Millimeter wave wide-beam circularly polarized double-layer microstrip patch antenna

Abstract

The application discloses a kind of millimeter wave wide-beam circular polarization double-layer microstrip patch antennas, belong to antenna technical field;It includes the upper layer dielectric plate and the lower layer dielectric plate of lamination, the upper surface of upper layer dielectric plate is equipped with parasitic patch, parasitic patch is cross type structure;The lower surface of upper layer dielectric plate is equipped with semi-cured layer;The upper surface of lower layer dielectric plate is equipped with radiation patch and parasitic branch, and parasitic branch is all right angle trapezoidal structure;Two groups of parasitic branch are respectively arranged at two diagonal positions of the upper surface of lower layer dielectric plate;Radiation patch is located in the region surrounded by parasitic branch;The lower surface of lower layer dielectric plate is equipped with ground metal plate, the inner conductor of coaxial feed line passes through small hole and is connected with radiation patch, and the outer conductor of coaxial feed line is connected with ground metal plate.The application works at 27.65GHz-34.21GHz, and can realize 113° maximum half-power beam width at 29GHz, and at the frequency point, 3db axial ratio width can reach about 170°, with good wide-beam circular polarization performance.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a millimeter-wave wide-beam circularly polarized double-layer microstrip patch antenna. Background Technology

[0002] Microstrip antennas are one of the most commonly used antenna types in radio frequency (RF) front-ends. Due to their simple structure, ease of fabrication, and low profile, they are widely used in various fields. To achieve millimeter-wave satellite communication, antenna elements need to have wide-beam circular polarization. Therefore, millimeter-wave wide-beam circularly polarized microstrip antennas have significant research value. However, due to their structural characteristics, microstrip antennas have narrow beams and operating frequencies, requiring techniques to broaden the antenna beamwidth and operating frequency band. This patent employs a parasitic patch structure to broaden the bandwidth, increasing the resonant point through the parasitic patch. Some wide-beam microstrip antennas also use parasitic patch structures to broaden the beamwidth. This method achieves a wide beam by using complementary radiation patterns between the parasitic patch radiation and the main radiating patch. Since this patent uses parasitic patches to broaden the operating frequency, this method is no longer applicable. Other wide-beam technologies applied to microstrip antennas include adding metal walls and adding reflectors. Since this patent uses dual-layer microstrip antenna technology, the technical approach of adding a metal wall above the antenna is no longer applicable.

[0003] In order to take into account the characteristics of circular polarization, there are certain requirements for the shape of the antenna and the added parasitic patch. The surface current of the main radiating patch needs to generate mutually perpendicular currents at 0° phase and 90° phase.

[0004] Therefore, to achieve a wideband microstrip antenna with circularly polarized beam, it is necessary to simultaneously consider the limitations imposed on the antenna by three characteristics. Currently, microstrip antenna technology struggles to achieve ideal results in all three aspects at the same time. Summary of the Invention

[0005] To address the problems existing in the above-mentioned background technology, the present invention proposes a millimeter-wave wide-beam circularly polarized dual-layer microstrip patch antenna; it operates from 27.65 GHz to 34.21 GHz, and can achieve a maximum half-power beamwidth of 113° at 29 GHz. Furthermore, at this frequency, the 3 dB axial ratio width can reach about 170°, exhibiting excellent wide-beam circular polarization performance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A millimeter-wave wide-beam circularly polarized dual-layer microstrip patch antenna includes a stacked upper dielectric substrate 7 and a lower dielectric substrate 5. The upper surface of the upper dielectric substrate is provided with a parasitic patch 2, which has a cross-shaped structure.

[0008] The lower surface of the upper dielectric plate is provided with a semi-cured layer 6;

[0009] The upper surface of the lower dielectric substrate is provided with a radial patch 1 and a parasitic branch 3, all of which are right-angled trapezoidal structures; two parasitic branches form a group, and there are two groups in total. The hypotenuses of the two parasitic branches in each group are directly opposite each other, and there is a gap between the two hypotenuses; the two groups of parasitic branches are respectively located at two diagonal positions on the upper surface of the lower dielectric substrate; the radial patch is located in the area enclosed by the parasitic branches;

[0010] The lower surface of the lower dielectric substrate is provided with a grounding metal plate. The grounding metal plate is provided with a small hole for the inner conductor of the coaxial feed line to pass through. The inner conductor of the coaxial feed line passes through the small hole and is connected to the radiating patch, and the outer conductor of the coaxial feed line is connected to the grounding metal plate.

