A filter antenna with broadband harmonic suppression characteristics

Abstract

The present application provides a filtering antenna with broadband harmonic suppression characteristics. The antenna provided in the present application includes a metal floor, a first dielectric substrate, a second dielectric substrate, a metal radiation patch, a metal coupling patch, a number of short-circuit metal posts, a feeding structure, and a number of supporting structures; the metal floor is arranged on the lower surface of the first dielectric substrate; the second dielectric substrate is arranged above the first dielectric substrate; the first dielectric substrate and the second dielectric substrate are connected by a number of supporting structures; the upper surface of the first dielectric substrate is provided with a metal radiation patch; the upper surface of the second dielectric substrate is provided with a metal coupling patch; the lower end of each short-circuit metal post is connected to the metal floor, and the upper end passes through the first dielectric substrate and is connected to the metal radiation patch. The antenna in the present application not only has a steep radiation gain filtering response, but also can achieve good harmonic suppression effect in a wider frequency band outside the high frequency band, and can be used as a preferred solution for anti-interference communication antennas.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a filtering antenna with broadband harmonic suppression characteristics. Background Art

[0002] In the prior art, antennas with out-of-band selectivity are typically designed by introducing a filter structure into the antenna feed line. This filter is then cascaded with the antenna radiator to achieve a filtering effect on the antenna's radiation gain. Typically, when a power amplifier or other nonlinear element in a wireless communication system is driven by a high-power or nonlinear signal, a series of harmonic signals are generated. These harmonic signals are integer multiples of the original signal frequency and extend into the frequency bandwidth used by the system. If these harmonic signals are not effectively suppressed, they may introduce interference, leading to spectrum pollution and communication interference. Therefore, designing a filter antenna with broadband harmonic suppression characteristics based on traditional filter antennas can meet current and future filter antenna requirements for RF front-end systems.

[0003] For example, the Chinese patent publication number CN117543193A, titled "A Decoupling Filter Antenna," is essentially a microstrip antenna fed by slot coupling. Its filtering function is achieved by adding metal shorting posts to the first and second dielectric substrates. The patent's detailed implementation method states that decoupling between different filtering antenna elements can be achieved, thereby achieving excellent performance such as a good directivity pattern and efficiency. However, the antenna consists of two patch antenna elements, resulting in a relatively large physical size.

[0004] The Chinese patent, publication number CN115275603B, provides a "Microstrip Filter Antenna Based on Feed Branches." Its essence is to utilize the electromagnetic distribution of the microstrip antenna and the point coupling between adjacent radiating planes to introduce a radiation null at the upper edge of the passband. Simultaneously, utilizing the antenna's feed branches, a radiation null is introduced at the lower edge of the passband, ultimately achieving a fusion design of the filter antenna. The patent's specific implementation method states that the antenna operates in a frequency range of 2.25 GHz to 2.47 GHz, with a relatively narrow operating bandwidth.

[0005] The Chinese patent application, "Broadband Patch Filter Antenna and Wireless Communication Device," with publication number CN219321623U, describes a three-layer structure comprising a dielectric substrate, a radiating patch, a parasitic patch, an upper feed branch, a lower feed branch, a metal floor, and a metal shorting post. The patent's detailed implementation states that the antenna's operating bandwidth can reach 36.8% within the 2.11GHz-3.06GHz frequency band. However, the antenna's overall three-layer structure results in a relatively high physical size.

[0006] The Chinese patent, publication number CN206225549U, provides a "Pyramidal Horn Filter Antenna Based on a Waveguide Structure." The filtering function is achieved by a multi-stage rectangular microwave resonant cavity, with the antenna serving as the final stage to radiate electromagnetic energy. The patent describes the antenna's operating bandwidth as narrow, with the specific embodiment of the patent stating a relative bandwidth of only 2.4%, and a relatively single polarization scheme.

[0007] The Chinese patent application, "A Reconfigurable Filter Antenna with Directional Pattern," published in publication number CN108258405B, is essentially a planar microstrip filter. The filtering function and radiation pattern are controlled by controlling the coupling between the branches and multimode resonators on the feeder line and the feeder and antenna. The patent's detailed implementation states that the antenna has an impedance bandwidth of 25% when operating at 5.2 GHz. In another aspect of the antenna design, the feeder's filtering structure is combined with the antenna's inherent band-stop characteristics to achieve the overall filtering effect.

