A filter antenna of aperture coupling type capable of suppressing ultra-wideband harmonics

Abstract

The application belongs to the technical field of antennas, and particularly relates to a mouth aperture coupling filter antenna capable of suppressing ultra-wideband harmonics. In order to solve the problems of low selectivity, narrow suppression bandwidth and large size of the harmonic suppression antenna in the current wireless communication, the application proposes an innovative design including a square radiation patch, a rectangular parasitic patch, a metal floor, a dielectric substrate and a microstrip feed line. The square radiation patch and the rectangular parasitic patch form an upper sideband radiation zero point through coupling, and an open rectangular ring groove etched on the metal floor forms a lower sideband radiation zero point, so as to improve the selectivity of the antenna passband; a planar coupling filter structure is loaded on the microstrip feed line, and an H-shaped gap is etched on the metal floor, while the size of the metal floor is reduced, the harmonic suppression reaches 22.53Hz (6.4f0), and the reflection coefficient is greater than -3dB.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to an aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics. Background Technology

[0002] With the increasing use of communication frequency bands in various fields, while spectral efficiency is constantly improving, new challenges are also emerging, such as the high likelihood of interference between devices operating in similar frequency bands. In the overall design of wireless communication systems, filtering antennas not only reduce the size of RF front-end equipment but also solve the loss problem caused by the connection between the filter and the antenna, thus reducing manufacturing costs. The filtering function of an antenna is mainly divided into filtering near-passband signals and filtering far-passband signals. The filtering performance of near-passband signals is reflected in the roll-off of the antenna's passband edge; a higher roll-off indicates better selectivity. Filtering far-passband signals is essentially harmonic suppression, primarily achieved through the suppression of the antenna's harmonics; a higher harmonics result in a wider suppression range for the signal.

[0003] Currently, antennas that filter near-passband signals mainly achieve this by adding stubs, short-circuit vias, or slots to the antenna feed line or radiator, creating multiple radiation nulls and improving the antenna's passband selectivity. Filtering signals far from the passband is equivalent to connecting the antenna in series with a low-pass filter. This is achieved through methods such as creating ground-hole structures, slotting the feed line or radiator, adding stubs, and short-circuit vias, which can effectively suppress the antenna's second and third harmonics. Simultaneous filtering of near- and far-passband signals is equivalent to connecting the antenna in series with a band-pass filter and a low-pass filter. Current research on filtering antennas mostly focuses on filtering only low-pass or far-passband signals. Antennas that simultaneously filter both near- and far-passband signals have low octave suppression and limited application range. Summary of the Invention

[0004] This invention addresses the aforementioned problems by providing an aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics. Near-passband filtering is achieved by etching two rectangular parasitic patches and an open rectangular annular groove on the ground plane. Ultra-wideband harmonic suppression is achieved by loading a planar coupled filter structure on the feed line and etching an H-shaped slot on the metal floor while simultaneously reducing the ground plane size to create a depression structure.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] An aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics includes an upper dielectric substrate, a metal ground plane, and a lower dielectric substrate arranged sequentially from top to bottom. A square radiating patch and a rectangular parasitic patch are etched on the upper surface of the upper dielectric substrate, and a capacitive load is placed on the edge of the rectangular parasitic patch. A rectangular slot, an open rectangular annular groove, and an H-shaped slot are etched on the upper surface of the metal ground plane. A microstrip feed line is disposed on the lower surface of the lower dielectric substrate, and a planar coupled filter structure is loaded on the microstrip feed line.

[0007] Furthermore, the square radiating patch is symmetrical about the y-direction and is located directly above the open rectangular annular groove.

[0008] Furthermore, two rectangular parasitic patches are etched on the upper surface of the upper dielectric substrate. The rectangular parasitic patches are symmetrical about the y-direction and about the square radiating patch.

[0009] Furthermore, the capacitive load is placed on the rear side of the rectangular parasitic patch.

[0010] Furthermore, the open rectangular annular groove is located at the center of the upper surface of the metal floor, and the opening of the open rectangular annular groove faces the rear side of the metal floor.

[0011] Furthermore, the rectangular slit is etched along the x-direction and located within an open rectangular annular groove, while the H-shaped slit is located at the front edge of the upper surface of the metal floor.

