A miniaturized wideband 5G millimeter wave filtering antenna based on substrate integrated waveguide

Abstract

The application discloses a miniaturized wideband 5G millimeter wave filtering antenna based on a substrate integrated waveguide, which comprises a dielectric substrate, a radiation patch, a driven patch, a metal layer, a metal ground plate, a microstrip feed line, a short-circuit through hole and a microstrip feed line to substrate integrated waveguide structure; the dielectric substrate comprises a first dielectric substrate, a second dielectric substrate and a third dielectric substrate; the metal layer comprises a planar inverted F antenna metal layer and a substrate integrated waveguide lower surface metal layer; the radiation patch and the planar inverted F antenna metal layer are printed on the upper surface of the first dielectric substrate; the driven patch is printed on the upper surface of the second dielectric substrate; the metal ground plate is printed on the upper surface of the third dielectric substrate and is etched with a rectangular feed gap and a U-shaped gap, and the microstrip feed line, the microstrip feed line to substrate integrated waveguide structure and the substrate integrated waveguide lower surface metal layer are printed on the lower surface of the third dielectric substrate. The application has the advantages of wide frequency band, small size, simple structure, high out-of-band gain suppression level and the like.

Description

Technical Field

[0001] The present invention relates to a communication antenna, and in particular to a miniaturized broadband 5G millimeter wave filtering antenna based on a substrate integrated waveguide. Background Art

[0002] Fifth-generation (5G) mobile communication technology, which operates in the millimeter-wave frequency band, has become a focus of attention in the current mobile communications industry. 5G millimeter-wave communication offers advantages such as high data transmission, large capacity, and low latency, while also alleviating the challenge of spectrum resource shortages. The 5G RF front-end (RFF) is a core component of 5G mobile communication modules, and filters and antennas are key components of the RFF. In 5G millimeter-wave RFFs, filters are often required to suppress out-of-band noise. With the continuous advancement of wireless communication technology, RF front-end systems are moving towards high integration, miniaturization, and high performance. Currently, in the millimeter-wave frequency band, antennas and filters can be compactly integrated. There are two typical filter-antenna design approaches: cascading filters and antennas, and integrating the filtering function into the antenna design without designing additional filtering circuits.

[0003] The first approach, cascading filters and antennas, involves directly incorporating filtering circuitry into the antenna's feed network. This approach offers advantages in terms of design simplicity and high out-of-band gain suppression. However, this approach also suffers from disadvantages such as high insertion loss from the additional filtering circuitry and large antenna size. A more common approach to cascading filters and antennas is to design the antenna cascade filtering circuitry using substrate-integrated waveguides. In recent years, several millimeter-wave filtering antennas have been implemented based on substrate-integrated waveguide filters. These antennas exhibit excellent out-of-band gain suppression. However, their bandwidth is typically narrow, which is insufficient for certain broadband applications. Furthermore, due to the integration of the substrate-integrated waveguide filter, some of these antennas are bulky. For example, Hui Chu, Yong-Xin Guo, et al. published "A 3-D millimeter-wave filtering antenna with high selectivity and low cross-polarization." This filtering antenna, consisting of a substrate-integrated waveguide and a cavity-backed dual-slot antenna, achieves out-of-band gain suppression exceeding 40 dB, but the impedance matching bandwidth is only 1.56%, and the antenna occupies 0.92 × 1λ. c 2 (λ cThe dual-polarization design in “A filtering dual-polarized antenna subarray targeting for base stations in millimeter-wave 5G wireless communications” by Nui Chu, Yong-Xin Guo, et al. occupies 1.73×1.73λ. c 2 of larger size.

