A broadband wide-angle circularly polarized phased array antenna

Abstract

The application provides a broadband wide-angle circularly polarized phased array antenna, which comprises an antenna unit, a feed network, a metal ground plate and a feed SMP connector; the antenna unit comprises a ring-shaped parasitic patch, a first layer of dielectric substrate, a ring-shaped excitation patch and a second layer of dielectric substrate; the ring-shaped parasitic patch is located on the upper surface of the first layer of dielectric substrate; the first layer of dielectric substrate is hollowed out at a position corresponding to the ring-shaped parasitic patch to form an air cavity; the ring-shaped excitation patch is located on the upper surface of the second layer of dielectric substrate; the second layer of dielectric substrate is provided with a metalized through hole at a position corresponding to the ring-shaped excitation patch, and the lower surface is provided with a metal coating; the antenna unit and the feed network form a multilayer dielectric substrate laminated structure, the laminated structure and the feed SMP connector are fixed on the metal ground plate, the feed SMP connector is connected with the feed network, and the feed network feeds the ring-shaped excitation patch through the metalized through hole. The application can expand the impedance and axial ratio bandwidth of the antenna and improve the axial ratio beam width of the antenna.

Description

Technical Field

[0001] This invention relates to the field of antennas, and more specifically to a wide-bandwidth, angle-polarized, phased array antenna. Background Technology

[0002] With the rapid development of satellite communication, remote control and telemetry, and radar technologies, and the need to track and measure high-speed targets under various polarization modes and weather conditions, single linearly polarized antennas, due to their limitations, can no longer meet system requirements. Circularly polarized antennas can receive incoming waves of arbitrary polarization, and electromagnetic waves radiated by a circularly polarized antenna can also be received by antennas of any polarization. They also possess advantages such as strong resistance to multipath reflection. Circularly polarized antennas can also resist interference from clouds and rain; in aviation and aerospace applications, they offer resistance to cloud and rain attenuation, multipath attenuation, and can eliminate polarization distortion caused by the Faraday rotation effect of the ionosphere. Due to these characteristics, circularly polarized antennas have been widely used in wireless communication, radar, and other fields in recent years.

[0003] Phased array antennas utilize beamforming technology to increase antenna gain by arranging antenna elements according to a specific pattern. By controlling the amplitude and phase parameters of each antenna element, the direction of the antenna beam can be changed, achieving beam scanning coverage of nearly hemispherical space. They offer advantages such as high gain and high pointing accuracy. As a crucial component of phased array antennas, the performance of the antenna element determines the overall performance of the phased array antenna. Microstrip antennas, due to their inherent advantages such as simple structure, low profile, easy polarization control, conformal integration with the carrier, and the ability to be integrated with microstrip circuits, have become one of the most commonly used elements in phased array antennas.

[0004] However, the most serious drawback of microstrip antennas is that the impedance bandwidth of a single patch antenna is too narrow, only a few percent. Therefore, a large amount of research focuses on bandwidth broadening techniques for microstrip antennas. The axial ratio of a circularly polarized microstrip antenna changes with the operating frequency more sensitively than the input impedance changes with frequency, making it more difficult to broaden the circular polarization bandwidth than to broaden the impedance bandwidth.

[0005] In the existing technology, researchers have proposed many solutions to address the narrow operating frequency band of phased array antenna elements, such as increasing the substrate thickness, reducing the substrate dielectric constant, and adding load matching networks. However, these methods all have some drawbacks. Further research on aspects such as widening the radiation pattern, axial beamwidth, and axial bandwidth of antenna elements is essential. Summary of the Invention

[0006] The purpose of this invention is to provide a wide bandwidth circularly polarized phased array antenna that expands the antenna's impedance, axial ratio bandwidth, and improves the antenna's axial ratio beamwidth by utilizing a design that covers parasitic patches and adds an air layer.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] A wide bandwidth angle circularly polarized phased array antenna includes antenna elements, a feed network, a metal ground plane and a feed SMP connector;

[0009] The antenna unit includes a ring-shaped parasitic patch, a first dielectric substrate, a ring-shaped excitation patch, and a second dielectric substrate. The ring-shaped parasitic patch is located on the upper surface of the first dielectric substrate. An air cavity is formed by hollowing out a position on the first dielectric substrate corresponding to the ring-shaped parasitic patch. The ring-shaped excitation patch is located on the upper surface of the second dielectric substrate. A metallized through-hole is provided on the second dielectric substrate at a position corresponding to the ring-shaped excitation patch, and the lower surface of the second dielectric substrate has a metal cladding.

