A Pattern Reconfigurable Left / Right-Hand Circularly Polarized Antenna

Abstract

The present invention discloses a pattern-reconfigurable left / right-hand circularly polarized antenna, which comprises a dielectric substrate, a circular patch, a horizontal loop, three L-shaped probes, four metal shorting pins, a broadband feeding network, an impedance matching circuit, and four vertical baluns; the horizontal loop is mainly composed of four printed dipoles; the dielectric substrate includes an upper dielectric substrate and a lower dielectric substrate; the horizontal loop and the circular patch are both etched on the back of the upper dielectric substrate, the broadband feeding network and the matching circuit are located on the back of the lower dielectric substrate, the three L-shaped probes, the four metal shorting pins, and the four vertical baluns are located between the upper dielectric substrate and the lower dielectric substrate; the broadband feeding network is connected to the impedance matching circuit; a radio frequency switch is loaded on the impedance matching circuit, the four metal shorting pins are located at the edge of the circular patch, and each vertical balun is printed on a dielectric substrate. The antenna has a low-profile structure, is easy to fabricate, and can realize the switching between left / right-hand circular polarization.

Description

Technical Field

[0001] The invention relates to the field of mobile communication antennas, and in particular to a left / right circular polarization antenna with reconfigurable directional pattern. Background Art

[0002] With the advancement of science and technology, people's demand for information has increased unprecedentedly, making communication technology develop by leaps and bounds. As an important branch of the communication field, wireless communication has been widely used in various fields such as national defense and people's livelihood because it has gotten rid of the dependence on physical transmission lines. The antenna is the information entrance and exit of radio equipment, and the performance of the antenna directly affects the communication quality of the entire wireless communication system.

[0003] The reconfigurable pattern antenna has the ability to reconstruct its radiation pattern. It requires that the signal be aimed at the target user by changing the pattern shape or the main beam radiation direction while keeping the antenna operating frequency band and polarization mode unchanged, thereby avoiding interference sources to suppress signal interference, save system energy, and improve the security and confidentiality of the communication system.

[0004] Circularly polarized waves have the characteristics of being able to be received by any linearly polarized waves, having orthogonal rotational directions, and having their rotational directions reversed when incident on symmetrical targets. Therefore, circularly polarized antennas can effectively suppress rain and fog interference and resist multipath reflections, and are widely used in communications, telemetry and remote sensing, electronic countermeasures, radio and television, and other fields.

[0005] Currently, the reconfigurable directional pattern antennas are mostly realized by two methods: dynamically changing the antenna radiator or changing the feeding path of the feeding network. The former places the RF switch that controls the polarization mode on the antenna radiator, and the latter places the controllable RF switch on the feeding structure. Summary of the invention

[0006] In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a left / right circularly polarized antenna with reconfigurable radiation pattern.

[0007] The present invention is achieved by at least one of the following technical solutions.

[0008] A pattern-reconfigurable left / right-hand circularly polarized antenna, comprising a dielectric substrate, a circular patch, a horizontal loop, three L-shaped probes, four metal shorting pins, a broadband feeding network, an impedance matching circuit, and four vertical baluns; the horizontal loop is mainly composed of four printed dipoles; the dielectric substrate includes an upper dielectric substrate and a lower dielectric substrate; the horizontal loop and the circular patch are both etched on the back of the upper dielectric substrate, the broadband feeding network and the matching circuit are located on the back of the lower dielectric substrate, and the three L-shaped probes, the four metal shorting pins, and the four vertical baluns are located between the upper dielectric substrate and the lower dielectric substrate; two L-shaped probes are distributed at the edge of the circular patch, one end of each of the two L-shaped probes is respectively connected to the output end of the impedance matching circuit, and the other ends are perpendicular to each other and respectively point to the center of the circular patch; the other L-shaped probe is located at the center of the circular patch, one end is connected to the output end of the matching circuit, and the other end extends towards the edge of the circular patch.

