Non-uniform metasurface filtering antenna with high suppression level

Abstract

The invention relates to the technical field of wireless communication, in particular to a non-uniform metasurface filtering antenna with a high suppression level. In order to design a filtering metasurface antenna with high suppression level, high gain and multiple radiation zero points, the filtering metasurface antenna comprises two dielectric layers and three metal layers. The upper layer metal is a 2 * 4 main patch array and four parasitic patches located above and below the 2 * 4 main patch array, and the 2 * 4 main patch array and the four parasitic patches form a non-uniform array structure. Intermittent butterfly-shaped gaps are etched in the middle metal layer. And the lower-layer metal is a T-shaped microstrip line feed structure loaded with two groups of rectangular split ring resonators with different sizes. The butterfly-shaped groove and the short-circuit via hole generate a radiation zero point at the edge of the lower passband, and the non-uniform metasurface structure generates a radiation zero point at the edge of the upper passband, thereby forming a basic filtering characteristic. Three radiation zero points are additionally arranged on the upper stop band and the lower stop band of the two rectangular split ring resonators respectively, and the out-of-band rejection level is further enhanced.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and particularly to a filter antenna in wireless communication, specifically a non-uniform metasurface filter antenna with a high suppression level. Background Technology

[0002] With the development of communication technologies such as 5G, millimeter wave, and IoT, antenna systems are facing higher demands for compact structure, high efficiency, and high out-of-band rejection. Traditional filter antennas often employ cascaded external filters, which can easily lead to increased system complexity, increased insertion loss, and increased integration difficulty.

[0003] In recent years, scholars have proposed various methods to realize antenna filtering functions. Among them, loading metasurfaces has become an effective means to balance filtering and radiation performance due to its compact structure and multi-mode control advantages. For example, a low-cost, high-gain filter patch antenna based on SISL uses an FR4 substrate to achieve four radiation nulls, a peak gain of 11.14 dBi, and an out-of-band rejection level of 17.8 dB, covering the 5G-N78 frequency band (Tong Wang, Ningning Yan, Mi Tian, ​​Yu Luo, and Kaixue Ma. A Low-Cost High-Gain Filtering Patch Antenna With Enhanced Frequency Selectivity Based on SISL for 5G Application. IEEE Antennas and Wireless Propagation Letters, 2022, 21(9):1772). A circularly polarized filter patch antenna, in order to integrate the filtering function, introduces four thin microstrip posts and four short pins in the patch, and etches two U-shaped slots in the feed circuit. A bandwidth of 4.1% and a peak gain of 8.3 dBi were achieved at 2.4 GHz, with an out-of-band rejection level exceeding 16 dB (Yang WJ, Pan YM, Zhang XY. A single-layer low-profile circularlypolarized filtering patch antenna. IEEE Antennas and Wireless Propagation Letters, 2021, 20(4): 602). However, current filtering antenna designs still face challenges in simultaneously achieving multiple radiating nulls, high rejection levels, and high gain.

[0004] Therefore, it is necessary to design a filtered metasurface antenna that combines high suppression level, high gain and multiple radiation nulls to meet the high performance requirements of modern wireless communication. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a non-uniform metasurface filter antenna with a high suppression level. It is a filter antenna structure that is compact, has high gain, and strong out-of-band suppression capability.

[0006] This invention comprises two dielectric substrates and three metal layers. The upper layer includes a 2×4 main patch array and four parasitic patches (top and bottom), forming a non-uniform metasurface radiating element, fed by a bottom microstrip feed line and a middle slot coupling. Radiation nulls at the lower passband edge are generated through butterfly slots and short-circuited metal vias, while the non-uniform metasurface structure generates radiation nulls at the upper passband edge, forming basic filtering characteristics. Adding two sets of rectangular open-loop resonators of different sizes adds three radiation nulls to the upper and lower stopbands respectively, further enhancing out-of-band suppression, ultimately achieving a high-gain, high-suppression filtered metasurface antenna.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention provides a non-uniform metasurface filter antenna with high suppression level, comprising an upper metal layer, a first dielectric layer, an intermediate metal layer, a second dielectric layer and a lower metal layer arranged sequentially from top to bottom;

[0009] The upper metal layer includes a non-uniform metasurface radiation structure consisting of a 2×4 master patch array and four parasitic patches located above and below it.

[0010] The intermediate metal layer has a butterfly-shaped slit with an intermittent middle section at its center.

[0011] The lower metal layer is a microstrip feed line, and two sets of rectangular open-ring resonators of different sizes are symmetrically loaded on both sides of the microstrip feed line; the microstrip feed line is coupled to the upper metal layer through a butterfly-shaped gap.

[0012] The second dielectric layer is provided with short-circuit metal vias.

[0013] Furthermore, the patches in the 2×4 patch array are divided into a first square metal patch and a second square metal patch. The first square metal patch consists of the four patches in the middle, and the second square metal patch is located on the left and right sides of the first square metal patch. Four parasitic patches are arranged on the top and bottom sides of the 2×4 patch array.

