A broadband dual-circularly polarized metasurface antenna with directional coupler

Abstract

The application discloses a broadband dual-circularly polarized metasurface antenna with a directional coupler, and specifically comprises the following parts: a square metasurface array is attached to the upper layer of an upper dielectric substrate; a square radiation microstrip and a parasitic microstrip are attached to the middle layer of the upper dielectric substrate; a rectangular radiation microstrip is slotted at four corner positions; a directional coupler is attached to the lower layer of a lower dielectric substrate; and a metal bottom plate is located on the upper layer of the lower dielectric substrate. The application adopts the mode of attaching a square metasurface, slotting a microstrip patch, attaching a parasitic patch and a directional coupler, and solves the demand of realizing dual-circular polarization and broadband of a traditional microstrip antenna; while ensuring the dual-circular polarization and broadband performance of the antenna, the influence of the antenna on the appearance of a carrier is minimized. The application can also be used as an antenna array unit of a satellite and a wireless system, and helps to obtain a high-performance broadband circularly polarized scanning metasurface array antenna.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless communication, and particularly relates to a wide-band dual-circularly-polarized metasurface antenna with a directional coupler. BACKGROUND

[0002] Circularly-polarized antennas have important positions in modern wireless communication, satellite navigation and radar systems due to their strong anti-multipath interference ability, flexible polarization matching and adaptability to complex propagation environment. In particular, in non-fixed angle communication, such as mobile terminals and satellites, circularly-polarized waves can effectively overcome the polarization mismatch problem caused by the angle between the two.

[0003] Metasurface antennas break the physical limit of traditional antennas and become a revolutionary technology due to their subwavelength unit structure and flexible regulation ability of electromagnetic waves. Since the generalized Snell's law was proposed in 2006, the development of metasurface antennas has been increasingly rapid, and the wide-band characteristics of metasurfaces have become increasingly obvious, while circularly-polarized antennas usually have a narrow frequency band. Therefore, in recent years, the research on metasurface antennas with circular polarization has gradually developed into a hot spot.

[0004] Traditional microstrip antennas have the defect of narrow band in terms of bandwidth, and the bandwidth is usually 5%-10%. With the rapid development of wireless communication systems, the performance of traditional microstrip antennas has begun to have obvious shortcomings. In order to expand the bandwidth, the method of opening slots on the radiation microstrip and increasing parasitic microstrips is usually used to achieve the purpose of expansion. The circularly-polarized antenna mentioned in the literature T. Shi, R. Chai, X. Chen, M. Li, T. Zhang and M. -C. Tang, "A Low-Profile, Circularly Polarized, Metasurface-Based Antenna With Enhanced Bandwidth and Stable High Gain," realizes circular polarization characteristics by opening slots on the patch, increasing short-circuit columns and increasing parasitic microstrips, but the structure size is large (0.7λ × 0.7λ × 0.03λ), and it is difficult to process the short-circuit columns, and the circular polarization bandwidth is narrow (3-dB axial ratio bandwidth is 10.2%). Although the microstrip antenna improves the wide-band or realizes the circular polarization, the antenna performance is only limited to the improvement of single circular polarization. Therefore, it is an urgent problem to be solved in the field of antenna technology to design a wide-band dual-circularly-polarized metasurface antenna, which has great practical significance. SUMMARY

[0005] In view of the problems existing in the prior art, the application provides a wide-band dual-circularly-polarized metasurface antenna with a directional coupler.

[0006] The application is achieved by a wide-band dual-circularly polarized metasurface antenna with a directional coupler, which is provided with a square metasurface patch array, a square radiation microstrip, a parasitic microstrip, a dielectric substrate and a metal bottom plate.

[0007] The square metasurface is attached to the upper dielectric substrate and located at the uppermost layer of the upper dielectric substrate, the square radiation microstrip and the parasitic microstrip are attached to the middle layer of the upper dielectric substrate and located at the middle layer of the antenna, the directional coupler is attached to the lower dielectric substrate and located at the lowermost layer of the lower dielectric substrate, and the metal bottom plate is located at the uppermost layer of the lower dielectric substrate.

