Dual-frequency broadband circularly polarized antenna

Abstract

According to the dual-frequency broadband circularly polarized antenna provided by the invention, a transmission array antenna and a double-arm helical antenna are designed through structural multiplexing, the transmission array antenna works in a millimeter wave frequency band and comprises a plurality of array plane units, and the double-arm helical antenna works in a microwave frequency band and comprises a plurality of array plane units. Comprising a third dielectric plate located below the second dielectric plate, a metal plate arranged below the third dielectric plate, a first spiral line and a second spiral line, the first spiral line and the second spiral line are arranged on a second metal layer, the first spiral line is nested in the second spiral line, and the third dielectric plate is of a balun structure of the double-arm spiral antenna. The two surfaces of the third dielectric plate are provided with index gradual change microstrip lines, the top of the third dielectric plate is inserted into the second dielectric plate and the first dielectric plate, and the two index gradual change microstrip lines are connected with the first spiral line and the second spiral line respectively. The double-arm helical antenna and the array surface of the transmission array are in a complete multiplexing relation, and miniaturization of the whole antenna system can be achieved to the maximum extent.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and in particular to a dual-frequency, broadband circularly polarized antenna. Background Art

[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 feature is that electromagnetic waves have strong diffraction and transmission capabilities for obstacles, and the propagation loss in the atmosphere is low, which is suitable for non-line-of-sight communication over long distances. However, its disadvantages are low communication rate, high latency, narrow bandwidth and increasingly scarce spectrum resources. In contrast, the millimeter wave frequency band can well make up for a series of defects in microwave frequency band communication, but it also faces problems such as high propagation loss, short propagation distance, and only applicable to line-of-sight communication. It can be seen that the microwave and millimeter wave frequency bands are complementary to each other in characteristics. Therefore, in the current and next-generation wireless communication systems, the mainstream research and development trend is to enable the communication system to support the operation of two frequency bands at the same time, that is, microwave / millimeter wave coexistence, which can effectively improve the communication capability 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] Since the frequency ratio between microwave and millimeter wave bands is very high, the traditional multi-mode resonance method is no longer applicable to the design of antennas with such a large frequency ratio. At present, an efficient and widely used solution is the co-aperture antenna. This solution combines two antennas of the same or different types organically by partially or completely reusing the structure, thereby achieving the coexistence of microwave / millimeter waves and miniaturization of the antenna system. For example, in references [1]-[4], co-aperture antenna designs of magnetoelectric dipole antenna / parallel plate resonator antenna, patch antenna / patch antenna array, patch antenna / slot antenna array, and reflectarray antenna / reflectarray antenna structure reuse are proposed. Although many co-aperture antenna designs have been proposed in the reported literature, there are still some problems that deserve further study and resolution. These problems include: 1) The reported dual-frequency co-aperture antennas generally have the problem of narrow bandwidth, which is mainly reflected in the two aspects that the bandwidths of the two frequency bands are both narrow or one of the two frequency bands is wide and the other is narrow, and the difference between the two frequency bands is huge. Since co-aperture antennas focus more on structural reuse and miniaturization of antenna size, it is very challenging to take into account the bandwidth performance of dual bands at the same time. Currently, there are few designs that can achieve broadband in both microwave and millimeter wave bands; 2) In order to compensate for the high transmission loss in the millimeter wave band, antennas in this band often need to form antenna arrays to obtain high gain. However, for traditional antenna arrays, the large and complex feeding network will cause the antenna to have high feeding loss, complex structure, and difficult design in the millimeter wave band; 3) Compared with linearly polarized antennas, circularly polarized antennas have many advantages, including suppressing multipath interference, reducing polarization mismatch, and immunizing Faraday rotation. However, most of the antennas that can currently achieve dual-band circular polarization have a relatively small frequency ratio (generally a frequency ratio of 1:1.5) [5]-[6] However, there are few reports on microwave / millimeter wave dual-frequency circularly polarized antennas with a large frequency ratio; 4) Most of the reported co-aperture antennas are partial reuse of antenna structures in different frequency bands, so the aperture reuse rate is low.