[0008] The Chinese patent application, "A Differential Dual-Band Dual-Polarized Antenna for 5G Sub-6G Base Station Systems," published in publication number CN109904613B, essentially introduces a band-stop stub on the feeder line and uses the antenna's inherent radiation null between the two frequency bands to achieve a dual-band, dual-polarized filtering effect. However, the introduction of the feeder line increases the overall insertion loss of the antenna, hindering effective radiation.

[0009] The Chinese patent application, "Compact Broadband Filter Antenna Based on Cross-Coupling Structure," published in CN111293413B, achieves a gain filtering effect by controlling feeder branches, floor slots, and U-shaped coupling patches to achieve a radiation null. However, the patent's detailed implementation details indicate that the antenna's relative operating bandwidth is only 20.6%, and its polarization is relatively single.

[0010] As can be seen, the aforementioned antennas all increase their size by introducing a filter-like structure into the feeder, resulting in less than ideal bandwidth. Furthermore, most antennas fail to address harmonic suppression across a wide frequency band, making them unsuitable candidates for harmonic suppression filter antennas. To further improve the wideband anti-interference performance of filter antennas, it is necessary to design a filter antenna with broadband harmonic suppression to address the frequency-domain anti-interference requirements of future wireless communication applications. Summary of the Invention

[0011] To address the narrow radiation gain suppression bandwidth problem of existing filtering antennas, this application provides a filtering antenna with broadband harmonic suppression characteristics. This antenna not only has a steep radiation gain filtering response, but also achieves good harmonic suppression across a wide frequency range outside the high-frequency band.

[0012] To achieve the above objectives, the antenna provided in this application includes: a metal floor, a radiating patch, a dielectric substrate, a metal shorting post, a feeding structure, and a supporting structure. The metal floor is disposed on the lower surface of a first dielectric substrate; a second dielectric substrate is disposed above the first dielectric substrate; an air layer is disposed between the first and second dielectric substrates; the first and second dielectric substrates are connected by a plurality of supporting structures; a metal radiating patch is disposed on the upper surface of the first dielectric substrate; a metal coupling patch is disposed on the upper surface of the second dielectric substrate; the lower end of each metal shorting post is connected to the metal floor, and the upper end of each metal shorting post passes through the first dielectric substrate and is connected to the metal radiating patch; and the feeding structure is used to transmit microwave signals to the metal radiating patch.

[0013] In this application, the metal radiating patch is generally square, but may also be circular, fan-shaped, or other shapes, and is symmetrical about the main polarization direction along the center. Two symmetrical slots are provided on the metal radiating patch at the bottom edge closest to the feed structure. The slots may have shapes including, but not limited to, rectangular, curved, fan-shaped, and arc-shaped. The theoretical overall length is 1 / 4 wavelength of the frequency corresponding to the minimum point of the radiation gain outside the high-frequency band. The slots produce a radiation gain filtering effect and adjust impedance matching.

[0014] In some implementations, the metal coupling patch is generally smaller than the metal radiating patch; the vertical projections of the center points of the metal coupling patch and the metal radiating patch overlap to prevent the metal coupling patch from obstructing the metal radiating patch. The metal coupling patch is provided with two symmetrical slots on one side near the bottom edge of the metal radiating patch, which produce a radiation gain filtering effect. The shapes of the slots include, but are not limited to, rectangular, curved, fan-shaped, and arc-shaped, and their overall length is theoretically 1 / 4 wavelength of the frequency corresponding to the minimum point of radiation gain outside the low-frequency band.

[0015] In some implementations, the metal coupling patch is provided with two symmetrical slots on a side away from the bottom edge of the metal radiating patch. The slots extend from the farthest point from the metal coupling patch toward the center of the metal coupling patch, thereby producing a radiation gain filtering effect. The slots may have shapes including, but not limited to, rectangular, meandering, fan-shaped, and arc-shaped. The theoretical overall length of the slots is 1 / 4 wavelength of the frequency corresponding to the minimum point of the high-frequency out-of-band radiation gain.

[0016] In some implementations, the metal short-circuit posts are symmetrically arranged about the center line of the metal radiation patch; the vertical projection of the center of the metal short-circuit posts is located at the center of the metal radiation patch; the number of metal short-circuit posts is an odd number, generally 5 or 7, and there is at least one metal short-circuit post located at the center of the metal radiation patch and two symmetrical metal short-circuit posts located at the outer edges of the metal radiation patch.