[0004] The second approach, integrating filtering into the antenna, involves integrating the filter with the antenna without designing additional filtering circuitry. Filtering is achieved by using specific resonant structures within the antenna, such as parasitic patches, slots, short-circuit vias, microstrip stubs, and metal rings, to create radiation nulls outside the operating passband. Because the resonant structures are designed to resonate outside the passband, their impact on antenna performance within the passband is minimal. These radiation nulls can be purposefully designed to control key antenna specifications such as impedance matching bandwidth, passband bandwidth, and out-of-band gain suppression. The primary design challenge of this approach is creating and controlling the radiation nulls. This approach eliminates the need for additional filtering circuitry and offers advantages such as lower insertion loss and more compact size. However, this method of modifying the antenna structure currently lacks comprehensive and rigorous calculation formulas and relies heavily on the researcher's experience and the optimization and debugging of electromagnetic simulation software to achieve accurate results. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems and provide a miniaturized broadband 5G millimeter-wave filter antenna based on substrate integrated waveguide, which has the advantages of wide bandwidth, small size, simple structure, and high out-of-band gain suppression level.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A miniaturized broadband 5G millimeter-wave filter antenna based on a substrate-integrated waveguide, comprising a dielectric substrate, a patch, a metal layer, a metal floor, a microstrip feeder, a short-circuit via, and a microstrip feeder-to-substrate integrated waveguide structure;

[0008] The dielectric substrates include three and are stacked together in sequence, the three dielectric substrates are respectively a first dielectric substrate, a second dielectric substrate and a third dielectric substrate; the patch includes a radiation patch and a driving patch; the metal layer includes a planar inverted F antenna metal layer and a substrate integrated waveguide bottom surface metal layer;

[0009] The radiation patch and the planar inverted-F antenna metal layer are printed on the upper surface of the first dielectric substrate; the driving patch is printed on the upper surface of the second dielectric substrate; the metal floor is printed on the upper surface of the third dielectric substrate, and a rectangular feed slot and a U-shaped slot are etched on the metal floor. The rectangular feed slots are provided with two and are symmetrically arranged, and the U-shaped slots are provided with two and are symmetrically arranged; the microstrip feed line, the microstrip feed line to substrate integrated waveguide structure and the metal layer on the lower surface of the substrate integrated waveguide are printed on the lower surface of the third dielectric substrate; the two ends of the microstrip feed line to substrate integrated waveguide structure are respectively connected to the microstrip feed line and the metal layer on the lower surface of the substrate integrated waveguide;

[0010] The short-circuit through holes include a first short-circuit through hole and a second short-circuit through hole; the first dielectric substrate and the second dielectric substrate are both provided with a plurality of first short-circuit through holes, and the first short-circuit through holes are connected between the metal layer of the inverted-F antenna and the metal floor; the third dielectric substrate is provided with a plurality of second short-circuit through holes, and the second short-circuit through holes are connected between the metal floor and the metal layer on the lower surface of the substrate integrated waveguide.

[0011] In a preferred embodiment of the present invention, the dielectric substrate is made of FerroA6M-E material and processed by low-temperature co-fired ceramic technology to obtain a low profile and smaller antenna size. While achieving miniaturization, the use of this technology also makes the antenna easy to integrate with the chip, and can be applied in the field of millimeter wave packaged antennas.

[0012] Furthermore, the thickness of the dielectric substrate is a multiple of 0.094 mm.

[0013] Furthermore, the thickness of the first dielectric substrate is 0.564 mm, the thickness of the second dielectric substrate is 0.47 mm, and the thickness of the third dielectric substrate is 0.094 mm.

[0014] In a preferred embodiment of the present invention, the size of the driving patch is 0.14λc×0.14λc, and the size of the driving patch is larger than that of the radiation patch to achieve good impedance matching.

[0015] In a preferred embodiment of the present invention, the size of the metal layer of the planar inverted-F antenna is 0.05λc×0.03λc.

[0016] In a preferred embodiment of the present invention, the two rectangular feeding slots are completely identical and have a length of 0.18λc, where λc is the wavelength at the center frequency of the passband.

[0017] In a preferred embodiment of the present invention, two rectangular feed slots are located between two U-shaped slots to obtain a better out-of-band gain suppression level.

