Millimeter wave broadband circularly polarized patch antenna

Abstract

The invention relates to a millimeter wave broadband circularly polarized patch antenna which comprises an excitation port, a micro-strip feeder line, a first dielectric plate, a metal floor, a cross-shaped groove, a second dielectric plate and a radiation patch. The microstrip feeder is printed on the lower surface of the first dielectric plate, the metal floor is printed on the upper surface of the first dielectric plate, the cross-shaped groove is etched in the center of the metal floor in a 45-degree inclined mode, the second dielectric plate is stacked on the first dielectric plate, and the radiation patch is printed on the upper surface of the second dielectric plate. The radiation patch comprises four overlapped elliptical patches with the same size, the elliptical patches are connected end to end to form a circular ring, the centers of the four patches are located on the diagonal lines of the second dielectric plate respectively, the distance between the center of each patch and the center of the second dielectric plate is equal, and every two spaced patches are in central symmetry. According to the invention, the non-completely symmetrical elliptical patches are overlapped, so that the resonance characteristics of the microstrip feed, the coupling gap and the radiation patch are mutually overlapped, a multi-resonance mode is formed, and the impedance bandwidth and the gain bandwidth are greatly expanded.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, and specifically relates to a millimeter-wave broadband circularly polarized patch antenna. Background Technology

[0002] With the rapid development of modern wireless communication technology, the evolution of communication systems towards the millimeter-wave band has become a clear trend. Within the millimeter-wave band, the K / Ka band (18GHz-40GHz) has attracted widespread attention due to its ability to provide a wider absolute bandwidth. Circularly polarized antennas, as a key component of modern wireless communication systems, possess unique advantages such as reducing multipath interference and overcoming polarization mismatch, making them particularly suitable for complex environments such as satellite communication. Currently, some publicly disclosed millimeter-wave broadband circularly polarized antenna patents demonstrate the following: In radiator design, the evolution has shifted from traditional rectangular / circular patches to irregular shapes, layering, and functionalization, combining stub loading and defective structures to overcome bandwidth limitations; in feeding methods, coupled feeding is now the primary method, replacing traditional coaxial feeding; in circular polarization implementation, the development has moved from single phase difference adjustment to a synergistic optimization of "structure + feeding"; and in material selection, high-frequency dielectric substrates and low-cost thin-film materials are being used in parallel, combining thermal bonding, multilayer PCB bonding, and 3D printing processes to drive antenna development towards low profile, lightweight, and easy integration.

[0003] Existing K / Ka band circularly polarized antenna technology suffers from a series of common drawbacks, mainly including the inherent contradiction between bandwidth and performance, the balance between complex structure and integration difficulty, and the high processing precision requirements unique to the millimeter-wave band, as detailed below: Chinese patent application CN117080730A discloses a Ka-band broadband circularly polarized antenna element. This antenna achieves Ka-band circular polarization through a dual-port signal input with a 90° phase difference and coaxial feeding, while utilizing a special notch design and SIW structure to achieve a wide operating bandwidth. The antenna achieves impedance matching in the 26.47GHz-31.90GHz band (relative bandwidth 19.3%) and circularly polarized signal output in the 25.00GHz-32.51GHz band (relative bandwidth 26.1%). However, this antenna relies on the Rogers 6002 / 6010 high-frequency substrate, limiting its application in flexible or low-cost scenarios (such as consumer satellite terminals).

[0004] Chinese patent application CN116960641A discloses a Ka-band broadband circularly polarized antenna element. This antenna features a novel irregular radiator design based on a combination of fan-shaped radiators, which is successfully applied to circularly polarized antenna design. Performance is optimized using a stub-loading antenna loading technique, achieving an impedance bandwidth covering the 25.9GHz-39.2GHz band (40.8%). The axial ratio of the antenna element is less than or equal to 3dB in the 26GHz-31.4GHz band (18.8%), achieving circularly polarized signal output. While the antenna loading technique effectively optimizes the impedance matching of the antenna element, its improvement on the axial ratio remains limited.