[0012] Furthermore, the rectangular slit, the open rectangular annular groove, and the H-shaped slit are symmetrical about the y-direction.

[0013] Furthermore, the microstrip feed line is located on the center line in the y direction on the lower surface of the lower dielectric substrate.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] This invention achieves near-passband signal filtering by introducing rectangular parasitic patches on both sides of a square radiating patch to form an upper sideband radiation null, and etching an open rectangular annular groove on a metal ground plane to form a lower sideband radiation null, based on a traditional aperture-coupled feed antenna. By loading a planar coupled filter structure on the microstrip feed line and etching an H-shaped slot on the metal ground plane while reducing the ground plane size to form a depression structure, harmonic suppression up to 6.44 octaves is achieved. Compared with existing filter antennas with harmonic suppression capabilities, this invention features a simpler structure, lower cost, and easier manufacturing. It can be applied to China Telecom's n78 band (3.4-3.5GHz) and 4G 22 band (3.41-3.49GHz), offering a wider application range, broader harmonic suppression bandwidth, higher selectivity, and smaller size. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the dual-band loop patch antenna of the present invention;

[0017] Figure 2 The reflection coefficient of the aperture-coupled filter antenna of the present invention, which can suppress ultra-wideband harmonics;

[0018] Figure 3 This invention relates to the gain of the aperture-coupled filter antenna that can suppress ultra-wideband harmonics;

[0019] Figure 4 This invention provides the normalized radiation patterns of the aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics at a frequency of 3.46 GHz in the E-plane and H-plane.

[0020] Among them, square radiating patch-1, rectangular parasitic patch-2, upper dielectric substrate-3, lower dielectric substrate-4, microstrip feed line-5, metal ground plane-6, rectangular slot-7, open rectangular annular groove-8, H-shaped slot-9, planar coupled filter structure-10, and capacitive load-11. Detailed Implementation

[0021] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0022] like Figure 1 As shown, an aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics in this embodiment includes an upper dielectric substrate 3, a metal ground plane 6, and a lower dielectric substrate 4 arranged sequentially from top to bottom. A square radiating patch 1 and a rectangular parasitic patch 2 are etched on the upper surface of the upper dielectric substrate 3. A capacitive load 11 is placed on the edge of the rectangular parasitic patch 2. A rectangular slot 7, an open rectangular annular groove 8, and an H-shaped slot 9 are etched on the upper surface of the metal ground plane 6. A microstrip feed line 5 is provided on the lower surface of the lower dielectric substrate 4, and a planar coupled filter structure 10 is loaded on the microstrip feed line 5.

[0023] The square radiating patch 1 is symmetrical about the y-direction and is located directly above the open rectangular annular groove 8. Two rectangular parasitic patches 2 are etched on the upper surface of the upper dielectric substrate 3. The rectangular parasitic patches 2 are symmetrical about the y-direction and about the square radiating patch 1. The capacitive load 11 is placed behind the rectangular parasitic patches 2.

[0024] The open rectangular groove 8 is located at the center of the upper surface of the metal floor 6, and the opening of the open rectangular groove 8 faces the rear side of the metal floor 6. The rectangular slot 7 is etched along the x-direction and is located within the open rectangular groove 8. The H-shaped slot 9 is located at the front edge of the upper surface of the metal floor 6. The rectangular slot 7, the open rectangular groove 8, and the H-shaped slot 9 are symmetrical about the y-direction.

[0025] The microstrip feed line 5 is located on the center line of the y direction on the lower surface of the lower dielectric substrate 4.

[0026] The specific dimensions and materials of this embodiment are as follows:

[0027] The upper dielectric substrate 3 and the lower dielectric substrate 4 are rectangular dielectric substrates with dimensions of 40mm×31.5mm and 40mm×35mm respectively. They are made of FR4 epoxy resin material with a dielectric constant of 4.4, a loss tangent of 0.02, and a thickness of 1mm.

[0028] The square radiating patch 1 has a side length of 15.5 mm and a resonant frequency of 3.46 GHz; the rectangular parasitic patch 2 has dimensions of 21.2 mm × 5.5 mm; the capacitive load 11 is an NPO chip capacitor with a capacitance of 1 pF and a package size of 0402, located 2 mm from the edge of the rectangular parasitic patch 2, forming a radiation null with a frequency of 3.68 GHz.

