Compact single-layer seven-mode broadband filtering antenna and array application thereof

Abstract

The invention discloses a compact single-layer seven-mode broadband filtering antenna and an array application thereof.The antenna adopts a single-layer dielectric substrate and is composed of a circular patch resonator and a square substrate integrated waveguide resonator, the circular patch resonator is combined with a square substrate integrated waveguide cavity, and therefore on the premise that the structural size is not increased, the size of the antenna is reduced, and the size of the antenna is reduced. Three in-band resonance points and an out-of-band radiation zero point are obtained. On the basis, gaps are introduced into the radiation edges of the two resonators, so that two additional modes are excited on each resonator, and an out-of-band radiation zero point is additionally excited. Through reasonable arrangement of the modes, a seven-mode broadband working characteristic with three out-of-band radiation zero points is finally formed. In addition, the antenna units can be tightly arranged in an array design in a zero-spacing mode, and the array density and performance are effectively improved. According to the invention, the filtering function and the antenna radiation characteristic are successfully integrated, and the antenna has the advantages of simple structure, compact layout and excellent performance.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to a microwave antenna structure, and particularly a compact single-layer seven-mode broadband filter antenna and its array application. Background Technology

[0002] In recent years, with the continuous development of wireless communication systems towards miniaturization, high integration, and multifunctionality, broadband filtering antennas have become an important research hotspot. Microstrip patch antennas, due to their significant advantages such as compact size, low profile, and ease of integration, have demonstrated great practical value. However, traditional microstrip patch antennas inherently suffer from a narrow operating bandwidth, which greatly limits their application in modern wireless communication systems.

[0003] To extend the bandwidth of patch antennas, various methods have been proposed, with the multimode concept becoming a mainstream approach. The most direct method to achieve multiple resonances is to use multiple resonators and simultaneously excite their resonant modes. For example, this can be achieved by stacking patches or introducing parasitic elements on the same plane as the patch resonators. However, such additional resonators inevitably lead to a significant increase in antenna size. Therefore, in recent years, much research has focused on redesigning resonator structures to excite multiple resonant modes within a single radiating element. The implementation methods mainly fall into two categories: the first involves modifying higher-order resonant modes by etching slots, adding short-circuit holes, adding metal strips, or optimizing patch shapes to enable them to work in conjunction with the fundamental mode to enhance bandwidth; the second involves introducing parasitic modes through specific structures (such as E-shaped, U-shaped, S-shaped patches or slots, L-probes, L-shaped feed strips, etc.). Compared to using multiple resonators, generating multiple resonances within a single resonator offers superior structural compactness. However, the design freedom within a single resonator is limited, which significantly restricts the number of available modes. Looking at multimode antennas based on single resonators, their modes are predominantly dual-mode. Furthermore, its structural complexity often increases significantly with the increase in bandwidth.

[0004] On the other hand, integration has become a promising technique in filtered antenna design. By eliminating the need for additional filtering circuitry, this approach significantly simplifies the antenna structure and effectively reduces in-band insertion loss. Existing technologies typically suppress stopband signal transmission by constructing cross-coupling or electro / magnetic hybrid coupling, or by employing the concept of radiation cancellation to generate radiation nulls to achieve filtering performance. Radiation cancellation can be achieved by using additional resonators to cancel out far-field radiation, by canceling out radiation from different radiation boundaries on a single resonator, or by using defective structures to generate back radiation to weaken front radiation, thus creating radiation nulls. However, these improvements in filtering performance come at the cost of increased structural complexity and size.

[0005] In summary, existing broadband multimode antennas and filter antennas struggle to achieve both significant bandwidth expansion and good out-of-band filtering characteristics while maintaining a simple and compact structure. Therefore, a novel antenna design is urgently needed to resolve the trade-offs between bandwidth, performance, complexity, and size. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a compact single-layer seven-mode broadband filtering antenna and its array. The antenna aims to solve the problems of narrow bandwidth of traditional microstrip patch antennas, and the complex structure and large size of existing broadband and filtering antenna designs, achieving both significant bandwidth expansion and high-selectivity out-of-band suppression within a compact single-layer structure.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A compact single-layer seven-mode broadband filter antenna, wherein the antenna is excited by a coaxial probe feeding method, comprising: First dielectric substrate; A floor formed on the lower surface of the dielectric substrate; A square substrate integrated waveguide resonator formed on the upper surface of the dielectric substrate; Metallized vias formed at the edge of a square substrate integrated waveguide resonator and penetrating the dielectric substrate; An elliptical aperture etched at the center of the square substrate integrated waveguide resonator; A circular patch resonator is formed on the upper surface of the dielectric substrate and located at the center of the elliptical aperture, and there is a gap between the circular patch resonator and the square substrate integrated waveguide resonator. The first set of arc-shaped slots etched on the circular patch resonator and extending inward from the edge of the circular patch resonator; The second set of arc-shaped slots is etched onto the square substrate integrated waveguide resonator and extends outward from the edge of the elliptical aperture.