[0005] Chinese patent application CN117080739A discloses a Ka-band circularly polarized antenna. This antenna achieves Ka-band circular polarization through a dual-port signal input with a 90° phase difference and coaxial feeding, while utilizing a special defect structure to achieve a high axial ratio. The antenna can output circularly polarized signals in the 26.38GHz-27.82GHz band (5.3%), with an axial ratio of 117°-152°. Because the antenna uses a multilayer dielectric substrate, its profile is relatively high, requiring high processing precision along with SIW metal vias; the use of dual coaxial feeding necessitates strict control of the phase difference, which can easily affect yield during mass production.

[0006] Chinese patent application CN117039433A discloses a thin-film phased array antenna and phased array antenna array based on a guide patch. This antenna improves the axial ratio bandwidth of the circularly polarized antenna element through a novel guide patch structure. It uses inexpensive PET and PVC materials and thermal bonding processes to replace the expensive high-frequency dielectric substrate and multilayer PCB bonding process, enabling the circularly polarized phased array antenna to achieve wide bandwidth scanning capability while significantly reducing its cost, thus solving the problem of high manufacturing costs faced by existing wide bandwidth circularly polarized phased array antennas. The impedance bandwidth of this antenna element covers the 27.1GHz-32.3GHz frequency band (17.5%), and the axial ratio bandwidth covers the 27.4GHz-31.7GHz frequency band (14.6%). However, PET (dielectric constant 3.2) and PVC (dielectric constant 3.1) have higher losses than Rogers series substrates, resulting in increased signal attenuation above 31GHz, affecting gain stability.

[0007] Chinese patent application CN117578075A discloses a millimeter-wave circularly polarized antenna based on orthogonal electric dipoles. The antenna's radiating structure is fed through a microstrip feed line, a metallic ground layer, and a butterfly-shaped slot, generating a wide-bandwidth circularly polarized wave with strong polarization performance. This antenna has a -10dB impedance covering the 26.3-28.2GHz frequency band with a relative bandwidth of 7.0%, and a 3dB axial ratio bandwidth covering the 26.8-28.2GHz frequency band with a relative bandwidth of 5.1%. While superior to traditional microstrip antennas, its bandwidth remains relatively narrow, making it insufficiently adaptable to ultra-wideband communication scenarios. Summary of the Invention

[0008] To address the problems in the background technology, this invention develops a millimeter-wave broadband circularly polarized patch antenna. By designing a novel patch structure, the antenna structure and feeding method are kept sufficiently simple while the resonant characteristics of the microstrip feeding, coupling slot, and radiating patch are superimposed, significantly expanding the impedance bandwidth and gain bandwidth.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A millimeter-wave broadband circularly polarized patch antenna includes an excitation port, a microstrip feed line, a first dielectric substrate, a metal ground plane, a cross-shaped slot, a second dielectric substrate, and a radiating patch. The microstrip feed line is printed on the lower surface of the first dielectric substrate, the excitation port is connected to the microstrip feed line, the metal ground plane is printed on the upper surface of the first dielectric substrate, the cross-shaped slot is etched at a 45° angle in the center of the metal ground plane, the second dielectric substrate is stacked on top of the first dielectric substrate, and the radiating patch is printed on the upper surface of the second dielectric substrate. The radiating patch includes four overlapping elliptical patches of equal size, connected end-to-end to form a ring. The centers of the four patches are located on the diagonals of the second dielectric substrate, and the distance between the center of each patch and the center of the second dielectric substrate is equal. Two patches spaced apart are centrally symmetrical.

[0010] Preferably, the first dielectric substrate has a thickness of 0.254 mm, and the second dielectric substrate has a thickness of 1.52 mm.

[0011] Preferably, the microstrip feed line is an integral unit, comprising a first microstrip feed line and a second microstrip feed line, wherein the length of the first microstrip feed line is 2.1 mm, the length of the second microstrip feed line is 3 mm, and the excitation port is connected to the first microstrip feed line.

[0012] Preferably, the width of each side of the cross-shaped groove is 0.47 mm, the length of the long side is 7.9 mm, and the length of the short side is 3 mm.

[0013] Preferably, the angle between the major axis of one set of two centrally symmetrical patches and the x-axis is 12°, and the angle between the major axis of the other set of two centrally symmetrical patches and the y-axis is 18°.

