Phased array antenna

Abstract

The present disclosure relates to the technical field of phased array antennas. Provided is a phased array antenna. The phased array antenna comprises a plurality of antenna units (1), each antenna unit (1) comprising: an intermediate substrate (11), which is provided with electric dipoles (112); and short-circuit parasitic branches (111), the number of which is two, wherein the two short-circuit parasitic branches (111) are respectively arranged on two sides of the intermediate substrate (11), and the short-circuit parasitic branches (111) are isolated from the electric dipoles (112). The present disclosure can improve the bandwidth of an end-fire circularly polarized phased array antenna.

Description

A phased array antenna

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on and claims the priority of Chinese patent application with application number 2023111251765 and application date September 1, 2023. The entire content of this Chinese patent application is hereby incorporated into this disclosure as a reference. Technical Field

[0003] The present disclosure relates to the technical field of phased array antennas, and in particular to a phased array antenna. Background Art

[0004] Wireless communication technologies are evolving at an increasingly rapid pace. With the advancement of radio technology, various standards exist in the existing low-frequency radio spectrum. While wireless transceiver systems for various communication purposes can utilize related technologies to increase system capacity and spectrum utilization, the low-frequency microwave band is nearing saturation and can no longer meet the needs of personalized wireless communications. Therefore, to meet more personalized wireless communication needs and develop new spectrum resources, the development of spectrum resources in the millimeter wave band has become an inevitable trend. Millimeter wave bands offer advantages such as short wavelengths, extremely wide bandwidths, and narrow beams, resulting in excellent directivity. Furthermore, compared to microwave bands, millimeter wave beams are much narrower for the same antenna size, and millimeter wave components are significantly smaller. Therefore, millimeter wave antennas and other devices can be used in wireless communication scenarios with limited space, such as mobile phone transceiver systems. Against the backdrop of the rapid development of wireless communication technology, millimeter wave array antennas hold great promise for development.

[0005] In existing antenna design technologies, phased array antennas are based on array antennas. By controlling the feed amplitude and phase shift of different array radiating elements, the direction and shape of the radiation pattern are changed, thereby achieving the goals of beam scanning, communication capacity adjustment, and spatial distribution and synthesis of signal power. Compared with traditional methods using mechanically rotating antennas, phased array antennas overcome the shortcomings of large inertia, slow rotation speed, and large size. They have the ability to quickly scan the antenna beam and can track and locate fast-moving targets. Circularly polarized phased array antennas also share some of the advantages of circularly polarized waves. They have unique advantages in resolving polarization mismatch, suppressing rain and fog interference, and eliminating the Faraday effect, and have broad prospects. However, in related technologies, end-fire circularly polarized phased array antennas suffer from narrow operating bandwidth and low beam gain.

[0006] In summary, how to improve the bandwidth of end-fire circularly polarized phased array antennas is one of the important issues that need to be solved urgently in this field.

[0007] Summary of the Invention

[0008] The purpose of the present disclosure is to provide a phased array antenna to address the deficiencies in the related art, which can improve the bandwidth of an end-fire circularly polarized phased array antenna.

[0009] The present disclosure provides a phased array antenna, comprising an antenna unit, wherein the antenna unit comprises:

[0010] an intermediate substrate, wherein an electric dipole is provided on the intermediate substrate;

[0011] The short-circuit parasitic branches are at least two in number, and the at least two short-circuit parasitic branches are respectively arranged on both sides of the intermediate substrate, and the short-circuit parasitic branches are isolated from the electric dipole.

[0012] In an optional embodiment, the number of the short-circuit parasitic branches is two.

[0013] In an optional embodiment, two dielectric substrates are further included;

[0014] The two dielectric substrates are respectively located on both sides of the middle substrate; the two short-circuit parasitic branches are respectively arranged in the two dielectric substrates.

[0015] In an optional embodiment, both of the two dielectric substrates are in contact with the middle substrate, and a short-circuit through hole for achieving electrical connection is provided on the dielectric substrate.