[0009] The four printed dipoles are distributed in a cross-symmetrical manner around the circular patch. Each vertical balun is printed on a dielectric substrate, and each vertical balun is located below a printed dipole. The printed dipole is connected to the broadband feeding network through the vertical balun; the broadband feeding network is connected to the impedance matching circuit; the four metal shorting pins are located below the circular patch, and the four metal shorting pins are symmetrically distributed at the edge of the circular patch and are used to connect the circular patch to the ground.

[0010] An RF switch is loaded on the impedance matching circuit.

[0011] The broadband feeding network feeds the horizontal loop; the impedance matching circuit enables four states to cover the same frequency band.

[0012] Further, each printed dipole is arc-shaped and has a length of 0.5λ 0 , where λ 0 is the free-space wavelength corresponding to the center frequency of 1.9 GHz; each printed dipole includes a main dipole and a parasitic dipole, and the parasitic dipole is located outside the main dipole.

[0013] The metal shorting pins are located at the edge of the circular patch.

[0014] Further, the upper dielectric substrate and the lower dielectric substrate have different thicknesses.

[0015] Further, each vertical balun is mainly composed of metal printed on the back of the dielectric substrate and a microstrip line located on the front of the dielectric substrate. The microstrip line includes a first microstrip line and a second microstrip line; one end of the first microstrip line is connected to the second microstrip line, and the other end of the first microstrip line is open; the metal is connected to a main dipole.

[0016] Further, the broadband feeding network includes a first Wilkinson power divider, a second Wilkinson power divider, and a third Wilkinson power divider. The first Wilkinson power divider, the second Wilkinson power divider, and the third Wilkinson power divider are connected in sequence. The output ends of the first Wilkinson power divider and the third Wilkinson power divider are respectively connected to the second microstrip line in a vertical balun.

[0017] Further, the impedance matching circuit is equipped with a first RF switch, a second RF switch, a third RF switch, a fourth RF switch, a fifth RF switch, a sixth RF switch, a seventh RF switch, an eighth RF switch, a ninth RF switch, a tenth RF switch, and an eleventh RF switch 1;

[0018] The first RF switch and the second RF switch are located at both ends of the third microstrip line. The first RF switch and the second RF switch are respectively connected to the ninth microstrip line and the fourth microstrip line; The third RF switch and the fourth RF switch are located at both ends of the tenth microstrip line. The third RF switch and the fourth RF switch are respectively connected to the ninth microstrip line and the eleventh microstrip line; The fifth RF switch and the sixth RF switch are located at both ends of the twelfth microstrip line. The fifth RF switch and the sixth RF switch are respectively connected to the ninth microstrip line and the eleventh microstrip line; The seventh RF switch and the eighth RF switch are located at both ends of the sixth microstrip line and are respectively connected to the seventh microstrip line and the fourth microstrip line; The tenth RF switch and the eleventh RF switch are located at both ends of the fifth microstrip line and are respectively connected to the fourth microstrip line and the seventh microstrip line; The fourth microstrip line and the eighth microstrip line are connected through the ninth RF switch; The second Wilkinson power divider in the broadband feeding network is connected to the ninth microstrip line;

[0019] The eighth microstrip line is connected to the third L-shaped probe; The seventh microstrip line is connected to the second L-shaped probe; The first L-shaped probe is connected to the eleventh microstrip line.

[0020] Further, for directional radiation and omnidirectional radiation, the switching between left / right circular polarization is generated by the λg / 2 path difference of the impedance matching circuit, where λg is the wavelength in the medium corresponding to the center frequency of 1.9 GHz.

[0021] Further, when the second RF switch, the seventh RF switch, the eighth RF switch, and the ninth RF switch are closed and other switches are open, directional left circular polarization is achieved; When the second RF switch, the ninth RF switch, the tenth RF switch, and the eleventh RF switch 1 are closed and other switches are open, directional right circular polarization is achieved; When the first RF switch, the fifth RF switch, and the sixth RF switch are closed and other switches are open, omnidirectional left circular polarization is achieved; When the first RF switch, the third RF switch, and the fourth RF switch are closed and other switches are open, omnidirectional right circular polarization is achieved.