[0014] Preferably, the center of symmetry of the cross-shaped groove coincides with the center of symmetry of the metal floor, and the axis of symmetry of the microstrip feed line coincides with the axis of symmetry of the lower surface of the dielectric substrate.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The millimeter-wave circularly polarized patch antenna of the present invention uses overlapping non-perfectly symmetrical elliptical patches to superimpose the resonant characteristics of microstrip feeding, coupling slots and radiating patches to form multiple resonant modes, which greatly expands the impedance bandwidth and gain bandwidth. The structure is simple, using only two dielectric substrates and no metal pillars, which greatly reduces the design complexity and manufacturing difficulty. Moreover, the microstrip slot coupling feeding method is simple and easy to integrate.

[0016] 2. The millimeter-wave circularly polarized patch antenna of the present invention has a -10dB impedance bandwidth covering the 20.04GHz-29.0GHz frequency band, with a relative bandwidth of 36.5%; a -3dB axial ratio bandwidth covering the 20.89GHz-26.87GHz frequency band, with a relative bandwidth of 25.0%; and a 3dB gain bandwidth covering the 20.14GHz-29.0GHz frequency band, with a relative bandwidth of 36.1%. It achieves a maximum gain of 7.64dBic at 26.8GHz, exhibits good gain stability across the entire frequency band, and can meet the requirements of broadband wireless communication systems.

[0017] 3. The millimeter-wave circularly polarized patch antenna of the present invention has a unified unit structure. Through reasonable layout, it can form a larger array antenna of 2×2 or more to achieve higher gain and extended bandwidth. Moreover, this type of antenna is a patch antenna, which is suitable for multilayer printed circuit board (PCB) processing and easy to mass-produce. Therefore, it has good application prospects in broadband wireless communication systems. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the planar structure of the present invention.

[0020] Figure 3 This is a diagram showing the planar structural dimensions of the present invention.

[0021] Figure 4 This is a side view of the present invention.

[0022] Figure 5 This is a comparison diagram of the antenna axial ratio of the present invention.

[0023] Figure 6 This is the impedance matching diagram for the antenna simulation of this invention.

[0024] Figure 7 This is a simulation gain diagram of the antenna of the present invention.

[0025] Figure 8 This is the radiation pattern of the antenna of the present invention at the XOZ plane at 22 GHz.

[0026] Figure 9 This is the radiation pattern of the antenna of the present invention in the YOZ plane at 24 GHz.

[0027] Figure 10 This is the radiation pattern of the antenna of the present invention at the XOZ plane at 26 GHz. Detailed Implementation

[0028] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0029] like Figures 1 to 4 As shown, the millimeter-wave broadband circularly polarized patch antenna of the present invention includes an excitation port 100, a microstrip feed line, a 0.254mm thick dielectric substrate 200, a metal ground plane 300, a cross-shaped slot 301 in the center of the ground plane, a 1.52mm thick dielectric substrate 400, and a radiating patch. Microstrip feed lines 101 and 102 are printed on the lower surface of the dielectric substrate 200. The excitation port 100 is connected to the microstrip feed line 101. The metal ground plane 300 is printed on the upper surface of the dielectric substrate 200. The cross-shaped slot 301 is etched in the center of the metal ground plane 300 at a 45-degree angle. The radiating patch is printed on the upper surface of the dielectric substrate 400. The dielectric substrate 400 is stacked on top of the dielectric substrate 200, and nylon posts are driven into the antenna during actual fabrication to fix both.

[0030] The radiating patch includes four elliptical patches of equal size connected end to end, namely radiating patch 500, radiating patch 501, radiating patch 502 and radiating patch 503. The centers of the four patches are located on the diagonal of the dielectric substrate 400, and the center of each patch is equidistant from the center of the dielectric substrate 400. Radiating patches 500 and 501, radiating patches 502 and 503 are centrally symmetrical.

[0031] The center of symmetry of the cross-shaped slot 301 coincides with the center of symmetry of the metal ground plane 300, and the axis of symmetry of the microstrip feed line coincides with the axis of symmetry of the lower surface of the dielectric substrate 200. The antenna is fed through the excitation port 100, and the energy is transferred to the first microstrip feed line 101. The microstrip feed line on the lower surface of the dielectric substrate 200 excites the cross-shaped slot 301 printed in the metal ground plane 300. The energy on the cross-shaped slot 301 is conducted to the radiating patch on the upper surface of the dielectric substrate 400 through coupling. The radiating patch consists of four overlapping elliptical patches of equal size. The current flows in the same direction on the opposite radiating patches, and the current between the orthogonal radiating patches has a 90° phase difference, ultimately producing circularly polarized radiation.