[0017] In some implementations, the feeding structure may employ other feeding methods, such as direct coaxial cable feeding or microstrip line side feeding. When direct coaxial cable feeding is employed, the inner core of the coaxial cable passes through the first dielectric substrate and is connected to the metal radiating patch disposed on the upper surface of the first dielectric substrate. The outer sheath of the coaxial cable is connected to the metal ground plane disposed on the lower surface of the first dielectric substrate, thereby forming a feeding port.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention prints a metal radiation patch on a first dielectric substrate and adds a metal short-circuit post, and prints a metal coupling patch on a second dielectric substrate and adds an edge groove, thereby generating a radiation gain zero outside the antenna's operating frequency band, forming a better radiation gain filtering effect, and can solve the problem of harmonic signals that may interfere with wireless communications.

[0020] 2. The present invention adopts the method of printing metal coupling patches on the upper second dielectric substrate, which expands the antenna working bandwidth while reducing the lateral physical size of the antenna, which is conducive to the miniaturization design requirements of the antenna.

[0021] 3. Compared with other forms of broadband filtering antennas, the antenna of the present invention has stable radiation gain within the working frequency band, and also has the advantages of simple structure, easy processing, small size, light weight, low cost, and easy maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0023] Figure 2 A top view of the lower metal patch structure of the present invention;

[0024] Figure 3 A top view of the upper coupling patch of the present invention;

[0025] Figure 4 is a side view of the present invention;

[0026] Figure 5 is a graph showing how the reflection coefficient of the antenna port changes with frequency;

[0027] Figure 6is the curve of the radiation gain of the antenna port changing with frequency;

[0028] Figure 7 is the gain pattern of the antenna operating at 3.5 GHz.

[0029] The meanings of the reference numerals are as follows:

[0030] 1. First dielectric substrate; 2. Second dielectric substrate; 3. Metal radiating patch; 4. Outer metal shorting post; 5. Inner metal shorting post; 6. Metal coupling patch; 7. Support post; 8. Coaxial feed line; 9. Metal floor. DETAILED DESCRIPTION

[0031] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] At the same time, in the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "upper, lower, inside and outside" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0034] Unless otherwise specified or limited, the terms "mounted, connected, and connected" in this disclosure should be understood broadly. For example, they may refer to fixed, removable, or integral connections. They may also refer to mechanical, electrical, or direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure.

[0035] This embodiment provides a filtering antenna with broadband harmonic suppression characteristics, and its three-dimensional structure and top and side view structures are as follows: Figures 1-4As shown, it includes: 1-first dielectric substrate; 2-second dielectric substrate; 3-metal radiation patch; 4-outer metal short-circuit column; 5-inner metal short-circuit column; 6-metal coupling patch; 7-support column; 8-coaxial feed line; 9-metal floor.

[0036] The first dielectric substrate 1 is arranged parallel to and above the metal floor 9. In this embodiment, the metal floor 9 is 70 mm long and 70 mm wide. The dielectric constant of the first dielectric substrate 1 is 2.65. The first dielectric substrate 1 is 70 mm long, 70 mm wide, and 2 mm thick. There is no air gap between the first dielectric substrate 1 and the metal floor 9.

[0037] A metal coupling patch 6 is provided on the upper surface of the second dielectric substrate 2. In this embodiment, the metal coupling patch 6 is arranged in an irregular rectangular shape, with a length of 30 mm and a width of 30 mm. Four rectangular grooves are provided on the metal coupling patch 6 to achieve harmonic suppression and radiation gain filtering effects.

[0038] A metal radiation patch 3 is provided on the upper surface of the first dielectric substrate 1. In this embodiment, the metal radiation patch 3 is arranged in an irregular rectangular shape, and the length of the metal radiation patch 3 is 30 mm and the width is 34 mm. Five inner metal short-circuit posts 5 and two outer metal short-circuit posts 4 are added to the metal radiation patch 3, the first dielectric substrate 1, and the metal floor 9 to produce a radiation gain filtering effect.

[0039] In this embodiment, there are 7 metal short-circuit posts, the lower end of each metal short-circuit post is connected to the metal floor 9, and the upper end of each metal short-circuit post is connected to the corresponding metal radiation patch 3;

[0040] The outer sheath of the coaxial feed line 8 is connected to the metal floor 9, and the inner core of the coaxial feed line 8 passes through the first dielectric substrate 1 and connects to the metal radiating patch 3, thereby forming a coaxial feed port. Optionally, the feed structure in this embodiment can also be changed to microstrip line side feeding or other feeding schemes.

