Dual-band wideband circularly polarized antenna

Abstract

The application provides a dual-frequency broadband circularly polarized antenna, which is designed by structural multiplexing of a transmissive array antenna and a dual-arm helical antenna, the transmissive array antenna works in a millimeter wave frequency band and comprises a plurality of array units, the dual-arm helical antenna works in a microwave frequency band and comprises a third dielectric plate located below a second dielectric plate, a metal plate arranged below the third dielectric plate, and a first spiral line and a second spiral line arranged on the second metal layer, the first spiral line is nested in the second spiral line, the third dielectric plate is a balun structure of the dual-arm helical antenna, both surfaces of the third dielectric plate are provided with exponential gradient microstrip lines, the top of the third dielectric plate is inserted into the second dielectric plate and a first dielectric plate, and the two exponential gradient microstrip lines are connected with the first spiral line and the second spiral line respectively. The dual-arm helical antenna and the transmissive array unit in the application are in a fully multiplexed relationship, and the miniaturization of the entire antenna system can be maximized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, in particular to a dual-frequency wideband circularly polarized antenna. BACKGROUND

[0002] Microwave and millimeter wave are the two most commonly used communication frequency bands in current wireless communication technology. For the microwave frequency band, its main characteristic is that the electromagnetic wave has strong diffraction and transmission ability to obstacles, and the propagation loss in the atmosphere is low, which is suitable for long-distance non-line-of-sight communication, but the disadvantages are low communication rate, high delay, narrow bandwidth and increasingly scarce spectrum resources. In comparison, the millimeter wave frequency band can well make up for a series of defects of microwave frequency band communication, but at the same time it also faces problems such as high propagation loss, short propagation distance, and is only suitable for line-of-sight communication. As can be seen, the microwave and millimeter wave frequency bands are complementary in characteristics, so in the current and next generation of wireless communication systems, the mainstream research and development trend is to enable the communication system to support the work of the two frequency bands at the same time, that is, microwave / millimeter wave coexistence, which can effectively improve the communication ability of the system and be more suitable for complex communication environments. As an important component for transmitting and receiving electromagnetic waves in the communication system, the antenna should also have the ability of microwave and millimeter wave dual-frequency communication.

[0003] Because of the high frequency ratio of microwave and millimeter wave bands, the traditional multi-mode resonance method is no longer suitable for the design of such large frequency ratio antennas. Currently, a widely used and efficient solution is the shared-aperture antenna. This solution combines two antennas of the same or different types through partial or full structural reuse, thereby achieving the coexistence of microwave / millimeter wave and the miniaturization of the antenna system. For example, in documents [1]-[4], the designs of shared-aperture antennas are proposed for the combination of magnetic electric dipole antennas / parallel plate resonators, patch antennas / patch antenna arrays, patch antennas / slot antenna arrays, and reflective array antennas / reflective array antenna structures. Although there are many designs of shared-aperture antennas reported in the literature, there are still some problems that need to be further studied and solved. These problems include: 1) The reported dual-band shared-aperture antennas generally have narrow bandwidths, which mainly manifest in two aspects: the bandwidths of both frequency bands are narrow, or one is wide and the other is narrow, or there is a large difference between the two. Since shared-aperture antennas focus more on structural reuse and antenna size miniaturization, it is a great challenge to simultaneously consider the bandwidth performance of dual-band, and there are few designs that can achieve wide bandwidths in both microwave and millimeter wave bands; 2) In order to compensate for the high transmission loss of the millimeter wave band, the antenna in this band often needs to form an antenna array to obtain high gain. However, for traditional antenna arrays, the large and complex feed network will lead to high feed loss, complex structure, and difficult design in the millimeter wave band; 3) Compared to linearly polarized antennas, circularly polarized antennas have many advantages, including suppressing multipath interference, reducing polarization mismatch, and being immune to Faraday rotation. However, most of the antennas that can achieve dual-band circular polarization have a small frequency ratio (generally 1:1.5) [5]-[6] , and there are few reports of microwave / millimeter wave dual-band circularly polarized antennas with large frequency ratios; 4) Most of the reported shared-aperture antennas are partial reuse of antenna structures of different frequency bands, so the aperture reuse rate is low.

[0004] [1] Y.-X. Sun, K. W. Leung and K. Lu, “Compact Dual Microwave / Millimeter-Wave Planar Shared-Aperture Antenna for Vehicle-to-Vehicle / 5G Communications,” IEEE Trans. Veh. Technol., vol. 70, no. 5, pp. 5071-5076, May 2021.