[0022] Further, the radius of the circular patch is 0.2λ 0 ;

[0023] The RF switch loaded on the impedance matching circuit is the key to realizing pattern and polarization reconfigurability. By reasonably controlling the switch, the directional / omnidirectional left / right circularly polarized waves can be realized accordingly.

[0024] Compared with the existing technologies, the effects of the present invention are as follows:

[0025] The antenna has a low-profile structure and is easy to fabricate. The switching between left / right circular polarization can be realized under different radiation patterns, and the four working modes all achieve a frequency band coverage of 1.82 - 2.01 GHz and a parameter index that the main polarization component is more than 15 dB larger than the cross-polarization component. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the overall structure of a pattern-reconfigurable left / right circularly polarized antenna in this embodiment;

[0027] Figure 2 It is a schematic diagram of the horizontal loop and circular patch composed of four arc-shaped printed dipoles;

[0028] Figure 3 It is a structural diagram of the broadband feeding network of the horizontal loop antenna;

[0029] Figure 4 It is a structural diagram of the balun for connecting the horizontal loop and the broadband feeding network;

[0030] Figure 5 It is a matching circuit diagram for enabling the four states to work in the same frequency band;

[0031] Figure 6 It is the S 11 bandwidth diagram;

[0032] Figure 7 It is the bandwidth diagram of the axial ratio of the four working modes;

[0033] Figure 8a It is the pattern of the directional left circular polarization working mode in the xoz plane at 1.9 GHz;

[0034] Figure 8b It is the pattern of the directional left circular polarization working mode in the yoz plane at 1.9 GHz;

[0035] Figure 9a It is the pattern of the directional right circular polarization working mode in the xoz plane at 1.9 GHz;

[0036] Figure 9b It is the pattern of the directional right circular polarization working mode in the yoz plane at 1.9 GHz;

[0037] Figure 10a It is the radiation pattern in the xoz plane at 1.9 GHz in the all-left-handed circular polarization operating mode;

[0038] Figure 10b It is the radiation pattern in the yoz plane at 1.9 GHz in the all-left-handed circular polarization operating mode;

[0039] Figure 11a It is the radiation pattern in the xoz plane at 1.9 GHz in the all-right-handed circular polarization operating mode;

[0040] Figure 11b It is the radiation pattern in the yoz plane at 1.9 GHz in the all-right-handed circular polarization operating mode;

[0041] Wherein: 1 - circular patch, 2 - horizontal loop, 3 - L-shaped probe, 4 - broadband feeding network, 5 - impedance matching circuit, 6 - vertical balun, 10 - metal on the back of the vertical balun, 11 - first microstrip line, 12 - second microstrip line, 21 - main dipole, 22 - parasitic dipole, 31 - first L-shaped probe, 32 - second L-shaped probe, 33 - third L-shaped probe, 41 - first Wilkinson power divider, 42 - second Wilkinson power divider, 43 - third Wilkinson power divider, 51 - third microstrip line, 52 - fourth microstrip line, 53 - fifth microstrip line, 54 - sixth microstrip line, 55 - seventh microstrip line, 56 - eighth microstrip line, 57 - ninth microstrip line, 58 - tenth microstrip line, 59 - eleventh microstrip line, 50 - twelfth microstrip line, 71 - first RF switch, 72 - second RF switch, 73 - third RF switch, 74 - fourth RF switch, 75 - fifth RF switch, 76 - sixth RF switch, 77 - seventh RF switch, 78 - eighth RF switch, 79 - ninth RF switch, 70 - tenth RF switch, 701 - eleventh RF switch. Detailed implementation manners

[0042] The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the implementation manners of the present invention are not limited thereto.