[0008] As a further optimization of the present invention, the first group of arc-shaped gaps consists of four gaps, which are symmetrically distributed.

[0009] As a further optimization of the present invention, the second group of arc-shaped gaps consists of four gaps, which are symmetrically distributed.

[0010] As a further optimization of the present invention, the coaxial probe is connected to the circular patch resonator.

[0011] The present invention also provides an antenna array, comprising: Second dielectric substrate; Multiple compact single-layer seven-mode broadband filter antennas, as described above, are arranged in a two-dimensional grid on the upper surface of the dielectric substrate. A feed network printed on the lower surface of the dielectric substrate is connected to the corresponding compact single-layer seven-mode broadband filter antenna via a coaxial feed probe, providing excitation signals for each compact single-layer seven-mode broadband filter antenna.

[0012] As a further optimization of the present invention, in the antenna array, adjacent compact single-layer seven-mode broadband filter antennas are arranged with zero spacing and share metallized vias.

[0013] As a further optimization of the present invention, the power supply network is an equal-power-sharing power supply network.

[0014] The present invention also provides a wireless communication device that integrates a compact single-layer seven-mode broadband filter antenna as described above, or an antenna array as described above.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Significantly Extended Operating Bandwidth: By combining a circular patch resonator with a square substrate integrated waveguide resonator and introducing arc-shaped gaps at the edges of both, the excitation and modulation of seven resonant modes were successfully achieved without altering the original resonant performance of the resonators. These modes are rationally arranged and merged to form a wide operating bandwidth. Experimental results show that, compared to traditional circular patch antennas, this invention achieves a fractional bandwidth of 25.35%, an increase of approximately 4.87 times, while maintaining a stable radiation pattern.

[0016] 2. Excellent built-in filtering characteristics: The above multimode resonant structure naturally generates three radiation zeros on both sides of the passband, achieving highly selective out-of-band suppression without any additional filtering circuits, thus improving the frequency selectivity performance of the antenna.

[0017] 3. Superior structural compactness and integration: All functions are implemented on a single-layer dielectric substrate, resulting in an extremely simple and compact structure. The square substrate-integrated waveguide resonator is achieved through metallized vias and conformally designed with the patch resonator without adding any extra volume. In particular, thanks to the unique layout of the closely spaced metallized vias around the antenna element and its internal radiation boundary, the antenna element can be compactly integrated in the array design with zero spacing, greatly improving the array's integration and performance, and overcoming the problem of traditional array elements requiring spacing to avoid mutual coupling.

[0018] 4. Universality of design method: The design concept proposed in this invention is not only applicable to a single antenna, but can be directly extended to two-dimensional antenna arrays with any number of elements, which has high application flexibility. Attached Figure Description

[0019] Figure 1Here are schematic diagrams of the antenna structure: (a) is a three-dimensional structural diagram and a reference coordinate diagram; (b) is a top view and a structural parameter diagram. Among them, 1 is a dielectric substrate; 2 is a ground plane; 3 is a circular patch resonator; 4 is a square substrate integrated waveguide resonator; 5 is the first set of arc-shaped slots; 6 is the second set of arc-shaped slots; 7 is an elliptical aperture; 8 is a coaxial probe; and 9 is a metallized via.

[0020] Figure 2 This is a schematic diagram of the front structure and reference coordinates of the antenna array; where 10 is the dielectric substrate and 11 is the feed network.

[0021] Figure 3 The results are the antenna frequency response calculated and tested using HFSS software; where (a) represents the reflection coefficient and radiation gain, and (b) represents the radiation efficiency.