[0008] The square metasurface is arranged in the form of an array and located at the uppermost layer of the entire antenna.

[0009] The parasitic microstrip is a rectangular microstrip and a half-encircling parasitic microstrip.

[0010] There is a gap between the square radiation microstrip and the rectangular parasitic microstrip and the half-encircling parasitic microstrip.

[0011] The rectangular radiation microstrip is provided with four grooves.

[0012] The directional coupler is located at the lowermost layer of the entire antenna and is installed with a radio frequency connector.

[0013] Further, the square radiation microstrip is a radiation unit of the antenna and is fed by a coaxial probe through the directional coupler at the bottom; the side length of the square radiation microstrip is 0.267l; the square radiation microstrip is slotted at a position 0.146l away from the center of the square radiation microstrip, which is used to adjust the resonance point of the antenna, the length of the slot is 0.085l, and the width of the slot is 0.01l.

[0014] Further, the parasitic microstrip is a parasitic unit of the antenna; the gap width between the parasitic microstrip and the square radiation microstrip is 0.005l; the length and width of the rectangular parasitic microstrip are 0.27l and 0.01l respectively; the length of the half-encircling parasitic microstrip is 0.27l, 0.055l, 0.2025l and 0.411l respectively, and the width is 0.01l; the circularly polarized metasurface antenna characteristics are realized by adjusting the gap between the square radiation microstrip and the parasitic microstrip and the size of the parasitic microstrip.

[0015] Further, the directional coupler is located at the lowermost layer of the antenna; the difference between the connected output port microstrip lines is 0.25l, and the center distance between the two incident ports is 0.184l; feeding any one of the two ports can realize circular polarization. Based on the power distribution and wavelength phase difference principle, the directional coupler generates electromagnetic waves with equal amplitude and 90° phase difference at the two output ports. The directional coupler and the square radiation patch are connected through a coaxial probe passing through a metal floor, and the metal floor is provided with a circular through hole with a radius of 0.053l at the probe.

[0016] The square radiation microstrip is a radiation unit of the antenna, and the antenna is fed by connecting a directional coupler through a coaxial probe; the side length of the square radiation microstrip is 0.267l; the square radiation microstrip is slotted at a position 0.146l away from the center of the square radiation microstrip, and the slot is used for adjusting a resonance point of the antenna, the slot length is 0.085l, and the slot width is 0.01l; the length and width of the parasitic microstrip are 0.27l and 0.01l respectively; the length of the half-surrounding parasitic microstrip is 0.27l, 0.055l, 0.2025l and 0.411l respectively, and the width is 0.01l; there is a gap with a width of 0.005l between the square radiation microstrip and the parasitic microstrip for radiating electromagnetic waves; the dielectric substrate is located on the upper and lower layers of the antenna; based on the power distribution and wavelength phase difference principle, the directional coupler generates electromagnetic waves with equal amplitude and a phase difference of 90 degrees at the two output ports. The directional coupler and the square radiation patch are connected through a coaxial probe passing through a metal ground plate, and the metal ground plate is provided with a circular through hole with a radius of 0.053l at the probe.

[0017] Based on the above technical scheme, the application has the following beneficial effects:

[0018] 1. The directional coupler and the parasitic microstrip are designed in cooperation: through the gap coupling between the two output ports of the directional coupler and the parasitic microstrip, dual circular polarization is realized in 8.34-10.66GHz (left-handed, axial ratio bandwidth 23.2%) and 8.02-10.61GHz (right-handed, axial ratio bandwidth 25.9%), breaking through the limitation of single polarization of traditional microstrip antennas.

[0019] 2. The radiation microstrip is slotted and integrated with the metasurface array: the square radiation microstrip is provided with L-shaped grooves at four corners to reduce the quality factor, and the electromagnetic regulation of the 4x4 metasurface array is combined to realize 26% impedance bandwidth (S11<-10dB) in 9-11.6GHz and stabilize the gain to 7.01-7.8dBi, covering the wideband communication demand.