[0005] [2] X.-H. Ding, W.-W. Yang, H. Tang, L. Guo and J.-X. Chen, “A Dual-Band Shared-Aperture Antenna for Microwave and Millimeter-Wave Applications in 5G Wireless Communication,” IEEE Trans. Antennas Propag., vol. 70, no. 12, pp. 12299-12304, Dec. 2022.

[0006] [3] C. Wang, W. Cao, W. Ma, C. Li and J. Jing, “Dual-Band Structure Reused Aperture-Sharing Antenna With Low Sidelobe and High Gain for 5G Communication,” IEEE Antennas Wireless Propag. Lett., vol. 23, no. 4, pp. 1386-1390, Apr. 2024.

[0007] [4] J. Zhu, S. Liao, X. Zhu, Y. Yang and Q. Xue, “C- / Ka-Band Aperture-Shared Dual Circularly Polarized Heterogeneous Reflectarray for Vehicular Communications,” IEEE Trans. Veh. Technol., vol. 73, no. 6, pp. 8671-8680, Jun. 2024.

[0008] [5] J.-D. Zhang, W. Wu and D.-G. Fang, “Dual-Band and Dual-Circularly Polarized Shared-Aperture Array Antennas With Single-Layer Substrate,” IEEE Trans. Antennas Propag., vol. 64, no. 1, pp. 109-116, Jan. 2016.

[0009] [6] X. Tong, Z. H. Jiang, Y. Li, F. Wu, R. Sauleau and W. Hong, “Dual-Wideband Dual-Circularly-Polarized Shared-Aperture Reflectarrays With a Single Functional Substrate for K- / Ka-Band Applications,” IEEE Trans. Antennas Propag., vol. 70, no. 7, pp. 5404-5417, Jul. 2022. SUMMARY

[0010] In order to at least solve one of the problems existing in the prior art, the present application provides a dual-frequency wideband circularly polarized shared-aperture antenna, which combines a dual-arm spiral antenna and a transmissive array antenna in an organic way through structural multiplexing. Since the transmissive array antenna itself adopts a spatial feeding mode, the antenna does not require a complex feeding network in the millimeter wave frequency band, and has the advantages of low feeding loss and high gain. In terms of structural design, the dual-arm spiral antenna and the transmissive array surface in the present application are in a completely multiplexed relationship, so that the aperture multiplexing rate of the antenna can reach nearly 100%, thereby maximizing the miniaturization of the entire antenna system.

[0011] In order to achieve the purpose of the present application, the present application provides a dual-frequency wideband circularly polarized antenna, which comprises a transmissive array antenna and a dual-arm spiral antenna,

[0012] The transmissive array antenna operates in the millimeter wave frequency band and comprises a plurality of array surface units, each of which comprises a first dielectric plate, a first metal layer arranged on the upper surface of the first dielectric plate, an Archimedes spiral line arranged on the first metal layer, a second dielectric plate, a second metal layer and a third metal layer arranged on the upper surface and the lower surface of the second dielectric plate, respectively, and a dipole arranged on the third metal layer and connected with the Archimedes spiral line, the first dielectric plate being located above the second dielectric plate;

[0013] The dual-arm spiral antenna operates in the microwave frequency band and comprises a third dielectric plate located below the second dielectric plate, a metal plate arranged below the third dielectric plate, and a first spiral line and a second spiral line arranged on the second metal layer, the first spiral line being nested in the second spiral line, the third dielectric plate being a balun structure of the dual-arm spiral antenna, both surfaces of the third dielectric plate being provided with exponential gradient microstrip lines, the top of the third dielectric plate being inserted into the second dielectric plate and the first dielectric plate, and the two exponential gradient microstrip lines being connected with the first spiral line and the second spiral line, respectively, the metal plate being used as a reflector plate of the dual-arm spiral antenna and for fixing a feeding horn.

[0014] Further, in the array unit, each Archimedes spiral has the same structure, and each Archimedes spiral is connected with a connecting metal via at a starting position, and each Archimedes spiral rotates around the respective connecting metal via by a certain angle.

[0015] Further, the second dielectric plate is also provided with a connecting metal via, and a concentric gap is arranged around each connecting metal via.