[0022] Figure 4 These are the normalized radiation patterns of the antennas calculated and fabricated using HFSS software; (a) is the radiation pattern at 3.75 GHz in the E and H planes, (b) is the radiation pattern at 4.25 GHz in the E and H planes, and (c) is the radiation pattern at 4.75 GHz in the E and H planes.

[0023] Figure 5 The results are the frequency response of the antenna array calculated and tested using HFSS software; where (a) represents the reflection coefficient and radiation gain, and (b) represents the radiation efficiency.

[0024] Figure 6 These are the normalized radiation patterns of the antenna array calculated and tested using HFSS software; (a) is the radiation pattern at 3.75 GHz in the E and H planes, (b) is the radiation pattern at 4.25 GHz in the E and H planes, and (c) is the radiation pattern at 4.75 GHz in the E and H planes. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Figure 1 Image (a) shows a schematic diagram of an embodiment of the compact single-layer seven-mode broadband filter antenna of the present invention, comprising: Single-layer dielectric substrate 1, made of F4B material, with a relative permittivity of ε r = 2.2, thickness h = 3mm; A floor 2 formed on the lower surface of the dielectric substrate 1; A square substrate integrated waveguide resonator 4 is formed on the upper surface of the dielectric substrate 1; Closely spaced metallized vias 9 are formed at the edge of the square substrate integrated waveguide resonator 4 and penetrate the dielectric substrate 1; An elliptical aperture 7 is etched at the center of the square substrate integrated waveguide resonator 4; A circular patch resonator 3 is formed on the upper surface of the dielectric substrate 1 and located at the center of the elliptical aperture 7. There is a gap between the circular patch resonator 3 and the square substrate integrated waveguide resonator 4. Through this design, the two resonators are organically combined without increasing the size of the overall structure, thus achieving compact integration. A first set of arc-shaped slots 5, etched inward from the edge of the circular patch resonator 3, and a second set of arc-shaped slots 6, etched outward from the edge of the elliptical aperture 7, are used to further excite multimodes. The geometric parameters (including arc length, width, and position) of these slots 5 and 6 are used to finely tune the frequency and radiation characteristics of the resulting multiple resonant modes.

[0027] The antenna described above is excited using a coaxial probe feeding method. The feeding probe 8 passes under the dielectric substrate 1 and connects to the circular patch resonator 3. The outer conductor of the coaxial connector (not shown separately in the figure) is connected to the ground plane 2.

[0028] By optimizing all the aforementioned geometric parameters, seven resonant modes can be successfully excited within a compact single-layer structure and merged into a wideband. Simultaneously, this structure naturally generates three radiation zeros on both sides of the passband, thus achieving excellent out-of-band rejection filtering without adding additional circuitry.

[0029] like Figure 1 As shown in (b), the antenna element is designed with the following dimensions: a 1 = 15.3 mm, a 2 = 7 mm, b 1 = 9.3 mm, b 2 = 16.2 mm, c 1 = 2.3 mm, c 2 = 3.4 mm, r = 14.65 mm, g = 5.2 mm, l = 51 mm, w 1 = 3.2 mm, w 2 = 1.8 mm, x 2 = 11 mm, θ 1 = 83°, θ 2 = 83°. Figure 3and Figure 4 A comparison of simulation and experimental results for the aforementioned antennas is provided.

[0030] like Figure 3 As shown, the measured -10 dB impedance bandwidth covers a frequency range of 3.7 GHz to 4.8 GHz, corresponding to a fractional bandwidth (FBW) as high as 25.88%. The seven modes excited within the passband are TM of the circular patch resonator. 11 TE of square substrate integrated waveguide resonators 11 and TE 21 The invention introduces four new modes, including a curved slot. Within this operating frequency band, the highest measured gain reaches 8.85 dBi, and the gain curve remains stable throughout the band, with a radiation efficiency consistently above 85%, demonstrating excellent radiation performance. Three radiation nulls were clearly observed on both sides of the passband, at frequencies of 3.57 GHz, 4.82 GHz, and 5.07 GHz, respectively. These radiation nulls significantly enhance the antenna's frequency selectivity. Calculations show high frequency selectivity of 164 dB / GHz and 92 dB / GHz at the lower and upper edges of the passband, respectively, indicating that this invention successfully integrates superior filtering capabilities into the antenna itself.