[0029] The metal floor 6 has dimensions of 35mm × 31.7mm, the rectangular slot 7 has dimensions of 11mm × 1mm, the open rectangular annular groove 8 has dimensions of 15mm × 12mm, a width of 1mm, and an opening size of 6mm, forming a radiation null point with a frequency of 3.06GHz. The H-shaped slot 9 is formed by combining three rectangular patches: a left rectangle, a middle rectangle, and a right rectangle. The left rectangle has dimensions of 1.2mm × 0.2mm, the middle rectangle has dimensions of 0.8mm × 0.2mm, and the right rectangle has the same dimensions as the left rectangle. It is 0.8mm away from the front edge of the metal floor 6 and can suppress harmonics at 20GHz.

[0030] The microstrip feed line 5 is a rectangular microstrip line with a length of 23 mm and a width of 1.8 mm.

[0031] The rectangular dimensions on the left and right sides of the planar coupled filter structure 10 are 3.2mm×2.25mm and 3mm×2mm, respectively, and the distances from the microstrip feed line 5 are 4mm and 2mm, respectively, which can suppress harmonics and spurious waves in the 5-18GHz range.

[0032] Figure 2 The reflection coefficients of the aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics in this example are listed, where the horizontal axis represents the frequency variable in GHz, and the vertical axis represents the reflection coefficient in dB. The antenna operates in the 3.37-3.59 GHz frequency band, with a relative bandwidth of 6.3%. The antenna's harmonic suppression band is 4-22.53 GHz, and the reflection coefficients are all greater than -3 dB, demonstrating ultra-wideband harmonic suppression characteristics.

[0033] Figure 3The gain of the aperture-coupled filter antenna for suppressing ultra-wideband harmonics in this example is listed, where the horizontal axis represents the frequency variation in GHz, and the vertical axis represents the gain in dBi. The antenna has two radiation nulls located at 3.68 GHz and 3.06 GHz, respectively, and the actual gain at the operating frequency of 3.46 GHz is 2.9 dBi. This antenna exhibits high selectivity.

[0034] Figure 4 Normalized radiation patterns of the E-plane and H-plane of an aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics are presented at 3.46 GHz. The normalized radiation pattern of the E-plane at 3.46 GHz is approximately forward-radiating, while the normalized radiation pattern of the H-plane is approximately circular, exhibiting good omnidirectional radiation characteristics.

[0035] The above embodiments of the present invention are examples provided to clearly illustrate the invention. Those skilled in the art can make changes to their form and details. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics, characterized in that, The substrate includes an upper dielectric substrate (3), a metal ground plane (6), and a lower dielectric substrate (4) arranged sequentially from top to bottom. A square radiating patch (1) and a rectangular parasitic patch (2) are etched on the upper surface of the upper dielectric substrate (3). A capacitive load (11) is placed on the edge of the rectangular parasitic patch (2). A rectangular slot (7), an open rectangular annular groove (8), and an H-shaped slot (9) are etched on the upper surface of the metal ground plane (6). A microstrip feed line (5) is provided on the lower surface of the lower dielectric substrate (4). A planar coupled filter structure (10) is loaded on the microstrip feed line (5). The square radiating patch (1) regarding y It is symmetrical in direction and located directly above the open rectangular annular groove (8); Two rectangular parasitic patches (2) are etched on the upper surface of the upper dielectric substrate (3), the rectangular parasitic patches (2) being about y The orientation is symmetrical, and the position is symmetrical about the square radiating patch (1); The capacitive load (11) is placed on the rear side of the rectangular parasitic patch (2); The open rectangular annular groove (8) is located at the center of the upper surface of the metal floor (6), and the opening of the open rectangular annular groove (8) faces the rear side of the metal floor (6); The rectangular slit (7) along x The directional etching is located within the open rectangular annular groove (8), and the H-shaped slit (9) is located at the front edge of the upper surface of the metal floor (6).

2. The aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics according to claim 1, characterized in that, The rectangular slit (7), the open rectangular annular groove (8), and the H-shaped slit (9) are related to y Symmetrical in direction.

3. The aperture-coupled filter antenna capable of suppressing ultra-wideband harmonics according to claim 1, characterized in that, The microstrip feed line (5) is located on the lower surface of the lower dielectric substrate (4). y On the center line of direction.

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