Patch antenna for W-band millimeter wave imaging

Abstract

The invention discloses a patch antenna for W-band millimeter wave imaging. The patch antenna for W-band millimeter wave imaging comprises a dielectric substrate, a radiation patch, a feed line, a coplanar waveguide structure, a first parasitic patch and a second parasitic patch, the surface of one side of the dielectric substrate is provided with the radiation patch and the feed line, and the other side of the dielectric substrate is provided with the grounding plate. The feed line is connected with the radiation patch; the coplanar waveguide structure is arranged on the dielectric substrate and is coplanar with the feed line; the coplanar waveguide structure comprises a first ground plane, a second ground plane and a third ground plane, the first ground plane and the second ground plane are arranged on two sides of the feed line, and the third ground plane is arranged on one side of the radiation patch; the first parasitic patch and the second parasitic patch are arranged on the two sides of the radiation patch. According to the invention, the working bandwidth of the patch antenna is effectively improved, a stable gain curve in a working frequency band is realized, the generation of surface waves is inhibited, and the radiation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of millimeter wave antennas, and in particular to a patch antenna for W-band millimeter wave imaging. Background Art

[0002] With the widespread application of millimeter-wave imaging technology in security inspection, non-destructive testing, biomedicine and other fields, the W-band (75-110GHz) has become an ideal frequency band due to its high resolution, strong penetration and non-ionizing characteristics. However, the front-end antennas of traditional W-band millimeter-wave imaging systems often face difficulties such as high dielectric loss, narrow antenna bandwidth (<5%), and high processing precision requirements, which greatly limit the resolution and real-time performance of the imaging system. Microstrip patch antennas are considered as candidate solutions for millimeter-wave imaging array antenna elements due to their compact structure, low profile, easy processing and low cost. However, their design in the W-band has the following problems: it is difficult to balance broadband and high radiation efficiency. The related technology will lead to a decrease in radiation efficiency while expanding the bandwidth; the mutual coupling effect between the array elements is high when the spacing between the antenna array is small; the antenna pattern is asymmetric and the gain is unstable. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a patch antenna for W-band millimeter wave imaging, which has the advantages of wide operating bandwidth, high radiation efficiency, and stable gain.

[0004] The present application proposes a patch antenna for W-band millimeter wave imaging, which includes a dielectric substrate, a feed line, a coplanar waveguide structure, a first parasitic patch, and a second parasitic patch; a radiation patch and a feed line are provided on one surface of the dielectric substrate, and a ground plane is provided on the other side; the feed line is connected to the radiation patch; the coplanar waveguide structure is provided on the dielectric substrate and is coplanar with the feed line; the coplanar waveguide structure includes a first ground plane, a second ground plane, and a third ground plane, the first ground plane and the second ground plane are provided on both sides of the feed line, and the third ground plane is provided on one side of the radiation patch; the first parasitic patch and the second parasitic patch are provided on both sides of the radiation patch.

[0005] According to the patch antenna of the present application, multi-mode resonance is introduced by loading a parasitic patch and a coplanar waveguide structure is set to optimize the feeding network, thereby effectively improving the operating bandwidth and achieving a stable gain curve within the operating frequency band. At the same time, the generation of surface waves is suppressed, the radiation efficiency is improved, the transmission loss is reduced, and the mutual coupling effect between the elements of the antenna array when the spacing is small is suppressed.

[0006] According to some embodiments of the present application, the patch antenna for W-band millimeter wave imaging further includes: a matching branch, and the matching branch is arranged on the feeding line.

[0007] According to some embodiments of the present application, the length of the matching branch is a quarter of a wavelength.

[0008] According to some embodiments of the present application, the feed line includes a first line segment and a second line segment, and the matching branch is connected between the first line segment and the second line segment.

[0009] According to some embodiments of the present application, the radiation patch is formed with a connection portion connected to the feeder line, and grooves are provided on both sides of the connection portion.

[0010] According to some embodiments of the present application, the third ground plane and the feeding line are respectively arranged on two sides of the radiation patch, and there is a gap between the third ground plane and the radiation patch.