[0041] In this embodiment, the metal radiation patch 3 and the metal coupling patch 6 are both made of metal materials and are respectively provided on the first dielectric substrate 1 and the second dielectric substrate 2 by printing or other methods.

[0042] In this embodiment, the metal floor 9 is made of metal material; the first dielectric substrate 1 and the second dielectric substrate 2 can be any low-loss dielectric material. As a low-cost option, this embodiment uses F4B as the dielectric substrate material.

[0043] In order to verify the beneficial effects of the antenna of the present invention, the following is further explained through experimental simulation:

[0044] 1. Simulation content

[0045] The above implementation is applied to a port reflection coefficient and a radiation gain curve of a filtering antenna with broadband harmonic suppression characteristics and is simulated and calculated using simulation software.

[0046] 2. Simulation results

[0047] Figure 5 This is a graph of the reflection coefficient when the antenna port in this embodiment is fed. It can be seen that the bandwidth in which the antenna port reflection coefficient is less than -10 dB is 26.5% (3.05-3.98 GHz), which can cover a wide 5G communication frequency band.

[0048] Figure 6 The following graph shows the change in radiation gain of the antenna in this embodiment when the antenna is powered. It can be seen that the gain of the antenna of this invention is 8.2±0.73 dBi within the operating frequency band. Outside the operating frequency band, the gain attenuates significantly, resulting in excellent gain filtering and excellent suppression of harmonics in the 4-10 GHz frequency band, including specific communication bands such as n77 and n78 in the 5G band. Given this excellent performance, this antenna is a preferred design solution for 5G anti-interference communication antennas.

[0049] Figure 7 The following figure shows the radiation pattern of the antenna in this embodiment operating at 3.5 GHz. It can be seen that the antenna's maximum radiation gain at this frequency is 8.0 dB, the 3dB beamwidth of the E-plane pattern is 65.6°, and the 3dB beamwidth of the H-plane pattern is 72.9°. The antenna exhibits stable directional radiation characteristics in both primary observation planes, verifying its superior performance in the 5G frequency band.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A filtering antenna with broadband harmonic suppression characteristics, characterized by: It includes a metal floor, a first dielectric substrate, a second dielectric substrate, a metal radiation patch, a metal coupling patch, a plurality of metal short-circuit columns, a feeding structure, and a plurality of supporting structures; the metal floor is arranged on the lower surface of the first dielectric substrate; The second dielectric substrate is disposed above the first dielectric substrate; An air layer is provided between the first dielectric substrate and the second dielectric substrate; the first dielectric substrate and the second dielectric substrate are connected by a plurality of supporting structures; The metal radiating patch is provided on the upper surface of the first dielectric substrate; the metal coupling patch is provided on the upper surface of the second dielectric substrate; two symmetrical slots are provided on the metal radiating patch at the bottom edge closest to the feeding structure; the size of the metal coupling patch is smaller than that of the metal radiating patch; the vertical projection of the center point of the metal coupling patch coincides with the center point of the metal radiating patch; the metal coupling patch has two symmetrical slots on the side close to the bottom edge of the metal radiating patch; the metal coupling patch has two symmetrical slots on the side away from the bottom edge of the metal radiating patch, and the slots extend from the farthest point from the metal coupling patch to the center of the metal coupling patch; the metal short-circuit posts are symmetrically arranged about the center line of the metal radiating patch; the vertical projection of the center of the metal short-circuit post is located at the center position of the metal radiating patch; the lower end of each metal short-circuit post is connected to the metal floor; the upper end of each metal short-circuit post passes through the first dielectric substrate and is connected to the metal radiating patch; the feeding structure is used to transmit microwave signals to the metal radiating patch.

2. The filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: The shapes of the metal radiation patch and the metal coupling patch include square, circular, trapezoidal, and fan-shaped, and are symmetrical with respect to the main polarization direction of the antenna.

3. The filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: The shapes of the symmetrical gaps on the metal radiation patch and the metal coupling patch include rectangular, bent, fan-shaped, and arc-shaped.

4. The filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: The number of the metal short-circuit posts is an odd number, and includes at least one metal short-circuit post located at the center of the metal radiation patch and two metal short-circuit posts located at the outer edges of the metal radiation patch.

5. The filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: The feeding structure is coaxial cable direct feeding or microstrip line side feeding; when coaxial cable direct feeding is adopted, the inner core of the coaxial cable passes through the first dielectric substrate and is connected to the metal radiation patch, and the outer skin is connected to the metal floor to form a feeding port.

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