[0004] [1] Y.-X.Sun, KWLeung and K.Lu, "Compact Dual Microwave / Millimeter-Wave Planar Shared-Aperture Antenna for Vehicle-to-Vehicle / 5GCommunications," 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-BandShared-Aperture Antenna for Microwave and Millimeter-Wave Applications in 5GWireless 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 ReusedAperture-Sharing Antenna With Low Sidelobe and High Gain for 5GCommunication,”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-SharedDual Circularly Polarized Heterogeneous Reflectarray for VehicularCommunications,”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-CircularlyPolarized Shared-Aperture Array Antennas With Single-Layer Substrate,”IEEETrans.Antennas Propag.,vol.64,no.1,pp.109-116,Jan.2016.

[0009] [6] Trans.AntennasPropag.,vol.70,no.7,pp.5404-5417,Jul.2022. Summary of the invention

[0010] In order to solve at least one of the problems existing in the prior art, the present invention proposes a dual-band broadband circularly polarized co-aperture antenna, which organically combines a dual-arm helical antenna and a transmission array antenna by means of structural multiplexing. Since the transmission array antenna itself adopts a space-feeding feeding method, 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 helical antenna and the transmission array plane in the present invention are in a fully multiplexed relationship, so the aperture multiplexing rate of the antenna can reach nearly 100%, which maximizes the miniaturization of the entire antenna system.

[0011] In order to achieve the purpose of the present invention, the present invention provides a dual-band broadband circularly polarized antenna, including a transmission array antenna and a double-arm helical antenna.

[0012] The transmission array antenna operates in the millimeter wave frequency band and includes a plurality of array units, each of which includes a first dielectric plate, a first metal layer arranged on the upper surface of the first dielectric plate, an Archimedean spiral arranged on the first metal layer, a second dielectric plate, a second metal layer and a third metal layer respectively arranged on the upper surface and the lower surface of the second dielectric plate, and a dipole arranged on the third metal layer and connected to the Archimedean spiral, wherein the first dielectric plate is located above the second dielectric plate;

[0013] The double-arm helical antenna operates in the microwave frequency band, and includes 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, wherein the first spiral line is nested in the second spiral line, the third dielectric plate is a balun structure of the double-arm helical antenna, exponential gradient microstrip lines are arranged on both sides of the third dielectric plate, the second dielectric plate and the first dielectric plate are inserted into the top of the third dielectric plate, and the two exponential gradient microstrip lines are respectively connected to the first spiral line and the second spiral line, and the metal plate is used as a reflector of the double-arm helical antenna and is used to fix the feeding horn.

[0014] Furthermore, in the array unit, each Archimedean spiral has the same structure, each Archimedean spiral is connected to a connecting metal through hole at a starting position, and each Archimedean spiral rotates around its own connecting metal through hole by a certain angle.

[0015] Furthermore, the second dielectric plate is also provided with connecting metal through holes, and a concentric gap is provided around each connecting metal through hole.

[0016] Furthermore, in the transmission array antenna, grounding metal through holes are provided on the second dielectric plate at positions corresponding to each pair of dipoles, and two arms of each pair of dipoles are respectively connected to corresponding connection metal through holes and grounding metal through holes.

[0017] Furthermore, the two arms of the dipole have the same structure and both include three sections of microstrip lines, which are a rectangular microstrip line, a first linear gradient microstrip line and a second linear gradient microstrip line connected in sequence.

[0018] Furthermore, the first medium plate and the second medium plate are both provided with mounting grooves, and the top of the third medium plate can be inserted into the mounting grooves.

[0019] Furthermore, the corners of each straight line segment of the first spiral line and the second spiral line are transition structures with linear gradient width, so as to reduce the influence of impedance discontinuity at the corners.