[0016] Further, in the transmission array antenna, a grounding metal via is arranged on the second dielectric plate and at a position corresponding to each pair of dipoles, and the two arms of each pair of dipoles are connected with the respective connecting metal via and grounding metal via.

[0017] Further, the two arms of the dipole have the same structure and each include three microstrip lines, namely a rectangular microstrip line, a first linearly tapered microstrip line and a second linearly tapered microstrip line connected in sequence.

[0018] Further, the first dielectric plate and the second dielectric plate are each provided with a mounting groove, and the top of the third dielectric plate can be inserted into the mounting groove.

[0019] Further, each straight line segment of the first spiral line and the second spiral line has a transition structure with linearly tapered width at a corner thereof, for reducing the influence of impedance discontinuity at the corner.

[0020] Further, the phase shift phase of the corresponding array unit is adjusted by changing the rotation angle ω between the Archimedes spiral and the dipole.

[0021] Further, the beam scanning in the millimeter wave frequency band is realized by changing the fixed position of the feed horn on the metal plate.

[0022] Further, the first spiral line and the second spiral line have different lengths.

[0023] Compared with the prior art, the present application can at least achieve the following beneficial effects:

[0024] (1) In the reported literature, there are few dual-frequency circularly polarized co-aperture antennas with a large frequency ratio (microwave / millimeter wave), and the present application proposes a related design scheme.

[0025] (2) In the reported literature, the bandwidth of the dual-frequency co-aperture antenna is narrow or cannot achieve wideband characteristics in both frequency bands simultaneously, while the present application can achieve the characteristics of dual-band bandwidth.

[0026] (3) The co-aperture antenna in the present application adopts the mode of multiplexing of double-arm spiral antennas and transmission arrays, and due to the spatial feeding characteristics of the transmission array antenna, the present application has the advantages of no need for complex feeding network, low feeding loss, high gain, etc. in the millimeter wave frequency band.

[0027] (4) In the application, the dual-arm helical antenna and the transmissive array are in a fully multiplexed relationship in structure, and therefore, the application has the advantage of high aperture multiplexing rate.

[0028] (5) The antenna of the application works in the form of dual-arm helical antenna and transmissive array antenna in the S-band and Ka-band respectively, and can obtain working bandwidths of 19.1% and 24.8% in the two frequency bands respectively, which is superior to the current technical level. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a perspective structural schematic view of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application.

[0030] Figure 2 is a side view of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application.

[0031] Figure 3 is an exploded view of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application.

[0032] Figure 4 is a top view of a first dielectric plate and a first metal layer on the surface thereof in an embodiment of the application.

[0033] Figure 5 is a top view of a second dielectric plate and a second metal layer on the upper surface thereof in an embodiment of the application.

[0034] Figure 6 is a bottom view of a second dielectric plate and a third metal on the lower surface thereof in an embodiment of the application.

[0035] Figure 7 is a structure of a third dielectric plate and metal layers on the front and back surfaces thereof in an embodiment of the application, as shown in the schematic view.

[0036] Figure 8 is a structural schematic view of an array element of a transmissive array antenna in an embodiment of the application.

[0037] Figure 9 is a transmission coefficient schematic view of an array element of a transmissive array antenna in an embodiment of the application.

[0038] Figure 10 is an S parameter performance schematic view of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application.

[0039] Figure 11 is a directional diagram of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application in a microwave frequency band.

[0040] Figure 12The figure is a directional diagram of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application in a millimeter wave frequency band.

[0041] Figure 13 The figure is a gain and axial ratio performance diagram of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application.

[0042] Figure 14 The figure is a beam scanning directional diagram of a dual-frequency wideband circularly polarized antenna provided by an embodiment of the application in a millimeter wave frequency band.

[0043] Figure 15 The figure is an axial ratio performance diagram of an antenna in a scanning process in a millimeter wave frequency band. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are some but not all of the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the application.

[0045] The application provides a microwave / millimeter wave large-frequency-ratio dual-frequency wideband circularly polarized antenna with structure multiplexing of a dual-arm helical antenna and a transmission array antenna, whose overall view, side view and exploded view are shown in Figure 1 、 Figure 2 and Figure 3 respectively. The antenna comprises a transmission array antenna and a dual-arm helical antenna, the transmission array antenna works in a millimeter wave frequency band and comprises a plurality of array surface units, each array surface unit comprises a first dielectric plate 31, a first metal layer 34 arranged on the upper surface of the first dielectric plate 31, an Archimedes spiral line arranged on the first metal layer 34, a second dielectric plate 32, a second metal layer 35 and a third metal layer 36 arranged on the upper surface and the lower surface of the second dielectric plate 32 respectively, and a dipole arranged on the third metal layer 36 and connected with the Archimedes spiral line, and the first dielectric plate 31 is located above the second dielectric plate 32.