[0011] Furthermore, each parasitic branch 3 has multiple metal pins connected to its bottom; the other end of each metal pin is connected to a grounded metal plate.

[0012] Furthermore, each parasitic branch 3 is connected to 5 metal pins, which penetrate the underlying dielectric substrate.

[0013] Furthermore, the radiating patch has a square structure, with square extensions at one pair of corners; and both square extensions extend outward along the same diagonal of the radiating patch; one corner of the other pair of corners of the radiating patch has a square notch.

[0014] Furthermore, the diagonal of the square extension is perpendicular to the hypotenuse of the parasitic branch.

[0015] Furthermore, the parasitic patch is located directly above the radiating patch.

[0016] The beneficial effects of the above-mentioned technical solution adopted by the present invention are as follows:

[0017] a) The antenna can achieve a maximum beamwidth of 113° at 29 GHz, which is about 20° wider than that of common microstrip antennas.

[0018] b) The antenna operates in the frequency band from 27.65 GHz to 34.21 GHz, with a bandwidth of 21.2%.

[0019] c) The antenna has a circularly polarized resonant point at 29 GHz, which can achieve an axial ratio of 170°, thus enabling wide-beam circular polarization at 29 GHz. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a millimeter-wave wide-beam circularly polarized double-layer microstrip patch antenna structure;

[0021] Figure 2 yes Figure 1 A schematic diagram of the upper surface of the middle and lower layer dielectric substrate.

[0022] Figure 3 yes Figure 1 A schematic diagram of the upper surface of the middle and upper layer dielectric substrate.

[0023] Figure 4 yes Figure 1 A side view diagram.

[0024] Figure 5 This is a graph showing the reflection coefficient of the antenna during operation.

[0025] Figure 6 It is a two-dimensional radiation pattern when the antenna is operating at 29 GHz and Φ = 0°.

[0026] Figure 7 It is a two-dimensional radiation pattern when the antenna is operating at 29 GHz and Φ = 90°.

[0027] Figure 8 This is the AR aspect ratio diagram when the antenna is operating at 29GHz. Detailed Implementation

[0028] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] A millimeter-wave wide-beam circularly polarized dual-layer microstrip patch antenna includes a stacked upper dielectric substrate 7 and a lower dielectric substrate 5. The upper surface of the upper dielectric substrate is provided with a parasitic patch 2, which has a cross-shaped structure.

[0031] The lower surface of the upper dielectric plate is provided with a semi-cured layer 6;

[0032] The upper surface of the lower dielectric substrate is provided with a radial patch 1 and a parasitic branch 3, all of which are right-angled trapezoidal structures; two parasitic branches form a group, and there are two groups in total. The hypotenuses of the two parasitic branches in each group are directly opposite each other, and there is a gap between the two hypotenuses; the two groups of parasitic branches are respectively located at two diagonal positions on the upper surface of the lower dielectric substrate; the radial patch is located in the area enclosed by the parasitic branches;

[0033] The lower surface of the lower dielectric substrate is provided with a grounding metal plate. The grounding metal plate is provided with a small hole for the inner conductor of the coaxial feed line to pass through. The inner conductor of the coaxial feed line passes through the small hole and is connected to the radiating patch, and the outer conductor of the coaxial feed line is connected to the grounding metal plate.

[0034] Furthermore, each parasitic branch 3 has multiple metal pins connected to its bottom; the other end of each metal pin is connected to a grounded metal plate.

[0035] Furthermore, each parasitic branch 3 is connected to 5 metal pins, which penetrate the underlying dielectric substrate.

[0036] Furthermore, the radiating patch has a square structure, with square extensions at one pair of corners; and both square extensions extend outward along the same diagonal of the radiating patch; one corner of the other pair of corners of the radiating patch has a square notch.

[0037] Furthermore, the diagonal of the square extension is perpendicular to the hypotenuse of the parasitic branch.

[0038] Furthermore, the parasitic patch is located directly above the radiating patch.

[0039] The following is a more specific embodiment:

[0040] With attachment Figures 1 to 4 Taking the antenna structure shown as an example, the antenna consists of a radiating patch, a parasitic branch, a grounding metal plate, a three-layer dielectric board, and a coaxial feed line.