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

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

[0022] Furthermore, the lengths of the first helical line and the second helical line are not equal.

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

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

[0025] (2) In the reported literature, the bandwidth of the dual-frequency co-aperture antenna is relatively narrow or cannot achieve broadband characteristics in two frequency bands at the same time, while the present invention can achieve dual-frequency broadband characteristics.

[0026] (3) The co-aperture antenna in the present invention uses a dual-arm helical antenna and a transmission array multiplexing method. Due to the spatial feeding characteristics of the transmission array antenna, the present invention has the advantages of no need for a complex feeding network, low feeding loss, and high gain in the millimeter wave frequency band.

[0027] (4) In the present invention, the two-arm helical antenna and the transmission array are in a completely multiplexed relationship in structure, so the present invention has the advantage of a high aperture multiplexing rate.

[0028] (5) The antenna of the present invention works in the form of a two-arm helical antenna and a transmission array antenna in the S band and Ka band, respectively, and can obtain an operating bandwidth of 19.1% and 24.8% in the two frequency bands, respectively. The bandwidth performance is better than the current technical level. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the three-dimensional structure of a dual-band broadband circularly polarized antenna provided by an embodiment of the present invention.

[0030] Figure 2 It is a side view of a dual-band wideband circularly polarized antenna provided by an embodiment of the present invention.

[0031] Figure 3 It is an exploded view of a dual-band broadband circularly polarized antenna provided by an embodiment of the present invention.

[0032] Figure 4 1 is a top view of a first dielectric plate and a first metal layer on the surface thereof in an embodiment of the present invention.

[0033] Figure 5 1 is a top view of the second dielectric plate and the second metal layer located on the upper surface thereof in an embodiment of the present invention.

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

[0035] Figure 7 The schematic diagram is a structure diagram of the third dielectric plate and the metal layers on the front and back surfaces thereof in an embodiment of the present invention.

[0036] Figure 8 It is a schematic structural diagram of an array unit of a transmission array antenna in an embodiment of the present invention.

[0037] Fig. 9 It is a schematic diagram of the transmission coefficient of the array element of the transmission array antenna in the embodiment of the present invention.

[0038] Fig.10 It is a schematic diagram of the S parameter performance of the dual-band broadband circularly polarized antenna provided in an embodiment of the present invention.

[0039] Fig.11 This is the directional diagram of the dual-band broadband circularly polarized antenna in the microwave frequency band provided by an embodiment of the present invention.

[0040] Fig.12This is the directional diagram of the dual-band broadband circularly polarized antenna in the millimeter wave frequency band provided by an embodiment of the present invention.

[0041] Fig.13 It is a schematic diagram of the gain and axial ratio performance of the dual-band broadband circularly polarized antenna provided in an embodiment of the present invention.

[0042] Fig.14 It is the beam scanning pattern of the dual-band broadband circularly polarized antenna in the millimeter wave frequency band provided by an embodiment of the present invention.

[0043] Fig.15 It is a schematic diagram of the axial ratio performance of the antenna during scanning in the millimeter wave frequency band. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The present invention provides a microwave / millimeter wave large frequency ratio dual-band broadband circularly polarized antenna with dual-arm helical antenna and transmission array antenna structure duplex, and its full view, side view and exploded view are shown in the following figures respectively. Figure 1 , Figure 2 and Figure 3 The antenna includes a transmission array antenna and a double-arm helical antenna. The transmission array antenna operates in the millimeter wave frequency band and includes a plurality of array units. Each array unit includes a first dielectric plate 31, a first metal layer 34 disposed on the upper surface of the first dielectric plate 31, an Archimedean spiral disposed on the first metal layer 34, a second dielectric plate 32, a second metal layer 35 and a third metal layer 36 disposed on the upper surface and the lower surface of the second dielectric plate 32, respectively, and a dipole disposed on the third metal layer 36 and connected to the Archimedean spiral. The first dielectric plate 31 is located above the second dielectric plate 32.