[0043] Such as Figure 1 And Figure 2A shown pattern-reconfigurable left / right-hand circularly polarized antenna includes a dielectric substrate, a circular patch 1, a horizontal loop 2, three L-shaped probes 3, four metal shorting pins, a broadband feeding network 4, an impedance matching circuit 5, and four vertical baluns 6; the horizontal loop 2 is mainly composed of four printed dipoles; the dielectric substrate includes an upper dielectric substrate and a lower dielectric substrate; the horizontal loop 2 and the circular patch 1 are etched on the back of the upper dielectric substrate, the broadband feeding network 4 and the matching circuit are located on the back of the lower dielectric substrate, and the three L-shaped probes 3, four metal shorting pins, and four vertical baluns 6 are located between the upper dielectric substrate and the lower dielectric substrate; the vertical parts of two L-shaped probes are located at the edge of the circular patch and are connected to the output end of the impedance matching circuit, and the horizontal parts extend towards the center of the circular patch. The horizontal parts of the two L-shaped probes are at 90°. The vertical part of the other L-shaped probe is located at the center of the circular patch and is connected to the output end of the matching circuit, and the horizontal part extends towards the edge of the circular patch.

[0044] The four printed dipoles are distributed symmetrically in a cross shape around the circular patch 1, each vertical balun 6 is located below a printed dipole, and the printed dipole is connected to the broadband feeding network 4 through the vertical balun 6; the broadband feeding network 4 is connected to the impedance matching circuit 5; the four metal shorting pins are located below the circular patch and are used to connect the circular patch and the ground.

[0045] An RF switch is loaded on the impedance matching circuit 5, the four metal shorting pins are located at the edge of the circular patch 1 and are symmetrically distributed, and each vertical balun 6 is printed on a dielectric substrate.

[0046] Each printed dipole is arc-shaped and has a length of 0.5λ0, where λ0 is the free space wavelength corresponding to the center frequency of 1.9 GHz; each printed dipole includes a main dipole 21 and a parasitic dipole 22, the width of the main dipole 21 is 22 mm, and the inner and outer radii of the main dipole 21 are 88 mm and 110 mm respectively; the width of the parasitic dipole 22 is 3 mm, and the inner and outer radii are 113 and 116 mm. The slot line spacing between the main dipole 21 and the parasitic dipole 22 is 0.8 mm, and the main dipole 21 is connected to the vertical balun 6.

[0047] The radius of the circular patch 1 is 0.27λ 0 ;

[0048] The metal shorting pins are located at the edge of the circular patch 1 and have a radius of 0.5 mm.

[0049] The upper dielectric substrate is the back of Rogers 6002 board with a thickness of 0.508 mm, a dielectric constant of 2.94, and a loss tangent of 0.0012.

[0050] The lower dielectric substrate is the back of Rogers 6002 board with a thickness of 1.016 mm, a dielectric constant of 2.94, and a loss tangent of 0.0012.

[0051] As Figure 4 shown, each vertical balun 6 is mainly composed of metal printed on the back of the dielectric substrate and a microstrip line located on the front of the dielectric substrate. The microstrip line includes a first microstrip line 11 and a second microstrip line 12. One end of the first microstrip line 11 is connected to the second microstrip line 12, and the other end of the first microstrip line 11 is open. The dielectric substrate is Rogers 6002 board with a thickness of 1.016 mm. The top of the metal 10 on the back of the dielectric substrate is connected to a main dipole 21, and the bottom is connected to the ground.

[0052] As Figure 3 shown, the broadband feed network 4 includes a first Wilkinson power divider 41, a second Wilkinson power divider 42, and a third Wilkinson power divider 43. The first Wilkinson power divider 41, the second Wilkinson power divider 42, and the third Wilkinson power divider 43 are connected in sequence. The output ends of the first Wilkinson power divider 41 and the third Wilkinson power divider 43 are respectively connected to the second microstrip line 12 in each vertical balun 6.