[0014] Furthermore, the non-uniform metasurface radiation structure exhibits bidirectional axisymmetry.

[0015] Furthermore, the intermittent butterfly-shaped gap in the middle of the intermediate metal layer can adjust the input impedance of the antenna and the position of the radiation null point at the lower passband edge.

[0016] Furthermore, the two sets of rectangular open-loop resonators of different sizes in the lower metal layer generate three out-of-band radiation zeros respectively, and adjusting their size can change the filtering performance of the antenna.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The radiation null point at the upper passband edge is generated by loading a non-uniform metasurface structure with parasitic patches.

[0019] The radiation zero point at the edge of the lower passband is generated by intermittent butterfly-shaped slots and short-circuit metal vias.

[0020] By loading two sets of rectangular open-loop resonators of different sizes on both sides of the microstrip feed line, three radiation zeros are added to the upper and lower stopbands respectively, further enhancing the out-of-band suppression level.

[0021] This antenna operates in the 5.7 GHz–6.1 GHz band with a relative bandwidth of 6.8% and a peak gain of 8.7 dBi. The out-of-band rejection levels in the upper and lower stopbands are 22.4 dB and 24 dB, respectively. This invention features high gain and high rejection levels, making it suitable for point-to-point or point-to-multipoint spread spectrum communication systems, high-speed wireless LANs, broadband wireless access systems, Bluetooth devices, and vehicle wireless automatic identification systems in the 5.8 GHz band.

[0022] This antenna has a fully planar structure, is compact, and is easy to manufacture. Attached Figure Description

[0023] Figure 1 The diagram shows the overall structure of the antenna, where 1-upper metal layer, 2-first dielectric layer, 3-middle metal layer, 4-second dielectric layer, 5-lower metal layer, 6-first square metal patch (P1), 7-second square metal patch (P2), 8-parasitic patch (P3), 9-intermittent butterfly-shaped slot, 10-short-circuit metal via, 11-microstrip feed line, 12-first rectangular open-loop resonator (SRR I), and 13-second rectangular open-loop resonator (SRR II).

[0024] Figure 2 For the antenna |S 11 |Curve.

[0025] Figure 3 This is the gain curve of the antenna.

[0026] Figure 4The parameters are the characteristic modes of the non-uniform metasurface at 6.58 GHz, where (a) is the mode importance curve and (b) is the mode current distribution and radiation map.

[0027] Figure 5 The antenna surface current diagrams are shown after loading the first rectangular open-loop resonator SRR I, where (a) is the current distribution of the microstrip feed at 3.68 GHz, (b) is the current distribution of the microstrip feed at 7.15 GHz, (c) is the current distribution of the butterfly slot at 3.68 GHz, (d) is the current distribution of the butterfly slot at 7.15 GHz, (e) is the current distribution of the metasurface at 3.68 GHz, and (f) is the current distribution of the metasurface at 7.15 GHz.

[0028] Figure 6 The surface current of the antenna at 7.7 GHz after loading the second rectangular open-loop resonator SRR II is given, where (a) is a microstrip feed, (b) is a butterfly slot, and (c) is a metasurface.

[0029] Figure 7 The radiation pattern of the antenna at the center frequency of 5.9 GHz is shown, where (a) is the E-plane and (b) is the H-plane. Detailed Implementation

[0030] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0031] like Figure 1 As shown, a non-uniform metasurface filter antenna with high suppression level in this embodiment includes an upper metal layer 1, a first dielectric layer 2, an intermediate metal layer 3, a second dielectric layer 4 and a lower metal layer 5 arranged sequentially from top to bottom;

[0032] The upper metal layer 1 includes a non-uniform metasurface radiation structure consisting of a 2×4 master patch array and four parasitic patches 8 located above and below it.

[0033] The patches in the 2×4 patch array are divided into a first square metal patch 6 (P1) and a second square metal patch 7 (P2). P1 consists of the four patches in the middle, and P2 is located on the left and right sides of P1. Four parasitic patches 8 (P3 / P4) are arranged on the upper and lower sides of the 2×4 patch array. This non-uniform metasurface radiation structure is bidirectionally axially symmetric.

[0034] The intermediate metal layer 3 has a butterfly-shaped slot 9 with a middle discontinuity. The length of the feed slot s1 and the middle of the slot have a discontinuity of length cx. The change of these lengths can adjust the input impedance of the antenna and the position of the radiation null point at the lower passband edge.

[0035] The lower metal layer 5 is a microstrip feed line 11, on which two sets of rectangular open-ring resonators of different sizes are symmetrically loaded on both sides; the microstrip feed line 11 is coupled to the upper metal layer 1 through a butterfly-shaped gap.

[0036] Two sets of rectangular open-loop resonators of different sizes are the first rectangular open-loop resonator (SRR I) 12 and the second rectangular open-loop resonator (SRR II), which respectively generate three out-of-band radiation nulls. Adjusting their size can change the filtering performance of the antenna.

[0037] The second dielectric layer 4 is provided with a short-circuit metal via 10.