[0020] 3. The coaxial probe connection and the small size layout: the directional coupler is directly connected to the center of the radiation microstrip through the coaxial probe, and the traditional short column structure is omitted, so that the overall size of the antenna is compressed to 0.57l x 0.57l x <0.16l, and the high frequency performance and compactness are considered, which is suitable for satellite array integration scene. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a wideband dual-circularly polarized metasurface antenna structure with a directional coupler provided by an embodiment of the application (perspective of a dielectric substrate).

[0022] Figure 2 is a top view of a wideband dual-circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application.

[0023] Figure 3 is a radiation microstrip and parasitic microstrip schematic diagram of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application.

[0024] Figure 4 is a directional coupler schematic diagram of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application.

[0025] Figure 5 is a side view schematic diagram of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application.

[0026] Figure 6 is a reflection coefficient curve diagram of port 1 of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application.

[0027] Figure 7 is a Phi=90° (E) plane pattern diagram of left circular polarization and right circular polarization of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application when port 1 is fed at a frequency point of 10 GHz.

[0028] Figure 8 is a Phi=0° (H) plane pattern diagram of left circular polarization and right circular polarization of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application when port 1 is fed at a frequency point of 10 GHz.

[0029] Figure 9 is a Phi=90° (E) plane pattern diagram of left circular polarization and right circular polarization of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application when port 1 is fed at a low frequency of 9 GHz.

[0030] Figure 10 is a Phi=0° (H) plane pattern diagram of left circular polarization and right circular polarization of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application when port 1 is fed at a low frequency of 9 GHz.

[0031] Figure 11 is a Phi=90° (E) plane pattern diagram of left circular polarization and right circular polarization of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application when port 1 is fed at a high frequency of 10.66 GHz.

[0032] Figure 12 is a Phi=0° (H) plane pattern diagram of left circular polarization and right circular polarization of a wideband dual circularly polarized metasurface antenna with a directional coupler provided by an embodiment of the application when port 1 is fed at a high frequency of 10.66 GHz.

[0033] Figure 13 is a gain variation curve of the antenna when port 1 is fed in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0034] Figure 14 is an axial ratio curve of the antenna when port 2 is fed in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0035] Figure 15 is a reflection coefficient curve of port 2 in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0036] Figure 16 is a Phi=90° (E) plane pattern of the left circular polarization and the right circular polarization of the antenna when port 2 is fed at a frequency point of 10 GHz in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0037] Figure 17 is a Phi=0° (H) plane pattern of the left circular polarization and the right circular polarization of the antenna when port 2 is fed at a frequency point of 10 GHz in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0038] Figure 18 is a Phi=90° (E) plane pattern of the left circular polarization and the right circular polarization of the antenna when port 2 is fed at a low frequency of 9 GHz in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0039] Figure 19 is a Phi=0° (H) plane pattern of the left circular polarization and the right circular polarization of the antenna when port 2 is fed at a low frequency of 9 GHz in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0040] Figure 20 is a Phi=90° (E) plane pattern of the left circular polarization and the right circular polarization of the antenna when port 2 is fed at a high frequency of 10.61 GHz in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0041] Figure 21 is a Phi=0° (H) plane pattern of the left circular polarization and the right circular polarization of the antenna when port 2 is fed at a high frequency of 10.61 GHz in the wideband dual circularly polarized metasurface antenna with a directional coupler provided by the embodiment of the application.

[0042] Figure 22 is an antenna simulation gain graph when port 2 is fed in the embodiment antenna.

[0043] Figure 23is an antenna simulation axial ratio graph when the antenna port 2 of the embodiment is fed. DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0045] In view of the problem that it is difficult to realize wideband characteristics for an antenna circular polarization unit in existing mobile communication, the present application adopts the mode of introducing a metasurface patch array, opening a slot on a microstrip patch, adding a parasitic microstrip and using a directional coupler; meanwhile, the wideband characteristics and circular polarization characteristics of the antenna are realized, and the problem of realizing wideband of the antenna under the condition of realizing circular polarization of the traditional microstrip antenna is solved.