[0046] The dual-arm helical antenna works in a microwave frequency band and comprises a third dielectric plate 33 located below the second dielectric plate 32, a metal plate arranged below the third dielectric plate 33 and used as a reflecting plate of the dual-arm helical antenna and used for fixing a feed horn 11, and a first spiral line 51 and a second spiral line 52 arranged on the second metal layer 35.

[0047] The double-layer PCB board is an array surface of the transmitting array antenna, comprising the first dielectric board 31 and the second dielectric board 32, and the first dielectric board 31 and the second dielectric board 32 are provided with metal layers, the metal layers on the two dielectric boards are sequentially the first metal layer 34, the second metal layer 35 and the third metal layer 36 from top to bottom, the first dielectric board 31 and the second dielectric board 32 are stacked, and the third dielectric board 33 is perpendicular to the first dielectric board 31 and the second dielectric board 32.

[0048] In some embodiments of the present application, the material of the first dielectric board 31 is Rogers 5880, the dielectric constant is 2.2, the loss tangent is 0.0009, and the size is 63mm*63mm*1.02mm; the material of the second dielectric board 32 is Rogers 4350, the dielectric constant is 3.66, the loss tangent is 0.004, and the size is 63mm*63mm*1.02mm; and the material of the third dielectric board 33 is FR4, the dielectric constant is 4, the loss tangent is 0.02, and the size is 12mm*9.5mm*0.5mm.

[0049] The top view of the first dielectric board 31 and the first metal layer 34 on the surface thereof is shown in Fig. 1. Figure 4 The first metal layer 34 is provided with Archimedes spirals 41 arranged periodically, and the period size is 4mm in some embodiments of the present application. Each Archimedes spiral 41 has the same structure, and each Archimedes spiral 41 is connected with a connecting metal via 42 at a starting position, and the connecting metal via 42 is formed on the first dielectric board 31, and each Archimedes spiral 41 rotates around the respective connecting metal via 42 by a certain angle. A first rectangular slot 43 is formed in the middle of the first dielectric board 31 for exposing the lower structure to facilitate welding of the third dielectric board 33 and the second dielectric board 32.

[0050] The angle of rotation of the Archimedes spiral 41 around the connecting metal via 42 is calculated according to the required phase shift phase of each unit.

[0051] The top view of the second dielectric board 32 and the second metal layer 35 on the upper surface thereof is shown in Fig. 2. Figure 5The second metal layer 35 is provided with two spiral lines, i.e. a first spiral line 51 and a second spiral line 52, which respectively form two arms of the spiral antenna, and the first spiral line 51 is nested in the second spiral line 52. The second dielectric plate 32 is also provided with the connecting metal through holes 42, and a circular concentric slot 54 is arranged around each connecting metal through hole 42 for isolating the second metal layer 35 and the connecting metal through hole 42, and the connecting metal through holes 42 on the second dielectric plate 32 are in one-to-one correspondence with the connecting metal through holes 42 on the first dielectric plate 31. A second rectangular slot 55 is formed in the middle of the second dielectric plate 32, and the third dielectric plate 33 is vertically inserted into the second rectangular slot 55. In some embodiments of the present application, a linearly tapered transition structure 53 is designed at the corner of each straight segment of each spiral line.

[0052] The bottom view of the second dielectric plate 32 and the third metal layer 36 on the lower surface thereof is shown in FIG. 4. Figure 6 The third metal layer 36 is provided with a plurality of pairs of dipoles 61 arranged periodically, and a grounding metal through hole 62 is arranged on the second dielectric plate 32 and at a position corresponding to each pair of dipoles 61, and the two arms of each pair of dipoles 61 are connected to the corresponding connecting metal through hole 42 and grounding metal through hole 62, respectively. The two arms of the dipole 61 are identical in structure and each include three microstrip lines, i.e. a rectangular microstrip line 63, a first linearly tapered microstrip line 64 and a second linearly tapered microstrip line 65 connected in sequence.