[0046] The dual-arm helical antenna operates in the microwave frequency band, and includes a third dielectric plate 33 located below the second dielectric plate 32, a metal plate arranged below the third dielectric plate 33, and a first helix 51 and a second helix 52 arranged on the second metal layer 35, wherein the metal plate is used as a reflector of the dual-arm helical antenna and for fixing the feed horn 11.

[0047] The double-layer PCB board is the array surface of the transmission array antenna, including the first dielectric plate 31 and the second dielectric plate 32. Metal layers are arranged on the first dielectric plate 31 and the second dielectric plate 32. The metal layers on the two dielectric plates are the first metal layer 34, the second metal layer 35 and the third metal layer 36 from top to bottom. The first dielectric plate 31 and the second dielectric plate 32 are stacked, and the third dielectric plate 33 is perpendicular to the first dielectric plate 31 and the second dielectric plate 32.

[0048] In some embodiments of the present invention, the material of the first dielectric plate 31 is Rogers 5880, with a dielectric constant of 2.2, a loss tangent of 0.0009, and a size of 63mm×63mm×1.02mm; the material of the second dielectric plate 32 is Rogers4350, with a dielectric constant of 3.66, a loss tangent of 0.004, and a size of 63mm×63mm×1.02mm; the material of the third dielectric plate 33 is FR4, with a dielectric constant of 4, a loss tangent of 0.02, and a size of 12mm×9.5mm×0.5mm.

[0049] The top view of the first dielectric plate 31 and the first metal layer 34 on the surface thereof is shown in FIG. Figure 4 As shown. The first metal layer 34 is provided with Archimedean spirals 41 arranged in a periodic manner. In some embodiments of the present invention, the periodicity is 4 mm. Each Archimedean spiral 41 has the same structure. Each Archimedean spiral 41 is connected to a connecting metal through hole 42 at the starting position. The connecting metal through hole 42 is provided on the first dielectric plate 31. Each Archimedean spiral 41 rotates around its own connecting metal through hole 42 by a certain angle. A first rectangular groove 43 is provided in the middle of the first dielectric plate 31 to expose the lower structure so as to facilitate welding the third dielectric plate 33 and the second dielectric plate 32 together.

[0050] The angle at which the Archimedean spiral 41 rotates around the connecting metal via 42 is calculated based on the phase shift required by each unit.

[0051] The top view of the second dielectric plate 32 and the second metal layer 35 on the upper surface thereof is shown in FIG. Figure 5As shown. Two spiral lines are arranged on the second metal layer 35, namely a first spiral line 51 and a second spiral line 52, and the two spiral lines respectively constitute the 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 connecting metal through holes 42, and a circular concentric gap 54 is arranged around each connecting metal through hole 42, which is used to isolate 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 opposite to the connecting metal through holes 42 on the first dielectric plate 31. A second rectangular groove 55 is opened in the middle of the second dielectric plate 32, and the third dielectric plate 33 is vertically inserted into the second rectangular groove 55. In some embodiments of the present invention, a transition structure 53 with a linear gradient in width is designed at the corner of each straight line segment of each spiral line.

[0052] The bottom view of the second dielectric plate 32 and the third metal layer 36 on its lower surface is as shown in FIG. Figure 6 As shown. A plurality of periodically arranged pairs of dipoles 61 are provided on the third metal layer 36, and a grounding metal through hole 62 is provided on the second dielectric plate 32 at a position corresponding to each pair of dipoles 61, and the two arms of each pair of dipoles 61 are respectively connected to the corresponding connecting metal through hole 42 and the grounding metal through hole 62. The two arms of the dipole 61 have the same structure, and both include three sections of microstrip lines, namely a rectangular microstrip line 63, a first linear gradient microstrip line 64, and a second linear gradient microstrip line 65 connected in sequence.