[0018] In one preferred embodiment of the present application, the two U-shaped slots are identical, and the length of each U-shaped slot is 0.18λc, where λc is the wavelength at the center frequency of the passband.

[0019] In one preferred embodiment of the present application, the opening of the U-shaped slot faces the rectangular feed slot.

[0020] In one preferred embodiment of the present application, the width of the end of the microstrip feed line conversion substrate integrated waveguide structure connected to the microstrip feed line is equal to the width of the microstrip feed line, and the width of the end of the microstrip feed line conversion substrate integrated waveguide structure connected to the lower surface metal layer of the substrate integrated waveguide is greater than the width of the microstrip feed line, and the reference width is 0.07λc, and the width needs to be adjusted appropriately to obtain good impedance matching and lower insertion loss.

[0021] In one preferred embodiment of the present application, the diameter of the first short-circuit through hole and the second short-circuit through hole is 0.1mm. The diameter of the short-circuit through hole can be adjusted appropriately, and according to the processing specification of the low-temperature co-fired ceramic technology, the commonly used through hole diameter is 0.10mm, 0.15mm, 0.20mm, 0.25mm.

[0022] In one preferred embodiment of the present application, the second short-circuit through hole is provided with two rows, and each row of second short-circuit through holes includes a plurality of second short-circuit through holes.

[0023] The rectangular feed slot and the U-shaped slot are located between the two rows of second short-circuit through holes.

[0024] Further, the pitch of each row of second short-circuit through holes is 0.3mm. The distance between the through holes in the same row is not less than three times the diameter of the through hole.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] The present application adopts a differential coupling feed mode to realize a relatively wide impedance matching bandwidth, and adopts an integrated substrate integrated waveguide, a loaded planar inverted F antenna, and a U-shaped slot loaded on the floor to generate two radiation zeros, thereby realizing a good out-of-band gain suppression level, and having the advantages of wide frequency band, small size, simple structure, high out-of-band gain suppression level, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 FIG. 1 is a perspective view of a substrate integrated waveguide-based miniaturized wideband 5G millimeter wave filtering antenna according to the present application.

[0028] Figure 2 FIG. 3 is a top view of a third dielectric substrate of the substrate integrated waveguide-based miniaturized wideband 5G millimeter wave filtering antenna according to the present application.

[0029] Figure 3This is a surface current distribution diagram of the passband center frequency radiation patch of the present invention.

[0030] Figure 4 This is a surface current distribution diagram of the low-frequency radiation zero-point radiation patch of the present invention.

[0031] Figure 5 This is the surface current distribution diagram of the passband center frequency and high-frequency radiation zero point metal floor of the present invention.

[0032] Figure 6 This is a reflection coefficient curve of the miniaturized broadband 5G millimeter-wave filtering antenna based on substrate integrated waveguide of the present invention.

[0033] Figure 7 This is a gain curve diagram of the miniaturized broadband 5G millimeter-wave filtering antenna based on substrate integrated waveguide of the present invention.

[0034] Figure 8 This is an efficiency curve diagram of the miniaturized broadband 5G millimeter-wave filtering antenna based on substrate integrated waveguide of the present invention.

[0035] Figure 9 This is the 25 GHz radiation pattern of the miniaturized broadband 5G millimeter wave filtering antenna based on substrate integrated waveguide of the present invention.

[0036] Figure 10 This is the 27 GHz radiation pattern of the miniaturized broadband 5G millimeter wave filtering antenna based on substrate integrated waveguide of the present invention.

[0037] Figure 11 This is the 30 GHz radiation pattern of the miniaturized broadband 5G millimeter wave filtering antenna based on substrate integrated waveguide of the present invention. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0039] See also Figure 1-2 The miniaturized broadband 5G millimeter-wave filter antenna based on substrate integrated waveguide of this embodiment includes a dielectric substrate, a patch, a metal layer, a metal floor 1, a microstrip feed line 2, a short-circuit through hole and a microstrip feed line to substrate integrated waveguide structure 3.

