Filtering antenna
By using the SIW feed structure and 'L'-shaped gap design of a double-layer dielectric substrate in the RF front end, the integration of antenna and filter is achieved, solving the problems of large size and high losses in traditional designs, and miniaturization is achieved and High out-of-band suppression effect.
Patent Information
- Application Number
- CN202411371608.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2024-12-06
AI Technical Summary
In traditional RF front-end design, antenna and filter design respectively lead to large physical sizes, complex circuits and additional losses, and there are design difficulties in millimeter wave band applications.
Using a SIW feed structure based on a double-layer dielectric substrate, the integration of antenna and filter is achieved by introducing a ‘L’-shaped slot and coplanar patch, forming a slot antenna based on the SIW feed network, and optimizing the filtering characteristics.
It realizes a miniaturized design, reduces cascade loss, improves port matching and antenna gain, expands bandwidth, and meets the high out-of-band suppression needs of the millimeter wave band.
Smart Images
Figure CN119093015A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of radio frequency communication technology, and in particular to a filtering antenna applied to a 5G millimeter wave frequency band. Background Art
[0002] With the rapid development of wireless communication technology, higher requirements are put forward for miniaturization and integration of various mobile terminal devices. However, in the traditional RF front-end design, the antenna and filter are designed separately and then cascaded together through impedance matching. This traditional design will inevitably lead to larger physical size, more complex circuit design, and additional insertion loss. In addition, with the increase in the number of antenna elements in antenna array technology, the number of filters has increased dramatically, which has brought difficulties to the miniaturization design of RF communication systems. In summary, in order to reduce the cascade loss of antennas and filters and improve the integration of antennas and RF front-ends, the integrated design of antennas and filters has begun to receive more and more attention from academia and industry.
[0003] Most filter antennas are designed for microwave applications, and applications in the millimeter wave band are still relatively rare. As a new communication method, millimeter wave wireless communication has the advantages of small size, light weight, high data transmission rate, good confidentiality, and strong anti-interference ability. Summary of the invention
[0004] In view of the above-mentioned defects, an object of the present invention is to provide a filter-based antenna for use in the millimeter wave frequency band, so that the antenna and the filter are integrated with each other to achieve a miniaturized design and higher out-of-band suppression.
[0005] The technical solution of the present invention is: a millimeter wave filtering antenna based on SIW feeding based on a double-layer dielectric substrate, which operates in the 5G FR2 band (n257, n258) and realizes filtering characteristics by introducing "L"-shaped gaps, coupling gaps, and coplanar patches.
[0006] The radiator includes a first dielectric plate and four rectangular patches arranged on the first dielectric plate, an "I"-shaped coplanar patch, and each rectangular patch has a pair of "L"-shaped slits;
[0007] The SIW feeding network comprises a dielectric substrate, a metal radiation layer, a metal stratum and a metal cylinder, wherein the metal radiation layer and the metal stratum are respectively fixed on both sides of the dielectric substrate, the metal cylinder is embedded in the dielectric substrate and respectively connected to the metal radiation layer and the metal stratum, the metal cylinder is arranged around the periphery of the dielectric substrate, and together with the metal radiation layer and the metal stratum, a SIW cavity of the SIW feeding network is enclosed;
[0008] The metal radiation layer is provided with a radiation gap, and the radiation gap is located in the metal radiation layer where the first dielectric substrate and the second dielectric substrate are pressed together. A ram-horn-shaped gap is etched on the metal grounding layer at the bottom of the second dielectric substrate.
[0009] The beneficial effects of the present invention are: compared with the traditional RF front-end structure, the filter and the antenna are integrated with each other, and there is no additional loss caused by the matching circuit; there is no need to introduce an external filter, and the matching degree between the ports is higher; the overall antenna size is small and easy to integrate.
[0010] Further, according to the filtering antenna radiation unit, a rectangular coupling gap is provided between the radiator and the SIW feeding network.
[0011] According to the filtering antenna radiation unit, the width of the coupling slot is 0.4 mm and the length is 0.1λ to 0.2λ; the coupling slot is located in the SIW cavity and the distance from the short-circuit end is 0.25λg.
[0012] Wherein, λ is the air wavelength corresponding to the center frequency of the radiation network, and λg is the medium wavelength corresponding to the suppression frequency of the radiation network.
[0013] The beneficial effects of the above scheme are: forming a slot antenna based on a SIW feeding network, introducing a radiation zero point in a required frequency band, and forming a preliminary integration of an antenna and a filter.
[0014] Furthermore, the feed network is provided with a first dielectric plate, four rectangular patches arranged on the first dielectric plate, and an I-shaped coplanar patch.