[0010] The antenna element and the feed network form a multilayer dielectric substrate laminate structure. The laminate structure and the feed SMP connector are fixed to the metal ground plane. The feed SMP connector is connected to the feed network. The feed network feeds the annular excitation patch through the metallized via.

[0011] Optionally, the power supply network includes a third dielectric substrate, a power divider, and a fourth dielectric substrate. The power divider is located on the lower surface of the third dielectric substrate, and both the upper surface of the third dielectric substrate and the lower surface of the fourth dielectric substrate have metal cladding.

[0012] Optionally, the power divider is a 1-to-4 power divider, wherein the input port of the 1-to-4 power divider is connected to the power supply SMP connector, and the four output ports are connected to the annular excitation patch through the four metallized through holes.

[0013] Optionally, the four output ports output four signals with equal amplitude and phases that differ by 90° sequentially.

[0014] Optionally, the 1-to-4 power divider is a stripline structure, and impedance matching is achieved by adjusting the stripline width between each output port.

[0015] Optionally, the inner conductor of the power supply SMP connector is connected to the input port of the 1-to-4 power divider and soldered to a pad located on the upper surface of the second dielectric substrate, while the outer conductor is connected to the metal ground plane.

[0016] Optionally, the dielectric substrates of the laminated structure are bonded together by prepreg.

[0017] Optionally, the antenna elements are arranged in a 4×4 array, and the spacing d between each antenna element satisfies the following formula:

[0018]

[0019] In the formula, λ is the wavelength and θ is the main beam angle.

[0020] Optionally, the annular excitation patch has two branches.

[0021] Optionally, the annular parasitic patch is provided with a slot.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] First, by adding an air cavity structure between the annular parasitic patch and the annular excitation patch, a stopband is generated within the antenna's operating frequency band to suppress the propagation of electromagnetic waves in that frequency band, thereby reducing the phase velocity of electromagnetic waves propagating between the top and bottom dielectric substrates and achieving the goal of reducing the antenna size.

[0024] Secondly, the multi-feed structure effectively suppresses high-order mode radiation, and the metal cladding separates the antenna from the power divider, eliminating the influence of parasitic radiation from the power divider on the antenna polarization performance. This feeding structure can broaden the antenna's VSWR bandwidth and axial ratio bandwidth, achieving excellent results.

[0025] Third, by using the parasitic radiating patch on the top dielectric substrate, the electrical length of the current on the surface of the radiating patch is extended, and the antenna size is further reduced. At the same time, this double-layer coupling patch and multi-feed structure can also increase the antenna's VSWR bandwidth, axial ratio bandwidth, and broaden the antenna's gain bandwidth.

[0026] Fourth, this invention employs miniaturization and broadband technology, and compared with traditional antennas, this antenna has the characteristics of compact structure, small size, light weight, wide bandwidth, and low cost. Attached Figure Description

[0027] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings described below are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0028] Figure 1 This is a front view of a 4×4 element phased array antenna according to an embodiment of the present invention;

[0029] Figure 2 yes Figure 1 Side view;

[0030] Figure 3 This is a front view of an antenna element in one embodiment of the present invention;

[0031] Figure 4 yes Figure 3 Side view;

[0032] Figure 5 This is a front view of the power supply network in one embodiment of the present invention;

[0033] Figure 6 yes Figure 5 Side view;

[0034] Figure 7 This is a front view of the ring-shaped excitation patch;

[0035] Figure 8 This is a front view of the annular parasitic patch;

[0036] Figure 9 This is a radiation pattern when the scanning angle is 0° in one embodiment of the present invention;

[0037] Figure 10 This is a radiation pattern when the scanning angle is 50° in one embodiment of the present invention. Detailed Implementation

[0038] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the solution proposed by the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the embodiments of the present invention. Please refer to the drawings to make the objectives, features, and advantages of the present invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the present invention, should still fall within the scope of the technical content disclosed in the present invention.

[0039] like Figure 1 , 2 As shown, a 4×4 wideband circularly polarized phased array antenna according to an embodiment of the present invention includes antenna elements 1, a feed network 2, a metal ground plane 3, and a feed SMP connector 4. In this embodiment, the antenna elements are arranged in a 4×4 array. In other embodiments, the antenna elements 1 may also be arranged in other ways, which is not limited by the present invention.

