Miniaturized slot coupling type single-layer broadband filtering antenna

Abstract

The invention discloses a miniaturized slot coupling type single-layer broadband filtering antenna, and belongs to the technical field of communication antenna design. Comprising a microstrip feeder line, a dielectric substrate, a coaxial feed probe, a short-circuit through hole and a metal grounding plate etched with a gap which are sequentially arranged from top to bottom, the microstrip feeder line on the upper surface of the dielectric substrate is arranged between the coaxial feed probe and the short-circuit through hole; three mutually coupled folding gaps and two U-shaped grooves symmetrically arranged on two sides of the three gaps are etched on the metal grounding plate. By using the hybrid electric / magnetic coupling effect between the gaps and the short-circuit through holes, under the condition of not adding an additional filter circuit, three resonance points are excited in a passband, and meanwhile, high roll-off radiation zero points are formed at the edges of the two sides of the passband, so that excellent filtering and radiation performance is obtained. While excellent passband radiation performance is maintained, good out-of-band rejection performance and frequency selectivity are achieved, and the requirements of modern wireless communication equipment for the space utilization rate and the integration degree are met.

Description

Technical Field

[0001] This invention relates to the field of communication antenna design technology, and in particular to a miniaturized slot-coupled single-layer broadband filter antenna. Background Technology

[0002] In traditional RF architectures, antennas and filters exist as independent components. When cascaded through transmission lines, they introduce additional insertion loss and impedance mismatch issues, which not only limit system efficiency but also increase device size and complexity, making it difficult to meet the dual demands of miniaturization and high performance in modern communication equipment. Against this backdrop, filtered antenna technology, which integrates antenna radiation and frequency selection filtering functions, provides an effective way to solve this problem.

[0003] Filtered antennas, through integrated design, directly embed the filtering function into the antenna structure without the need for explicit filtering circuitry. This improves integration while eliminating the inherent losses of traditional cascaded architectures. In recent years, the development of hybrid electro-magnetic coupling theory has provided new insights for filtered antenna design. This theory, by adjusting the electrical and magnetic coupling strength between resonators, can flexibly generate tunable radiation nulls, thereby effectively improving out-of-band suppression performance. Numerous studies have enhanced specific coupling effects through methods such as folded slot lines and adjusting patch orientation, achieving the design of high-performance filtered antennas.

[0004] However, most broadband filter patch antennas rely on multi-layer substrates or complex feeding networks to achieve multiple resonant points and high out-of-band rejection, which not only increases design complexity and manufacturing cost, but also poses greater challenges to the stability and reliability of the system. Summary of the Invention

[0005] The purpose of this invention is to provide a miniaturized slot-coupled single-layer broadband filter antenna that achieves excellent operating bandwidth and bandpass filtering response without adding additional filtering structures.

[0006] To achieve the above objectives, the present invention provides a miniaturized slot-coupled single-layer broadband filter antenna, comprising a microstrip feed line, a dielectric substrate, a coaxial feed probe, a metallized short-circuit via, and a metal ground plane; the microstrip feed line is printed on the upper surface of the dielectric substrate, the coaxial feed probe and the metallized short-circuit via are both disposed on the dielectric substrate, and the microstrip feed line is located between the coaxial feed probe and the metallized short-circuit via; the metal ground plane is printed on the lower surface of the dielectric substrate, and three mutually coupled main folded slots and two U-shaped slots symmetrically disposed on both sides of the main folded slots are etched on the metal ground plane; the main folded slots are located at the center of the metal ground plane, and the main folded slots include a first slot located at the center, a second slot and a third slot respectively disposed on both sides of the first slot; the two U-shaped slots are a first U-shaped slot and a second U-shaped slot.

[0007] Preferably, the number of metallized short-circuit vias is one, and the metallized short-circuit via is disposed throughout the dielectric substrate.

[0008] Preferably, the first U-shaped gap and the second U-shaped gap have the same shape and size, and are arranged symmetrically with respect to the center of the dielectric substrate. The first U-shaped gap and the second U-shaped gap are both located at the edge of the dielectric substrate.

[0009] Preferably, the first gap, the second gap, and the third gap are all located in the middle region of the two U-shaped gaps, and all three are regular folded structures. Furthermore, the first gap, the second gap, and the third gap are symmetrically arranged with respect to the transverse central axis of the dielectric substrate.

[0010] Preferably, the microstrip feed line has a rectangular structure and is arranged along a direction parallel to the upper and lower bottom edges of the dielectric substrate.

[0011] Preferably, the first slit and the second slit are coupled to generate a resonant mode and a radiation null at low frequencies; the first slit and the third slit are coupled to generate a resonant mode and a radiation null at high frequencies.

