3 is in the downside of coupling hole 5, the upper surface of upper metal sheet 4 is formed with one deck dielectric layer 6, the upper surface of dielectric layer 6 is formed with a plurality of radiation piece 7, carry out the interconnection through the microstrip line between the radiation piece 7, just the microstrip line is located the upside of coupling hole 5.

As shown in fig. 1, the height of the ridge gap waveguide 3 is smaller than the height of the metal pin 2. The upper metal plate 4 is fixedly connected with the metal base plate 1 through a support column, so that an air gap 8 is formed between the upper metal plate 4 and the upper surface of the metal pin 2, preferably, the air gap 8 may be 0.05 mm. Further, as shown in fig. 1, the whole of the radiation pieces 7 is rectangular, the four radiation pieces 7 are arranged in a circumferential manner, an extension portion is formed on the inner side of each radiation piece 7, and the extension portions are interconnected through the microstrip line. The microstrip line comprises a central feeder line 9 positioned in the middle and lateral feeder lines 10 positioned at two ends of the central feeder line 9, and four lateral feeder lines 10 are arranged and are respectively connected with the extending parts on each radiating patch 7. Preferably, the radiation pieces 7 have a length of 1.6mm, a width of 1.25mm and a thickness of 18 μm, and the center-to-center distance between adjacent radiation pieces 7 is 2.45 mm in both x and y directions (0.49 λ at 60 GHz)₀）。

Thus, the problems associated with grating lobes will be much smaller than other gap waveguide slot array antennas. Microstrip patches are a narrow band resonant structure. There are many techniques available to increase the bandwidth of microstrip patch antennas. To extend the bandwidth, the coupling slot is used to feed the patch's center feed. Due to the large number of design parameters, aperture coupled feeding provides greater radiation mode symmetry and greater impedance bandwidth design ease.

Microstrip patches are a narrow band resonant structure. To extend the bandwidth, a coupling slot is used to feed the patch center feed. The aperture coupled feed provides a better symmetric radiation pattern, with a larger impedance bandwidth being easier to design due to a large number of design parameters. In the present application, power is distributed using a topology of microstrip T-junctions, and power is distributed using microstrip T-junctions having broadband characteristics. Therefore, by properly designing the length and width of the aperture and the width of the center feed line, a wider impedance matching is achieved. The lower layer contains some metal pins and ridges forming an RGW distribution network. Periodic metal pins are implanted on either side of the ridge to create the desired stop band characteristics and prevent the wave from propagating in unwanted directions. The pin size is selected to achieve a cutoff bandwidth of 40GHz-100 GHz. As shown in fig. 3, there is a small air gap between the top surface of the metal pin 2 and the upper metal plate 4, so that no electrical contact is required between them. The RGW feed structure excites a coupling slot etched in the substrate ground plane. By optimizing the dimensions of the coupling slot and the microstrip feed line, four patches can be excited with the same amplitude and phase. Note that the four radiating patches have the same electric field phase and amplitude, which indicates that the sub-array has a maximum at the broadside.

The antenna element is designed to have dimensions of 4.9 x 4.9mm in the x and y directions². The infinite array method used involves mutual coupling between sub-arrays. As shown in FIG. 4, the reflection coefficient of the antenna element shows | S11<The bandwidth of-10 dB is 56.5-66 GHz (15.5%).

Aperture-coupled microstrip antenna arrays fed by ridge-gap waveguide (RGW) feed networks at the 60GHz band are studied in this application. An array of 16 antenna elements was designed and simulated. The main advantages are that: this structure can maintain a two-layer planar profile compared to a three-layer slot array comprising a feed network, a cavity layer and a radiating slot layer. The proposed antenna element has dimensions of 4.9mm (0.98 λ 0) x 4.9mm (0.98 λ 0), and if scanning is required, less than 8.8mm (1.76 λ 0) x 8.8mm (1.76 λ 0) within allowable limits. In addition, a 4 x 4 array antenna is presented in this application with 15.5% impedance bandwidth at operating frequency (57.5-67.2 GHz), reflection coefficient below-10 dB, gain above 21.5dBi, and side lobe levels in the E-and H-planes below-13 dB. Simulations and measurements show that the proposed array antenna has high gain and high efficiency for 60GHz applications. The metallic feed network can be easily manufactured by Computer Numerical Control (CNC) milling, forming or electro-discharge machining.

For high gain applications, an antenna array with 4 x 4 is designed, and the composite feed network is implemented by interconnecting T-junction power dividers as shown in fig. 5. On the lower layer, an RGW power divider is designed, 16 array antennas on the upper layer are designed through 16 rectangular coupling slots, and a feed network is designed on the basis of a quarter-wave impedance transformer and a matched T-shaped junction.

Specifically, as shown in fig. 5 to 6, the present invention further discloses a gap waveguide feed millimeter wave microstrip array antenna, which includes 16 millimeter wave microstrip antenna units, and the connection between the antenna units is realized by connecting a power divider 11 with ridge gap waveguides in the antenna units. A via hole is formed in the center of the metal base plate 1 in the array antenna, an input waveguide 12 is formed in the via hole, the input waveguide 12 is connected with the power divider 11, and an input signal is distributed to the ridge gap waveguide 3 in the antenna unit through the power divider 11 for transmission.