[0016] In an optional embodiment, the short-circuit parasitic stubs and the electric dipoles are both arranged along a first direction.

[0017] In an optional embodiment, the intermediate substrate is a substrate-integrated waveguide substrate, and in an operating mode, the electric field is directed in a second direction; the first direction is perpendicular to the second direction.

[0018] In an optional embodiment, a magnetic dipole and a transmission line are further provided on the intermediate substrate; the magnetic dipole is arranged along the second direction, and the magnetic dipole and the electric dipole are connected via a quarter-wavelength microstrip planar double conductor.

[0019] In an optional embodiment, the antenna unit includes a power splitter, and the power splitter is used to distribute the power of the input signal to form a multi-path signal.

[0020] In an optional embodiment, the antenna unit further includes a plurality of phase shifters, each of the plurality of phase shifters is connected to the power divider, and the phase shifters correspond one-to-one to the multiple signals.

[0021] In an optional embodiment, the multiple signals output after passing through the phase shifter have the same phase, or increase or decrease along the first direction with equal phase differences.

[0022] In an optional embodiment, the power splitter includes three cascaded one-to-two power splitters.

[0023] Compared to related technologies, the present invention introduces two short-circuited parasitic branches in each antenna element, located on the left and right sides of the central substrate. These branches are used to uniformly distribute the electric field magnitude and phase across a wide range, thereby expanding the operating bandwidth. By isolating the short-circuited parasitic branches from the electric dipole contact, ensuring that they have different potential distributions, the short-circuited parasitic branches can receive electromagnetic fields polarized in a first direction through a coupling effect. The superposition of electric fields in the first direction achieves the goal of widening the operating bandwidth of the end-fire circularly polarized phased array antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a structural block diagram of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0025] FIG2 is a schematic diagram of a power division and phase shifting network of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0026] FIG3 is a schematic diagram of a uniformly tapered phase shift network of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0027] FIG4 is a schematic diagram of another uniformly tapered phase shift network of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0028] FIG5 is a 3D schematic diagram of a radiating portion of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0029] FIG6 is a top view of a radiating portion of an end-fire circularly polarized phased array antenna in the xz plane according to an embodiment of the present disclosure.

[0030] FIG7 is a top view of a radiating portion of an end-fire circularly polarized phased array antenna in the xy plane according to an embodiment of the present disclosure.

[0031] FIG8 is a planar three-dimensional structure diagram 1 of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0032] FIG9 is a planar three-dimensional structure diagram 2 of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0033] FIG10 is a planar three-dimensional structure diagram 3 of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0034] FIG11 is a curve showing the reflection coefficient of an end-fire circularly polarized phased array antenna as a function of frequency according to an embodiment of the present disclosure.

[0035] FIG12 is a left-handed circularly polarized gain curve of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure.

[0036] FIG13 is a curve showing the axial ratio characteristics of an end-fire circularly polarized phased array antenna varying with frequency according to an embodiment of the present disclosure.

[0037] FIG14 is a radiation E-plane pattern of an end-fire circularly polarized phased array antenna under different phase shift networks according to an embodiment of the present disclosure.

[0038] Explanation of the reference numerals: 1-antenna unit, 11-intermediate substrate, 12-dielectric substrate, 13-power divider, 14-phase shifter; 111-short-circuited parasitic branch, 112-electric dipole, 113-magnetic dipole. DETAILED DESCRIPTION

[0039] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present disclosure, but are not to be construed as limiting the present disclosure.

[0040] In response to the problems raised in the background technology, the present disclosure solves them through the following specific embodiments.

[0041] Referring to Figures 1 to 10 , this embodiment provides a phased array antenna comprising an antenna unit 1. In a specific implementation, multiple antenna units 1 form an end-fire circularly polarized phased array antenna. Antenna units 1 correspond one to one with phase shifters 14, with each antenna unit 1 connected to a corresponding phase shifter 14. By configuring various power divider and phase shift networks, beam scanning characteristics can be achieved in a specific spatial region.