[0053] The third dielectric plate 33 is a balun structure of a double-arm helical antenna. The third dielectric plate 33 and the metal layers on its front and back surfaces are as follows: Figure 7 As shown. The first exponential gradient microstrip line 71 and the second exponential gradient microstrip line 72 are respectively arranged on the metal layers on the front and back sides of the third dielectric plate 33, and the width changes of the two microstrip lines satisfy the 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 exponential gradient microstrip line 71 and the second exponential gradient microstrip line 72 pass through the second dielectric plate 32 via the second rectangular groove 55 and are respectively connected to the first spiral line 51 and the second spiral line 52, and the connection method is welding.

[0054] The microwave band and millimeter wave band feeds use 50 ohm coaxial connectors and WR-28 waveguide coaxial converters respectively. The feeding ports are port 1 and port 2 respectively. Port 1 and port 2 are arranged on the third dielectric plate 33 and the feeding horn 11 respectively.

[0055] The 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 the first metal plate 37. The first metal plate 37 is a reflector of a double-arm helical antenna, on which a plurality of screw holes are provided, and a gap is provided on the first metal plate 37 to facilitate the 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 is used to completely cover the gap on the first metal plate 37, thereby 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 material, and both have a thickness of 2 mm.

[0057] In terms of working principle, in the microwave frequency band, the two-arm helical antenna is excited by an exponentially gradient balun. The balun structure can provide differential excitation for the two-arm helical antenna, and is also used to achieve impedance matching between the 50-ohm coaxial connector and the two-arm helical antenna. At the corners of each straight line segment of each spiral line, a transition structure with a linear gradient in width is designed. This structure is mainly used to reduce the impact of impedance discontinuity at the corners, thereby achieving a wider impedance bandwidth. In the present invention, the two arms of the helical antenna are not equal in length (the lengths of the first spiral line 51 and the second spiral line 52 are not equal, and either one can be longer or the other shorter). This can effectively improve the axial ratio characteristics of the microwave frequency band, thereby increasing the axial ratio bandwidth. In the millimeter wave band, the array unit of the transmission array antenna is a transceiver-transmitter type, and the array unit structure is as follows: Figure 8 As shown. In the array unit, the dipole 61 and the Archimedean spiral 41 are used as the receiving unit and the transmitting unit respectively, and the two are connected through a metal through hole and share the same metal floor. The receiving antenna and the transmitting antenna of this array unit both have broadband characteristics, which is conducive to the realization of a broadband transmission array antenna. Fig. 9 The figure shows the transmission coefficient of the array unit. It can be seen that the array unit can convert the x-polarized linear polarized incident wave into a right-hand circularly polarized wave. In the frequency range of 27 GHz to 40 GHz, the array unit can achieve a transmission loss of less than 2.1 dB. The phase shift required for each array unit on the array can be calculated by the Fermat principle. The specific phase shift method can adopt the unit rotation method, that is, the phase shift phase is adjusted by changing the rotation angle ω between the transmitting unit (Archimedes spiral) and the receiving unit (dipole). The magnitude of the phase shift phase is the same as the change in the rotation angle ω. Fig. 9The figure also shows the relationship between the unit phase shift and the frequency at different rotation angles. It can be seen that at different rotation angles ω, the curves of the phase shift of the array unit and the frequency are almost a set of parallel lines. This shows that the phase change of the array unit has a non-dispersive characteristic, which can ensure the broadband performance of the transmission array antenna. In some embodiments of the present invention, the focal diameter ratio of the transmission array is 0.5.