[0012] Preferably, the first U-shaped gap and the second U-shaped gap cooperate to adjust the working bandwidth of the antenna, improve the frequency selectivity of the antenna, and generate a radiation null at low frequency.

[0013] Therefore, the present invention employs the above-mentioned miniaturized slot-coupled single-layer broadband filter antenna, which has the following beneficial effects: 1) It has a wide passband, covering 1.85GHz-3.15GHz, and the radiation gain curve is stable at 5dBi within the passband range, forming an excellent radiation filtering effect; 2) It has high frequency selectivity on both sides of the passband, with lower stopband and upper stopband rejection levels reaching 14.61dB and 14.5dB, respectively; 3) The design process is convenient, the structure is simple, the size is small, the profile is low, the cost is low, and the maintenance is easy, which is in line with the application prospects of radio frequency front-end.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the filter antenna according to an embodiment of the present invention; Figure 2 This is a top view of the filter antenna according to an embodiment of the present invention.

[0016] Figure 3 This is a bottom view of the filter antenna according to an embodiment of the present invention.

[0017] Figure 4 This is a side view of the filter antenna according to an embodiment of the present invention.

[0018] Figure 5 This is a graph showing the simulation results of the S-parameters and Realized Gain of the filtered antenna in an embodiment of the present invention.

[0019] Figure 6 These are simulation results of the radiation patterns of the filter antenna in this embodiment of the invention at three resonant points of 1.9 GHz, 2.3 GHz and 3.08 GHz, on the E and H planes; where (a1) and (a2) are 1.9 GHz; (b1) and (b2) are 2.3 GHz; and (c1) and (c2) are 3.08 GHz.

[0020] Figure Labels 1. Microstrip feed line; 2. Dielectric substrate; 3. Metal ground plane; 4. Coaxial feed probe; 5. Short-circuit via; 31. First slot; 32. Second slot; 33. Third slot; 34. U-shaped slot; 341. First U-shaped slot; 342. Second U-shaped slot. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] Example 1 This invention discloses a miniaturized slot-coupled single-layer broadband filter antenna, which is described below in conjunction with the appendix. Figure 1-6The present invention will be specifically described below, along with its specific technical parameters. The miniaturized slot-coupled single-layer broadband filter antenna of this embodiment has a single-layer substrate structure, resulting in a simple and compact overall structure. It eliminates the need for additional filtering circuitry. Through the hybrid electro-magnetic coupling effect between the slots and the cooperation of the metallized short-circuit vias, it achieves the integration of broadband radiation and high-selectivity filtering. Its three-dimensional structure, top view, bottom view, and side view are shown below. Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, it mainly includes a microstrip feed line 1, a dielectric substrate 2, a metal ground plane 3, a coaxial feed probe 4, and a metallized short-circuit via 5; wherein the metal ground plane 3 is etched with a first gap 31, a second gap 32, a third gap 33, and a U-shaped gap 34, and the U-shaped gap 34 is further divided into a first U-shaped gap 341 and a second U-shaped gap 342.

[0024] In this embodiment, the filtered antenna has a layered layout from top to bottom. The microstrip feed line 1 is printed on the upper surface of the dielectric substrate 2, and the metal ground plane 3 is printed on the lower surface of the dielectric substrate 2. The external dimensions of the metal ground plane 3 match the external dimensions of the dielectric substrate 2. The coaxial feed probe 4 and the metallized short-circuit via 5 are both disposed inside the dielectric substrate 2. The microstrip feed line 1 is located between the coaxial feed probe 4 and the metallized short-circuit via 5 to realize the antenna feeding.

[0025] Three interconnected main folded slots (first slot 31, second slot 32, and third slot 33) are etched at the center of the metal ground plane 3. The first U-shaped slot 341 and the second U-shaped slot 342 are symmetrically arranged on both sides of the main folded slots and are both close to the edge of the dielectric substrate 2. Through the coupling design of the slots and the cooperation of the short-circuit vias, multiple resonant points are excited in the passband, and high roll-off radiation zero points are formed on both sides of the passband.

[0026] In this embodiment, a low-loss dielectric substrate 2 is selected, with a dielectric constant of 3.2 and a loss tangent of 0.0032. To achieve antenna miniaturization, the dielectric substrate 2 is designed as a cuboid structure with a thickness of 1 mm, a length of 70 mm, and a width of 50 mm. The dielectric substrate 2 provides support for the antenna components while ensuring low-loss transmission of electromagnetic signals.