[0031] In addition, by Figure 4 The radiation patterns at the low, center, and high frequencies of the passband show that the antenna exhibits consistent and stable directional radiation characteristics throughout the entire operating frequency band, with a clear main lobe direction and low sidelobe levels, further demonstrating its reliability in practical applications.

[0032] The simulation and measurement results above fully demonstrate that the compact single-layer seven-mode broadband filter antenna provided by this invention successfully achieves multiple excellent characteristics such as wide bandwidth, high gain, high efficiency, high selective filtering and stable radiation. All performance indicators far exceed those of traditional microstrip patch antennas, proving its great practical value and market potential.

[0033] Figure 2 The diagram shown is a structural schematic of an embodiment of the antenna array described in this invention. The antenna array includes four antenna elements arranged in a 2×2 configuration. The antenna array is composed of two dielectric substrates, one above the other.

[0034] On the upper dielectric substrate 1, four of the aforementioned single-layer seven-mode broadband filter antenna elements are arranged in a close-packed, zero-pitch configuration. Adjacent antenna elements share the metallized via walls 9 of their square substrate integrated waveguide resonators 4; that is, a row of vias simultaneously serves as the boundary between two adjacent elements. This zero-pitch shared via wall layout is key to achieving high-density integration, significantly improving the array's integration density. Although the antenna elements are arranged in a close-packed, zero-pitch configuration, the built-in radiation boundary of each antenna element ensures good isolation between elements, effectively suppressing the adverse effects of mutual coupling on array performance.

[0035] The lower dielectric substrate 10 is disposed below the upper dielectric substrate 1. In this embodiment, the lower dielectric substrate 10 is made of Rogers 4003 material, which has a relative permittivity of [missing information]. ε r = 2.2, thickness h = 0.508 mm. The power supply network 11 is printed on the lower surface of the underlying dielectric substrate 10. This power supply network 11 is a classic 1-to-4 T-junction equal power divider, used to equally distribute the input signal to the four output ports. Those skilled in the art will understand that the power supply network 11 can also be a Wilkinson power divider or any other form of equal or unequal power divider network to adapt to different array excitation requirements.

[0036] Each antenna element is excited by a feed probe 8. The feed probe 8 passes under the lower dielectric substrate 10, connects to an output port of the feed network 11, and continues to extend upward, passing through the upper dielectric substrate 1, and finally connects to the corresponding circular patch resonator 3.

[0037] Figure 5 and Figure 6 Simulation and experimental results for this antenna array are provided. Figure 5 As shown, the measured -10 dB impedance bandwidth of the array is 25.47% (frequency range: 3.7 GHz to 4.78 GHz), which is highly consistent with the bandwidth of its individual antennas, indicating that the antenna performance is not affected under tight integration. Throughout the passband, the measured efficiency of the array is higher than 81%, and a peak gain of 14.42 dBi is measured at 4.63 GHz, fully demonstrating the high efficiency and high gain characteristics of this array design. Furthermore, the filtering characteristics of the individual antennas are maintained within the array. The measured results show that the three radiated nulls are clearly located at 3.57 GHz, 4.8 GHz, and 5.1 GHz, enabling the array to achieve extremely high frequency selectivity at the passband edges as well, at 162 dB / GHz (lower edge) and 88 dB / GHz (upper edge), respectively, comparable to the performance of a single antenna.

[0038] like Figure 6As shown, the antenna array exhibits stable and consistent directional radiation patterns at the low, medium, and high characteristic frequency points within the passband. The main lobe beamwidth is concentrated, and the sidelobe level is effectively suppressed, demonstrating its radiation reliability in practical operation.

[0039] This embodiment fully demonstrates that the antenna element and its array application described in this invention successfully resolve the contradiction between high-density integration and high-performance indicators. Under extreme conditions of close-packed, zero-pitch arrangement, the array not only maintains the wide bandwidth, high gain, and high efficiency characteristics of the antenna element itself, but also fully preserves the filtering function, achieving high-selectivity out-of-band suppression, while maintaining stable and reliable radiation performance. This provides an effective solution for the design of next-generation high-performance, highly integrated wireless communication front-end systems.