[0053] As Figure 5 shown, the impedance matching circuit 5 includes two parts. The first part is mainly composed of a third microstrip line 51, a fourth microstrip line 52, a fifth microstrip line 53, a sixth microstrip line 54, a seventh microstrip line 55, and an eighth microstrip line 56. The second part is mainly composed of a ninth microstrip line 57, a tenth microstrip line 58, an eleventh microstrip line 59, and a twelfth microstrip line 50. The seventh microstrip line 55, the eighth microstrip line 56, and the eleventh microstrip line 59 are respectively connected to the shorter ends of three L-shaped probes 3. The feeding point of the antenna is located on the third microstrip line 51. RF switches are installed between adjacent microstrip lines. Among them, the widths of the third microstrip line 51, the fourth microstrip line 52, the fifth microstrip line 53, the sixth microstrip line 54, the seventh microstrip line 55, the eighth microstrip line 56, and the ninth microstrip line 57 are 2.5 mm. The widths of the tenth microstrip line 58 and the twelfth microstrip line 50 are 0.68 mm. The width of the eleventh microstrip line 59 is 1.4 mm.

[0054] The impedance matching circuit 5 is installed with a first RF switch 71, a second RF switch 72, a third RF switch 73, a fourth RF switch 74, a fifth RF switch 75, a sixth RF switch 76, a seventh RF switch 77, an eighth RF switch 78, a ninth RF switch 79, a tenth RF switch 70, and an eleventh RF switch 701; the first RF switch 71 and the second RF switch 72 are located at both ends of the third microstrip line 51 and are respectively connected to the ninth microstrip line 57 and the fourth microstrip line 52. The third RF switch 73 and the fourth RF switch 74 are located at both ends of the tenth microstrip line 58 and are respectively connected to the ninth microstrip line 57 and the eleventh microstrip line 59. The fifth RF switch 75 and the sixth RF switch 76 are located at both ends of the twelfth microstrip line 50 and are respectively connected to the ninth microstrip line 57 and the eleventh microstrip line 59. The seventh RF switch 77 and the eighth RF switch 78 are located at both ends of the sixth microstrip line 54 and are respectively connected to the seventh microstrip line 55 and the fourth microstrip line 52. The tenth RF switch 70 and the eleventh RF switch 701 are located at both ends of the fifth microstrip line 53 and are respectively connected to the fourth microstrip line 52 and the seventh microstrip line 55. The fourth microstrip line 52 is connected to the eighth microstrip line 56 through the ninth RF switch 79. The second Wilkinson power divider 42 in the broadband feeding network 4 is connected to the ninth microstrip line 57. The eighth microstrip line 56 is connected to the third L-shaped probe 31; the seventh microstrip line 55 is connected to the second L-shaped probe 32; the first L-shaped probe 33 is connected to the eleventh microstrip line 59.

[0055] When the second RF switch 72, the seventh RF switch 77, the eighth RF switch 78, and the ninth RF switch 79 are closed and other switches are open, the feeding path is composed of the third microstrip line 51, the fourth microstrip line 52, the sixth microstrip line 54, the seventh microstrip line 55, and the eighth microstrip line 56, feeding only the circular patch 1 to generate a directional left-handed circularly polarized wave. When the second RF switch 72, the ninth RF switch 79, the tenth RF switch 70, and the eleventh RF switch 701 are closed and other switches are open, the feeding path is composed of the third microstrip line 51, the fourth microstrip line 52, the fifth microstrip line 53, the seventh microstrip line 55, and the eighth microstrip line 56 to generate a directional right-handed circularly polarized wave, where the length difference between the fifth microstrip line 53 and the sixth microstrip line 54 is λg / 2. Here, λg is the wavelength in the medium corresponding to the center frequency of 1.9 GHz. When the first RF switch 71, the fifth RF switch 75, and the sixth RF switch 76 are closed and other switches are open, the ninth microstrip line 57, the eleventh microstrip line 59, and the twelfth microstrip line 50 feed the circular patch 1 and the horizontal loop 2 simultaneously to generate a fully left-handed circularly polarized wave. When the first RF switch 71, the third RF switch 73, and the fourth RF switch 74 are closed and other switches are open, when the ninth microstrip line 57, the tenth microstrip line 58, and the eleventh microstrip line 59 feed the circular patch 1 and the horizontal loop 2 simultaneously, a fully right-handed circularly polarized wave is generated, where the length difference between the tenth microstrip line 58 and the twelfth microstrip line 50 is λg / 2.