[0032] The antenna impedance was adjusted by changing the widths of microstrip line 101 and the second microstrip line 102 to ensure smooth excitation of the cross-shaped slot 301. The coupling strength was adjusted by regulating the length and width of the microstrip feed and the cross-shaped slot, optimizing impedance matching. By adjusting the different rotation angles of the two pairs of radiating patches, the structural symmetry was disrupted. Simultaneously, the resonant characteristics of the microstrip feed, coupling slot, and radiating patches superimposed each other, forming multiple resonant modes and expanding the impedance and gain bandwidths. After experimental comparison, the final... Figure 3 The optimal dimensions are shown in Table 1. Table 1 Where: f_l1: length of microstrip feed line 102; f_l2: Length of microstrip feed line 101; s_w: Width of each side of the cross-shaped groove 301; s_l1: The length of the long side of the cross-shaped groove 301; s_l2: Length of the short side of the cross-shaped groove 301; r_ap1: The angle between the major axis of patches 500 and 501 and the x-axis; r_ap2: The angle between the major axis of patches 502 and 503 and the y-axis.

[0033] like Figure 5 , Figure 6 and Figure 7 The figure shows the simulation results of the antenna of the present invention. The simulation results show that the -10dB impedance bandwidth of the antenna of the present invention covers the frequency band of 20.04GHz-29.0GHz, with a relative bandwidth of 36.5%; the -3dB axial ratio bandwidth covers the frequency band of 20.89GHz-26.87GHz, with a relative bandwidth of 25.0%; the 3dB gain bandwidth covers the frequency band of 20.14GHz-29.0GHz, with a relative bandwidth of 36.1%, and reaches a maximum gain of 7.64dBic at 26.8GHz.

[0034] like Figure 8 , Figure 9 and Figure 10 As shown, the XOZ radiation patterns of the antenna at 22GHz, 24GHz and 26GHz respectively show that the antenna has good right-hand circular polarization characteristics.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A millimeter-wave broadband circularly polarized patch antenna, characterized in that: The device includes an excitation port, a microstrip feed line, a first dielectric substrate, a metal ground plane, a cross-shaped groove, a second dielectric substrate, and a radiating patch. The microstrip feed line is printed on the lower surface of the first dielectric substrate, the excitation port is connected to the microstrip feed line, the metal ground plane is printed on the upper surface of the first dielectric substrate, the cross-shaped groove is etched at a 45° angle in the center of the metal ground plane, the second dielectric substrate is stacked on top of the first dielectric substrate, and the radiating patch is printed on the upper surface of the second dielectric substrate. The radiating patch comprises four overlapping elliptical patches of equal size, connected end-to-end to form a ring. The centers of the four patches are located on the diagonals of the second dielectric substrate, and the distance between the center of each patch and the center of the second dielectric substrate is equal. Two patches spaced apart are centrally symmetrical.

2. The millimeter-wave broadband circularly polarized patch antenna as described in claim 1, characterized in that: The first dielectric substrate has a thickness of 0.254 mm, and the second dielectric substrate has a thickness of 1.52 mm.

3. The millimeter-wave broadband circularly polarized patch antenna as described in claim 1, characterized in that: The microstrip feed line is a single unit, comprising a first microstrip feed line and a second microstrip feed line. The first microstrip feed line has a length of 2.1 mm, and the second microstrip feed line has a length of 3 mm. The excitation port is connected to the first microstrip feed line.

4. The millimeter-wave broadband circularly polarized patch antenna as described in claim 1, characterized in that: The width of each side of the cross-shaped groove is 0.47 mm, the length of the long side is 7.9 mm, and the length of the short side is 3 mm.

5. The millimeter-wave broadband circularly polarized patch antenna as described in claim 1, characterized in that: One set of two centrally symmetrical patches has a major axis direction that makes an angle of 12° with the x-axis, and another set of two centrally symmetrical patches has a major axis direction that makes an angle of 18° with the y-axis.

6. The millimeter-wave broadband circularly polarized patch antenna as described in claim 1, characterized in that: The center of symmetry of the cross-shaped groove coincides with the center of symmetry of the metal floor, and the axis of symmetry of the microstrip feed line coincides with the axis of symmetry of the lower surface of the dielectric substrate.

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