[0040] See also Figure 1-2 The dielectric substrates include three and are stacked together in sequence. The three dielectric substrates are respectively a first dielectric substrate 4, a second dielectric substrate 5 and a third dielectric substrate 6; the patch includes a radiation patch 7 and a driving patch 8; the metal layer includes a planar inverted F antenna metal layer 9 and a substrate integrated waveguide bottom surface metal layer 10.

[0041] See also Figure 1-2 The radiation patch 7 and the planar inverted-F antenna metal layer 9 are printed on the upper surface of the first dielectric substrate 4; the driving patch 8 is printed on the upper surface of the second dielectric substrate 5; the metal floor 1 is printed on the upper surface of the third dielectric substrate 6, and a rectangular feeding slot 11 and a U-shaped slot 12 are etched on the metal floor 1 (specifically, the U-shaped slot 12 refers to a slot with a U-shaped structure, including a U-shaped structure, an E-shaped structure, etc.), the rectangular feeding slot 11 is provided with two and is symmetrically arranged, and the U-shaped slot 12 is provided with two and is symmetrically arranged; the microstrip feed line 2, the microstrip feed line to substrate integrated waveguide structure 3 and the substrate integrated waveguide lower surface metal layer 10 are printed on the lower surface of the third dielectric substrate 6; the two ends of the microstrip feed line to substrate integrated waveguide structure 3 are respectively connected to the microstrip feed line 2 and the substrate integrated waveguide lower surface metal layer 10.

[0042] See also Figure 1-2 The short-circuit through holes include a first short-circuit through hole 13 and a second short-circuit through hole 14; the first dielectric substrate 4 and the second dielectric substrate 5 are each provided with a plurality of first short-circuit through holes 13, and the first short-circuit through holes 13 are connected between the planar inverted-F antenna metal layer 9 and the metal floor 1; the third dielectric substrate 6 is provided with a plurality of second short-circuit through holes 14, and the second short-circuit through holes 14 are connected between the metal floor 1 and the metal layer 10 on the lower surface of the substrate integrated waveguide.

[0043] Specifically, the dielectric substrate adopts FerroA6M-E material and is processed by low-temperature co-fired ceramic technology to obtain a low profile and smaller antenna size. While achieving miniaturization, the use of this technology also makes the antenna easy to integrate with the chip, and can be applied in the field of millimeter wave packaged antennas.

[0044] Furthermore, the thickness of the dielectric substrate is a multiple of 0.094 mm.

[0045] Furthermore, the thickness of the first dielectric substrate 4 is 0.564 mm, the thickness of the second dielectric substrate 5 is 0.47 mm, and the thickness of the third dielectric substrate 6 is 0.094 mm.

[0046] Specifically, the size of the driving patch 8 is 0.14λc×0.14λc, and the size of the driving patch 8 is slightly larger than that of the radiation patch 7 to achieve good impedance matching.

[0047] Specifically, the size of the planar inverted-F antenna metal layer 9 is 0.05λc×0.03λc.

[0048] Specifically, the two rectangular feeding slots 11 are identical, and have a length of 0.18λc, where λc is the wavelength at the center frequency of the passband.

[0049] Specifically, the two rectangular feeding slots 11 are located between the two U-shaped slots 12 to obtain a better out-of-band gain suppression level.

[0050] Specifically, the two U-shaped slots 12 are identical, and have a length of 0.18λc, where λc is the wavelength at the center frequency of the passband.

[0051] Specifically, the opening of the U-shaped slot 12 faces the rectangular feeding slot 11 .

[0052] Specifically, the width of one end of the microstrip feed line to substrate integrated waveguide structure 3 connected to the microstrip feed line 2 is equal to the width of the microstrip feed line 2, and the width of one end of the microstrip feed line to substrate integrated waveguide structure 3 connected to the metal layer 10 on the lower surface of the substrate integrated waveguide is greater than the width of the microstrip feed line 2. The reference width is 0.07λc, and the width needs to be appropriately adjusted to obtain good impedance matching and lower insertion loss.