[0027] There is one metallized short-circuit via 5. Both the coaxial feed probe 4 and the metallized short-circuit via 5 penetrate vertically along the dielectric substrate 2, and their distance from the top and bottom edges of the dielectric substrate 2 is 34.5 mm, maintaining a vertically centered arrangement. The coaxial feed probe 4 is 16 mm from the left edge and 34 mm from the right edge of the dielectric substrate 2; the metallized short-circuit via 5 is 30.2 mm from the left edge and 19.8 mm from the right edge of the dielectric substrate 2. Their distance is adapted to the length of the microstrip feed line 1 to ensure effective transmission of the feed signal. The microstrip feed line 1 is a rectangular conductive structure, arranged parallel to the top and bottom edges of the dielectric substrate 2. Its length is 14.2 mm and its width is 1 mm. Its distance from the top and bottom edges of the dielectric substrate 2 is 34.5 mm. It connects to the coaxial feed probe 4 on the left and extends to the metallized short-circuit via 5 on the right, serving as the antenna feed structure to realize the input and transmission of radio frequency signals, while also adjusting the impedance characteristics of the antenna in conjunction with the short-circuit via 5.

[0028] The metal ground plane 3 is a cuboid conductive layer that matches the dielectric substrate 2. All the gaps etched on its surface are 1.5 mm wide to ensure the consistency of electromagnetic coupling. Each gap has a regular folded structure and is arranged symmetrically, as shown in the following structure: U-shaped slots 34 include a first U-shaped slot 341 and a second U-shaped slot 342, which are identical in shape and size. They are centrally symmetrical about the center of the dielectric substrate 2 and are respectively arranged close to the left and right edges of the dielectric substrate 2. The distance between the edge of the slot and the side of the dielectric substrate 2 is 2mm. Each U-shaped slot 34 consists of two identical horizontal slots and one vertical slot, wherein the length of the horizontal slot is 12mm and the length of the vertical slot is 46mm, forming a standard U-shape.

[0029] Main folding gaps: including a first gap 31, a second gap 32, and a third gap 33, all three are located in the middle area of ​​the two U-shaped gaps 34 and are symmetrically arranged with respect to the transverse central axis of the dielectric substrate 2; the second gap 32 is located on the left, the third gap 33 is located on the right, and the first gap 31 is located at the center of the second gap 32 and the third gap 33. Each of the three gaps consists of two transverse gaps, two short vertical gaps, and one long vertical gap. The length adaptation design of each gap is as follows: First gap 31: The horizontal gap length is 9mm, the vertical short gap length is 6.5mm, and the vertical long gap length is 42mm. The distance between the edge of the vertical long gap and the left side of the dielectric substrate 2 is 27.5mm, and the distance between the edge and the right side is 21mm. Second gap 32: The horizontal gap length is 7.5mm, the vertical short gap length is 6.5mm, the vertical long gap length is 35mm, and the distance between the edge of the vertical long gap and the left side of the dielectric substrate 2 is 9.5mm and the distance between the edge and the right side is 39mm. The third gap 33 has a horizontal gap length of 5.5 mm, a vertical short gap length of 2.5 mm, and a vertical long gap length of 20 mm. The distance between the edge of the vertical long gap and the left side of the dielectric substrate 2 is 31.4 mm, and the distance between the edge of the vertical long gap and the right side is 17.1 mm.

[0030] The core of the filter antenna in this embodiment utilizes the hybrid electro-magnetic coupling effect between the slots and the synergistic effect of the metallized short-circuit via 5 to achieve an integrated design of filtering and radiation, without the need for additional filtering circuitry. The specific coupling principle is as follows: The first slot 31 and the second slot 32 are coupled to each other, which excites the resonant mode in the lower frequency range and forms the corresponding radiation null, providing a basis for the operation of the antenna in the low frequency range. The first slit 31 and the third slit 33 are coupled to each other, exciting another resonant mode in the higher frequency band, and forming a radiation null in the high frequency band at the same time, which, together with the low frequency resonant mode, achieves broadband coverage. The first U-shaped slot 341 and the second U-shaped slot 342 form additional radiation nulls in the low-frequency band, and at the same time, they work with the main folding slot to adjust the overall operating bandwidth of the antenna and improve the frequency selectivity of the antenna. The metallized short-circuit via 5 not only adjusts the impedance matching characteristics of the antenna, but also works in conjunction with the coupling effect of each slot to form high roll-off radiation nulls at both edges of the passband, enhancing the out-of-band suppression effect. Ultimately, it excites three resonant points within the passband, achieving excellent filtering and radiation performance.