[0011] According to some embodiments of the present application, the feeding line is extended along a first direction and connected to the radiating patch, and the first parasitic patch and the second parasitic patch are arranged on a geometric center line of the radiating patch perpendicular to the first direction and close to the radiating patch.

[0012] According to some embodiments of the present application, the first parasitic patch and the second parasitic patch are symmetrically arranged with respect to the radiation patch, and the first ground plane and the second ground plane are symmetrically arranged with respect to the feeding line.

[0013] According to some embodiments of the present application, the ground plane and the first ground plane, the second ground plane, and the third ground plane are all connected through metallized vias.

[0014] According to some embodiments of the present application, the ground plate covers the other side surface of the dielectric substrate.

[0015] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0017] Figure 1 is a schematic structural diagram of a patch antenna according to some embodiments of the present application;

[0018] Figure 2 is a top view of a patch antenna according to some embodiments of the present application;

[0019] Figure 3 is a graph showing simulation results of the reflection coefficient of a patch antenna according to some embodiments of the present application;

[0020] Figure 4 is a diagram of voltage standing wave ratio simulation results of a patch antenna according to some embodiments of the present application;

[0021] Figure 5 is the far-field radiation pattern of the patch antenna at phi = 0° (E-plane) according to some embodiments of the present application;

[0022] Figure 6 is the far-field radiation pattern of the patch antenna at phi = 90° (H-plane) according to some embodiments of the present application;

[0023] Figure 7 is a curve showing a change in the main radiation direction gain of the patch antenna as a function of frequency according to some embodiments of the present application;

[0024] Figure 8 is a schematic diagram of an array structure of a patch antenna according to some embodiments of the present application;

[0025] Figure 9 is a graph showing simulation results of reflection coefficients of an array structure of patch antennas according to some embodiments of the present application;

[0026] Figure 10 This is a diagram showing the simulation results of the isolation of feed ports of adjacent units in the array structure of the patch antenna according to some embodiments of the present application.

[0027] Reference numerals:

[0028] Dielectric substrate 10; feed line 20; first line segment 21; second line segment 22; first ground plane 31; second ground plane 32; third ground plane 33; radiation patch 40; groove 41; first parasitic patch 51; second parasitic patch 52; matching branch 60; ground plane 70; metallized via 80. DETAILED DESCRIPTION

[0029] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0030] Reference below Figure 1-Figure 2 A patch antenna for W-band millimeter wave imaging according to an embodiment of the present invention is described.

[0031] The present application proposes a patch antenna for W-band millimeter wave imaging, which includes a dielectric substrate 10, a feed line 20, a coplanar waveguide structure, a first parasitic patch 51, and a second parasitic patch 52; a radiation patch 40 and a feed line 20 are provided on one side of the dielectric substrate 10, and a ground plane 70 is provided on the other side; the feed line 20 is connected to the radiation patch 40; the coplanar waveguide structure is provided on the dielectric substrate 10 and is coplanar with the feed line 20; the coplanar waveguide structure includes a first ground plane 31, a second ground plane 32, and a third ground plane 33, the first ground plane 31 and the second ground plane 32 are provided on both sides of the feed line 20, and the third ground plane 33 is provided on one side of the radiation patch; the first parasitic patch 51 and the second parasitic patch 52 are provided on both sides of the radiation patch 40.

[0032] According to the patch antenna of the present application, the feed line 20 adopts a microstrip transmission line. Taking into account the high dielectric loss and radiation loss of the W-band microstrip transmission line, as well as the convenience of connecting the antenna to the microwave integrated circuit chip, the patch antenna of the present application is provided with a coplanar waveguide structure, and a first ground plane 31 and a second ground plane 32 are provided on both sides of the feed line 20. At the same time, a third ground plane 33 is provided on one side of the radiation patch 40. The first ground plane 31 and the second ground plane 32 use metal floors to realize a grounded coplanar waveguide, so that the feed line 20 has a single stable working mode in the W band and low radiation loss. Furthermore, the present application loads a first parasitic patch 51 and a second parasitic patch 52 (hereinafter collectively referred to as parasitic patches) on both sides of the radiation patch 40, introduces a multi-mode resonance point through electromagnetic coupling between the radiation patch 40 and the parasitic patch, improves the working bandwidth of the patch antenna, and broadens the beam width of the patch antenna. In addition, the present application adopts a grounded coplanar waveguide-fed microstrip patch antenna solution, which has a compact structure and helps to reduce the mutual coupling effect between array elements when the spacing between antenna arrays is small; at the same time, a low-profile design can be achieved, and the height of the patch antenna is less than 0.1 working wavelengths, which simplifies the antenna structure, reduces processing costs, and is suitable for large-scale production.