[0046] The application principle of the present application will be described in detail below with reference to the drawings.

[0047] As shown in Figure 1 and Figure 2 , the wideband double circular polarization metasurface antenna with a directional coupler provided by the embodiment of the present application comprises:

[0048] (1) a square metasurface patch 1, the square metasurface patch 1 is located at the uppermost layer of the antenna, the square metasurface patch 1 adopts a 4x4 array mode and is printed on the 6 of the upper dielectric substrate, so as to improve the antenna gain;

[0049] (2) a square radiation microstrip 2, the square radiation microstrip 2 is located at the middle layer of the upper dielectric substrate 6, the square radiation microstrip 2 is manufactured by a printed circuit process and is printed on the 6 of the upper dielectric substrate; four L-shaped grooves 3 are opened on the square radiation microstrip 2 along the center symmetric position, so as to adjust the resonance;

[0050] (3) a half-encircling parasitic microstrip 4 and a rectangular parasitic microstrip 5, the half-encircling parasitic microstrip 4 and the rectangular parasitic microstrip 5 are located at the middle layer of the upper dielectric substrate 6 and are printed on both sides of the square radiation microstrip 2, so as to expand the bandwidth and enhance the circular polarization performance of the antenna;

[0051] (4) a directional coupler 9, the directional coupler 9 is located at the lower layer of the lower dielectric substrate 10, and the directional coupler 9 is connected with the square radiation patch 2 by the coaxial probe 8;

[0052] (5) an upper dielectric substrate 6 and a lower dielectric substrate 10, the upper dielectric substrate 6 is located at the upper layer of the entire antenna, and the lower dielectric substrate 10 is located at the lower layer of the entire antenna;

[0053] (6) a metal bottom plate 7, the metal bottom plate 7 is located in the middle of the upper dielectric substrate 6 and the lower dielectric substrate 10, the metal bottom plate 7 is reserved with a probe hole at the corresponding position of the coaxial probe 8, and the coaxial probe 8 is connected with the directional coupler 9 and the square radiation microstrip 2.

[0054] The principle of realizing the wideband characteristic of the application is that:

[0055] By opening the L-shaped groove 3 on the square radiation microstrip 2, the surface current distribution of the square radiation microstrip 2 is changed, the resonance points of the antenna are increased, and the wideband characteristic is realized. The principle of realizing the circular polarization characteristic is that the directional coupler 9 outputs the electromagnetic signals fed in with a phase difference of 90°, so that the electromagnetic signals are orthogonal in the X direction and the Y direction, the circular polarization is excited, the half-encircling parasitic microstrip 4 and the rectangular parasitic microstrip 5 are introduced to further improve the circular polarization characteristic; by adjusting the gap between the square radiation microstrip 2 and the half-encircling parasitic microstrip 4 and the rectangular parasitic microstrip 5, other merged modes can be excited, so that the circular polarization characteristic of the antenna is enhanced, and the bandwidth of the antenna can also be expanded.

[0056] The application effect of the application will be described in detail in combination with simulation.

[0057] 1. Simulation content

[0058] Please refer to Figures 6 to 13 . The port reflection coefficient, the antenna pattern and the gain of the antenna in the above embodiment are simulated by using a simulation software.

[0059] 2. Simulation results

[0060] Figure 6 , Figure 15 is a curve of the port reflection coefficient changing with the working frequency obtained by simulating the antenna in the embodiment. It can be seen that the two ports show good wideband characteristics. The frequency band in which the reflection coefficients of the port 1 and the port 2 are lower than -10 dB is 9 GHz-11.6 GHz (26%), and the wideband characteristic of the antenna is well realized, which can meet the bandwidth demand of mobile communication.

[0061] Figure 7 , Figure 8 is the Phi=90° plane pattern and the Phi=0° plane pattern obtained by simulating the antenna in the embodiment, which are obtained at the frequency point 10 GHz. It can be seen that the E plane and the H plane of the antenna obtain ideal left-handed circular polarization patterns at the frequency point.