[0040] In summary, this invention combines a circular patch resonator with a square substrate integrated waveguide cavity, achieving three in-band resonant points and one out-of-band radiation null point without increasing structural dimensions. Furthermore, gaps are introduced at the radiation edges of both resonators, allowing each resonator to excite two additional modes and an additional out-of-band radiation null point. By strategically arranging these modes, a seven-mode broadband operating characteristic with three out-of-band radiation null points is ultimately formed. Compared to traditional circular patch antennas, this antenna achieves a 25.35% fractional bandwidth and stable radiation directional characteristics (bandwidth broadened by approximately 4.87 times) while maintaining the same single-layer structure and nearly uniform dimensions, and significantly improves out-of-band suppression performance. Moreover, thanks to the unique layout of the closely spaced metallized vias around the antenna and its internal radiation boundaries, the antenna elements can be tightly arranged in an array design with zero spacing, effectively improving array density and performance. This invention successfully integrates filtering function with antenna radiation characteristics, and has the advantages of simple structure, compact layout and superior performance. It successfully achieves miniaturization, high integration and filtering function integration of antenna system without sacrificing performance, and is suitable for wireless communication systems with high requirements for miniaturization and integration.

[0041] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention. For example, the number of antenna elements is not limited to 2×2, but can be any m×n array; the feed probe can be connected to the substrate integrated waveguide resonator; the circular patch resonator can also be replaced with other shapes, such as polygonal (hexagonal, octagonal) patches, elliptical patches, etc.; the square substrate integrated waveguide resonator can also be replaced with rectangular, polygonal, circular, etc. substrate integrated waveguide resonators; the elliptical aperture can be adjusted to rectangular, polygonal, circular, etc. shapes; the shape and number of arc-shaped slots can also be adjusted; the feed network can be designed with different power division ratios or phase relationships as needed. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A compact single-layer seven-mode broadband filter antenna, characterized in that, The antenna is excited by a coaxial probe (8) feeding method, including: First dielectric substrate (1); A floor (2) formed on the lower surface of the dielectric substrate (1); A square substrate integrated waveguide resonator (4) is formed on the upper surface of the dielectric substrate (1). Metallized vias (9) formed at the edge of the square substrate integrated waveguide resonator (4) and penetrating the dielectric substrate (1). An elliptical aperture (7) is etched at the center of the square substrate integrated waveguide resonator (4). A circular patch resonator (3) is formed on the upper surface of the dielectric substrate (1) and located at the center of the elliptical aperture (7). There is a gap between the circular patch resonator (3) and the square substrate integrated waveguide resonator (4). The first set of arc-shaped slots (5) are etched on the circular patch resonator (3) and extend inward from the edge of the circular patch resonator (3). The second set of arc-shaped slots (6) are etched on the square substrate integrated waveguide resonator (4) and extend outward from the edge of the elliptical aperture (7).

2. The compact single-layer seven-mode broadband filter antenna as described in claim 1, characterized in that, The first group of arc-shaped gaps (5) consists of four, and they are symmetrically distributed.

3. The compact single-layer seven-mode broadband filter antenna as described in claim 1, characterized in that, The second group of arc-shaped gaps (6) consists of four, and they are symmetrically distributed.

4. The compact single-layer seven-mode broadband filter antenna as described in claim 1, characterized in that, The coaxial probe (8) is connected to the circular patch resonator (3).

5. An antenna array, characterized in that, include: Second dielectric substrate (10); Multiple compact single-layer seven-mode broadband filter antennas as described in any one of claims 1 to 4 are arranged in a two-dimensional grid on the upper surface of the dielectric substrate (10). A feed network (11) printed on the lower surface of the dielectric substrate (10) is connected to the corresponding compact single-layer seven-mode broadband filter antenna through a coaxial feed probe (8) to provide excitation signals for each compact single-layer seven-mode broadband filter antenna.

6. The antenna array as described in claim 5, characterized in that, In the antenna array, adjacent compact single-layer seven-mode broadband filter antennas are arranged with zero spacing and share a metallized via (9).

7. The antenna array as described in claim 5, characterized in that, The power supply network (11) is an equal-power distribution power supply network.

8. A wireless communication device, characterized in that, It integrates a compact single-layer seven-mode broadband filter antenna as described in any one of claims 1 to 4, or an antenna array as described in any one of claims 5 to 7.

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