[0053] Specifically, the diameters of the first short-circuit through hole 13 and the second short-circuit through hole 14 are both 0.1 mm. The diameters of the short-circuit through holes can be adjusted appropriately. According to the processing specifications of low-temperature co-fired ceramic technology, commonly used through hole diameters are 0.10 mm, 0.15 mm, 0.20 mm, and 0.25 mm.

[0054] See also Figure 1-2 The second short-circuit through holes 14 are provided in two rows, and each row of the second short-circuit through holes 14 includes a plurality of second short-circuit through holes 14 ; the rectangular feeding slot 11 and the U-shaped slot 12 are both located between the two rows of the second short-circuit through holes 14 .

[0055] Furthermore, the spacing between the second short-circuit through holes 14 in each row is 0.3 mm, and the distance between through holes in the same row is not less than three times the diameter of the through holes.

[0056] See also Figure 1-2 The working principle of the miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide of this embodiment is as follows:

[0057] The surface current distribution of the antenna's radiation patch 7 and the planar inverted-F antenna at the passband center frequency is shown as follows: Figure 3 As shown in Figure 1, at the center frequency of the passband, most of the current flows in the same direction, and the current density on the radiating patch 7 is large. At this time, the antenna radiates normally and the gain is at a normal level. At the frequency point where the low-frequency radiation zero point is located, the surface current distribution of the antenna's radiating patch 7 and the planar inverted F antenna is as follows: Figure 4As shown. At this time, the current with high current density is mainly concentrated on the surface of the planar inverted F antenna, and the current density on the radiation patch 7 is very small. In addition, the current on the planar inverted F antenna is opposite to the current on the radiation patch 7, generating radiation in the opposite direction to the radiation patch 7. Therefore, the radiation from the opposite current produces a canceling effect, forming a radiation null in the low frequency band. As for the U-shaped gap etched on the floor, Figure 5 The surface current distribution of the metal floor 1 of the proposed antenna at the passband center frequency and the high-frequency radiation null is shown. At the passband center frequency, the surface current on the floor is concentrated around the rectangular feed slot, indicating normal radiation. At the high-frequency radiation null frequency, the surface current on the metal floor 1 is mainly concentrated near the U-shaped slot, preventing normal radiation. The surface current density of the antenna's radiating patch 7 and the planar inverted-F antenna is very low, and the gain is relatively low, resulting in another radiation null in the high-frequency band.

[0058] By adjusting the size of the planar inverted-F antenna metal layer 9 and the length of the U-shaped slot, the frequencies of the low-frequency radiation zero point and the high-frequency radiation zero point can be adjusted respectively to achieve frequency tuning.

[0059] The reflection coefficient of the antenna is Figure 6 As shown, S 11 The impedance matching bandwidth with a response of less than -10dB is 24.32GHz to 30GHz (21%), and the frequency range basically covers the N257, N258, and N261 bands in the 5G millimeter wave communication band, achieving good impedance matching. Figure 7 As shown in the figure, the maximum gain in the passband is 5.3dBi, there is a radiation zero at 18.2GHz and 35.8GHz respectively, and a good out-of-band gain suppression level of more than 16dB is achieved in the frequency range of 18-38GHz. The antenna radiation efficiency response is shown in Figure 8 As shown in the figure, the radiation efficiency within the passband is basically greater than 85%, achieving good radiation efficiency, and the radiation efficiency outside the band is less than 20%, achieving good suppression. The overall size of the antenna is 0.75λc×0.54λc×0.1λc, achieving a compact size.

[0060] Compared with other millimeter wave filter antennas, the present invention has the following advantages: First, the antenna structure is simple and easy to process in the millimeter wave frequency band. Second, compared with other substrate integrated waveguide millimeter wave filter antennas, the proposed antenna is small in size and low in profile, and has the advantage of miniaturization. At the same time, on the basis of miniaturization, it achieves an impedance matching bandwidth of 21% and an out-of-band gain suppression level higher than 16dB. The radiation patterns of the antenna at three different frequency points in the passband are as follows: Figure 9 、 Figure 10 、 Figure 11As shown, the radiation pattern is stable within the passband and the cross-polarization is kept at a small level.