[0058] In terms of antenna performance, S parameters such as Fig.10 As shown in the figure, in the range of 1.75-2.38GHz (30.5%) and 27-40GHz (38.8%), the S parameter of the antenna is lower than -10dB, and the isolation between port 1 and port 2 is higher than 28dB, which shows that the antenna can achieve wide impedance bandwidth in the S-band and Ka-band, and the isolation between ports is high. The directional patterns of the microwave band (1.85GHz, 2GHz, 2.15GHz) and millimeter wave band (31GHz, 34GHz, 37GHz) are shown in the figure below. Fig.11 and Fig.12 As shown in the figure, it can be seen that the antenna has good radiation performance in both frequency bands, with low side lobes and cross polarization. Fig.13 As shown, in the microwave band, the 3-dB gain bandwidth and the 3-dB axial ratio bandwidth are 1.85-2.4 GHz (26.5%) and 1.83-2.24 GHz (20.1%), respectively, and the peak gain is 8.3 dBic; in the millimeter wave band, the 3-dB gain bandwidth and the 3-dB axial ratio bandwidth are 30-38.5 GHz (24.8%) and 28.5-40 GHz (33.6%), respectively, and the peak gain is 22 dBic. These results show that the antenna has wide gain bandwidth and wide axial ratio bandwidth in both frequency bands. Fig.14 The figure shows the beam scanning pattern of the millimeter wave frequency band. The antenna can achieve a scanning loss of less than 3dB within a scanning angle range of ±28°. Fig.15 The figure shows the axial ratio performance during the scanning process. It can be seen that the axial ratio can be kept less than 3dB during the beam scanning process, indicating that the antenna has good beam scanning performance.

[0059] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dual-band broadband circularly polarized antenna, characterized in that: Including transmission array antenna and double-arm helical antenna, The transmission array antenna operates in the millimeter wave frequency band and includes a plurality of array units, each of which includes a first dielectric plate, a first metal layer arranged on the upper surface of the first dielectric plate, an Archimedean spiral arranged on the first metal layer, a second dielectric plate, a second metal layer and a third metal layer respectively arranged on the upper surface and the lower surface of the second dielectric plate, and a dipole arranged on the third metal layer and connected to the Archimedean spiral, wherein the first dielectric plate is located above the second dielectric plate; The double-arm helical antenna operates in the microwave frequency band, and includes 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, wherein the first spiral line is nested in the second spiral line, the third dielectric plate is a balun structure of the double-arm helical antenna, exponential gradient microstrip lines are arranged on both sides of the third dielectric plate, the second dielectric plate and the first dielectric plate are inserted into the top of the third dielectric plate, and the two exponential gradient microstrip lines are respectively connected to the first spiral line and the second spiral line, and the metal plate is used as a reflector of the double-arm helical antenna and is used to fix the feeding horn.

2. A dual-band wideband circularly polarized antenna according to claim 1, characterized in that: In the array unit, each Archimedean spiral has the same structure, each Archimedean spiral is connected to a connecting metal through hole at a starting position, and each Archimedean spiral rotates around its own connecting metal through hole by a certain angle.

3. A dual-band wideband circularly polarized antenna according to claim 2, characterized in that: The second dielectric plate is also provided with connecting metal through holes, and a concentric gap is provided around each connecting metal through hole.

4. A dual-band wideband circularly polarized antenna according to claim 3, characterized in that: In the transmission array antenna, grounding metal through holes are arranged on the second dielectric plate at positions corresponding to each pair of dipoles, and two arms of each pair of dipoles are respectively connected to corresponding connection metal through holes and grounding metal through holes.

5. The dual-band wideband circularly polarized antenna according to claim 1, characterized in that: The two arms of the dipole have the same structure and both include three sections of microstrip lines, which are 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, characterized in that: The first medium plate and the second medium plate are both provided with mounting grooves, and the top of the third medium plate can be inserted into the mounting grooves.

7. The dual-band wideband circularly polarized antenna according to claim 1, characterized in that: The corners of each straight line segment of the first spiral line and the second spiral line are transition structures with linear gradient width, so as to reduce the influence of impedance discontinuity at the corners.

8. The dual-band wideband circularly polarized antenna according to claim 1, characterized in that: The phase shift of the corresponding array unit is adjusted by changing the rotation angle ω between the Archimedean spiral and the dipole.

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

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

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