[0042] Specifically, in order to improve the bandwidth of the phased array antenna, in this embodiment, each phased array antenna includes a plurality of antenna units 1. The plurality of antenna units 1 are arranged along a first direction.

[0043] The antenna unit 1 includes an intermediate substrate 11 and a short-circuit parasitic branch 111 (see Figures 7 to 9 of this disclosure). The intermediate substrate 11 is a substrate integrated waveguide (SIW) substrate of the feed layer, and its working mode is the main mode TE 10 mode, which propagates along the SIW transmission line, with the electric field pointing in the second direction. At the end of the SIW transmission line, the impedance matching between the antenna and the transmission line is improved by expanding the width of the SIW transmission line.

[0044] As shown in Figures 7-9 of the present disclosure, the intermediate substrate 11 is provided with an electric dipole 112, a magnetic dipole 113, and a transmission line. The electric dipole 112 is distributed along a first direction, and the antenna unit guides electromagnetic waves from the SIW opening to the electric dipole 112 arranged along the first direction via a quarter-wavelength microstrip planar twin conductor. The planar microwave transmission twin conductor acts as the dipole's excitation port, stimulating the electric dipole 112 to operate with polarization along the first direction. At the SIW opening, the magnetic field is distributed along the first direction, and the magnetic field energy is radiated into free space, which is equivalent to the radiation of the magnetic dipole 113 placed along the second direction. The polarization direction of the magnetic dipole 113 is the second direction. The magnetic dipole 113 is arranged along the second direction and is connected to the electric dipole 112 via a quarter-wavelength microstrip planar twin conductor. The magnetic dipole 113 polarized in the second direction and the electric dipole 112 polarized in the first direction are connected by a quarter-wavelength microstrip planar double conductor. This structure causes the initial phase of the magnetic dipole 113 in the second direction to lead the initial phase of the electric dipole 112 in the first direction by 90 degrees. At the same time, the amplitudes of the electromagnetic fields of the two are almost equal. This structure for controlling the spatial distribution of the electromagnetic field can produce a narrowband circularly polarized wave. Considering that the electric field in the second direction leads the electric field in the first direction by 90 degrees and the electric field amplitudes are almost equal, the antenna radiates left-handed circularly polarized waves along the third direction. Specifically, the first direction, the second direction, and the third direction are perpendicular to each other, and the third direction is perpendicular to the intermediate substrate 11. In conjunction with the accompanying drawings, the first direction refers to the x-axis direction in the accompanying drawings, the second direction refers to the y-axis direction in the accompanying drawings, and the third direction refers to the z-axis direction in the accompanying drawings.

[0045] Since the working bandwidth of the electric dipole 112 excited by the microstrip planar dual-conductor is relatively narrow, the end-fire circularly polarized phased array antenna array cannot be used in a broadband range. Therefore, this embodiment introduces a pair of short-circuit parasitic branches 111 to adjust the size and phase of the electric field in the first direction to be uniformly distributed in the broadband range, thereby expanding its working bandwidth. Specifically, the short-circuit parasitic branches 111 are arranged along the first direction, and the electric dipole 112 is arranged along the first direction. The number of the short-circuit parasitic branches 111 is at least two, and can specifically be two, three, four, five, six, etc. Taking the number of short-circuit parasitic branches 111 as two as an example, the two short-circuit parasitic branches 111 are respectively arranged on both sides of the intermediate substrate 11 (for example, the left and right sides shown in Figure 7), and the short-circuit parasitic branches 111 are isolated from the electric dipole 112. That is, by isolating the short-circuit parasitic branches 111 from contact with the electric dipole 112, different potential distributions of the two are ensured. Due to the coupling effect, the short-circuited parasitic branch 111 can still receive the electromagnetic field polarized in the first direction. The superposition of the electric field in the first direction can achieve the purpose of widening the working frequency band of the phased array antenna array.