[0040] Specifically, in combination Figure 3 , 4As shown, the antenna unit 1 includes an annular parasitic patch 15, a first dielectric substrate 11, an annular excitation patch 16, and a second dielectric substrate 13. The annular parasitic patch 15 is located on the upper surface of the first dielectric substrate 11. An air cavity 17 is formed by hollowing out a position on the first dielectric substrate 11 corresponding to the annular parasitic patch 15 to broaden the antenna bandwidth. The annular excitation patch 16 is located on the upper surface of the second dielectric substrate 13. A metallized via 5 is provided on the second dielectric substrate 13 at a position corresponding to the annular excitation patch 16, and a metal cladding 111 is provided on the lower surface of the second dielectric substrate 13. The first dielectric substrate 11 can be made of a substrate with a dielectric constant of 2.94 and a thickness of 1.58 mm, and the second dielectric substrate 13 can be made of a substrate with a dielectric constant of 2.94 and a thickness of 1.0168 mm. The metallized via 5 refers to a through-hole with metal plated on its inner wall, which allows the metal cladding connected to the upper and lower parts of the metallized via 5 to be conductive. The metal cladding 111 can be a copper-clad metal layer. Furthermore, as... Figure 7 and Figure 8 As shown, slots 151 can be made on the annular parasitic patch 15, and stubs 161 can be added to the annular excitation patch 16 to disturb the surface current distribution of the antenna and improve the antenna impedance matching characteristics and axial ratio performance.

[0041] The size of the annular patch (including the annular parasitic patch 15 and the annular excitation patch 16) in the antenna element 1 can be determined according to the antenna's operating frequency.

[0042]

[0043]

[0044] In the formula, C is the speed of light in a vacuum, R1 is the outer diameter of the annular patch, R2 is the inner diameter of the annular patch, and ε r is the dielectric constant of the patch.

[0045] In this embodiment, the antenna elements 1 are arranged into a 4×4 array. To avoid excessive spacing between antenna elements, which could lead to grating lobes at large beam tilt angles, the spacing between each antenna element 1 should satisfy the formula:

[0046] In the formula: λ is the wavelength; θ is the main beam angle.

[0047] Because antenna element 1 is affected by the surrounding antennas in the array, the mutual coupling effect of the current on the antenna increases as the antenna spacing decreases, thus affecting the antenna performance. Therefore, the spacing of antenna element 1 is optimized, and the final spacing of antenna element 1 can be taken as 15.5mm.

[0048] like Figure 6 As shown, the power supply network 2 includes a third dielectric substrate 21, a power divider 24, and a fourth dielectric substrate 23. The power divider 24 is located on the lower surface of the third dielectric substrate 21. The upper surface of the third dielectric substrate 21 has a metal cladding layer 211, and the lower surface of the fourth dielectric substrate 23 has a metal cladding layer 212. The third dielectric substrate 21 and the fourth dielectric substrate 23 may be made of substrates with a dielectric constant of 3.5 and a thickness of 0.508 mm.

[0049] The antenna unit 1 and the feed network 2 can be laminated to form a four-layer dielectric substrate laminate structure. The laminate structure and the feed SMP connector 4 are fixed on the metal ground plane 3. The feed SMP connector 4 is connected to the feed network 2. The feed network 2 feeds the annular excitation patch 16 through the metallized through-hole 5.

[0050] Furthermore, in the four-layer dielectric substrate laminate structure, the dielectric substrates are bonded together by prepregs, making the overall structure more compact. For example, the first dielectric substrate 11 and the second dielectric substrate 13 are bonded together by a prepreg 12, the second dielectric substrate 13 and the third dielectric substrate 21 are bonded together by a prepreg 14, and the third dielectric substrate 21 and the fourth dielectric substrate 23 are bonded together by a prepreg 22. The prepregs 12, 14, and 22 can be made of materials with a dielectric constant of 2.81 and a thickness of 0.1 mm.

[0051] like Figure 5 As shown, the power divider 24 is a 1-to-4 power divider. The input port 241 of the 1-to-4 power divider is connected to the power supply SMP connector 4, and the four output ports 242-245 are respectively connected to the annular excitation patch 16 through the four metallized vias 5. The 1-to-4 power divider has a stripline structure. The input impedance of the input port 241 is 50 ohms, and the output impedance of the four output ports 242-245 is 100 ohms. Impedance matching is achieved by adjusting the stripline width between each output port. The output ports 242-245 output four signals with equal amplitude and sequentially 90° phase difference, which power the annular excitation patch through the metallized vias 5, thereby achieving good circular polarization performance.