[0038] Specifically, the first dielectric layer uses Rogers RO4003C material with a thickness of 3.454 mm, and the second dielectric layer uses Rogers RO4003C material with a thickness of 0.508 mm. Both have a dielectric constant εr of 3.55. The upper, middle, and lower metal layers are made of copper.

[0039] The specific parameters of the antenna structure in this embodiment are shown in Table 1.

[0040] Table 1. Specific parameters of antenna structure (unit: mm)

[0041] parameter a b <![CDATA[w1]]> <![CDATA[w2]]> <![CDATA[w3]]> g cx cy Value 40 40 7 11 7 1 0.5 0.5 parameter sw wf <![CDATA[S1]]> f <![CDATA[Lc1]]> <![CDATA[Lc2]]> <![CDATA[Lc4]]> <![CDATA[Lc5]]> Value 3 1 30 19.75 6 10 5 5 parameter <![CDATA[f1]]> we w d <![CDATA[r1]]> <![CDATA[y1]]> <![CDATA[y2]]> Value 1 12.5 1.1 0.2 0.1 6 9

[0042] Figure 2 For the antenna |S 11 | Curve. The horizontal axis represents frequency (GHz), and the vertical axis represents amplitude (dB). The results show that the antenna satisfies |S 11 | Impedance matching requirement of ≤-10 dB, with a relative bandwidth of 6.8%.

[0043] Figure 3 The antenna's gain curve is shown. The highest gain in the passband reaches 8.7 dBi, and the out-of-band rejection levels in the upper and lower stopbands are 22.4 dB and 24 dB, respectively. There are a total of 5 radiation nulls f in both stopbands. o1 -f o5 .

[0044] Figure 4 The parameters for the characteristic modes of the non-uniform metasurface at 6.58 GHz are given. Characteristic mode analysis was used to analyze four characteristic modes with resonant frequencies around 6.85 GHz. The main currents of modes 1 to 4 are distributed on patch P3, not on patch P1. The butterfly-shaped gap in the intermediate layer cannot effectively excite these modes, thus generating a radiation null point f. o1 .

[0045] Figure 5 The antenna surface current map is shown after loading the first rectangular open-loop resonator 12 (SRR I). After loading this structure, the antenna generates two radiation nulls at 3.68 GHz and 7.15 GHz. At these two frequencies, the current distribution is mainly concentrated around the feed line and resonator, with very little current coupled to the upper metasurface through the butterfly slot, thus forming radiation nulls f. o3 and f o4 .

[0046] Figure 6 The antenna surface current at 7.7 GHz is determined after loading the second set of rectangular open-loop resonators SRR II. After loading this structure, the antenna produces a radiation null at 7.7 GHz. At this frequency, the current distribution is mainly concentrated around the feed line and resonators, with very little current coupled to the upper metasurface through the butterfly slot, thus forming the radiation null f. o5 .

[0047] Figure 7 The antenna radiation pattern is shown at the center frequency of 5.9 GHz. Both the E-plane and H-plane exhibit good directivity.

[0048] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0049] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A non-uniform metasurface filter antenna with high suppression level, characterized in that, It includes an upper metal layer (1), a first dielectric layer (2), an intermediate metal layer (3), a second dielectric layer (4), and a lower metal layer (5) arranged sequentially from top to bottom; The upper metal layer (1) includes a non-uniform metasurface radiation structure consisting of a 2×4 master patch array and four parasitic patches (8) located above and below it; The intermediate metal layer (3) has a butterfly-shaped slit (9) with a central interruption. The lower metal layer (5) is a microstrip feed line (11), and two sets of rectangular open-ring resonators of different sizes are symmetrically loaded on both sides of the microstrip feed line (11); the microstrip feed line (11) is coupled to the upper metal layer (1) through a butterfly-shaped gap; The second dielectric layer (4) is provided with a short-circuit metal via (10).

2. The non-uniform metasurface filter antenna with high suppression level according to claim 1, characterized in that, The patches in the 2×4 patch array are divided into a first square metal patch (6) and a second square metal patch (7). The first square metal patch (6) consists of four patches in the middle, and the second square metal patch (7) is located on the left and right sides of the first square metal patch (6). Four parasitic patches (8) are arranged on the upper and lower sides of the 2×4 patch array.

3. A non-uniform metasurface filter antenna with high suppression level according to claim 1 or 2, characterized in that, The non-uniform metasurface radiation structure is bidirectional axisymmetric.

4. The non-uniform metasurface filter antenna with high suppression level according to claim 1, characterized in that, The intermittent butterfly-shaped slit (9) in the middle of the intermediate metal layer (3) can adjust the input impedance of the antenna and the position of the radiation null point at the lower passband edge.

5. A non-uniform metasurface filter antenna with high suppression level according to claim 1, characterized in that, The two sets of rectangular open-loop resonators of different sizes in the lower metal layer (5) generate three out-of-band radiation zeros respectively, and the filtering performance of the antenna can be changed by adjusting their size.

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