[0015] Four rectangular patches and one I-shaped coplanar patch arranged on the first dielectric plate are symmetrically arranged with the center point of the coupling gap as the center, the I-shaped coplanar patch is located at the center of the axis, and the four rectangular patches are located on the left and right sides of the I-shaped patch.
[0016] The beneficial effects of the above scheme are:
[0017] (1) The use of four rectangular patches and one I-shaped coplanar patch greatly improves the antenna gain of the filtering antenna and makes up for the insufficient gain of the traditional slot antenna.
[0018] (2) The four rectangular patches and one I-shaped coplanar patch are coupled to each other, producing a filtering effect. This allows the filter to be integrated into the antenna, greatly reducing the size of the integrated antenna and filter.
[0019] Furthermore, a pair of "L"-shaped slots are etched on the rectangular patch, with the right-angled ends of the "L"-shaped slots facing the center point of the rectangular patch, and then a horn-shaped slot is etched on the metal grounding layer at the bottom of the second dielectric substrate.
[0020] The beneficial effect of the above scheme is that the filtering performance is optimized and the bandwidth is expanded without affecting the size and profile height of the antenna by using the etching gap and slotting method.
[0021] The filtering antenna is manufactured by using Rogers 4350B and PCB technology. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a structural schematic diagram of a filtering antenna radiation unit according to an embodiment of the present invention;
[0023] Figure 2 It is a structural schematic diagram of the front side of the first dielectric plate according to an embodiment of the present invention;
[0024] Figure 3 The figure is a schematic structural diagram of the interface between the first and second dielectric plates according to an embodiment of the present invention.
[0025] Figure 4 It is a schematic structural diagram of the back side of the second dielectric plate according to an embodiment of the present invention.
[0026] Figure 5 This is a simulation and measured graph of the return loss of the filtering antenna radiation unit according to an embodiment of the present invention, wherein the horizontal axis is the operating frequency in GHz, and the vertical axis is the return loss in dB.
[0027] Figure 6 This is a gain simulation and measured diagram of the filtering antenna radiation unit according to an embodiment of the present invention, where the horizontal axis is the operating frequency in GHz and the vertical axis is the gain in dB. DETAILED DESCRIPTION
[0028] The present invention will be described in further detail below in conjunction with the accompanying drawings.
[0029] See also Figure 1 to Figure 6 , Figure 1 The structure diagram of the filtering antenna 100 according to the first embodiment of the present invention is shown. The filtering antenna 100 includes a first metal layer 10, a second metal layer 20 and a third metal layer 30;
[0030] In the embodiment of the present invention, Figure 2 As shown, the first metal layer 10 includes an “I”-shaped coplanar patch 11 disposed on the first dielectric plate, four rectangular patches 12, and an “L”-shaped gap 13 etched on the rectangular patches.
[0031] like Figure 3 As shown, the second metal layer 20 includes a SIW transmission line 21 , a coupling rectangular slot 22 , and a short-circuit terminal 23 .
[0032] like Figure 4 As shown, the third metal layer 30 includes a SIW transmission line 31 , a ram-horn-shaped DGS gap 32 , and a short-circuit terminal 33 .
[0033] In this embodiment, the first dielectric plate and the second dielectric plate are pressed together, and a SIW cavity is opened at the center of the second dielectric plate, which is surrounded by a metal cylinder and upper and lower metal layers to form the SIW feeding network, and the first dielectric plate and the second dielectric plate are pressed together. Optionally, the first dielectric plate and the second dielectric plate are both Rogers 4350B (Rogers RO4350B material is a proprietary glass cloth reinforced, ceramic / hydrocarbon composite material, which has both the electrical properties of PTFE / glass cloth and the processability of epoxy resin / glass.). Optionally, the width of the first dielectric plate and the second dielectric plate is 1-1.2λ; the height of the first dielectric plate is 0.4λ~0.45λ, and the height of the second dielectric plate is 0.6λ~0.65λ.
[0034] As an optional embodiment, the first metal layer includes four rectangular patches and one I-shaped coplanar patch symmetrically arranged with the center point of the coupling slot as the center. Each rectangular patch 12 is provided with an L-shaped slot 13, and the right-angle end of the coupling slot 13 faces the center point of the rectangular patch. The high-frequency suppression characteristics of the filtering antenna 100 can be adjusted (see Figure 6 , the maximum gain and the high frequency gain are suppressed by 20db, the out-of-band suppression is high, and it can meet the actual antenna design requirements), and at the same time it can reduce the return loss. Specifically, the width of the "L"-shaped gap 13 is 0.2mm, and the length is 0.1λ~0.15λ; where λ is the air wavelength corresponding to the center frequency of the radiation network.