[0046] Specifically, to isolate the short-circuited parasitic stub 111 from the electric dipole 112, this embodiment further includes two dielectric substrates 12 (see Figures 5-6, 8-10 of this disclosure). The two dielectric substrates 12 are located on the upper and lower sides of the intermediate substrate 11 (i.e., the intermediate substrate 11 is sandwiched between the two dielectric substrates 12); the two short-circuited parasitic stubs 111 are disposed within the two dielectric substrates 12. In other words, a pair of dielectric substrates 12 are introduced in the third direction to isolate the short-circuited parasitic stub 111 from the electric dipole 112. Both dielectric substrates 12 abut against the intermediate substrate 11 and are provided with short-circuit vias for electrical connection. Specifically, the short-circuited parasitic stubs are positioned along a first direction to couple electric field energy from the first direction. They are positioned at the upper and lower ends of the short-circuited ends of the electric dipole 112 (i.e., the ends along the third direction), similar to the capacitive loading structure of an antenna. In other words, the electric dipole 112 and the pair of short-circuit parasitic branches 111 located on the two dielectric substrates 12 are all arranged along the first direction, and their projections in the third direction overlap. This effectively increases coupling and improves the radiation of the electric dipole 112. In a specific implementation, the intermediate substrate 11 is provided with a structure compatible with the short-circuit via. The short-circuit parasitic branches 111 are located on the dielectric substrates 12, and the two dielectric substrates 12 are separated by the intermediate substrate 12. In a specific implementation, the short-circuit via is a trumpet-shaped metal via, that is, the inner wall of the short-circuit via is coated with a metal layer.

[0047] Through the above configuration, the two dielectric substrates 12 can influence the waveguide environment of the electric dipole 112 and the magnetic dipole 113, ensuring that the surrounding dielectric constant is the same as that of the dielectric substrate 12, which facilitates impedance matching for the circularly polarized end-fire antenna. In a specific implementation, the two dielectric substrates 12 are placed on the antenna unit 1 and are each provided with a metal slot with partial or no ghosting along the z-axis. The metal slot is located on one side of the second direction, i.e., the radiation direction.

[0048] In a specific implementation, the antenna unit 1 includes a power divider 13 and a phase shifter 14. The power divider 13 is used to distribute the power of the input signal to form a multi-channel signal. A plurality of phase shifters 14 are connected to the power divider 13, and the phase shifters 14 correspond one-to-one to the multi-channel signals. The power divider 13 and the phase shifter 14 constitute a power divider phase shifting network. The power divider phase shifting network distributes the power of the microwave input signal through a one-to-two power divider. Three one-to-two power dividers can be cascaded to form a one-to-four power divider, which is followed by a microwave phase shifter. The phase shift range can include any angle. The multi-channel signals output after the phase shifter 14 have the same phase, or increase or decrease along the first direction according to an equal phase difference. The typical data of the four-way signal phase shift given in the present disclosure are: 1 group (0 degrees, 0 degrees, 0 degrees, 0 degrees), 2 groups (0 degrees, -100 degrees, -200 degrees, -300 degrees), and 3 groups (0 degrees, 100 degrees, 200 degrees, 300 degrees). The above-mentioned data is only an embodiment. Specifically, the four-way signal phase shift can be expressed as (x0, x0+x1, x0+2*x1, x0+3*x1), where x0 represents the phase shift of the first signal, and x1 represents the phase difference between two adjacent signals. Among the multiple antenna units 1 in the present disclosure, there should be an antenna unit in which the phase shifts of multiple signals increase uniformly in sequence, an antenna unit in which the phase shifts of multiple signals are equal, and an antenna unit in which the phase shifts of multiple signals decrease in sequence. The microwave signal passes through the power divider and uses the phase shifting characteristics of the above-mentioned phase shifter 14 to complete the phase shift. In the end-fire circularly polarized array antenna, the four signals have different beam arrival times to adjust the propagation direction of the composite beam, so as to achieve the purpose of phase control and scanning. In a specific implementation, the phase modulation of the end-fire circularly polarized phased array antenna only occurs in the first direction, and the beam in the second direction does not have the scanning capability, that is, the composite beam of the end-fire circularly polarized phased array antenna can be phase scanned in the first direction and maintain the radiation characteristics of the antenna unit 1 in the second direction. It should be pointed out that the multi-path signals described in this disclosure are not limited to four paths. The above four-path signal is only an exemplary description. In actual application, the number of signal paths can be divided into other numbers as needed.