[0033] According to the patch antenna of the present application, by loading parasitic patches to introduce multi-mode resonance and setting a coplanar waveguide structure to optimize the feeding network, the operating bandwidth can be improved, while suppressing surface waves to improve radiation efficiency, improve gain stability, reduce radiation loss, and reduce the mutual coupling effect between array elements when the antenna array is closely spaced.

[0034] According to some embodiments of the present application, the patch antenna for W-band millimeter-wave imaging further includes a matching branch 60, which is provided on the feed line 20 and has a length of one-quarter wavelength. In this embodiment, the quarter-wavelength matching branch 60 provided on the feed line 20 can match the output impedance of the feed line 20 with the input impedance of the radiating patch, thereby achieving good impedance matching between the feed line 20 and the radiating patch 40, further improving the operating bandwidth of the antenna.

[0035] According to some embodiments of the present application, the feeder line 20 includes a first line segment 21 and a second line segment 22, and the matching branch 60 is connected between the first line segment 21 and the second line segment 22. In this embodiment, Figure 1 、 2 As shown, the matching branch 60 is disposed in the middle of the feed line 20, which can more effectively adjust the electromagnetic field distribution of the feed network, achieve precise impedance matching, and reduce interference with the radiation field of the radiating patch 40. Furthermore, the arrangement of the matching branch 60 in this embodiment makes the patch antenna more compact and easier to manufacture. In some embodiments, the matching branch 60 and the first and second line segments 21 and 22 form an integral structure. The matching branch 60 can be implemented by performing standard PCB processes such as photolithography and etching on the feed line 20, without the need for additional processing steps.

[0036] Specifically, the matching branch 60 is mainly based on the principle of quarter-wavelength impedance transformer. The input impedance of the radiation patch 40 (excluding the feeding line) is measured by electromagnetic simulation software, and then the input impedance value is matched to the 50-ohm feeding coplanar waveguide line through a quarter-wavelength line. Its size and position can be obtained through simulation testing.

[0037] According to some embodiments of the present application, the radiating patch 40 is formed with a connection portion connected to the feeder line 20, and grooves 41 are provided on both sides of the connection portion. In this embodiment, the connection between the radiating patch 40 and the feeder line 20 is slotted to form the grooves 41, which reduces discontinuities during signal transmission and further improves the operating bandwidth of the antenna.

[0038] According to some embodiments of the present application, the third ground plane 33 and the feed line 20 are respectively disposed on both sides of the radiation patch 40, and a gap is formed between the third ground plane 33 and the radiation patch 40. Figure 1 、 2 As shown, the third ground plane 33 can meet the physical structural symmetry through the above arrangement, thereby improving the symmetry of the radiation pattern, improving the asymmetry between the feeding part and the radiating part, and optimizing the far-field pattern.

[0039] According to some embodiments of the present application, the ground plane 70 is connected to the first ground plane 31, the second ground plane 32, and the third ground plane 33 via metallized vias 80. In this embodiment, the metallized via connections can ensure stable signal transmission and enhance electromagnetic shielding. The metallized vias 80 pass through the dielectric substrate 10.

[0040] According to some embodiments of the present application, the feed line 20 is extended along a first direction and connected to the radiation patch 40, and the first parasitic patch 51 and the second parasitic patch 52 are arranged on the geometric center line of the radiation patch 40 perpendicular to the first direction. Figure 1 、 2 As shown, the first direction is the X direction shown in the figure, the feed line 20 is extended along the X direction, and the first parasitic patch 51 and the second parasitic patch 52 are arranged on the geometric center line of the radiating patch 40 in the Y direction and are arranged close to the radiating patch 40. In the patch antenna, the radiating aperture is the two sides of the radiating patch perpendicular to the feed line, and the two sides parallel to the feed line hardly participate in the radiation. The parasitic patch of this embodiment uses proximity coupling to use part of the energy of the non-radiating side for radiation, thereby improving the radiation efficiency of the patch antenna; at the same time, being arranged close to the radiating patch 40 can reduce the mutual coupling effect between adjacent antenna units caused when forming an antenna array. In addition, the gap between the radiating patch 40 and the parasitic patch can be equivalent to a capacitive load, which can effectively improve the antenna operating bandwidth. The size and position of the parasitic patch can be optimized by simulation parameters to select the optimal value.