[0053] The third dielectric plate 33 is a balun structure of the dual-arm spiral antenna. The structure of the third dielectric plate 33 and the metal layers on the front and back surfaces thereof is shown in FIG. 5. Figure 7 The first exponentially tapered microstrip line 71 and the second exponentially tapered microstrip line 72 are respectively arranged on the metal layers on the front and back surfaces of the third dielectric plate 33, and the width variation of the two microstrip lines satisfies an exponential function. The top of the third dielectric plate 33 is inserted into the second dielectric plate 32 and the first dielectric plate 31, and the first exponentially tapered microstrip line 71 and the second exponentially tapered microstrip line 72 are respectively connected to the first spiral line 51 and the second spiral line 52 after passing through the second dielectric plate 32 via the second rectangular slot 55, and the connection mode is welding.

[0054] The feeding of the microwave frequency band and the millimeter wave frequency band respectively adopts a 50-ohm coaxial connector and a WR-28 waveguide coaxial converter, and the feeding ports are port 1 and port 2, which are respectively arranged on the third dielectric plate 33 and the feeding horn 11.

[0055] Beam scanning in the millimeter-wave band is achieved by changing the fixed position of the feed horn 11 on the metal plate. The metal plate includes a first metal plate 37 and a second metal plate 38 located below it. The first metal plate 37 is the reflector of the double-arm helical antenna, with multiple screw holes and a gap to allow for movement of the feed horn 11. The second metal plate 38 is used to fix the feed horn 11 and is connected to the first metal plate 37 by screws. During the movement of the feed horn 11, the second metal plate 38 completely covers the gap on the first metal plate 37, thus ensuring the integrity of the reflector.

[0056] In some embodiments of the present invention, the first metal plate 37 and the second metal plate 38 are both made of metal and have a thickness of 2 mm.

[0057] In terms of operating principle, in the microwave band, the dual-arm spiral antenna is excited by an exponentially graded balun. This balun structure provides differential excitation for the dual-arm spiral antenna and also achieves impedance matching between the 50-ohm coaxial connector and the dual-arm spiral antenna. At each corner of the straight segment of each spiral, a transition structure with linearly graded width is designed. This structure is mainly used to reduce the impact of impedance discontinuities at the corners, thereby achieving a wider impedance bandwidth. In this invention, the two arms of the spiral antenna are not of equal length (the lengths of the first spiral 51 and the second spiral 52 are not equal; either one can be longer than the other). This effectively improves the axial ratio characteristics in the microwave band, thereby increasing the axial ratio bandwidth. In the millimeter-wave band, the array element of the transmission array antenna is a transmit-receive element type, and the array element structure is as follows: Figure 8 As shown, in the array element, dipole 61 and Archimedean spiral 41 serve as the receiving and transmitting elements, respectively, connected by a metal through-hole and sharing the same metal ground plane. This array element has broadband characteristics for both its receiving and transmitting antennas, which is beneficial for realizing a broadband transmission array antenna. Figure 9 The diagram shows the transmission coefficient of the array element. It can be seen that this array element can convert an x-polarized linearly polarized incident wave into a right-hand circularly polarized wave. Within the frequency range of 27 GHz to 40 GHz, this array element can achieve a transmission loss of less than 2.1 dB. The required phase shift for each array element can be calculated using Fermat's principle. The specific phase shifting method can employ the element rotation method, i.e., adjusting the phase shift by changing the rotation angle ω between the transmitting element (Archimedean spiral) and the receiving element (dipole). The magnitude of the phase shift is the same as the change in rotation angle ω. Figure 9The diagram also illustrates the relationship between the phase shift of the element and frequency under different rotation angles. It can be seen that, at different rotation angles ω, the curves showing the phase shift of the array element as a function of frequency are almost a set of parallel lines. This indicates that the phase change of the array element has non-dispersive characteristics, ensuring the broadband performance of the transmission array antenna. In some embodiments of this invention, the focal diameter ratio of the transmission array is 0.5.