[0049] The present invention can utilize the abundant frequency band resources of the millimeter wave band and adopt end-fire circularly polarized phased array antenna technology to realize a circularly polarized phased array antenna with beam scanning in a wide bandwidth. The present invention utilizes the technology of loading short-circuited parasitic branches to obtain a broadband end-fire circularly polarized antenna unit, ensuring the wide bandwidth of the array antenna. The phase shifter designed in the present invention can obtain the required beam scanning characteristics, thereby achieving E-plane coverage requirements, and has the advantages of easy implementation, miniaturization, and low cost.

[0050] In order to further illustrate the principle and effect of the present disclosure, an embodiment is provided below for further description.

[0051] Referring to Figures 2 through 4, this example uses three cascaded one-to-two power splitters to form a one-to-four power splitter, followed by a microwave phase shifter that allows for arbitrary phase shifts. Phase shifting is achieved by leveraging the phase shifting characteristics of these phase shifters. In an end-fire circularly polarized phased array antenna, the four signals have different beam arrival times, adjusting the propagation direction of the resulting beam for phase control and scanning.

[0052] Figure 5 is a schematic perspective view of the radiating portion of an end-fire circularly polarized phased array antenna. As shown in Figure 5, the dielectric substrate 12 and the intermediate substrate 11 are positioned closely together along the third direction, electrically connected via an array of short-circuit vias. The width of the transmission line is the same as the width of the electric dipole 112, and the transmission line is parallel to the second direction, with the transmission direction along the second direction. Figure 6 shows a top view of the end-fire circularly polarized phased array antenna in the xz plane. As shown in Figure 6, the projection of the end-fire circularly polarized phased array antenna in the z-axis direction has some overlap. This is because the electric dipole 112 and a pair of short-circuit parasitic stubs 111 located on the two dielectric substrates 12 are all positioned along the first direction, causing their projections in the z-axis direction to overlap. The projection of the short-circuit parasitic stub of one antenna unit is periodically spaced 1.05 mm along the first direction. Figure 7 shows a top view of the end-fire circularly polarized phased array antenna in the xy plane.

[0053] As shown in Figures 8-10, the three-dimensional planar structure of the end-fire circularly polarized phased array antenna in this example at different phases includes three substrate layers: a middle substrate 11 and two dielectric substrates 12 above and below the middle substrate 11. The SIW substrate 11 has dimensions of 8 mm in length, 8 mm in width, and 0.5 mm in height; the upper and lower dielectric substrates 12 have dimensions of 1.95 mm in length, 1.95 mm in width, and 0.5 mm in height. The metal short-circuit vias on the SIW substrates have a diameter of 0.25 mm, with a spacing of 0.1 mm between adjacent metal short-circuit vias. The dielectric constant of all three substrate layers is 3.55. Short-circuit parasitic stubs 111 are placed on the dielectric substrates 12, separated by the middle substrate. The short-circuit parasitic stubs have dimensions of 0.49 mm in length and 0.26 mm in width.

[0054] FIG11 is a curve showing how the reflection coefficient of the antenna varies with frequency. This example covers the 22 GHz-34 GHz frequency band, and the reflection coefficient is -4 dB < S11 < 19 dB.