[0041] According to some embodiments of the present application, the first parasitic patch 51 and the second parasitic patch 52 are symmetrically arranged with respect to the radiation patch 40, and the first ground plane 31 and the second ground plane 32 are symmetrically arranged with respect to the feeder line 20. The symmetrical arrangement of the structure of this embodiment can improve the symmetry of the radiation pattern.

[0042] According to some embodiments of the present application, a ground plane 70 covers the other surface of the dielectric substrate 10. In this embodiment, by maximizing the effective area of the ground plane 70, a complete return path can be provided for the RF signal, forming a complete shielding layer, providing better electromagnetic shielding, optimizing the radiation pattern, and improving signal integrity.

[0043] The patch antenna for W-band millimeter wave imaging of this application was simulated and tested, and the test results are as follows: Figure 3-7 shown.

[0044] Figure 3 The figure shows the reflection coefficient simulation results of the patch antenna for W-band millimeter wave imaging of this application, which are obtained by simulating the feed port using the three-dimensional high-frequency electromagnetic field simulation software Ansys HFSS. Figure 3As shown, with the return loss lower than -10dB as the standard, the operating bandwidth of the patch antenna for W-band millimeter wave imaging is 75.1GHz-83.3GHz, and the relative bandwidth exceeds 10%. Figure 4 The voltage standing wave ratio (VSWR) of the patch antenna for W-band millimeter wave imaging of the present application is demonstrated, and the voltage standing wave ratio is less than 2 in the above-mentioned frequency range.

[0045] Figure 5 and Figure 6 The far-field radiation patterns of this application's W-band millimeter-wave imaging patch antenna at phi = 0° (E-plane) and phi = 90° (H-plane) are shown. The patch antenna has a peak gain of 7.5dBi, a 3dB beamwidth of ±50° in the E-plane, and ±30° in the H-plane.

[0046] Figure 7 The following graph shows the gain variation in the main radiation direction of the W-band millimeter-wave imaging patch antenna of this application as a function of frequency. It can be seen that the gain of the W-band millimeter-wave imaging patch antenna of this application is stable and consistently maintained above 7dBi within the operating frequency band, making it suitable for W-band millimeter-wave imaging systems.

[0047] In some embodiments, the patch antennas for W-band millimeter wave imaging of the present application can also be used in array combination, such as Figure 8 As shown in FIG, this embodiment uses three patch antennas for W-band millimeter wave imaging to form a 1×3 antenna unit array structure, and the spacing between each patch antenna unit for W-band millimeter wave imaging is 4.5 mm. In order to verify the impact of the antenna array structure on the working bandwidth and the mutual coupling characteristics, the patch antenna array structure for W-band millimeter wave imaging of this embodiment was simulated and tested. The test results are shown in FIG. Figure 9 、 10 shown.

[0048] Figure 9 This figure shows the reflection coefficient simulation results for three W-band millimeter-wave imaging patch antenna units in the patch antenna array structure for W-band millimeter-wave imaging described in this application. It can be seen that the array's composition has a negligible impact on the operating bandwidth of the W-band millimeter-wave imaging patch antenna units, and each port in the array maintains an operating bandwidth of 75.1 GHz to 83.3 GHz.

[0049] Figure 10 This figure shows the simulation results of feed port isolation between adjacent elements in the patch antenna array structure for W-band millimeter-wave imaging. It can be seen that with an array element spacing of 4.5mm, adjacent W-band millimeter-wave imaging patch antenna elements can achieve port isolation greater than 25dB within the operating frequency band, demonstrating excellent isolation performance.