[0056] The present invention realizes the reconfiguration of four radiation modes by using 11 RF switches. Figure 6 It is the S 11 bandwidth diagram of four operating modes. The antenna bandwidth is 1.61 - 2.06 GHz. Figure 7 It is the bandwidth diagram of the axial ratio of four operating modes. The antenna bandwidth is 1.82 - 2.01 GHz. Figures 8 and Figure 8b are the directional left-handed circularly polarized (LHCP, Broadside) radiation patterns. The solid lines in the figures are the simulated co-polarization, and the dashed lines are the cross-polarization. Figures 9 and 9b are the directional right-handed circularly polarized (RHCP, Broadside) radiation patterns. Figures 10 and Figure 10b are the fully left-handed circularly polarized (LHCP, Conical) radiation patterns. Figures 11 and Figure 11b are the fully right-handed circularly polarized (RHCP, Conical) radiation patterns. The antenna bandwidth is 1.82 - 2.01 GHz, the radiation pattern is stable, and the co-polarization component is more than 15 dB larger than the cross-polarization component.

[0057] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A pattern-reconfigurable left / right-hand circularly polarized antenna, characterized in that, it includes a dielectric substrate, a circular patch (1), a horizontal loop (2), three L-shaped probes, four metal shorting pins, a broadband feeding network (4), an impedance matching circuit (5), and four vertical baluns (6); the horizontal loop (2) is mainly composed of four printed dipoles; the dielectric substrate includes an upper dielectric substrate and a lower dielectric substrate; the horizontal loop (2) and the circular patch (1) are both etched on the back of the upper dielectric substrate, the broadband feeding network (4) and the matching circuit are located on the back of the lower dielectric substrate, and the three L-shaped probes, the four metal shorting pins, and the four vertical baluns (6) are located between the upper dielectric substrate and the lower dielectric substrate; two L-shaped probes are distributed on the edge of the circular patch (1), one end of each of the two L-shaped probes is respectively connected to the output end of the impedance matching circuit (5), and the other ends are perpendicular to each other and respectively point to the center of the circular patch (1); another L-shaped probe is located at the center of the circular patch (1), one end is connected to the output end of the matching circuit, and the other end extends towards the edge of the circular patch (1); the four printed dipoles are symmetrically distributed in a cross around the circular patch (1); each vertical balun (6) is printed on a dielectric substrate, each vertical balun (6) is located below a printed dipole, and the printed dipole is connected to the broadband feeding network (4) through the vertical balun (6); the broadband feeding network (4) is connected to the impedance matching circuit (5); the four metal shorting pins are located below the circular patch (1), and the four metal shorting pins are symmetrically distributed on the edge of the circular patch (1) and are used to connect the circular patch (1) to the ground; an RF switch is loaded on the impedance matching circuit (5); the impedance matching circuit (5) is equipped with a first RF switch (71), a second RF switch (72), a third RF switch (73), a fourth RF switch (74), a fifth RF switch (75), a sixth RF switch (76), a seventh RF switch (77), an eighth RF switch (78), a ninth RF switch (79), a tenth RF switch (70), and an eleventh RF switch (701); The first RF switch (71) and the second RF switch (72) are located at both ends of the third microstrip line (51). The first RF switch (71) and the second RF switch (72) are respectively connected to the ninth microstrip line (57) and the fourth microstrip line (52); The third RF switch (73) and the fourth RF switch (74) are located at both ends of the tenth microstrip line (58). The third RF switch (73) and the fourth RF switch (74) are respectively connected to the ninth microstrip line (57) and the eleventh microstrip line (59); The fifth RF switch (75) and the sixth RF switch (76) are located at both ends of the twelfth microstrip line (50). The fifth RF switch (75) and the sixth RF switch (76) are respectively connected to the ninth microstrip line (57) and the eleventh microstrip line (59); The seventh RF switch (77) and the eighth RF switch (78) are located at both ends of the sixth microstrip line (54) and are respectively connected to the seventh microstrip line (55) and the fourth microstrip line (52); The tenth RF switch (70) and the eleventh RF switch (701) are located at both ends of the fifth microstrip line (53) and are respectively connected to the fourth microstrip line (52) and the seventh microstrip line (55); The fourth microstrip line (52) and the eighth microstrip line (56) are connected through the ninth RF switch (79); The second Wilkinson power divider (42) in the broadband feeding network (4) is connected to the ninth microstrip line (57); The eighth microstrip line (56) is connected to the third L-shaped probe (31); The seventh microstrip line (55) is connected to the second L-shaped probe (32); The first L-shaped probe (33) is connected to the eleventh microstrip line (59); When the second RF switch (72), the seventh RF switch (77), the eighth RF switch (78) and the ninth RF switch (79) are closed and other switches are open, a directional left-handed circular polarization is achieved; When the second RF switch (72), the ninth RF switch (79), the tenth RF switch (70) and the eleventh RF switch (701) are closed and other switches are open, a directional right-handed circular polarization is achieved; When the first RF switch (71), the fifth RF switch (75) and the sixth RF switch (76) are closed and other switches are open, a full left-handed circular polarization is achieved; When the first RF switch (71), the third RF switch (73) and the fourth RF switch (74) are closed and other switches are open, a full right-handed circular polarization is achieved.