[0041] The radiating patch employs a classic circularly polarized radiating patch structure. Using a perturbation method, two square extensions are added to the square radiating patch to generate circularly polarized radiation. Due to the induction of parasitic stubs on the radiating patch's current, a square notch is cut at the lower right corner of the radiating patch to ensure circular polarization performance. The main radiating patch feeds energy to the upper parasitic patch through coupling.

[0042] The use of a cross-shaped parasitic patch effectively broadens the operating frequency and generates circularly polarized radiation, enabling the antenna to operate effectively in the Ka-band. The parasitic patch can be viewed as a combination of two rectangular strips; the aspect ratio of these strips directly affects the antenna's polarization performance. By optimizing the dimensions of the rectangular strips, an aspect ratio close to 3:1 was ultimately chosen. This cross-shaped parasitic patch introduces impedance, causing the antenna to resonate in the Ka-band.

[0043] The middle dielectric substrate of the antenna is a semi-cured polypropylene (PP) layer, which is the adhesive layer used during processing. All three dielectric substrates of this antenna are made of the same material. Experiments show that the size of the dielectric substrate affects the resonant frequency of the antenna. The material of the dielectric substrate directly affects the radiation pattern and resonant frequency of the antenna. A higher dielectric constant will reduce the antenna's radiation gain, degrading its performance. Conversely, a lower dielectric constant will degrade the antenna's polarization performance. Therefore, considering both the antenna's gain and polarization performance, Rogers RT / duroid5880 was selected as the dielectric substrate material.

[0044] Parasitic stubs 3 are loaded around the radiating patch 1, and coupling occurs between the parasitic stubs and the main radiating patch, which to some extent extends the beamwidth. Furthermore, numerous metal pins of a grounded metal plate are located beneath the parasitic stubs 3. The equivalent capacitance generated between these metal pins lowers the resonant frequency, resulting in a smaller antenna size compared to a conventional antenna at the same resonant frequency. Therefore, the introduction of parasitic stubs allows for further miniaturization of the antenna, making its size highly flexible. By selecting appropriate ground plane and dielectric substrate dimensions, wide beamwidth functionality can be achieved.

[0045] The system consists of a radiating patch 1, a parasitic patch 2, a parasitic branch 3, a ground plane 4, a lower dielectric substrate, an upper dielectric substrate and a PP layer, and a coaxial feed line 8. The radiating patch is located between the lower dielectric substrate and the intermediate PP layer; the parasitic patch 2 is a cross-shaped parasitic patch located above the upper dielectric substrate 6; the parasitic branch is loaded around the radiating patch, and the centers of the radiating patch and the parasitic patch are symmetrically distributed along a vertical line with the center of the dielectric substrate; the coaxial feed line is directly connected to the radiating patch through the lower dielectric substrate.

[0046] The radiating patch, based on a circularly polarized patch antenna structure obtained through perturbation, adds square corners to a pair of opposite corners of a rectangular patch. These corners are used to influence the surface current to generate circularly polarized radiation. Due to the influence of parasitic stubs, a portion of the material is removed from the non-square corner side of the main radiating patch near the feed to ensure circular polarization.

[0047] The topmost parasitic unit is a cross-shaped parasitic patch. This patch is excited by a radiating patch through coupling. The structure can be viewed as a combination of two vertical rectangular strips. The aspect ratio of these rectangular strips is approximately 3:1.

[0048] The parasitic branches can be viewed as L-shaped structures loaded near the two opposite corners of the main radiating patch, and are slotted. Furthermore, two rows of metal pins are loaded on the underside of each L-shaped slotted parasitic patch for short-circuit connections.

[0049] In summary, the rectangular diagonal of the radiating patch, the size of the parasitic patch, the shape of the parasitic stubs, the material and thickness of the dielectric substrate, and the feeding method all affect antenna performance. After fully balancing the influence of these parameters, the following parameters are used to design this antenna:

[0050] The radiating patch measures 2.034mm × 2.034mm, with a square extension measuring 0.5mm × 0.5mm and a cut-out square notch measuring 0.65mm × 0.65mm.

[0051] The parasitic patch can be viewed as a combination of two vertical rectangles, one of which measures 2.4mm × 0.8mm.