[0061] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide, characterized in that: It includes a dielectric substrate, a patch, a metal layer, a metal floor, a microstrip feeder, a short-circuit through hole, and a microstrip feeder-substrate integrated waveguide structure; The dielectric substrates include three and are stacked together in sequence, the three dielectric substrates are respectively a first dielectric substrate, a second dielectric substrate and a third dielectric substrate; the patch includes a radiation patch and a driving patch; the metal layer includes a planar inverted F antenna metal layer and a substrate integrated waveguide bottom surface metal layer; The radiation patch and the planar inverted-F antenna metal layer are printed on the upper surface of the first dielectric substrate; The driving patch is printed on the upper surface of the second dielectric substrate; The metal floor is printed on the upper surface of the third dielectric substrate, and is etched with rectangular feed slots and U-shaped slots. Two rectangular feed slots are provided and are symmetrically arranged, and two U-shaped slots are provided and are symmetrically arranged. The microstrip feed line, the microstrip feed line to substrate integrated waveguide structure, and the metal layer on the lower surface of the substrate integrated waveguide are printed on the lower surface of the third dielectric substrate. The two ends of the microstrip feed line to substrate integrated waveguide structure are respectively connected to the microstrip feed line and the metal layer on the lower surface of the substrate integrated waveguide. The short-circuit through holes include a first short-circuit through hole and a second short-circuit through hole; the first dielectric substrate and the second dielectric substrate are both provided with a plurality of first short-circuit through holes, and the first short-circuit through holes are connected between the metal layer of the inverted-F antenna and the metal floor; the third dielectric substrate is provided with a plurality of second short-circuit through holes, and the second short-circuit through holes are connected between the metal floor and the metal layer on the lower surface of the substrate integrated waveguide.

2. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The dielectric substrate is made of FerroA6M-E material and is processed by low-temperature co-fired ceramic technology; The thickness of the dielectric substrate is a multiple of 0.094 mm, the thickness of the first dielectric substrate is 0.564 mm, the thickness of the second dielectric substrate is 0.47 mm, and the thickness of the third dielectric substrate is 0.094 mm.

3. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The size of the driving patch is 0.14λc×0.14λc, and the size of the driving patch is larger than that of the radiation patch.

4. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The size of the metal layer of the planar inverted-F antenna is 0.05λc×0.03λc.

5. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The two rectangular feed slots are identical, with a length of 0.18λc, where λc is the wavelength at the center frequency of the passband.

6. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: Two rectangular feed slots are located between the two U-shaped slots; The opening of the U-shaped slot faces the rectangular feeding slot.

7. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The two U-shaped slots are identical, with a length of 0.18λc, where λc is the wavelength at the center frequency of the passband.

8. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The width of one end of the microstrip feeder to substrate integrated waveguide structure connected to the microstrip feeder is equal to the width of the microstrip feeder, and the width of one end of the microstrip feeder to substrate integrated waveguide structure connected to the metal layer on the lower surface of the substrate integrated waveguide is greater than the width of the microstrip feeder.

9. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The diameters of the first short-circuit through hole and the second short-circuit through hole are both 0.1 mm.

10. The miniaturized broadband 5G millimeter wave filter antenna based on substrate integrated waveguide according to claim 1, characterized in that: The second short-circuit through holes are provided in two rows, each row of the second short-circuit through holes includes a plurality of second short-circuit through holes; the spacing between the second short-circuit through holes in each row is 0.3 mm, and the spacing between the second short-circuit through holes in the same row is not less than three times the diameter of the second short-circuit through holes; The rectangular feeding slot and the U-shaped slot are both located between two rows of second short-circuit through holes.

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