[0035] In this embodiment, optionally, a rectangular coupling gap 22 is provided between the second metal layer, that is, the radiator and the SIW feeding network. The coupling gap 22 is located at the center of the SIW cavity, and the distance from the short-circuit end 23 is 0.25λg. Wherein, λ is the air wavelength corresponding to the center frequency of the radiation network, and λg is the medium wavelength corresponding to the suppression frequency of the radiation network.
[0036] In this embodiment, the third metal layer is optionally provided with a horn-shaped DGS gap 32. The horn-shaped DGS gap 32 is located at the center of the SIW cavity, and the distance from the short-circuit end 23 is 0.4-0.5λ. Wherein, λ is the air wavelength corresponding to the center frequency of the radiation network. The low-frequency suppression characteristics of the filtering antenna 100 can be adjusted (see Figure 6, the maximum gain and low-frequency suppression reach 20db, the out-of-band suppression is high, which can meet the actual antenna design requirements), and at the same time reduce the return loss. Specifically, the width of the ram-horn type DGS gap 32 is 0.1mm, which is a left-right symmetrical structure, and the total length of the left ram-horn is 0.4-0.6λ; where λ is the air wavelength corresponding to the center frequency of the radiation network.
[0037] Example
[0038] This embodiment uses the Keysight E8361A vector network analyzer to perform small signal testing on the antenna. Figure 5 The comparison between the measured and simulated results of the filtering antenna shown. The simulated results of the reflection coefficient of the antenna can reach 24.32GHz-28.71GHz in the passband of -10dB. The measured results of the reflection coefficient of the antenna can reach 23.88GHz-28.74GHz in the passband of -10dB.
[0039] like Figure 6 The figure shows the comparison between the measured and simulated gain of the filtering antenna. The maximum simulated gain is 6.34dB. Compared with the maximum gain, the high frequency suppression is more than 20dB, and the low frequency suppression is more than 21dB. The maximum measured gain is 6.34dB. Compared with the maximum gain, the high frequency suppression is more than 20dB, and the low frequency suppression is more than 17dB. The difference between the measured and simulated gain and suppression is mainly due to the measurement error in the actual measurement process, and the processing accuracy also has a certain influence.
[0040] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0041] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.
Claims
1. A millimeter wave filtering antenna based on SIW feeding and based on a double-layer dielectric substrate, characterized in that: Including radiator and SIW feeding network. The radiator includes a first dielectric plate and a first layer of metal arranged on the first dielectric plate. The feeding network includes a second dielectric plate, the top of the second dielectric plate and the bottom of the first dielectric plate are pressed together, a second layer of metal is arranged on the front of the second dielectric plate; a third layer of metal is arranged on the back of the second dielectric plate, and a SIW cavity is opened at the center of the second dielectric plate, which is surrounded by a metal cylinder and upper and lower metal layers to form the SIW feeding network.
2. The radiator according to claim 1, characterized in that An "I"-shaped coplanar patch, four rectangular patches and an "L"-shaped gap etched on the rectangular patch are arranged on the first dielectric plate. The right-angle end of the "L"-shaped gap faces the center point of the rectangular patch.
3. The SIW feeding network according to claim 1, characterized in that: The front side of the second dielectric plate is provided with a second metal layer, the second metal layer includes a SIW transmission line, a coupled rectangular gap, and a short circuit end. The back side of the second dielectric plate is provided with a third metal layer, the third metal layer includes a SIW transmission line, a horn-shaped DGS gap, and a short circuit end.
4. The first metal layer according to claim 2, characterized in that The four rectangular patches and one I-shaped coplanar patch arranged on the first dielectric plate are symmetrically arranged with the center point of the coupling gap as the center, the I-shaped coplanar patch is located at the center of the axis, and the four rectangular patches are located on the left and right sides of the I-shaped patch.
5. The rectangular patch unit according to claim 4, characterized in that: An "L"-shaped gap is etched on a rectangular patch. The right-angle end of the "L"-shaped gap faces the center point of the rectangular patch. The width of the "L"-shaped gap is 0.2mm and the length is 0.1λ~0.15λ; where λ is the air wavelength corresponding to the center frequency of the radiation network.
6. The second metal layer according to claim 3, characterized in that The coupling slot is located at the center of the SIW cavity, and the distance from the short-circuit end is 0.25λg, where λg is the dielectric wavelength corresponding to the suppression frequency of the radiation network.
7. The third metal layer according to claim 3, characterized in that: A ram-horn DGS gap is provided. The ram-horn DGS gap is located in the center of the SIW cavity, and the distance from the short-circuit end is 0.4-0.5λ. The width of the ram-horn DGS gap is 0.1mm, and it is a left-right symmetrical structure. The total length of the left ram-horn is 0.4-0.6λ; where λ is the air wavelength corresponding to the center frequency of the radiation network.
8. An antenna, characterized in that: It comprises the filtering antenna unit as claimed in any one of claims 1 to 7.