[0062] Figure 9 , Figure 10 is the Phi=90° plane pattern and the Phi=0° plane pattern obtained by simulating the antenna in the embodiment, which are obtained at the frequency point 9 GHz. It can be seen that the E plane and the H plane of the antenna obtain ideal left-handed circular polarization patterns at the frequency point.

[0063] Figure 11 , Figure 12 Phi=90° and Phi=0° plane patterns obtained from simulation of the example antenna at frequency 10.66 GHz. It can be seen that at this frequency the E-plane and H-plane of the antenna obtain ideal left-hand circular polarized patterns.

[0064] Figure 13 is a simulation gain pattern for port 1 feed of the example antenna.

[0065] Figure 14 is a simulation axial ratio pattern for port 1 of the example antenna.

[0066] Figure 16 , Figure 17 Phi=90° and Phi=0° plane patterns obtained from simulation of the example antenna at frequency 10 GHz. It can be seen that at this frequency the E-plane and H-plane of the antenna obtain ideal right-hand circular polarized patterns.

[0067] Figure 18 , Figure 19 Phi=90° and Phi=0° plane patterns obtained from simulation of the example antenna at frequency 9 GHz. It can be seen that at this frequency the E-plane and H-plane of the antenna obtain ideal right-hand circular polarized patterns.

[0068] Figure 20 , Figure 21 Phi=90° and Phi=0° plane patterns obtained from simulation of the example antenna at frequency 10.61 GHz. It can be seen that at this frequency the E-plane and H-plane of the antenna obtain ideal right-hand circular polarized patterns.

[0069] Figure 22 is a simulation gain pattern for port 2 feed of the example antenna.

[0070] Figure 23 is a simulation axial ratio pattern for port 2 of the example antenna.

[0071] The application discloses a broadband dual-circularly polarized metasurface antenna with a directional coupler, which adopts edge feeding to radiate circularly polarized electromagnetic waves; the whole antenna has broadband dual-circularly polarized characteristics, the overall size of the antenna is 0.57 lambda x 0.57 lambda, and the thickness of the antenna is less than 0.16 lambda; the antenna has the characteristics of a small size while realizing the broadband characteristics. When the antenna realizes left-handed circular polarization, the frequency band range is 9GHz-11.6GHz (26%); when the antenna realizes right-handed circular polarization, the frequency band range is 9GHz-11.6GHz (26%); the principle of realizing the broadband characteristics is that the quality factor of the square radiation microstrip is reduced by slotting the square radiation microstrip, the square radiation microstrip surface current distribution is changed, and the resonance points of the antenna are increased to realize the broadband characteristics; the square radiation microstrip and the parasitic microstrip are left with a gap, the square radiation microstrip edge current is converged, the square radiation microstrip edge field distribution is disturbed, the electric field intensity of the edge of the square radiation microstrip is increased compared with that of the edge of the microstrip without the gap, and the square radiation microstrip edge and the parasitic microstrip also participate in the antenna radiation. The antenna can realize dual-circularly polarized characteristics; when the antenna realizes left-handed circular polarization, the circularly polarized frequency band range is 8.34GHz-10.66GHz (23.2%); when the antenna realizes right-handed circular polarization, the circularly polarized frequency band range is 8.02GHz-10.61GHz (25.9%); the principle of realizing the circularly polarized characteristics is that the directional coupler outputs the fed electromagnetic signals in a way that the phase difference is 90 degrees, so that the signals are orthogonal in the X direction and the Y direction, and the circularly polarized characteristics are excited; the parasitic microstrip is introduced on both sides of the square radiation microstrip, the parasitic microstrip surface current is orthogonal every quarter of a period on the side of the rectangular parasitic microstrip and the half-encircling parasitic microstrip close to the gap, the surface current flow distance of the square radiation microstrip can be effectively increased on the two surrounding microstrips of the half-encircling parasitic microstrip, and the surface current of the two surrounding microstrips is also orthogonal every quarter of a period, so that the circularly polarized bandwidth of the antenna is further expanded. The antenna also has the characteristics of stable gain in the corresponding frequency band range; when the antenna realizes left-handed circular polarization, the antenna has the highest gain of 7.66dBi (10GHz) and the lowest gain of 7.01dBi (8.16GHz and 10.35GHz, respectively) in the frequency band range of 8.16GHz-10.35GHz; when the antenna realizes right-handed circular polarization, the antenna has the highest gain of 7.56dBi (10GHz) and the lowest gain of 7dBi (8.16GHz and 10.35GHz, respectively) in the frequency band range of 8.42GHz-10.27GHz.