[0055] Figure 12 shows the left-handed circularly polarized gain curve of an end-fire circularly polarized phased array antenna according to an embodiment of the present disclosure. As shown in Figure 12, this example incorporates a short-circuited parasitic stub in each of the upper and lower substrates, effectively increasing coupling, improving the radiation of the electric dipole 112, and boosting the antenna's gain.

[0056] Figure 13 shows a curve showing the axial ratio characteristics of an end-fire circularly polarized phased array antenna as a function of frequency, according to an embodiment of the present disclosure. As can be seen from Figure 13, the axial ratio of this example fluctuates between 2dB and 4dB in the 23GHz-32GHz frequency band, demonstrating a relatively small axial ratio and good axial ratio characteristics.

[0057] Figure 14 shows the E-plane radiation patterns of an end-fire circularly polarized phased array antenna in different phase-shifting networks according to an embodiment of the present disclosure. As shown in Figure 14, the E-plane patterns of this embodiment, in different phase-shifting networks, have a scanning range of ±60°, demonstrating that the end-fire circularly polarized phased array antenna provided by the present disclosure has excellent beam scanning characteristics.

[0058] The above describes in detail the structure, features and effects of the present disclosure based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present disclosure, but the present disclosure is not limited to the scope of implementation shown in the drawings. Any changes made in accordance with the concept of the present disclosure, or modifications to equivalent embodiments with equivalent changes, which do not exceed the spirit covered by the description and drawings, should be within the scope of protection of the present disclosure.

Claims

1. A phased array antenna, comprising a plurality of antenna units, each of the antenna units comprising: an intermediate substrate, on which an electric dipole is disposed; The short-circuit parasitic branches are at least two in number, at least two of the short-circuit parasitic branches are respectively arranged on both sides of the intermediate substrate, and the short-circuit parasitic branches are isolated from the electric dipole.

2. The phased array antenna according to claim 1, characterized in that: The number of the short-circuit parasitic branches is two.

3. The phased array antenna according to claim 1, further comprising two dielectric substrates, the intermediate substrate being sandwiched between the two dielectric substrates; and the two short-circuit parasitic branches being respectively disposed in the two dielectric substrates.

4. The phased array antenna according to claim 3, wherein: The two dielectric substrates are both in contact with the middle substrate, and each of the dielectric substrates is provided with a short-circuit through hole for achieving electrical connection.

5. The phased array antenna according to claim 1, wherein: The short-circuit parasitic branches and the electric dipoles are arranged along a first direction, and the short-circuit parasitic branches are placed on both sides of the intermediate substrate in the first direction.

6. The phased array antenna according to claim 5, wherein: The intermediate substrate is a substrate integrated waveguide substrate. In the working mode, the electric field is directed in the second direction; the first direction is perpendicular to the second direction.

7. The phased array antenna according to claim 6, wherein: A magnetic dipole and a transmission line are also provided on the intermediate substrate; the magnetic dipole is arranged along the second direction, and the magnetic dipole is connected to the electric dipole through a quarter-wavelength microstrip planar double conductor.

8. The phased array antenna according to claim 6, wherein: The projection of the short-circuit parasitic branch in a third direction overlaps with the projection of the electric dipole in the intermediate substrate in the third direction, and the third direction is perpendicular to the first direction and the second direction.

9. The phased array antenna according to any one of claims 1 to 8, wherein: Each of the antenna units includes a power divider, and the power divider is used to distribute the power of the input signal to form a multi-path signal.

10. The phased array antenna according to claim 9, wherein: Each of the antenna units further includes a plurality of phase shifters, and the plurality of phase shifters are all connected to the power divider, and the phase shifters correspond to the multi-path signals one by one.

11. The phased array antenna according to claim 10, wherein: The multi-path signals outputted after passing through the plurality of phase shifters have the same phase, or increase or decrease along the first direction with an equal phase difference.

12. The phased array antenna according to claim 9, wherein: The power divider includes three cascaded one-to-two power dividers.

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