[0058] Regarding antenna performance, the S-parameters are as follows: Figure 10 As shown, in the 1.75-2.38 GHz (30.5%) and 27-40 GHz (38.8%) ranges, the antenna's S-parameters are below -10 dB, while the isolation between port 1 and port 2 is above 28 dB. This indicates that the antenna can achieve a wide impedance bandwidth in both the S-band and Ka-band, with high isolation between ports. The radiation patterns in the microwave band (1.85 GHz, 2 GHz, 2.15 GHz) and millimeter-wave band (31 GHz, 34 GHz, 37 GHz) are shown below. Figure 11 and Figure 12 As shown, the antenna exhibits good radiation pattern performance in both frequency bands, with low sidelobes and cross-polarization. Gain and axial ratio... Figure 13 As shown, in the microwave band, the 3-dB gain bandwidth and 3-dB axial ratio bandwidth are 1.85-2.4GHz (26.5%) and 1.83-2.24GHz (20.1%), respectively, with a peak gain of 8.3dBic; in the millimeter-wave band, the 3-dB gain bandwidth and 3-dB axial ratio bandwidth are 30-38.5GHz (24.8%) and 28.5-40GHz (33.6%), respectively, with a peak gain of 22dBic. These results indicate that the antenna has wide gain bandwidth and wide axial ratio bandwidth in both frequency bands. Figure 14 The image shows the beam pattern in the millimeter-wave band. This antenna can achieve a scanning loss of less than 3dB within a scanning angle range of ±28°. Figure 15 The image shows the axial ratio performance during the scanning process. It can be seen that the axial ratio can be kept less than 3dB during beam scanning, indicating that the antenna has good beam scanning performance.

[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dual-band wideband circularly polarized antenna, characterized in that, The transmission array antenna and the dual-arm helical antenna are included, The transmission array antenna operates in a millimeter wave frequency band and includes a plurality of array elements, each of which includes a first dielectric plate, a first metal layer arranged on an upper surface of the first dielectric plate, an Archimedes spiral arranged on the first metal layer, a second dielectric plate, a second metal layer and a third metal layer arranged on an upper surface and a lower surface of the second dielectric plate respectively, and a dipole arranged on the third metal layer and connected to the Archimedes spiral, the first dielectric plate being arranged above the second dielectric plate. The dual-arm helical antenna operates in a microwave frequency band and includes a third dielectric plate arranged below the second dielectric plate, a metal plate arranged below the third dielectric plate, and a first spiral and a second spiral arranged on the second metal layer, the first spiral being nested in the second spiral, the third dielectric plate being a balun structure of the dual-arm helical antenna, both surfaces of the third dielectric plate being provided with exponential gradient microstrip lines, the top of the third dielectric plate being inserted into the second dielectric plate and the first dielectric plate, and the two exponential gradient microstrip lines being connected to the first spiral and the second spiral respectively, the metal plate being used as a reflecting plate of the dual-arm helical antenna and for fixing a feed horn.

2. The dual-band wideband circularly polarized antenna according to claim 1, wherein, In the array element, each Archimedes spiral has the same structure, and each Archimedes spiral is connected to a connecting metal via at a starting position.

3. The dual-band wideband circularly polarized antenna according to claim 2, wherein, The second dielectric plate is also provided with a connecting metal via, and a concentric slot is arranged around each connecting metal via.

4. The dual-band wideband circularly polarized antenna according to claim 3, characterized in that, In the transmission array antenna, a grounding metal via is arranged on the second dielectric plate and at a position corresponding to each pair of dipoles, and the two arms of each pair of dipoles are connected to the corresponding connecting metal via and the grounding metal via respectively.

5. The dual-band wideband circularly polarized antenna according to claim 1, wherein, The two arms of the dipole have the same structure and each include three microstrip lines, namely a rectangular microstrip line, a first linear gradient microstrip line and a second linear gradient microstrip line connected in sequence.

6. The dual-band wideband circularly polarized antenna according to claim 1, wherein, The first dielectric plate and the second dielectric plate are each provided with a mounting groove, and the top of the third dielectric plate can be inserted into the mounting groove.

7. The dual-band wideband circularly polarized antenna according to claim 1, wherein, The corners of each straight section of the first spiral and the second spiral are transition structures with linearly varying width, which are used to reduce the influence of impedance discontinuity at the corners.

8. The dual-band wideband circularly polarized antenna according to claim 1, wherein, The phase shift phase of the corresponding array element is adjusted by changing the rotation angle ω between the Archimedes spiral and the dipole.

9. The dual-band wideband circularly polarized antenna according to claim 1, wherein, Beam scanning in the millimeter wave frequency band is achieved by changing the fixed position of the feed horn on the metal plate.

10. The dual-band wideband circularly polarized antenna according to any one of claims 1-9, characterized in that, The lengths of the first spiral and the second spiral are not equal.

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