[0031] To understand the performance of the filter antenna in this embodiment, simulation and debugging were performed using the electromagnetic simulation software ANSYS ElectronicsDesktop. The simulation results are as follows: Figure 5 , Figure 6 As shown. Figure 5 As shown, the antenna in this invention has a bandwidth of 51.5% with S-parameters less than -10dB, covering the 1.86GHz-3.15GHz frequency band, and can be applied to 5G communication-related frequency bands. It was also found that the gain within the operating frequency band stabilizes at 5dBi, forming three deep radiation nulls at both edges of the passband. The gain curve rapidly fades outside the passband, exhibiting excellent filtering performance and excellent out-of-band harmonic suppression capability, with an out-of-band suppression level exceeding 14.6dB. This demonstrates promising application prospects for anti-interference communication antennas.

[0032] Figure 6 Simulation results show the E-plane and H-plane radiation patterns of the filtered antenna at three resonant points: 1.9 GHz, 2.3 GHz, and 3.08 GHz. It can be seen that the antenna exhibits stable end-fire radiation characteristics within its operating bandwidth, and the cross-polarization level remains consistently low, with cross-polarization suppression exceeding 20 dB, verifying the antenna's excellent radiation performance. Figure 6As shown, the maximum radiation of the main polarization on the E-plane points to the 0° and 180° directions, and the cross-polarization is distributed in four lobes. The H-plane exhibits typical bidirectional radiation characteristics, with radiation concentrated in the 0° and 180° directions and forming depressions in the 90° and 270° directions. The cross-polarization suppression exceeds 20dB, demonstrating the best polarization purity and radiation performance.

[0033] Therefore, the present invention adopts the above-mentioned miniaturized slot-coupled single-layer broadband filter antenna, realizing the miniaturization and low profile design of the antenna, without complex feed network and additional filter circuit, and has the characteristics of simple design, low manufacturing cost and easy processing and maintenance. It can be directly integrated into the radio frequency front-end equipment, and meets the stringent requirements of modern wireless communication equipment for space utilization and integration.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A miniaturized slot-coupled single-layer broadband filter antenna, characterized in that, The device includes a microstrip feed line (1), a dielectric substrate (2), a coaxial feed probe (4), a metallized short-circuit via (5), and a metal ground plane (3). The microstrip feed line (1) is printed on the upper surface of the dielectric substrate (2). The coaxial feed probe (4) and the metallized short-circuit via (5) are both disposed on the dielectric substrate (2), and the microstrip feed line (1) is located between the coaxial feed probe (4) and the metallized short-circuit via (5). The metal ground plane (3) is printed on the lower surface of the dielectric substrate (2). Furthermore, the metal ground plate (3) is etched with three mutually coupled main folding gaps and two U-shaped gaps (34) symmetrically arranged on both sides of the main folding gaps; the main folding gaps are located at the center of the metal ground plate (3), and the main folding gaps include a first gap (31) located at the center, a second gap (32) and a third gap (33) respectively located on both sides of the first gap (31); the two U-shaped gaps (34) are the first U-shaped gap (341) and the second U-shaped gap (342).

2. The miniaturized slot-coupled single-layer broadband filter antenna according to claim 1, characterized in that, The number of metallized short-circuit vias (5) is one, and the metallized short-circuit via (5) is disposed through the dielectric substrate (2).

3. The miniaturized slot-coupled single-layer broadband filter antenna according to claim 1, characterized in that, The first U-shaped gap (341) and the second U-shaped gap (342) have the same shape and size. They are arranged symmetrically with respect to the center of the dielectric substrate (2), and the first U-shaped gap (341) and the second U-shaped gap (342) are both located at the edge of the dielectric substrate (2).

4. The miniaturized slot-coupled single-layer broadband filter antenna according to claim 1, characterized in that, The first gap (31), the second gap (32) and the third gap (33) are all located in the middle area of ​​the two U-shaped gaps (34). All three are regular folded structures, and the first gap (31), the second gap (32) and the third gap (33) are symmetrically arranged with respect to the transverse central axis of the dielectric substrate (2).

5. The miniaturized slot-coupled single-layer broadband filter antenna according to claim 1, characterized in that, The microstrip feed line (1) has a rectangular structure and is arranged along the direction parallel to the top and bottom edges of the dielectric substrate (2).

6. The miniaturized slot-coupled single-layer broadband filter antenna according to claim 1, characterized in that, The first slit (31) is coupled to the second slit (32) to generate a resonant mode and a radiation null at low frequencies; the first slit (31) is coupled to the third slit (33) to generate a resonant mode and a radiation null at high frequencies.

7. The miniaturized slot-coupled single-layer broadband filter antenna according to claim 1, characterized in that, The first U-shaped slot (341) and the second U-shaped slot (342) work together to adjust the working bandwidth of the antenna, improve the frequency selectivity of the antenna, and generate a radiation null at low frequencies.

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