For measurement purposes, a broadband tight transition is designed between the input waveguide and the ridge gap waveguide 3 (RGW), as shown in fig. 6. It is observed that at the end of the ridge-gap waveguide 3, two steps are used, which causes the mode of the RGW to be converted to the TE10 mode of the rectangular waveguide. The transition is designed and optimized to achieve minimum reflection and insertion loss in the operating band. The left and right sides of the feed layer are mirrored due to the differential output provided by the transition transitions in the two ridge-gap waveguides 3. The input power to the waveguide excites the antenna through a designed transition and then flows through an RGW 16 power splitter. All parameters of the transition, power divider and microstrip structure are optimized for the desired matching.

The designed array antenna was manufactured by standard CNC milling techniques and was fed by a standard rectangular waveguide for experimental validation of the array antenna operation. The measurement, gain and radiation pattern at S11 were performed by a millimeter wave band vector network analyzer in an outdoor test range measurement system. The simulated and measured antenna array input reflection coefficients are shown in fig. 7. The measurement bandwidth-10 dB of | < S11| < is 15.5% of 57.5-67.2 GHz. The differences between the measurement results and the simulation results are due to manufacturing tolerances and assembly tolerances. Fig. 8 shows frequency characteristics such as directivity, gain, and aperture efficiency of the antenna. However, the difference between the measured gain and the simulated directivity results is less than 1 dB. This difference is partly due to metal losses in the simulation and measurement setup caused by the deviation of the dielectric and the tolerances of the manufactured antenna. The total radiation efficiency of the antenna array is still higher than 75% over the operating frequency band. The difference between the simulated and measured values at 60-61GHz is the measurement uncertainty that is considered in the measurement chamber to be ± 0.25dB or about 0.5dB due to the use of a standard gain horn. Figures 9a-9f show simulated and measured normalized radiation patterns for the E-plane and the H-plane at 67 GHz. The main reason for the small difference is the measurement uncertainty. The 3dB beamwidth radiation pattern measured at 62GHz is approximately 13 and 15 in the E and H planes, and further the maximum sidelobe level measured at 62GHz is-13.5 dB, the front-to-back ratio is better than 25dB, and the cross polarization level in the antenna axis is-28 dB.

In summary, the array antenna described in the present application has an impedance bandwidth of 15.5% at an operating frequency (57.5-67.2 GHz), a reflection coefficient lower than-10 dB, a gain higher than 21.5dBi, and a side lobe level of an E-plane and an H-plane lower than-13 dB, and the RGW-fed antenna array can be widely applied to microstrip antennas.

Claims

1. A gap waveguide feed millimeter wave microstrip antenna unit which is characterized in that: the metal base plate comprises a metal base plate (1), wherein a plurality of metal pins (2) are formed on the upper surface of the metal base plate (1), ridge gap waveguides (3) are formed between the metal pins (2) and are close to the middle, the ridge gap waveguides (3) are fixed on the upper surface of the metal base plate (1), the inner side ends of the ridge gap waveguides (3) are located in the middle of the metal base plate (1), the outer side ends of the ridge gap waveguides (3) are located at the edge part of the metal base plate (1), an upper metal plate (4) is arranged on the upper surface of the metal pins (2), a coupling hole (5) is formed in the center of the upper metal plate (4), the inner side ends of the ridge gap waveguides (3) are located on the lower side of the coupling hole (5), a dielectric layer (6) is formed on the upper surface of the upper metal plate (4), a plurality of radiation pieces (7) are formed on the upper surface of the dielectric layer (6), the radiation pieces (7) are interconnected through microstrip lines, and the microstrip lines are positioned on the upper side of the coupling hole (5); the height of the ridge gap waveguide (3) is smaller than that of the metal pin (2); the upper metal plate (4) is fixedly connected with the metal base plate (1) through a support column, so that an air gap (8) is formed between the upper metal plate (4) and the upper surface of the metal pin (2).

2. The gap waveguide fed millimeter wave microstrip antenna element of claim 1 wherein: the air gap (8) is 0.05 mm.

3. The gap waveguide fed millimeter wave microstrip antenna element of claim 1 wherein: the whole of the radiation pieces (7) is rectangular, the four radiation pieces (7) are arranged in a circumferential mode, an extension portion is formed on the inner side of each radiation piece (7), and the extension portions are interconnected through the microstrip lines.

4. The gap waveguide fed millimeter wave microstrip antenna element of claim 3 wherein: the microstrip line comprises a central feeder line (9) located in the middle and lateral feeder lines (10) located at two ends of the central feeder line (9), and four lateral feeder lines (10) are arranged and are respectively connected with the extending portions on the radiating fins (7).

5. The gap waveguide fed millimeter wave microstrip antenna element of claim 3 wherein: the coupling hole (5) is opposite to the medium layer (6) between the extending parts.

6. The gap waveguide fed millimeter wave microstrip antenna element of claim 1 wherein: the length of the radiation pieces (7) is 1.6mm, the width of the radiation pieces is 1.25mm, the thickness of the radiation pieces is 18 mu m, and the center distance between every two adjacent radiation pieces (7) is 2.45 mm in the x direction and the y direction.

7. The utility model provides a clearance waveguide feed millimeter wave microstrip array antenna which characterized in that: comprising 16 millimeter wave microstrip antenna elements according to any of claims 1-6, the connection between said antenna elements being realized by a power splitter (11) connected to a ridge gap waveguide in said antenna elements.

8. The gap waveguide fed millimeter wave microstrip array antenna of claim 7 wherein: a through hole is formed in the center of a metal bottom plate (1) in the array antenna, an input waveguide (12) is formed in the through hole, the input waveguide (12) is connected with the power divider (11), and an input signal is distributed to a ridge gap waveguide (3) in the antenna unit through the power divider (11) to be transmitted.