2. The pattern-reconfigurable left / right-handed circularly polarized antenna according to claim 1, characterized in that, Each printed dipole is arc-shaped and has a length of 0.5λ 0 , where λ 0 is the free-space wavelength corresponding to the center frequency of 1.9 GHz; each printed dipole includes a main dipole (21) and a parasitic dipole (22), and the parasitic dipole (22) is located outside the main dipole (21).

3. The pattern-reconfigurable left / right-handed circularly polarized antenna according to claim 1, characterized in that, the thicknesses of the upper dielectric plate and the lower dielectric plate are different.

4. The pattern-reconfigurable left / right-handed circularly polarized antenna according to claim 1, characterized in that, Each vertical balun (6) is mainly composed of a metal (10) printed on the back of the dielectric substrate and a microstrip line located on the front of the dielectric substrate. The microstrip line includes a first microstrip line (11) and a second microstrip line (12); one end of the first microstrip line (11) is connected to the second microstrip line (12), and the other end of the first microstrip line (11) is open; the metal (10) is connected to a main dipole (21).

5. The pattern-reconfigurable left / right-hand circularly polarized antenna according to claim 1, characterized in that the broadband feeding network (4) includes a first Wilkinson power divider (41), a second Wilkinson power divider (42) and a third Wilkinson power divider (43). The first Wilkinson power divider (41), the second Wilkinson power divider (42) and the third Wilkinson power divider (43) are connected in sequence. The output ends of the first Wilkinson power divider (41) and the third Wilkinson power divider (43) are respectively connected to the second microstrip line (12) in a vertical balun (6).

6. The pattern-reconfigurable left / right-hand circularly polarized antenna according to claim 1, characterized in that the impedance matching circuit (5) includes two parts. The first part is mainly composed of a third microstrip line (51), a fourth microstrip line (52), a fifth microstrip line (53), a sixth microstrip line (54), a seventh microstrip line (55) and an eighth microstrip line (56); the second part is mainly composed of a ninth microstrip line (57), a tenth microstrip line (58), an eleventh microstrip line (59), a twelfth microstrip line (50); the seventh microstrip line (55), the eighth microstrip line (56) and the eleventh microstrip line (59) are respectively connected to the short ends of three L-shaped probes; the feeding point of the antenna is located on the third microstrip line (51).

7. The pattern-reconfigurable left / right-hand circularly polarized antenna according to claim 1, characterized in that for directional radiation and omnidirectional radiation, the switching between left / right-hand circular polarization is generated by the λg / 2 path difference of the impedance matching circuit (5), where λg is the wavelength in the medium corresponding to the center frequency of 1.9 GHz.

8. The pattern-reconfigurable left / right-hand circularly polarized antenna according to claim 1, characterized in that The radius of the circular patch (1) is 0.27λ 0 , where λ 0 is the free space wavelength corresponding to the center frequency of 1.9 GHz.

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