[0052] Furthermore, the inner conductor diameter of the power supply SMP connector 4 can be 0.45mm, which is connected to the input port 241 of the power divider 24 and soldered to the pad 18 located on the upper surface of the second dielectric substrate 13, while the outer conductor is connected to the metal ground plane 3.

[0053] In this invention, the circularly polarized antenna element employs a multilayer dielectric substrate lamination and a four-point feeding structure. The antenna element is fed by rotating sequentially by 90° and an adjustable air layer is introduced to improve the antenna's axial ratio performance. Compared to traditional antennas, the phased array antenna is smaller in size, and its operating bandwidth, circular polarization bandwidth, and especially its beam coverage are further improved. The power divider is located directly below the antenna element, making the antenna structure more compact and easier to use.

[0054] Figure 9 , Figure 10 This is the antenna radiation pattern, where Figure 9 This is the radiation pattern when the scan angle is 0°. Figure 10 The radiation pattern is shown when the scanning angle is 50°. As can be seen from the radiation pattern, the antenna pattern is stable and meets the usage requirements.

[0055] In summary, this invention has the following advantages: First, by adding an air cavity structure between the annular parasitic patch and the annular excitation patch, a stopband is generated within the antenna's operating frequency band to suppress the propagation of electromagnetic waves in that band, thereby reducing the phase velocity of electromagnetic waves propagating between the top and bottom dielectric substrates and achieving the goal of reducing antenna size. Second, the multi-feed structure effectively suppresses high-order mode radiation, and the metal cladding separates the antenna and the power divider, eliminating the influence of parasitic radiation from the power divider on the antenna polarization performance. This feeding structure can broaden the antenna's VSWR bandwidth and axial ratio bandwidth, achieving excellent results. Third, the parasitic radiating patch on the top dielectric substrate extends the electrical length of the current on the surface of the radiating patch, further reducing the antenna size. Simultaneously, this double-layer coupling patch and multi-feed structure can also increase the antenna's VSWR bandwidth, axial ratio bandwidth, and broaden the antenna's gain bandwidth. Fourth, this invention employs miniaturization and broadband technology, resulting in a more compact structure, smaller size, lighter weight, wider bandwidth, and lower cost compared to traditional antennas.

[0056] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0057] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A wide-bandwidth, wide-angle circularly polarized phased array antenna, characterized in that, It includes antenna elements, feed network, metal ground plane, and feed SMP connector; The antenna unit includes a ring-shaped parasitic patch, a first dielectric substrate, a ring-shaped excitation patch, and a second dielectric substrate. The ring-shaped parasitic patch is located on the upper surface of the first dielectric substrate. An air cavity is formed by hollowing out the first dielectric substrate at a position corresponding to the ring-shaped parasitic patch. The ring-shaped excitation patch is located on the upper surface of the second dielectric substrate and has two branches. The ring-shaped parasitic patch has a slot. Metallized through-holes are provided on the second dielectric substrate at positions corresponding to the ring-shaped excitation patch. The lower surface of the second dielectric substrate has a metal cladding. The antenna unit and the feed network form a multilayer dielectric substrate laminate structure. The dielectric substrates of the laminate structure are bonded together by prepreg. The laminate structure and the feed SMP connector are fixed to the metal ground plane. The feed SMP connector is connected to the feed network. The feed network feeds the annular excitation patch through the metallized via. The power supply network includes a third dielectric substrate, a 1-to-4 power divider, and a fourth dielectric substrate. The 1-to-4 power divider is a stripline structure, and impedance matching is achieved by adjusting the stripline width between each output port. The 1-to-4 power divider is located on the lower surface of the third dielectric substrate. Both the upper surface of the third dielectric substrate and the lower surface of the fourth dielectric substrate have metal cladding. The input port of the 1-to-4 power divider is connected to the power supply SMP connector, and the four output ports are connected to the annular excitation patch through four metallized vias. The four output ports output four signals with equal amplitude and phase differences of 90°.

2. The wide bandwidth and angle circularly polarized phased array antenna as described in claim 1, characterized in that, The inner conductor of the power supply SMP connector is connected to the input port of the 1-to-4 power divider and soldered to the pad located on the upper surface of the second dielectric substrate, while the outer conductor is connected to the metal ground plane.

3. The wide bandwidth and angle circularly polarized phased array antenna as described in claim 1, characterized in that, The antenna elements are arranged in a 4×4 array, and the spacing d between each antenna element satisfies the following formula: In the formula, For wavelength, Main beam angle.

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