[0072] To sum up, the application adopts the way of slotting on the microstrip patch, increasing the parasitic microstrip and introducing the directional coupler; meanwhile, the wideband characteristics and the dual circular polarization characteristics of the antenna are realized, and the demand of realizing the wideband dual circular polarization of the traditional microstrip antenna is solved. The application can minimize the influence of the antenna on the shape of the carrier while ensuring the high performance of the antenna. In addition, the antenna technology of the application can also be used as the antenna array unit of the radar and satellite, which is helpful to obtain the high-performance wideband circularly polarized metasurface antenna.

[0073] The above merely describes the preferred embodiments of the application and is not intended to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A broadband dual-circularly polarized metasurface antenna with a directional coupler, characterized in that, It includes an upper dielectric substrate (6), a lower dielectric substrate (10), and a metal base plate (7) located between the two. A square metasurface array (1) is attached to the upper surface of the upper dielectric substrate (6) and is composed of square metal patches arranged in a 4×4 array. A square radiating microstrip (2) is attached to the middle layer of the upper dielectric substrate (6), and L-shaped grooves (3) are opened at its four corners. Parasitic microstrips, including rectangular parasitic microstrips (5) and semi-circular parasitic microstrips (4), are attached to the middle layer of the upper dielectric substrate (6) and are located on adjacent sides of the square radiating microstrips (2) in an L-shape distribution. A directional coupler (9) is attached to the lower surface of the lower dielectric substrate (10). The output port of the directional coupler (9) is connected to the square radiating microstrip (2) through a circular through hole in the metal base plate (7) via a coaxial probe (8). The square radiating microstrip (2) is provided with a gap of 0.005λ between itself and the semi-circular parasitic microstrip (4) and the rectangular parasitic microstrip (5); The semi-circular parasitic microstrip (4) consists of four microstrips, one of which is a rectangular strip a adjacent to the side of the square radiating microstrip (2), one of which is a rectangular strip b extending vertically from the center of the rectangular strip, one of which is a strip c extending perpendicularly to the rectangular strip b, and the last of which is a rectangular strip d parallel to the rectangular parasitic microstrip (5) and perpendicular to and connected to strip c. The lengths of a, b, c and d are 0.27λ, 0.055λ, 0.2025λ and 0.411λ, respectively, and the width is 0.01λ. The length and width of the rectangular parasitic microstrip (5) are 0.27λ and 0.01λ, respectively; λ is the wavelength of the center frequency in free space.

2. The broadband dual-circularly polarized metasurface antenna with a directional coupler as described in claim 1, characterized in that, The metal patch units of the square metasurface array (1) are square, with a unit side length of 0.117λ and a gap of 0.012λ between adjacent units.

3. A broadband dual-circularly polarized metasurface antenna with a directional coupler as described in claim 1, characterized in that, The square radiating microstrip (2) has a side length of 0.269λ. The four corners of the square radiating microstrip (2) are slotted at a distance of 0.146λ from the center of the square radiating microstrip (2). The length of the slot is 0.085λ and the width is 0.01λ.

4. A broadband dual-circularly polarized metasurface antenna with a directional coupler as described in claim 1, characterized in that, The input and output ports of the directional coupler (9) adopt a microstrip line structure. The lengths of the microstrip lines at the two output ports differ by 0.25λ, and the center-to-center distance between the two input ports is 0.184λ.

5. A broadband dual-circularly polarized metasurface antenna with a directional coupler as described in claim 1, characterized in that, The radius of the circular through hole in the metal base plate (7) is 0.053λ.

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