[0050] According to the above test results, the patch antenna for W-band millimeter-wave imaging in this application has a wider operating bandwidth and beamwidth while maintaining a compact structure and low-profile design. It ultimately achieves an operating bandwidth of 75-83GHz (10%), a stable gain curve within the band, and a symmetrical radiation pattern, which can well meet the performance requirements of the W-band millimeter-wave imaging system for the transceiver front end. In addition, the grounded coplanar waveguide structure makes the patch antenna for W-band millimeter-wave imaging in this application easy to integrate with millimeter-wave circuits, providing core hardware support for W-band high-resolution millimeter-wave imaging equipment.

[0051] To sum up, compared with the existing technology, the present application has the following technical effects: 1. The radiating patch is loaded with a parasitic patch and multi-mode resonance is introduced, which not only improves the impedance bandwidth, but also widens the unit beam width; 2. The feeding line is provided with a quarter-wavelength matching branch to achieve good impedance matching between the feeding line and the radiating patch, thereby improving the working bandwidth of the antenna; 3. The radiating patch is provided with a groove to reduce the discontinuity in the signal transmission process and improve the working bandwidth of the antenna; 4. A third ground plane is provided to improve the symmetry of the radiation pattern by satisfying the physical structural symmetry; 5. The grounded coplanar waveguide fed microstrip patch antenna scheme is adopted to achieve a low-profile design, reduce transmission loss, simplify the antenna structure, reduce processing costs, and provide convenience for large-scale production and application.

[0052] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0053] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0054] In the description of the present invention, "plurality" means two or more.

[0055] In the description of the present invention, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact with each other, or the first and second features not being in direct contact with each other but being in contact with each other via another feature therebetween.

[0056] In the description of the present invention, “on”, “above” and “above” a first feature of a second feature include the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0057] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0058] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A patch antenna for W-band millimeter wave imaging, characterized in that: include: A dielectric substrate, wherein a radiation patch and a feeder circuit are provided on one side of the dielectric substrate, and a ground plane is provided on the other side; the feeder circuit is connected to the radiation patch; A coplanar waveguide structure, the coplanar waveguide structure being arranged on the dielectric substrate and coplanar with the feed line; the coplanar waveguide structure comprising a first ground plane, a second ground plane, and a third ground plane, the first ground plane and the second ground plane being arranged on both sides of the feed line, and the third ground plane being arranged on one side of the radiation patch; A first parasitic patch and a second parasitic patch, wherein the first parasitic patch and the second parasitic patch are arranged on both sides of the radiation patch.

2. The patch antenna for W-band millimeter wave imaging according to claim 1, characterized in that: Also includes: A matching branch is provided on the feeder line.

3. The patch antenna for W-band millimeter wave imaging according to claim 2, characterized in that: The length of the matching branch is one quarter of the working wavelength.

4. The patch antenna for W-band millimeter wave imaging according to claim 2, characterized in that: The feed line includes a first line segment and a second line segment, and the matching branch is connected between the first line segment and the second line segment.

5. The patch antenna for W-band millimeter wave imaging according to claim 1, characterized in that: The radiation patch is formed with a connection portion connected to the feeder line, and grooves are provided on both sides of the connection portion.

6. The patch antenna for W-band millimeter wave imaging according to claim 1, characterized in that: The third ground plane and the feeding line are respectively arranged on two sides of the radiation patch, and there is a gap between the third ground plane and the radiation patch.

7. The patch antenna for W-band millimeter wave imaging according to claim 1, characterized in that: The feeding line is extended along a first direction and connected to the radiation patch. The first parasitic patch and the second parasitic patch are arranged on a geometric center line of the radiation patch that is perpendicular to the first direction and are close to the radiation patch.

8. The patch antenna for W-band millimeter wave imaging according to claim 1, wherein: The first parasitic patch and the second parasitic patch are symmetrically arranged with respect to the radiation patch, and the first ground plane and the second ground plane are symmetrically arranged with respect to the feeding line.

9. The patch antenna for W-band millimeter wave imaging according to claim 1, characterized in that: The ground plane and the first ground plane, the second ground plane, and the third ground plane are all connected through metallized vias.

10. The patch antenna for W-band millimeter wave imaging according to claim 1, characterized in that: The ground plate covers the other side surface of the dielectric substrate.

Images