[0052] The parasitic branch can be viewed as consisting of two L-shaped parasitic patches with slits and metal leads. The long side of the L-shaped patch is 2.4 mm, and the width is 0.8 mm. The slit width is 0.1 mm and it is located at the corner of the L-shaped patch. The distance between the L-shaped patch and the main radiating patch is 0.065 mm.

[0053] The grounding metal plate 3 is selected to be 2.8mm×2.8mm in size.

[0054] The three-layer dielectric substrate has dimensions of 5.36mm x 5.36mm. Considering actual processing requirements, the thickness of the lower dielectric substrate is 0.381mm; the thickness of the PP layer is 0.127mm; and the thickness of the upper dielectric substrate is 0.254mm. All three layers are made of Rogers RT / duroid5880 material.

[0055] The size of the coaxial cable directly affects the power supply effect. Considering actual manufacturing requirements, a 0.3mm diameter inner conductor and a 0.3×2.3mm diameter outer surface are used. Calculations show that this size can effectively match an input impedance of 50Ω.

[0056] Figure 5 This is a simulation graph of the antenna's reflection coefficient. The graph shows that the antenna has an operating bandwidth of -10 dB between 27.65 GHz and 34.21 GHz, and -15 dB between 28.06 GHz and 32.34 GHz.

[0057] Figure 6 and Figure 7The radiation pattern of the antenna operating at 29 GHz is shown, exhibiting a wide beamwidth at Φ = 0° and Φ = 90°. In the Φ = 0° plane, the beamwidth ranges from -52.70° to 53.78°. In the Φ = 90° plane, the beamwidth ranges from -56.61° to 55.51°. Notably, in the Φ = 45° plane, the beamwidth ranges from -58.78° to 57.22°. This wide beamwidth provides a large scanning range when the element is used as a phased array element. Simulations of the antenna at different frequencies within the operating band show no significant changes in its radiation pattern.

[0058] Figure 8 The antenna's axial ratio at 29 GHz is shown, indicating that the antenna has a wide axial ratio beam at 29 GHz, making it well-suited for phased array scanning.

[0059] In summary, this antenna operates in the Ka-band, achieving a wide beamwidth and circular polarization, with an operating bandwidth ranging from 27.65 GHz to 34.21 GHz. It can be effectively applied to millimeter-wave satellite communications.

Claims

1. A millimeter-wave wide-beam circularly polarized dual-layer microstrip patch antenna, comprising a stacked upper dielectric substrate (7) and a lower dielectric substrate (5), characterized in that, The upper surface of the upper dielectric plate is provided with a parasitic patch (2), which has a cross-shaped structure; The lower surface of the upper medium plate is provided with a semi-cured layer (6). The upper surface of the lower dielectric substrate is provided with a radial patch (1) and parasitic branches (3), all of which are right-angled trapezoidal structures; two parasitic branches form a group, and there are two groups in total. The hypotenuses of the two parasitic branches in each group are directly opposite each other, and there is a gap between the two hypotenuses; the two groups of parasitic branches are respectively located at two diagonal positions on the upper surface of the lower dielectric substrate; the radial patch is located in the area enclosed by the parasitic branches; The lower surface of the lower dielectric substrate is provided with a grounding metal plate. The grounding metal plate is provided with a small hole for the inner conductor of the coaxial feed line to pass through. The inner conductor of the coaxial feed line passes through the small hole and is connected to the radiating patch, and the outer conductor of the coaxial feed line is connected to the grounding metal plate. Each parasitic branch (3) has multiple metal pins connected to its bottom; the other end of the metal pins is connected to a grounded metal plate. Each parasitic branch (3) has 5 metal pins connected to it, and the metal pins penetrate the lower dielectric plate. The radiating patch has a square structure, with square extensions at one pair of corners; both square extensions extend outward along the same diagonal of the radiating patch; and one corner of the other pair of corners of the radiating patch has a square notch.

2. The millimeter-wave wide-beam circularly polarized double-layer microstrip patch antenna according to claim 1, characterized in that, The diagonal of the square extension is perpendicular to the hypotenuse of the parasitic branch.

3. The millimeter-wave wide-beam circularly polarized double-layer microstrip patch antenna according to claim 1, characterized in that, The parasitic patch is located directly above the radiation patch.

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